- 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 magnetism of the Earth; also, the branch of science that deals with the Earth's magnetism. Formerly called terrestrial magnetism, geomagnetism involves any topic pertaining to the magnetic field observed near the Earth's surface, within the Earth, and extending upward to the magnetospheric boundary. Modern usage of the term is generally confined to historically recorded observations to distinguish it from the sciences of archeomagnetism and paleomagnetism, which deal with the ancient magnetic field frozen respectively in archeological artifacts and geologic structures.
Industry:Science
The ratio of the complex amplitude of spatially averaged acoustic pressure over a surface to the complex amplitude of volume velocity on that surface. The unit is the newton-second/meter<sup>5</sup>, or the mks acoustic ohm. In the cgs system the unit is the dyne-second/centimeter<sup>5</sup>. The volume velocity is the integral over the surface of the particle velocity normal to the surface. Acoustic impedance measures the degree to which an acoustic medium impedes the fluid motion created by an imposed pressure. It was originally defined by analogy to electrical systems.
Industry:Science
The science that embraces the properties, composition, and structure of matter, the changes in structure and composition that matter undergoes, and the accompanying energy changes. It is important to distinguish chemical change, implicit in this definition, and changes in physical form. An example of the latter is the conversion of liquid water to solid or gas by cooling or heating; the water substance is unchanged. In chemical change, such as the rusting of iron, the metal is consumed as it reacts with air in the presence of water to form the new substance, iron oxide.
Industry:Science
The study of the structure, preparation, properties, and reactions of carbon compounds. The term organic was early applied to compounds derived from plant and animal sources. These substances from living systems were usually distillable liquids or low-melting solids and were flammable, in contrast to metals, salts, and oxides from mineral sources. Until about 1830 it was held by some that organic compounds contained some special quality, or vital force. This notion was dispelled, but the term organic remained and became broadened to include carbon compounds in general.
Industry:Science
The main objective of combinatorial chemistry is synthesis of arrays of chemical or biological compounds called libraries. These libraries are screened to identify useful components, such as drug candidates. Synthesis and screening are often treated as separate tasks because they require different conditions, instrumentation, and scientific expertise. Synthesis involves the development of new chemical reactions to produce the compounds, while screening aims to identify the biological effect of these compounds, such as strong binding to proteins and other biomolecular targets.
Industry:Science
The nucleus of the atom of heavy hydrogen, H<sup>2</sup> (deuterium). The deuteron <i>d</i> is composed of a proton and a neutron. As the simplest multinucleon nucleus, the deuteron has been the subject of extensive study. Its binding energy is 2.227 MeV; that is, this is the amount of energy which must be added to a deuteron for it to dissociate into a proton and a neutron. The accurate determination of this dissociation energy provides the means of calculating the mass of the neutron, the mass of the deuteron (2.014187 amu) and proton being known from other experiments.
Industry:Science
The term computer-to-plate (CTP) is used within the printing industry to refer to devices, technologies, and work flow related to imaging aluminum or polyester printing plates without the use of film. In the 1990s, computer-to-plate matured rapidly from a concept of questionable validity to a well-established, practical manufacturing method. Although the current number of users represents only a small fraction of the total number of printing firms worldwide, it is expected that computer-to-plate will become the predominant method of imaging printing plates in the next decade.
Industry:Science
The term medicine has two general meanings. The first indicates any material, notably in the drug category, which is given to prevent, alleviate, beneficially alter, or stop a disease process. In the second and broader sense, medicine denotes the field of science devoted to healing. Many subdivisions exist and more ramifications appear almost daily. Included in the area of medicine are many clinical specialties, including surgery, pediatrics, psychiatry, obstetrics, and others. Internal medicine is the specialization which deals with internal diseases of a nonsurgical nature.
Industry:Science
The protection, development, and efficient management of water resources for beneficial purposes. Water's physical and chemical properties make it essential to life and civilization. It is combined with carbon dioxide by green plants in the synthesis of carbohydrates, from which all other foods are formed. It is a highly efficient medium for dissolving and transporting nutrients through the soil and throughout the bodies of plants and animals. It can also carry deadly organisms and toxic wastes. Water is a raw material that is indispensable for many domestic and industrial purposes.
Industry:Science
The reversible exchange of ions of the same charge between a solution and an insoluble solid in contact with it; or between two immiscible solvents, one of which contains a soluble material with immobilized ionic groups. Ions are atoms or molecules containing charge-bearing groups. Their interactions are dominated by the electrostatic forces between charge centers. These interactions are attractive when the ions are of opposite charge, or repulsive when the ions have the same charge. Ions with a net negative charge are called anions, and those with a net positive charge are cations.
Industry:Science
