- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
The structured absorption on the high-energy side of an x-ray absorption edge. The absorption edges for an element are abrupt increases in x-ray absorption that occur when the energy of the incident x-ray matches the binding energy of a core electron (typically a 1<i>s</i> or a 2<i>p</i> electron). For x-ray energies above the edge energy, a core electron is ejected from the atom. The ejected core electron can be thought of as a spherical wave propagating outward from the absorbing atom. The photoelectron wavelength is determined by its kinetic energy, which is in turn determined by the difference between the incident x-ray energy and the core-electron binding energy. As the x-ray energy increases, the kinetic energy of the photoelectron increases, and thus its wavelength decreases.
Industry:Science
The study of behavior change in response to drugs, chemicals, or other environmental conditions or agents (collectively referred to here as toxicants). Changes in behavior, as well as changes in sensation, mood, intellectual function, and motor coordination, are used by behavioral toxicologists to identify risks associated with exposure to potential toxicants and to determine mechanisms by which toxicants can affect the central nervous system. The information gained through behavioral toxicology can be used by scientists and government agencies to set limits in permissible levels of exposure to an environmental toxicant. Techniques employed in behavioral toxicology include epidemiologic surveys, field-based research, and laboratory-based experiments using human or nonhuman subjects.
Industry:Science
The science that applies laws and principles of physics, especially continuum and particulate mechanics and hydraulics of porous media, to solve problems encountered in civil engineering that are related to force-deformation behavior of soil and the flow of fluids through soil. Civil engineers use the term soil for a naturally occurring multiphase material consisting of gas or liquid and solid particles, whether or not the material supports plant life. The term geotechnics or geotechnical engineering refers to a subspecialty of civil engineering that combines the disciplines traditionally known as soil mechanics, soil dynamics, rock mechanics, earthwork engineering, and foundation engineering for the design or analysis of natural or constructed facilities of, in, or on rock or soil.
Industry:Science
The portion of the central nervous system within the spinal canal of the vertebral column, that is, the entire central nervous system except the brain. The spinal cord extends from the foramen magnum at the base of the skull to a variable level of the spinal canal; it terminates at the lumbar level in humans and extends well into the caudal region in fishes. Paired spinal nerves enter the spinal canal between each pair of vertebrae and connect with the spinal cord. The number of spinal nerves varies widely in vertebrates; in humans there are 31 pairs (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal). In tetrapods there are spinal cord enlargements where the large spinal nerves extend to the limbs, a cervical enlargement cranially, and a lumbosacral enlargement caudally.
Industry:Science
The study of the fate and effects of radioactive materials in the environment. As a hybrid field of scientific endeavor, it is founded upon, and derives its basic principles from, both of its parent disciplines, that is, basic ecology and radiation biology. Following the discovery of ionizing radiation and radioactive particles in biological studies in the 1940s and 1950s, these phenomena were studied under what were usually controlled laboratory conditions. Soon after, however, a need was demonstrated for a better understanding of the fate and effects of radioactive materials that were being released into the environment following the use or testing of nuclear weapons. This need became an important factor in the emergence of radioecology as a scientific discipline in its own right.
Industry:Science
The subfield of anthropology that deals with human and nonhuman primate evolution, the biological bases of human behavior, and human biological variability and its significance. Some refer to the field as biological anthropology to signal the close links with other biological sciences. The term physical anthropology is largely an American and British invention; in most European and many other countries physical anthropologists are the only anthropologists, while persons who study behavioral aspects of the human condition are known as archeologists, ethnologists, linguists, or prehistorians. In Great Britain, and increasingly in the United States and elsewhere, the term human biology is also used instead of physical anthropology, especially in relation to curricula in the health sciences.
Industry:Science
The product of polymerization of amino acids or the condensation of a diamine with a dicarboxylic acid. Polyamides are a class of polymers in which individual structral units are joined by amide bonds (R–CO–NH<sub>2</sub>). Whitish, translucent, and high-melting polyamide resins can be essentially transparent and amorphous when their melts are quenched. On cold drawing and annealing, most become quite crystalline and translucent. However, some polyamides based on bulky repeating units are inherently amorphous. The polymers are used for fibers, bristles, bearings, gears, molded objects, coatings, and adhesives. The term nylon formerly referred specifically to synthetic polyamides as a class. Because of many applications in mechanical engineering, nylons are considered engineering plastics.
Industry:Science
The ratio of charge to mass, expressed as <i>e</i>/<i>m</i>, of a particle. The acceleration of a particle in electromagnetic fields is proportional to its specific charge. Specific charge can be determined by measuring the velocity υ which the particle acquires in falling through an electric potential <i>V</i> (υ = √<span style="border-top:1px solid black;">2<i>eV</i>/<i>m</i></span> ); by measuring the frequency of revolution in a magnetic field <i>H</i> (the so-called cyclotron frequency ω = <i>eH</i>/<i>mc</i>, where <i>c</i> is the velocity of light); or by observing the orbit of the particles in combined electric and magnetic fields. In the mass spectrograph, the fields are arranged so that particles of differing velocities but of the same <i>e</i>/<i>m</i> are focused at a point.
Industry:Science
The tendency for an alternating current to concentrate near the outer part or “skin” of a conductor. For a steady unidirectional current through a homogeneous conductor, the current distribution is uniform over the cross section; that is, the current density is the same at all points in the cross section. With an alternating current, the current is displaced more and more to the surface as the frequency increases. The conductor's effective cross section is therefore reduced so the resistance and energy dissipation are increased compared with the values for a uniformly distributed current. The effective resistance of a wire rises significantly with frequency; for example, for a copper wire of 1-mm (0.04-in.) diameter, the resistance at a frequency of 1 MHz is almost four times the dc value.
Industry:Science
The term commonly applied to the larger, orange-colored fruit of the <i>Cucurbita</i> species, used when ripe as a table vegetable, in pies, or for autumn decoration. The flesh is somewhat coarse and strongly flavored, hence generally not served as a baked vegetable. Although some taxonomists would restrict the term pumpkin to the species <i>Cucurbita pepper</i> and <i>C. moschata</i>, it is also used in referring to <i>C. mixta</i>. Popular varieties (cultivars) are Connecticut Field and Small Sugar. Canned pumpkin is usually made from a blend of pumpkins and winter squashes. Cultural practices are similar to those used for squash. Harvesting generally begins when the fruits are mature, usually 4 months after planting. New Jersey, Illinois, and California are important producing states.
Industry:Science
