- 行业: Printing & publishing
- Number of terms: 178089
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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.
Any of the chemical messengers produced by the thyroid gland. For many years it was generally believed that the thyroid gland produced only two closely related hormones, thyroxine and triiodothyronine. However, in 1961 a new hormonal principle, calcitonin, was discovered by Harold Copp. He originally thought that this substance was secreted by the parathyroid glands, but in 1963 it was established that the source of this hormone in mammals was the thyroid gland, and it was renamed thyrocalcitonin. In 1967 it was isolated in pure form and in 1968, synthesized. It is a polypeptide containing a single chain of 33 amino acids, in contrast to thyroxine and triiodothyronine which are iodinated thyronines.
Industry:Science
Any one of a number of annual crucifer species of Asiatic origin belonging to the plant order Capparales. Mustards eaten as greens are <i>Brassica juncea</i>, <i>B. juncea</i> var. <i>crispifolia</i>, and <i>B. hirta</i>. Table mustard and oils are obtained from <i>B. nigra</i>. Cultural practices are similar to those used for spinach. Southern Giant Curled and Ostrich Plume are popular varieties for greens. Long days and high temperatures favor undesirable seed-stalk development. Harvesting is usually 1½–2 months after planting. Important production centers for mustard greens are in the South, where the crop is popular. Montana and the West Coast states are important sources of mustard seed.
Industry:Science
Engineers have known for decades that efficient, almost complete heat or other exchange could be achieved between two fluids flowing in opposite directions in separate tubes. Such countercurrent systems have been “invented” numerous times by living organisms for all types of exchange function. They are most commonly found in the circulatory, respiratory, and excretory (kidney) systems, serving in heat, oxygen, and ion exchange. Biological countercurrent systems can be classified into two main types: downhill exchanges and hairpin multipliers. In both cases, the basic mechanism is the same—exchange of substance between fluids flowing in opposite directions—but the consequences are very different.
Industry:Science
Double star systems in which the two components are too close to be seen separately but which reveal their duplicity by periodic changes in brightness as each star successively passes between the other and the Earth, that is, eclipses the other. Studies of the light changes and the radial velocity changes of each component permit the computation of the radii, masses, and densities of the components—important quantities that cannot be measured directly in single stars. In addition, these close double stars are useful in studies of mass loss and of stellar evolution. Since eclipsing stars are variable in light, they are included in general variable star catalogs under the same system of nomenclature.
Industry:Science
Either a propulsion system or a complete vehicle driven by such a propulsive engine. A rocket engine provides the means whereby chemical matter is burned to release the energy stored in it and the energy expended, in this example, by ejection at high velocity of the products of combustion (the working fluid). The ejection imparts motion to the vehicle in a direction opposite to that of the ejected matter. A rocket vehicle is propelled by rocket reaction and includes all components necessary for such propulsion, a payload such as an explosive charge, scientific instruments, or a human crew. A rocket vehicle also includes guidance and control equipment mounted in a structural airframe or spaceframe.
Industry:Science
An unwanted plant or a plant whose negative values outweigh the positive values in a given situation. Weeds cost growers millions of dollars each year in reduced yield and quality of agricultural products. Especially in tropical areas, irrigation systems have become unusable because of clogging with weeds. Weeds can harbor deleterious disease organisms and insects that harm crops cost livestock producers millions of dollars. In addition, weeds can cause allergic reactions and serious skin problems (poison ivy), break up pavement, slow or stop water flow in municipal water supplies, interfere with power lines, cause fire hazards around buildings and along railroad tracks, and produce poisonous plant parts.
Industry:Science
Forensic science is the application of scientific knowledge to legal matters. This means that crime investigations are assisted by processing evidence using scientific methods. Cyber forensics is a subset of forensic science for processing digital evidence. Cyber forensics does not necessarily apply to legal matters. It encompasses a large number of activities, from computer crime investigations to locating specific data on digital devices. Cyber forensics is not limited to crimes or incidents committed with computers. It also includes the processing of electronic data from mobile devices such as cellular telephones, personal digital assistants (PDAs), music players, or microchips with storage capability.
Industry:Science
Aqueous compartments enclosed by lipid bilayer membranes; liposomes are also known as lipid vesicles. Phospholipid molecules consist of an elongated nonpolar (hydrophobic) structure with a polar (hydrophilic) structure at one end. When dispersed in water, they spontaneously form bilayer membranes, also called lamellae, which are composed of two monolayer layer sheets of lipid molecules with their nonpolar (hydrophobic) surfaces facing each other and their polar (hydrophilic) surfaces facing the aqueous medium. The membranes enclose a portion of the aqueous phase much like the cell membrane which encloses the cell; in fact, the bilayer membrane is essentially a cell membrane without its protein components.
Industry:Science
Changes of any property of an aggregation of matter and energy, accompanied by thermal effects. The participants in a process are first identified as a system to be studied; the boundaries of the system are established; the initial state of the system is determined; the path of the changing states is laid out; and, finally, supplementary data are stated to establish the thermodynamic process. These steps will be explained in the following paragraphs. At all times it must be remembered that the only processes which are allowed are those compatible with the first and second laws of thermodynamics: Energy is neither created nor destroyed and the entropy of the system plus its surroundings always increases.
Industry:Science
As the electronic distribution of documents, especially via Web sites, has become more widespread, those responsible for managing document content have looked for new approaches and tools to perform management functions in an efficient and cost-effective manner. Markup languages are useful for organizing and formatting document content for display, exchange, and distribution; however, markup languages are not very helpful with managing and searching large amounts of document content. Consequently, many individuals have realized that the power of database management systems (DBMS) to efficiently store, update, secure, and speedily retrieve data should be applied to the problem of document management as well.
Industry:Science
