History, 19th Century: Time period from 1801 through 1900 of the common era.History, 17th Century: Time period from 1601 through 1700 of the common era.History, 18th Century: Time period from 1701 through 1800 of the common era.History, 20th Century: Time period from 1901 through 2000 of the common era.History, 15th Century: Time period from 1401 through 1500 of the common era.History, 16th Century: Time period from 1501 through 1600 of the common era.History, Medieval: The period of history from the year 500 through 1450 of the common era.Th2 Cells: Subset of helper-inducer T-lymphocytes which synthesize and secrete the interleukins IL-4, IL-5, IL-6, and IL-10. These cytokines influence B-cell development and antibody production as well as augmenting humoral responses.Th1 Cells: Subset of helper-inducer T-lymphocytes which synthesize and secrete interleukin-2, gamma-interferon, and interleukin-12. Due to their ability to kill antigen-presenting cells and their lymphokine-mediated effector activity, Th1 cells are associated with vigorous delayed-type hypersensitivity reactions.History, 21st Century: Time period from 2001 through 2100 of the common era.History, Ancient: The period of history before 500 of the common era.Th17 Cells: Subset of helper-effector T-lymphocytes which synthesize and secrete IL-17, IL-17F, and IL-22. These cytokines are involved in host defenses and tissue inflammation in autoimmune diseases.Famous PersonsMedicine in ArtHistoryPaintingsPersia: An ancient civilization, known as early as 2000 B.C. The Persian Empire was founded by Cyrus the Great (550-529 B.C.) and for 200 years, from 550 to 331 B.C., the Persians ruled the ancient world from India to Egypt. The territory west of India was called Persis by the Greeks who later called the entire empire Persia. In 331 B.C. the Persian wars against the Greeks ended disastrously under the counterattacks by Alexander the Great. The name Persia in modern times for the modern country was changed to Iran in 1935. (From Webster's New Geographical Dictionary, 1988, p546 & Asimov, Words on the Map, 1962, p176)Leper Colonies: Residential treatment centers for individuals with leprosy.History of MedicineCivilization: The distinctly human attributes and attainments of a particular society.Nobel PrizePaleopathology: The study of disease in prehistoric times as revealed in bones, mummies, and archaeologic artifacts.Embryology: The study of the development of an organism during the embryonic and fetal stages of life.Medicine in Literature: Written or other literary works whose subject matter is medical or about the profession of medicine and related areas.Manuscripts as Topic: Compositions written by hand, as one written before the invention or adoption of printing. A manuscript may also refer to a handwritten copy of an ancient author. A manuscript may be handwritten or typewritten as distinguished from a printed copy, especially the copy of a writer's work from which printed copies are made. (Webster, 3d ed)Scurvy: An acquired blood vessel disorder caused by severe deficiency of vitamin C (ASCORBIC ACID) in the diet leading to defective collagen formation in small blood vessels. Scurvy is characterized by bleeding in any tissue, weakness, ANEMIA, spongy gums, and a brawny induration of the muscles of the calves and legs.Burial: The act or ceremony of putting a corpse into the ground or a vault, or into the sea; or the inurnment of CREMAINS.Archaeology: The scientific study of past societies through artifacts, fossils, etc.Eugenics: The attempt to improve the PHENOTYPES of future generations of the human population by fostering the reproduction of those with favorable phenotypes and GENOTYPES and hampering or preventing BREEDING by those with "undesirable" phenotypes and genotypes. The concept is largely discredited. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Portraits as Topic: Graphic representations, especially of the face, of real persons, usually posed, living or dead. (From Thesaurus for Graphic Materials II, p540, 1995)History of NursingAnthropology: The science devoted to the comparative study of man.Climate: The longterm manifestations of WEATHER. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Neurology: A medical specialty concerned with the study of the structures, functions, and diseases of the nervous system.Books, Illustrated: Books containing photographs, prints, drawings, portraits, plates, diagrams, facsimiles, maps, tables, or other representations or systematic arrangement of data designed to elucidate or decorate its contents. (From The ALA Glossary of Library and Information Science, 1983, p114)Literature, MedievalPlague: An acute infectious disease caused by YERSINIA PESTIS that affects humans, wild rodents, and their ectoparasites. This condition persists due to its firm entrenchment in sylvatic rodent-flea ecosystems throughout the world. Bubonic plague is the most common form.Anatomy: A branch of biology dealing with the structure of organisms.SculptureBooksMummies: Bodies preserved either by the ancient Egyptian technique or due to chance under favorable climatic conditions.Mythology: A body of stories, the origins of which may be unknown or forgotten, that serve to explain practices, beliefs, institutions or natural phenomena. Mythology includes legends and folk tales. It may refer to classical mythology or to a body of modern thought and modern life. (From Webster's 1st ed)Greenhouse Effect: The effect of GLOBAL WARMING and the resulting increase in world temperatures. The predicted health effects of such long-term climatic change include increased incidence of respiratory, water-borne, and vector-borne diseases.EuropeHistory, Modern 1601-: The period of history from 1601 of the common era to the present.United StatesPublic Health: Branch of medicine concerned with the prevention and control of disease and disability, and the promotion of physical and mental health of the population on the international, national, state, or municipal level.Magic: Beliefs and practices concerned with producing desired results through supernatural forces or agents as with the manipulation of fetishes or rituals.ArtManuscripts, MedicalPhilosophy: A love or pursuit of wisdom. A search for the underlying causes and principles of reality. (Webster, 3d ed)Naval Medicine: The practice of medicine concerned with conditions affecting the health of individuals associated with the marine environment.Philosophy, MedicalPolitics: Activities concerned with governmental policies, functions, etc.Geography: The science dealing with the earth and its life, especially the description of land, sea, and air and the distribution of plant and animal life, including humanity and human industries with reference to the mutual relations of these elements. (From Webster, 3d ed)Anthropology, Physical: The comparative science dealing with the physical characteristics of humans as related to their origin, evolution, and development in the total environment.Spectrometry, Mass, Fast Atom Bombardment: A mass spectrometric technique that is used for the analysis of a wide range of biomolecules, such as glycoalkaloids, glycoproteins, polysaccharides, and peptides. Positive and negative fast atom bombardment spectra are recorded on a mass spectrometer fitted with an atom gun with xenon as the customary beam. The mass spectra obtained contain molecular weight recognition as well as sequence information.Croatia: Created 7 April 1992 as a result of the division of Yugoslavia.Forecasting: The prediction or projection of the nature of future problems or existing conditions based upon the extrapolation or interpretation of existing scientific data or by the application of scientific methodology.Medical Illustration: The field which deals with illustrative clarification of biomedical concepts, as in the use of diagrams and drawings. The illustration may be produced by hand, photography, computer, or other electronic or mechanical methods.Textbooks as Topic: Books used in the study of a subject that contain a systematic presentation of the principles and vocabulary of a subject.Climate Change: Any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). It may result from natural factors such as changes in the sun's intensity, natural processes within the climate system such as changes in ocean circulation, or human activities.Psychoanalysis: The separation or resolution of the psyche into its constituent elements. The term has two separate meanings: 1. a procedure devised by Sigmund Freud, for investigating mental processes by means of free association, dream interpretation and interpretation of resistance and transference manifestations; and 2. a theory of psychology developed by Freud from his clinical experience with hysterical patients. (From Campbell, Psychiatric Dictionary, 1996).Skeleton: The rigid framework of connected bones that gives form to the body, protects and supports its soft organs and tissues, and provides attachments for MUSCLES.Science: The study of natural phenomena by observation, measurement, and experimentation.Engraving and EngravingsReligion and Medicine: The interrelationship of medicine and religion.Fur Seals: A group comprised of several species of eared seals found in two genera, in the family Otariidae. In comparison to SEA LIONS, they have an especially dense wooly undercoat.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Bacteriology: The study of the structure, growth, function, genetics, and reproduction of bacteria, and BACTERIAL INFECTIONS.Materia Medica: Materials or substances used in the composition of traditional medical remedies. The use of this term in MeSH was formerly restricted to historical articles or those concerned with traditional medicine, but it can also refer to homeopathic remedies. Nosodes are specific types of homeopathic remedies prepared from causal agents or disease products.Theology: The study of religion and religious belief, or a particular system or school of religious beliefs and teachings (from online Cambridge Dictionary of American English, 2000 and WordNet: An Electronic Lexical Database, 1997)Numismatics: Study of coins, tokens, medals, etc. However, it usually refers to medals pertaining to the history of medicine.Medicine, Traditional: Systems of medicine based on cultural beliefs and practices handed down from generation to generation. The concept includes mystical and magical rituals (SPIRITUAL THERAPIES); PHYTOTHERAPY; and other treatments which may not be explained by modern medicine.Economic Development: Mobilization of human, financial, capital, physical and or natural resources to generate goods and services.Population Dynamics: The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.Societies, Hospital: Societies having institutional membership limited to hospitals and other health care institutions.Communicable DiseasesSmallpox: An acute, highly contagious, often fatal infectious disease caused by an orthopoxvirus characterized by a biphasic febrile course and distinctive progressive skin eruptions. Vaccination has succeeded in eradicating smallpox worldwide. (Dorland, 28th ed)Epidemiology: Field of medicine concerned with the determination of causes, incidence, and characteristic behavior of disease outbreaks affecting human populations. It includes the interrelationships of host, agent, and environment as related to the distribution and control of disease.Democracy: A system of government in which there is free and equal participation by the people in the political decision-making process.Physiology: The biological science concerned with the life-supporting properties, functions, and processes of living organisms or their parts.Periostitis: Inflammation of the periosteum. The condition is generally chronic, and is marked by tenderness and swelling of the bone and an aching pain. Acute periostitis is due to infection, is characterized by diffuse suppuration, severe pain, and constitutional symptoms, and usually results in necrosis. (Dorland, 27th ed)Theft: Unlawful act of taking property.Social Change: Social process whereby the values, attitudes, or institutions of society, such as education, family, religion, and industry become modified. It includes both the natural process and action programs initiated by members of the community.Th1-Th2 Balance: Homeostatic control of the immune system by secretion of different cytokines by the Th1 and Th2 cells. The concentration dependent binding of the various cytokines to specific receptors determines the balance (or imbalance leading to disease).Founder Effect: A phenomenon that is observed when a small subgroup of a larger POPULATION establishes itself as a separate and isolated entity. The subgroup's GENE POOL carries only a fraction of the genetic diversity of the parental population resulting in an increased frequency of certain diseases in the subgroup, especially those diseases known to be autosomal recessive.Symbolism: A concept that stands for or suggests something else by reason of its relationship, association, convention, or resemblance. The symbolism may be mental or a visible sign or representation. (From Webster, 3d ed)Citrus aurantiifolia: A plant species of the genus CITRUS, family RUTACEAE that provides the familiar lime fruit. Its common name of lime is similar to the limetree (TILIA).Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.ItalyMortality: All deaths reported in a given population.Developmental Biology: The field of biology which deals with the process of the growth and differentiation of an organism.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Population Growth: Increase, over a specific period of time, in the number of individuals living in a country or region.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Disease Outbreaks: Sudden increase in the incidence of a disease. The concept includes EPIDEMICS and PANDEMICS.Clinical Medicine: The study and practice of medicine by direct examination of the patient.Fossils: Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.Terminology as Topic: The terms, expressions, designations, or symbols used in a particular science, discipline, or specialized subject area.Psychiatry: The medical science that deals with the origin, diagnosis, prevention, and treatment of mental disorders.France: A country in western Europe bordered by the Atlantic Ocean, the English Channel, the Mediterranean Sea, and the countries of Belgium, Germany, Italy, Spain, Switzerland, the principalities of Andorra and Monaco, and by the duchy of Luxembourg. Its capital is Paris.Genealogy and HeraldryAwards and PrizesWorld Health: The concept pertaining to the health status of inhabitants of the world.Conservation of Natural Resources: The protection, preservation, restoration, and rational use of all resources in the total environment.Rain: Water particles that fall from the ATMOSPHERE.EnglandIslam: A monotheistic religion promulgated by the Prophet Mohammed with Allah as the deity.Research: Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. (Webster, 3d ed)HungaryCrops, Agricultural: Cultivated plants or agricultural produce such as grain, vegetables, or fruit. (From American Heritage Dictionary, 1982)GreeceOceans and Seas: A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).Ecology: The branch of science concerned with the interrelationship of organisms and their ENVIRONMENT, especially as manifested by natural cycles and rhythms, community development and structure, interactions between different kinds of organisms, geographic distributions, and population alterations. (Webster's, 3d ed)GermanyWater Movements: The flow of water in enviromental bodies of water such as rivers, oceans, water supplies, aquariums, etc. It includes currents, tides, and waves.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Education, Medical: Use for general articles concerning medical education.Models, Theoretical: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Suntan: An induced skin pigment (MELANIN) darkening after exposure to SUNLIGHT or ULTRAVIOLET RAYS. The degree of tanning depends on the intensity and duration of UV exposure, and genetic factors.PortugalBiological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Great BritainMolecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Cercopithecinae: A subfamily of the Old World monkeys, CERCOPITHECIDAE. They inhabit the forests and savannas of Africa. This subfamily contains the following genera: CERCOCEBUS; CERCOPITHECUS; ERYTHROCEBUS; MACACA; PAPIO; and THEROPITHECUS.North AmericaSocial Welfare: Organized institutions which provide services to ameliorate conditions of need or social pathology in the community.South AmericaEurope, EasternAgriculture: The science, art or practice of cultivating soil, producing crops, and raising livestock.RussiaTime Factors: Elements of limited time intervals, contributing to particular results or situations.Yersinia pestis: The etiologic agent of PLAGUE in man, rats, ground squirrels, and other rodents.Communicable Disease Control: Programs of surveillance designed to prevent the transmission of disease by any means from person to person or from animal to man.Schools, Medical: Educational institutions for individuals specializing in the field of medicine.Internationality: The quality or state of relating to or affecting two or more nations. (After Merriam-Webster Collegiate Dictionary, 10th ed)Industry: Any enterprise centered on the processing, assembly, production, or marketing of a line of products, services, commodities, or merchandise, in a particular field often named after its principal product. Examples include the automobile, fishing, music, publishing, insurance, and textile industries.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Societies, Medical: Societies whose membership is limited to physicians.Demography: Statistical interpretation and description of a population with reference to distribution, composition, or structure.Emigration and Immigration: The process of leaving one's country to establish residence in a foreign country.General Surgery: A specialty in which manual or operative procedures are used in the treatment of disease, injuries, or deformities.DNA, Mitochondrial: Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.Developed Countries: Countries that have reached a level of economic achievement through an increase of production, per capita income and consumption, and utilization of natural and human resources.Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Public Health Practice: The activities and endeavors of the public health services in a community on any level.Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)PolandGenetics, Population: The discipline studying genetic composition of populations and effects of factors such as GENETIC SELECTION, population size, MUTATION, migration, and GENETIC DRIFT on the frequencies of various GENOTYPES and PHENOTYPES using a variety of GENETIC TECHNIQUES.Cardiology: The study of the heart, its physiology, and its functions.Spain: Parliamentary democracy located between France on the northeast and Portugual on the west and bordered by the Atlantic Ocean and the Mediterranean Sea.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Genetic Variation: Genotypic differences observed among individuals in a population.Social Justice: An interactive process whereby members of a community are concerned for the equality and rights of all.Arctic Regions: The Arctic Ocean and the lands in it and adjacent to it. It includes Point Barrow, Alaska, most of the Franklin District in Canada, two thirds of Greenland, Svalbard, Franz Josef Land, Lapland, Novaya Zemlya, and Northern Siberia. (Webster's New Geographical Dictionary, 1988, p66)Pacific OceanHaplotypes: The genetic constitution of individuals with respect to one member of a pair of allelic genes, or sets of genes that are closely linked and tend to be inherited together such as those of the MAJOR HISTOCOMPATIBILITY COMPLEX.Hydrogen Bonding: A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.Biodiversity: The variety of all native living organisms and their various forms and interrelationships.Life Expectancy: Based on known statistical data, the number of years which any person of a given age may reasonably expected to live.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.SwitzerlandNutritional Physiological Phenomena: The processes and properties of living organisms by which they take in and balance the use of nutritive materials for energy, heat production, or building material for the growth, maintenance, or repair of tissues and the nutritive properties of FOOD.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.LondonPhylogeography: A field of study concerned with the principles and processes governing the geographic distributions of genealogical lineages, especially those within and among closely related species. (Avise, J.C., Phylogeography: The History and Formation of Species. Harvard University Press, 2000)Environment: The external elements and conditions which surround, influence, and affect the life and development of an organism or population.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Population Density: Number of individuals in a population relative to space.Asia: The largest of the continents. It was known to the Romans more specifically as what we know today as Asia Minor. The name comes from at least two possible sources: from the Assyrian asu (to rise) or from the Sanskrit usa (dawn), both with reference to its being the land of the rising sun, i.e., eastern as opposed to Europe, to the west. (From Webster's New Geographical Dictionary, 1988, p82 & Room, Brewer's Dictionary of Names, 1992, p34)Cholera: An acute diarrheal disease endemic in India and Southeast Asia whose causative agent is VIBRIO CHOLERAE. This condition can lead to severe dehydration in a matter of hours unless quickly treated.Oxygen Isotopes: Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.Congresses as Topic: Conferences, conventions or formal meetings usually attended by delegates representing a special field of interest.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Geologic Sediments: A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)Infant Mortality: Postnatal deaths from BIRTH to 365 days after birth in a given population. Postneonatal mortality represents deaths between 28 days and 365 days after birth (as defined by National Center for Health Statistics). Neonatal mortality represents deaths from birth to 27 days after birth.Biomedical Research: Research that involves the application of the natural sciences, especially biology and physiology, to medicine.Infant, Newborn: An infant during the first month after birth.Brazil
... developed in the late 19th century and efforts in theoretical explanation of atomic emission spectra eventually led to quantum ... The production of line spectra by the atoms of an element indicate that an atom can radiate only a certain amount of energy. ... This leads to the conclusion that bound electrons cannot have just any amount of energy but only a certain amount of energy. ... If only a single atom of hydrogen were present, then only a single wavelength would be observed at a given instant. Several of ...
Most 19th-century chemists defined the valence of an element as the number of its bonds without distinguishing different types ... The quest for the underlying causes of valence led to the modern theories of chemical bonding, including the cubical atom (1902 ... "the number of pairs of electrons which any given atom shares with the adjacent atoms is called the covalence of that atom". The ... The concept of valence was developed in the second half of the 19th century and was successful in explaining the molecular ...
More than six billion knots and links have been tabulated since the beginnings of knot theory in the 19th century. To gain ... Lord Kelvin's theory that atoms were knots in the aether led to Peter Guthrie Tait's creation of the first knot tables for ... Mathematical studies of knots began in the 19th century with Gauss, who defined the linking integral (Silver 2006). In the ... These topologists in the early part of the 20th century-Max Dehn, J. W. Alexander, and others-studied knots from the point of ...
... such basic things as the energy levels and sizes of atoms. The effort at resolving these problems led to the development of ... some difficulties were discovered in the late 19th century that could only be resolved by more modern physics. When combined ... By the end of the 20th century, classical mechanics in physics was no longer an independent theory. Along with classical ... Similarly, the different behaviour of classical electromagnetism and classical mechanics under velocity transformations led to ...
Their speculation on atoms, taken from Leucippus, bears a passing and partial resemblance to the 19th-century understanding of ... Money when used with sense leads to generosity and charity, while money used in folly leads to a common expense for the whole ... Thus, iron atoms are solid and strong with hooks that lock them into a solid; water atoms are smooth and slippery; salt atoms, ... "atoms". These classical "atoms" are nearer to humans' modern concept of "molecule" than to the atoms of modern science. The ...
This theory was developed by John Dalton in the 18th century. At this stage, it wasn't clear what atoms were - although they ... and others in the 19th century. From that time to the 1920s, physicists were seeking to explain atomic spectra and blackbody ... The superposition of these emitted waves from many oscillators would then lead to a wave which moved more slowly. Max Planck ... by John Newlands and Dmitri Mendeleyev around the mid to late 19th century. Later, the connection between atomic physics and ...
In the 19th century, it was thought that magnetic fields are due to currents in matter, and Ampère postulated that permanent ... While the laws of chemical binding made it clear to nineteenth century chemists that atoms were real, among physicists the ... Once modern quantum mechanics was formulated, atomism was no longer in conflict with experiment, but this did not lead to a ... But many faulty arguments survived from the 19th century, when statistical mechanics was considered dubious. The lapses in ...
The phenomena that would allow the deconstruction of the atom were discovered in the last decade of the 19th century: the ... At the same time, the structure of the atom and its nucleus was discovered, leading to the release of "atomic energy" (nuclear ... Early in the 19th century, John Dalton suggested the modern atomic theory, based on Democritus's original idea of individible ... From classical antiquity through the 19th century, science as a type of knowledge was more closely linked to philosophy than it ...
The idea that all matter is composed of elementary particles dates from at least the 6th century BC. In the 19th century, John ... The early 20th century explorations of nuclear physics and quantum physics led to proofs of nuclear fission in 1939 by Lise ... The word atom, after the Greek word atomos meaning "indivisible", has since then denoted the smallest particle of a chemical ... It also became the most energetic collider of heavy ions after it began colliding lead ions. Earlier facilities include the ...
... with each atom having a characteristic signature due to the quantum nature of these orbitals. This since has led to the core of ... while findings of William Herschel in the 19th century showed that light also consisted of infrared rays. Joseph von Fraunhofer ... Tyson describes the work of the 11th century Arabic scientist Ibn al-Haytham, considered to be one of the first to postulate on ... The episode includes a look at the contributions of the 10th century physicist Ibn al-Haytham, described as the "father of the ...
... which in turn makes it agree with the mean solar second of the mid-19th century (McCarthy & Seidelmann 2009, pp. 81-2, 191-7). ... 9). A series of experiments beginning in the late 1930s led to the development of the first atomic clock by Louis Essen and J. ... Their clock was based on a transition in the cesium atom (McCarthy & Seidelmann 2009, pp. 157-9). Due to the accuracy the ... Until the beginning of the 19th century, the length of the tropical year was found by comparing equinox dates that were ...
Kragh, Helge (January 1982). "Julius Thomsen and 19th-century speculations on the complexity of atoms". Annals of Science. 39: ... William H. Cropper (2004). Great Physicists: The Life and Times of Leading Physicists from Galileo to Hawking. Oxford ...
... emerged as an offshoot of thermodynamics late in the 19th century. Another important event in the 19th century was the ... The EPR thought experiment led to the Bell inequalities, which were then tested to various degrees of rigor, leading to the ... The Ptolemaic and Copernican models of the Solar system, the Bohr model of hydrogen atoms and nuclear shell model are good ... Among the great conceptual achievements of the 19th and 20th centuries were the consolidation of the idea of energy (as well as ...
In the 19th century chemists found it puzzling that benzene could be so unreactive toward addition reactions, given its ... with all the contributing atoms in the same plane Contributing atoms arranged in one or more rings A number of π delocalized ... This property led to the term "aromatic" for this class of compounds, and hence the term "aromaticity" for the eventually ... Additionally, the nitrogen atom is also sp2-hybridized and has one electron in a p-orbital, which adds up to 6 p-electrons, ...
Some difficulties were discovered in the late 19th century that could only be resolved by more modern physics. Some of these ... The effort at resolving these problems led to the development of quantum mechanics. Since the end of the 20th century, the ... Statistical mechanics, which provides a framework for relating the microscopic properties of individual atoms and molecules to ... These advances, made predominantly in the 18th and 19th centuries, extend substantially beyond Newton's work, particularly ...
... which led to a new era, generally referred to as modern physics. In the 19th century, experimenters began to detect unexpected ... Quantum mechanics is the theory of atoms and subatomic systems. Approximately the first 30 years of the 20th century represent ... In the 19th century, the connection between heat and mechanical energy was established quantitatively by Julius Robert von ... At the end of the 19th century, physics had evolved to the point at which classical mechanics could cope with highly complex ...
... died in the 19th century and no actual examples of the pipes have survived. From the 19th century the instruments used appear ... "Against the Atom Bomb". The leading voice of protest in Thatcherite Britain in the 1980s was Billy Bragg, whose style of ... From the mid-19th century accordions became progressively more popular as a folk instrument in the county, as in the rest of ... From the 19th century accordions have been a popular and accepted part of the local folk sound. Folk songs from the West ...
... "atom", long used by the atomist philosophy. However, in the 20th century, the "atoms" of the chemists were found to be composed ... This in turn led to further meetings at which the positivists again attacked the supposition that there were atoms. The matter ... The particles of chemical matter for which chemists and other natural philosophers of the early 19th century found experimental ... He argued that atoms just crashing into other atoms could never produce the beauty and form of the world. In Plato's Timaeus, ( ...
... and the underlying principles were established in the second half of the 19th century by Robert Wilhelm Bunsen and Gustav ... The atomic vapor produced by this discharge is composed of ions, ground state atoms, and fraction of excited atoms. When the ... They were led by Sir Alan Walsh at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Division of ... depending on the ionization potential of the analyte atoms and the energy available in a particular flame) atoms may be in part ...
The study of gas discharges in the mid 19th century led to the discovery of anode and cathode rays, which turned out to be ... was an early 19th-century attempt to explain the properties of the chemical elements using the internal structure of the atom. ... It would take the better part of a century for this problem to be resolved. In the mid-nineteenth century, Julius Plücker ... His work on isotopes also led to his formulation of the Whole Number Rule which states that "the mass of the oxygen isotope ...
The history of organometallic chemistry includes the 19th-century discoveries of Zeise's salt and nickel tetracarbonyl. These ... Each molecule contains an atom of rhodium bound between two planar aromatic systems of five carbon atoms known as ... Nevertheless, the observation led Wilkinson and F. Albert Cotton to attempt the synthesis of rhodocenium and iridocenium salts ... The atom labels used are the same as those shown in the crystal structure above. Within the unsubstituted cyclopentadienyl ...
... the Atom Cafe, and the nautical themed Port 'o' Call bar. Smith, Dawn (1987). "19th Century Nelson Hotels". 2 (1). Nelson: ... The hotel lobby has the main desk slightly left of the entrance, and a grand staircase, leading to the mezzanine, and then to ...
... the study led by Jen on the trapping of hydrogen atoms in a solid hydrogen matrix at liquid helium temperatures "allowed Norman ... he was awarded a scholarship funded as a result of the Boxer Rebellion of the late 19th century to attend Beijing's prestigious ... Overcoming numerous obstacles and objections, he led the first trip by a group of Chinese-American scientists to the People's ... In 1972, following Richard Nixon's visit to China, Jen led a ground-breaking delegation of Chinese American scientists to that ...
Most 19th-century chemists defined the valence of an element as the number of its bonds without distinguishing different types ... and ionic bonding leads to octets by the transfer of electrons from one atom to the other. The term covalence is attributed to ... The maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element ... The maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element ...
... blossomed in the 19th century. The growth of other disciplines, such as geophysics, in the 20th century led to the development ... Chemistry also involves understanding the properties and interactions of individual atoms and molecules for use in larger-scale ... In the 18th century and 19th century, scientists including Charles-Augustin de Coulomb, Alessandro Volta, and Michael Faraday ... By the 19th century, the study of science had come into the purview of professionals and institutions. In so doing, it ...
During the 19th century, three previously encountered diseases and one emerging infectious disease, cholera, reached epidemic proportions. Epidemics of the 19th century were faced without the medical advances that made 20th-century epidemics much more rare and less lethal. Micro-organisms (viruses and bacteria) had been discovered in the 18th century, but it was not until the late 19th century that the experiments of Lazzaro Spallanzani and Louis Pasteur disproved spontaneous generation conclusively, allowing germ theory and Robert Koch's discovery of micro-organisms as the cause of disease transmission. ...
The Soviet Heavy Draft is a Russian breed of heavy draft horse. It derives from the Belgian Brabant heavy draft breed. It was developed in the former Soviet Union for agricultural draft work, and was recognized as a breed in 1952.:324 It is one of several heavy draft breeds developed in the Soviet Union in the twentieth century, others being the Russian Heavy Draft - which derived mainly from the Ardennais - and the Vladimir Heavy Draft, which was derived principally from the Clydesdale. The Russian Empire had no indigenous breeds of heavy draft horse.:277 The origins of the Soviet Heavy Draft date to the late nineteenth century, at the Khrenovski stud farm in Voronezh Oblast. Imported ...
Two conflicting perspectives exist for the early history of Seattle. There is the "establishment" view, which favors the centrality of the Denny Party (generally the Denny, Mercer, Terry, and Boren families), and Henry Yesler. A second, less didactic view, advanced particularly by historian Bill Speidel and others such as Murray Morgan, sees David Swinson "Doc" Maynard as a key figure, perhaps the key figure. In the late nineteenth century, when Seattle had become a thriving town, several members of the Denny Party still survived; they and many of their descendants were in local positions of power and influence. Maynard was about ten years older and died relatively young, so he was not around to make his own case. The Denny Party were ...
There are competing theories regarding how and why public toilets (or "bathrooms" in the United States) first became separated by sex in the United States and Europe. Under one theory, offered by Terry Kogan, sex-separation as a standard did not emerge in the U.S. until the late nineteenth century.[2] Under another view, offered by W. Burlette Carter, sex-separation has long been the standard in the U.S. and Great Britain and most of the world where women's well-being was valued.[1] She argues that when people used chamber pots, sex-separation could be achieved by placing the pot in a separated space. In single-use privies and similar spaces, that separation was achieved by allowing only one "sex" to use the ...
Throughout the nineteenth century...American cities annexed adjacent land and grew steadily...the predominant view in the nineteenth century was the doctrine of forcible annexation."[19] However that would change toward the end of the century: "the first really significant defeat for the consolidation movement came when Brookline spurned Boston in 1874. [Thereafter] virtually every other Eastern and Middle Western city was rebuffed by wealthy and independent suburbs."[20] By the turn of the 19th century, a middle class expectation of having residential space had emerged, which Jackson attributes to work of Andrew Jackson Downing, Calvert ...
The Massina Empire (Var.: Maasina or Macina: also: Dina of Massina, Sise Jihad state, and Caliphate of Hamdullahi) was an early nineteenth-century Fulbe Jihad state centered in the Inner Niger Delta area of what is now the Mopti and Ségou Regions of Mali. Its capital was at Hamdullahi. The Fulas of the region had for centuries been the vassals of larger states, including the Mali Empire (13th-14th centuries), the Songhai Empire (15th century), the Moroccan pashas of Tomboctou (16th century), and the Bambara Empire at Ségou (17th century). By the early 1800s, many of these larger states had declined in power and inspired by ...
NINES is the Networked Infrastructure for Nineteenth-century Electronic Scholarship, a scholarly organization in British and American nineteenth-century studies supported by ARP, a software development group assembling a suite of critical and editorial tools for digital scholarship. It was founded in 2003 by Jerome McGann at the University of Virginia. NINES serves as a clearinghouse for peer-reviewed digital resources, which can be collected, annotated, and re-used in online "exhibits." It is powered by open-source Collex software. In 2011, the NINES model was expanded to include a sister site in eighteenth-century studies, called 18thConnect. ...
The Aubrac is a French breed of domestic beef cattle. It originates on the Plateau de l'Aubrac in the Massif Central in central southern France, from which it also takes its name. It has a wheat-coloured coat and dark hooves, switch, muzzle and eyes. The Aubrac originated in the early nineteenth century on the Plateau de l'Aubrac in the Massif Central, which spans the modern départements of the Aveyron, the Cantal and the Lozère, in the regions of Auvergne-Rhône-Alpes and Occitanie. Some limited cross-breeding took place in the twentieth century: with the Mézine, now extinct, 1935-1945; with the Maraîchine, 1945-1955; and ...
Alfred Henry Sturtevant va néixer a Jacksonville, Illinois, Estats Units el 21 de novembre de 1891. A partir de 1908 va estudiar a la Universitat de Colúmbia. Es va interessar des de molt jove per l'obra de Gregor Mendel i aviat va publicar una obra sobre els pedigrees dels cavalls vistos a través de la genètica mendeliana. El 1928, ell i la seva família es traslladaren a Pasadena per treballar en el California Institute of Technology, on va ser professor de genètica. Sturtevant també es va interessar per la taxonomia, la política iel periodisme.. ...
1921: Hjalmar Gotfried Carlson · 1922: Frederick Arthur Halsey · 1923: John Ripley Freeman · 1926: Robert Andrews Millikan · 1927: Wilfred Lewis · 1928: Julian Kennedy · 1930: William Le Roy Emmet · 1931: Albert Kinsbury · 1933: Ambrose Swasey · 1934: Willis Carrier · 1935: Charles Thomas Main · 1936: Edward Bausch · 1937: Edward P. Bullard Jr. · 1938: Stephen Joseph Pigott · 1939: James Emmet Gleason · 1940: Charles Kettering · 1941: Theodore von Kármán · 1942: Ervin George Bailey · 1943: Lewis Ketcham Sillcox · 1944: Edward G. Budd · 1945: William Frederick Durand · 1946: Morris E. Leeds · 1947: Paul Walter Kiefer · 1948: Frederick George Keyes · 1949: Fred L. Dornbrook · 1950: Harvey Coles Knowles ...
Cafodd ei geni yn Lerpwl, yn ferch y diplomydd George Browne. Roedd hi'n byw ger Abergele. Priododd Capten Alfred Hemans yn 1812. ...
醒龍的兩個標本目前都存放在倫敦大學學院。醒龍的正模標本(編號UCL B54)發現於賴索托,包含一個部分頭顱骨與骨骸。古生物學家Richard Thulborn在1914年首次敘述這個標本,他認為該化石是狼鼻龍的一個新種,並密名為伴侶醒龍(L. consors),consors在拉丁語中意為「同伴」或「配偶」。編號UCL B54標本缺乏狼鼻龍所擁有的犬齒型牙齒,但Thulborn認為這代表該個體是個雌性[6]。在Thulborn的首次醒龍研究中,並沒有完全敘述牠們頭顱骨與骨骸。一顆發現於瑞士的牙齒,年代屬於三疊紀最晚期,被歸類於醒龍。但這顆牙齒沒有醒龍、畸齒龍科、或鳥臀目的特徵,因此沒有被廣泛的接受[7]。. 在1975年,詹姆斯·霍普森(James Hopson)重新敘述了一個發現於南非的破碎畸齒龍科頭顱骨(編號UCL ...
Alfred Matthew "Weird Al" Yankovic (1959. október 23. -) amerikai zenész, leginkább paródiáiról ismert. Dalszövegei nagyrészt népszerű - kultúrát parodizáló - elemeket tartalmaznak, köztük a televízió, filmek, étel, zene, honlapok és hírek. Bár népszerűségét a paródiák hozták meg számára, albumain saját, humoros szerzeményei vannak többségben.. ...
Centuries*Centuries. *The 19th Century. *The 20th Century. *The 21st Century. * Subjects*Subjects ... Thomas Steitz (69) and Israeli Ada Yonath (70)won the 2009 Nobel Prize in chemistry for atom-by-atom mapping of the protein- ... 1938 Gertrude Stein led a campaign to award the Nobel Peace Prize to Adolf Hitler. Stein was also a close friend of Bernard Fey ... The 60 carbon atom is called a buckminsterfullerene.. (SFC, 10/10/96, p.A15)(AP, 10/9/97). 1996 Oct 8, The Nobel Prize in ...
... developed in the late 19th century and efforts in theoretical explanation of atomic emission spectra eventually led to quantum ... The production of line spectra by the atoms of an element indicate that an atom can radiate only a certain amount of energy. ... This leads to the conclusion that bound electrons cannot have just any amount of energy but only a certain amount of energy. ... If only a single atom of hydrogen were present, then only a single wavelength would be observed at a given instant. Several of ...
How can a few simple carbon atoms lead to millions of possible alkane structures? How does structure affect their physical ... And what curious role did they play in 19th-century whaling? x ... Structure of the Atom and Chemical Bonding. Take a more ... hydrocarbons where one or more hydrogen atoms are replaced by a halogen atom. Youíll examine how larger halogen atoms decrease ... the energetic rationale for chemical bonding between atoms to create compounds, how specific collections of atoms bonded in ...
More than six billion knots and links have been tabulated since the beginnings of knot theory in the 19th century. To gain ... Lord Kelvins theory that atoms were knots in the aether led to Peter Guthrie Taits creation of the first knot tables for ... Mathematical studies of knots began in the 19th century with Gauss, who defined the linking integral (Silver 2006). In the ... These topologists in the early part of the 20th century-Max Dehn, J. W. Alexander, and others-studied knots from the point of ...
It describes 19th-century developments that led to the concept of the mole, Topics include atomic weight, molecular weight, and ... Extending our example, two moles of 12C atoms contains 2 times 6.02 x 1023 atoms, which equals 12.04 x 1023 atoms, which can be ... the concept started with 19th-century chemists who were puzzling out the nature of atoms, gas particles, and those particles ... The group decided that the mass of one 12C atom would be set as 12 atomic mass units (amu), and the atomic mass of the atoms of ...
network of racial critical atoms said enjoyed in Sector-Wide History with client storing 19th-century testing. 2500002013-01- ... But you can accurately do your cent a lead cancer of a heart. And if you teach that in download Aeronautical Air Ground Data ... As world of the focus I lie on addition and neighbours in twentieth-century Britain and America, I have a much installation in ... 3-5 sales nineteenth-century) that make probed by the Department of Education to receive able changes as established in their ...
Reports of using ozone for medicinal purposes date to the late 19th Century. Laboratory studies have shown the HIV virus to be ... Ozone therapy: Ozone molecules are composed of three oxygen atoms. Ozone exists high in the earths atmosphere and absorbs ... In addition, research suggests that iridology may lead to inappropriate treatment. Iridology is therefore not recommended as a ... Although used for centuries to help prevent diseases, the relationship of green tea consumption and human cancer in general ...
It attempts to describe and account for the properties of molecules and atoms and their... ... The spectra of light emitted by gaseous atoms had been studied extensively since the mid-19th century. It was found that ... Bohr led the way in 1913 with his model of the hydrogen atom, but it was... ... A beam of silver atoms is passed through magnet A. The atoms in the state with ms = +1/2 are deflected upward and emerge as ...
By the late 19th century, scientists also began to theorize that the atom was made up of more than one fundamental unit. ... ongoing research and improved methods have led scientists to conclude that atoms are actually composed of even smaller ... It was not until the 19th century that the theory of atoms became articulated as a scientific matter, with the first evidence- ... atoms of a specific element are all the same, down to the very last atom; atoms of different elements can be told apart by ...
Most 19th-century chemists defined the valence of an element as the number of its bonds without distinguishing different types ... and ionic bonding leads to octets by the transfer of electrons from one atom to the other. The term covalence is attributed to ... The maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element ... The maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element ...
This combination led scientists to learn more about the structure of the atom for each element in terms of the behavior of its ... It would not be until the second half of the 19th century that scientists would have the tools to understand the elements ... In the middle of the 19th century, two German scientists, Gustav Kirchhoff (1824-1887) and Robert Bunsen (1811-1899), ... These colors are visible evidence of the behavior of electrons in atoms as energy is added into an atom, but this connection ...
Year 9 Chemistry Atomic Theory of Matter  In the early 19th century, John Dalton proposed that there was a certain point at ... The term he used to describe these particles was atom.  Available scientific evidence at the time led Dalton to propose the ... octect rule: atoms bond in order to get a full valence electron shell Polarity of molecule: - a bond is polar when the two ... 0.5-1.7) *look back to the note in notebook* - out of the two atoms in the bond, one is slightly negatively charged while one ...
For starters, if you insist on a strictly 19th-century analysis, atoms are unstable. The electron will spiral in towards the ... X201C;Lead-Acid Battery Half-Cell Reactions”. www.av8n.com/physics/lead-acid.htm. 1. That’s true by definition; ... But there are other things that seem just as elementary but cannot be explained in terms of 19th-century physics. The Gibbs " ... You must account for all the atoms. The same applies to electrochemical equations, i.e. oxidation-reduction reactions. You must ...
... but by atoms. Earlier, this had been clearly understood by Gaudin in the first half of the 19th Century. ... He achieved brilliant results for crystals, thus beginning the discipline of crystalline symmetry, which led, at the end of the ... But in science, the concept of symmetry arose in the 17th Century and, in a more general form, in the 18th and 19th centuries. ... during the 19th Century. Those notions were developed by human culture over many centuries, and came into scientific thought as ...
Since the 19th century, silver salts, eg, silver halides, have been used as photosensitive compounds for photography ... a seed is formed through atom-by-atom addition to the initial nuclei. In the final step, the seeds grow mainly in size while ... This leads to the formulation of a wide range of nanostructured inks for a huge range of applications. Such inks are mainly ... Three distinct stages can be roughly recognized (Figure 3).32,33 Nucleation, the clustering of few atoms and/or ions, is the ...
In the 19th century chemists found it puzzling that benzene could be so unreactive toward addition reactions, given its ... with all the contributing atoms in the same plane Contributing atoms arranged in one or more rings A number of π delocalized ... This property led to the term "aromatic" for this class of compounds, and hence the term "aromaticity" for the eventually ... Additionally, the nitrogen atom is also sp2-hybridized and has one electron in a p-orbital, which adds up to 6 p-electrons, ...
... formulated in the 19th century. A Theory Runs Into Trouble. In the domain of everyday life, electromagnetic forces are familiar ... electromagnetism and the forces that bind the atom. ... Richard Feynman Dead at 69; Leading Theoretical Physicist. By ... By the 1940s the two great revolutions of 20th-century physics were in full swing. Einsteins theory of relativity had ... Leading Theoretical Physicist. Order Reprints, Todays Paper,Subscribe ...
This dream led Kekule to propose that benzene consists of a ring of six carbon atoms with alternating C. C single bonds and C=C ... The structure of benzene was a recurring problem throughout most of the 19th century. The first step toward solving this ... the carbon atoms is sp2 hybridized. This leaves us with one electron in a 2p orbital on each of the six carbon atoms. ... product of this reaction is a compound in which a bromine atom has been substituted for a hydrogen atom, not added to the ...
Coincidentally, it was another UCL researcher - William Ramsay - who first discovered the noble gases in the late 19th century ... The research, led by Seoul National University astronomy Bon-Chul Koo, is detailed in the Dec. 12 edition of the journal ... "Discovering argon hydride ions here was unexpected because you dont expect an atom like argon, a noble gas, to form molecules ... Space is part of Future US Inc, an international media group and leading digital publisher. Visit our corporate site. ...
... and its close development with thermochemistry led to the development in the second half of the 19th century of chemical ... There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to ... Chemistry of the 19th century was characterized by the development of atomism (seeATOMISM). In the 17th and 18th centuries, the ... In the 19th century, these terms came to indicate the presence or absence of carbon in a given compound, and subsequently they ...
Niels Bohrs atomic model led to the idea of the atom as an entity with a central dense nucleus surrounded by fuzzy ... It was only with the advent of atomic physics and quantum theory in the 20th century that these questions started to be ... By showing how different atoms shared electrons in different ways so that they were held together by a variety of forces - weak ... Contingency and emergence confer a special status on DNA the chemical as opposed to DNA the collection of atoms described by ...
Niels Bohrs atomic model led to the idea of the atom as an entity with a central dense nucleus surrounded by fuzzy ... It was only with the advent of atomic physics and quantum theory in the 20th century that these questions started to be ... By showing how different atoms shared electrons in different ways so that they were held together by a variety of forces - weak ... Contingency and emergence confer a special status on DNA the chemical as opposed to DNA the collection of atoms described by ...
Since the middle of the 19th century, the law known as the conservation of energy came to be regarded as the fundamental axiom ... Ultimately, one must go back to the dynamics and movements of atoms, that is, explain everything on the basis of atoms. ... This principle led to an understanding of the development of cosmic bodies, the sun and the earth, in the light of which all ... However, the process of evolution was also known to the natural science of the 19th century. Scientists were well acquainted ...
In 1784, Le Sage posited that gravity could be a result of the collision of atoms, and in the early 19th century, he expanded ... leading to a net force acting on bodies.[citation needed] Mechanistic models fell out of favor because most of them lead to an ... In the late 19th century, Lord Kelvin pondered the possibility of a theory of everything.[61] He proposed that every body ... By the end of the 19th century, Le Verrier showed that the orbit of Mercury could not be accounted for entirely under Newtonian ...
This difficulty led the Danish physicist Niels Bohr, in 1913, to postulate that in an atom the classical theory does not hold, ... In the late 19th and early 20th centuries, however, experimental findings raised doubts about the completeness of Newtonian ... Atoms that are moving wander out of the field, while the coldest atoms cluster at the center. Because a few very cold atoms ... that would define each atoms position. As the atoms slowed to almost a stop, their positions became so fuzzy that each atom ...
  • These topologists in the early part of the 20th century-Max Dehn, J. W. Alexander, and others-studied knots from the point of view of the knot group and invariants from homology theory such as the Alexander polynomial. (wikipedia.org)
  • In the last several decades of the 20th century, scientists became interested in studying physical knots in order to understand knotting phenomena in DNA and other polymers. (wikipedia.org)
  • Thus, quantum mechanics attracted some of the ablest scientists of the 20th century, and they erected what is perhaps the finest intellectual edifice of the period. (britannica.com)
  • This was superseded by Albert Einstein 's theory of relativity in the early 20th century. (wikipedia.org)
  • Newton's classical mechanics were superseded in the early 20th century, when Einstein developed the special and general theory of relativity . (wikipedia.org)
  • In the late 19th and early 20th centuries, however, experimental findings raised doubts about the completeness of Newtonian theory. (bibliotecapleyades.net)
  • By the end of the 19th century, the private sector came to dominate the infrastructure, introducing improvements in rail transport that laid the foundation for industrial development in the 20th century. (popularmechanics.com)
  • However, the reality of chemical atoms was controversial until the beginning of the 20th century and the phrase "fundamental building blocks" has always been ambiguous. (stanford.edu)
  • However, it required the insights of chemical engineers during the 20th Century to make mass produced polymers a viable economic reality . (pafko.com)
  • The 20th century brought tremendous advancement in the understanding of the marvellous and dynamic chemistry of living organisms, and a molecular explanation of health and disease is exciting. (extramarks.com)
  • And, best of all, should some theist timidly observe that 20th-century atheists shed oceans of blood dwarfing anything ever achieved by theists, the New Atheist can then rail against the uncaring and immoral God who lets innocents suffer and die. (catholicexchange.com)
  • I imagine it can't be too much different from maternal and abortion mortality at the very beginning of the 20th Century. (blogspot.com)
  • Theoretical physicist Boris Yakobson and his Rice colleagues are among many looking for a way to speed up ORR for fuel cells, which were discovered in the 19th century but not widely used until the latter part of the 20th. (rice.edu)
  • By the second decade of the 20th century, the wheat industry was booming. (abs.gov.au)
  • OSU researcher and lead author Xianyong Wu compared this movement to the different mode of transportation of metal-ions through liquid electrolytes. (newstarget.com)
  • Bohr led the way in 1913 with his model of the hydrogen atom, but it was. (britannica.com)
  • Furthermore, when benzene reacts with Br 2 in the presence of FeBr 3 , the product of this reaction is a compound in which a bromine atom has been substituted for a hydrogen atom, not added to the compound the way an alkene adds bromine. (kentchemistry.com)
  • He found that these negatively charged 'corpuscles', as he called them, have a mass 1000 times smaller than the hydrogen atom. (nobelprize.org)
  • Other discrete lines for the hydrogen atom were found in the UV and IR regions. (quizover.com)
  • Ji and his teammates directed their attention at the upper half of the periodic table, specifically the hydrogen atom with its single proton. (newstarget.com)
  • STATIONARY STATES or wave patterns, associated with the energy levels of a Rydberg atom (a highly excited hydrogen atom) in a strong magnetic field can exhibit chaotic qualities. (ex.ac.uk)
  • Quite in contrast, the classical theory behind electromagnetic waves, such as light or radio waves , is a so-called continuum theory, that does not explicitly account for the fact that matter consists of individual atoms. (phys.org)
  • Often, this doping is controlled almost to the level of individual atoms, and typically about one dopant atom is added per million atoms of substrate. (wired.com)
  • The quest for the underlying causes of valence led to the modern theories of chemical bonding, including the cubical atom (1902), Lewis structures (1916), valence bond theory (1927), molecular orbitals (1928), valence shell electron pair repulsion theory (1958), and all of the advanced methods of quantum chemistry . (wikipedia.org)
  • In organic chemistry, the term aromaticity is used to describe a cyclic (ring-shaped), planar (flat) molecule with a ring of resonance bonds that exhibits more stability than other geometric or connective arrangements with the same set of atoms. (wikipedia.org)
  • The philosophy of chemistry developed in the 18 th and 19 th centuries through the work of Dalton, Lavoisier, Liebig, Kekule, Mendeleev and other thinkers. (fieldofscience.com)
  • Valence , also spelled valency , in chemistry , the property of an element that determines the number of other atoms with which an atom of the element can combine. (britannica.com)
  • The turn of the century 1900 was also a turning point in the history of chemistry. (nobelprize.org)
  • Consequently, a survey of the Nobel Prizes in Chemistry during this century will provide an analysis of important trends in the development of this branch of the Natural Sciences, and this is the aim of the present essay. (nobelprize.org)
  • When Aristotle wrote the first systematic treatises on chemistry in the 4th century BCE, his conceptual grasp of the nature of matter was tailored to accommodate a relatively simple range of observable phenomena. (stanford.edu)
  • In the 21st century, chemistry has become the largest scientific discipline, producing over half a million publications a year ranging from direct empirical investigations to substantial theoretical work. (stanford.edu)
  • The so called "modern scientific method" of its development was quite slow, but at the same time an early one for chemistry began among chemists in the 9th century when a well-known chemist of that time Jābir ibn Hayyān, also known as "Geber" was treated as "the father of chemistry" for introducing an experimental and systematic approach to scientific research. (conceptdraw.com)
  • The mentioned theory was overturned by another chemist Antoine Lavoisier from France by the end of the century, who basically established the "new science" in a way of elucidating the so called "conservation of mass" principle as well as developing a new system of the nomenclature which is still widely used in chemistry. (conceptdraw.com)
  • The reactions, transformations and interactions studied in chemistry are usually the result of interactions between different atoms. (conceptdraw.com)
  • Such interactions may lead to the re-arrangements of the chemical bonds holding atoms together, being studied in a chemistry laboratory. (conceptdraw.com)
  • The 19th Century saw enormous advances in polymer chemistry . (pafko.com)
  • Therefore, chemistry does not involve the subatomic realm but the properties of atoms and the regulations regulating their compositions and how knowledge of these properties can be used for different purposes. (extramarks.com)
  • Current chemistry explores materials as small as single atoms and as large and complex as deoxyribonucleic acid, which comprises millions of atoms and with the aid of increasingly sophisticated instruments. (extramarks.com)
  • At the same time the chemists discovered organic chemistry, allowing them, in the next century, to make millions of new compounds that nature never thought of and didn't want. (truthout.org)
  • And over the course of the 19th century, the word "science" became increasingly associated with the scientific method itself, as a disciplined way to study the natural world, including physics, chemistry, geology and biology. (1host2u.ir)
  • In this portion of the course, you will investigate the structure of the atom, the energetic rationale for chemical bonding between atoms to create compounds, how specific collections of atoms bonded in specific ways create motifs called functional groups, and ultimately the ways in which the bonds in these functional groups form and break in chemical reactions that can be used to convert one compound into another. (thegreatcourses.com)
  • By standardizing the number of atoms in a sample of an element, we also get a standardized mass for that element that can be used to compare different elements and compounds to one another. (visionlearning.com)
  • The concept of valence was developed in the second half of the 19th century and helped successfully explain the molecular structure of inorganic and organic compounds. (wikipedia.org)
  • The exact inception, however, of the theory of chemical valencies can be traced to an 1852 paper by Edward Frankland , in which he combined the older radical theory with thoughts on chemical affinity to show that certain elements have the tendency to combine with other elements to form compounds containing 3, i.e., in the 3-atom groups (e.g. (wikipedia.org)
  • The Chinese, who invented fireworks in the 7th century CE, knew that the many colors produced by fireworks come from different chemical compounds. (learner.org)
  • The chemists of the 19th century established a large body of empirical information leading to the realization that patterns exist in the types of compounds that elements can form. (britannica.com)
  • These atoms are the building blocks of the microstructures of compounds and hence are the fundamental units of chemical analysis. (stanford.edu)
  • It studies the structure, properties, change of matter and composition, including topics about atoms, about how they form the so called "chemical bonds" for creating the chemical compounds, etc. (conceptdraw.com)
  • Over the next two centuries, more elements were discovered and knowledge concerning their properties and their compounds was acquired by chemists. (coursera.org)
  • Force which holds together the smallest particles or atoms of chemical compounds. (google.co.nz)
  • Early in the 19th century it was established that Chemical Compounds have a fixed composition, and Proust, who contributed much to prove this, also showed that two bodies may combine in more than one proportion, and that for each combination the relative proportions are fixed. (google.co.nz)
  • In Psychology in Twentieth-Century Thought and Society edited by Mitchell Ash and William Woodward. (gutenberg-e.org)
  • Twentieth Century physics and cosmology have revealed an astonishing path towards our existence, which appears to be predicated on a delicate interplay between the three fundamental forces that govern the behavior of matter at very small distances and the long-range force of gravity. (springer.com)
  • Structures which match a, possibly ambiguous, pattern of atoms and bonds . (daylight.com)
  • The answer is usually to store the structure at the most basic primitive level of atoms and bonds. (daylight.com)
  • Nanotubes have an advantage over nanoribbons because of their curvature, which distorts chemical bonds around their circumference and leads to easier binding, the researchers found. (rice.edu)
  • For decades, he has been pondering the different ways atoms might be arranged in crystals, discovering that arrangements previously thought to be impossible were actually allowed. (nautil.us)
  • A new paper from the lab of Rice chemist James Tour demonstrates an environmentally friendly way to make bulk quantities of graphene oxide (GO), an insulating version of single-atom-thick graphene expected to find use in all kinds of material and electronic applications. (redorbit.com)
  • In the early 17th century, Galileo Galilei found that all objects tend to accelerate equally in free fall . (wikipedia.org)
  • Prout's hypothesis was an early 19th century attempt to explain the properties of the chemical element s using the internal structure of the atom . (academic.ru)
  • France was an early adopter among the West due to the influence of Jesuit missionaries, who brought the practice to French clinics in the 16th century. (bayareahq.com)
  • The point at which chemical structures and formulae become recognizable today is in the early 19th century. (daylight.com)
  • In download Feminism and Its Discontents: A Century of Struggle with Psychoanalysis 2000, depending SOA in Transforming shelf traps is miscarriages to find mentors in a critical and early time. (geile-internetseiten.de)
  • During the early modern period in the West the words "science" and "philosophy of nature" were sometimes used interchangeably and not until the 17th century, natural philosophy (which is today called "natural science") was considered a separate branch of philosophy. (1host2u.ir)
  • A bromide is a compound containing a bromide ion i.e. a bromine atom with a singular negative charge. (laxcrossword.com)
  • Such "chemical equations" usually involve atoms as subjects and the number of atoms on the right as well as on the left in the equation for a chemical transformation is known to be equal. (conceptdraw.com)
  • As discussed in the next section, this is an important clue to the electronic structure of the atom. (learner.org)
  • In this presentation, we explore the possibility of an Aether, through examining the structure of the atom within the context of Metaphysics and Sacred Geometry. (glastonburyplg.com)
  • The first such discovery was with the atom neon , which was shown by mass spectrometry to have at least two stable isotopes: neon-20 with 10 proton s and 10 neutron s and neon-22 with 10 protons and 12 neutrons. (academic.ru)
  • The carbon-atom chains would be difficult to make but would be twice as strong as two-dimensional graphene sheets. (innovations-report.com)
  • That makes it a true one-dimensional material, unlike atom-thin sheets of graphene that have a top and a bottom or hollow nanotubes that have an inside and outside. (innovations-report.com)
  • You could look at it as an ultimately thin graphene ribbon, reduced to just one atom, or an ultimately thin nanotube," he said. (innovations-report.com)
  • The Rice researchers, including lead author and former postdoctoral associate Xiaolong Zou and graduate student Luqing Wang, used computer simulations to discover why graphene nanoribbons and carbon nanotubes modified with nitrogen and/or boron, long studied as a substitute for expensive platinum, are so sluggish and how they can be improved. (rice.edu)
  • At 1,500 degrees Celsius, the heat burns off all but the strongly bound carbon atoms, ultimately turning them into rudimentary graphene nanoribbons aligned in a way that prevents the ribbons from easily zipping into graphene's familiar honeycomb lattice. (eurekalert.org)
  • In the 1860s, Lord Kelvin's theory that atoms were knots in the aether led to Peter Guthrie Tait's creation of the first knot tables for complete classification. (wikipedia.org)
  • Moon is a co-author in the study that found phosphorus in Cassiopeia A . The research, led by Seoul National University astronomy Bon-Chul Koo, is detailed in the Dec. 12 edition of the journal Science along with the separate argon gas study. (space.com)
  • This article is a sequel to V.I. Vernadsky 's 1938 work, 'Problems of Biogeochemistry II: On the Fundamental Material-Energetic Distinction Between Living and Nonliving Natural Bodies of the Biosphere,' which was published in the Winter 2000-2001 issue of 21st Century Science & Technology. (bibliotecapleyades.net)
  • Carnot died of cholera eight years later, before he could see his efficiency formula develop over the 19th century into the theory of thermodynamics: a set of universal laws dictating the interplay among temperature, heat, work, energy and entropy-a measure of energy's incessant spreading from more- to less-energetic bodies. (wired.com)
  • His method for creating Hydrogen Peroxide became widely used during the 19th century since there was little knowledge that this component was already created by Earth's natural processes of evaporation and condensation. (infobarrel.com)
  • reat prominence and led to his ideas being widely accepted. (google.co.nz)
  • The quantum mechanics problem is treated using time-dependent perturbation theory and leads to the general result known as Fermi's golden rule. (wikipedia.org)
  • Shrinking technology-a single-ion engine and three-atom fridge were both experimentally realized for the first time within the past year-is forcing them to extend thermodynamics to the quantum realm, where notions like temperature and work lose their usual meanings, and the classical laws don't necessarily apply. (wired.com)
  • At about the time of Poincare's seminal work on classical chaos, Max Planck started another revolution, which would lead to the modern theory of quantum mechanics. (ex.ac.uk)
  • This feature leads to the question of how chaos makes itself felt when moving from the classical world to the quantum world. (ex.ac.uk)
  • The results of such analysis have helped improve clinical care , suggested improvements in diagnostic and therapeutic devices , and led to mechanical wonders such as artificial organs . (pafko.com)
  • Research into artificial atoms could lead to one startling endpoint: programmable matter that changes its makeup at the flip of a switch. (wired.com)
  • This led Carothers to foresee the possibility of making artificial fibers from linear-condensation superpolymers. (encyclopedia.com)
  • This painstaking task, requiring years of patient work under laboratory conditions primitive even by late 19 th -century standards and finally yielding a material so radioactive that it glows , contributed greatly to her heroic image. (lemoyne.edu)
  • The International Committee for Weights and Measures-a group that defines the metric system's units of measurement (for more information, see our module on The Metric System )-defines one mole as the number of atoms in exactly 12 grams of carbon-12 ( 12 C, Figure 2). (visionlearning.com)
  • On the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms. (academic.ru)
  • The determination of the weights of the Atoms now became the object of study and the im3rovement of the balance a matter of importance. (google.co.nz)