- 行业: Printing & publishing
- Number of terms: 178089
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- 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.
An important class of metamorphic rocks exposed at the surface of the Earth's crust, and inferred to make up a large portion of the deeper crust. Granulites are known from experimental petrologic studies to have formed at higher temperatures, and in many cases, higher pressures, than most other crustal rock assemblages. Thus, they are believed to have formed at considerable depths in the crust. The transport of whole granulite terrains, sometimes hundreds of kilometers in lateral dimension, from depths of 12–18 mi (20–30 km), poses a major problem.
Industry:Science
An important concept of chemical reactions which is useful in systematizing the chemistry of many substances. Oxidation can be represented as involving a loss of electrons by one molecule and reduction as involving an absorption of electrons by another. Both oxidation and reduction occur simultaneously and in equivalent amounts during any reaction involving either process.
Industry:Science
An important goal of medicine is to provide patients with minimally invasive medical procedures. With such procedures infection and blood loss are minimized, procedure and recovery times are shortened, and procedures can be offered on an outpatient basis. High-intensity focused ultrasound (HIFU), also known as focused ultrasound surgery (FUS), is emerging as a modality for minimally invasive therapy, and is gaining clinical acceptance as an alternative to surgical procedures.
Industry:Science
An important group of metallic raw materials required for the steel industry. Ferroalloys are the principal source of such additions as silicon, Si, and manganese, Mn, which are required for even the simplest plain-carbon steels; and chromium, Cr, vanadium, V, tungsten, W, titanium, Ti, and molybdenum, Mo, which are used in both low- and high-alloy steels. Also included are many other more complex alloys. Ferroalloys are unique in that they are brittle and otherwise unsuited for any service application, but they are important as the most economical source of these elements for use in the manufacture of the engineering alloys. These same elements can also be obtained, at much greater cost in most cases, as essentially pure metals. The ferroalloys contain significant amounts of iron and usually have a lower melting range than the pure metals and are therefore dissolved by the molten steel more readily than the pure metal. In other cases, the other elements in the ferroalloy serve to protect the critical element against oxidation during solution and thereby give higher recoveries. Ferroalloys are used both as deoxidizers and as a specified addition to give particular properties to the steel.
Industry:Science
An important immune function involving the dissolution of certain cells. There are a number of different cytolytic cells within the immune system that are capable of lysing a broad range of cells. The most thoroughly studied of these cells are the cytotoxic lymphocytes, which appear to be derived from different cell lineages and may employ a variety of lytic mechanisms. Cytotoxic cells are believed to be essential for the elimination of oncogenically or virally altered cells, but they can also play a detrimental role by mediating graft rejection or autoimmune disease. There are two issues regarding cytotoxic lymphocytes that are of concern: one is the target structure that is being recognized on the target cell, that is, the cell that is killed, which triggers the response; and the other is the lytic mechanism.
Industry:Science
An important messenger molecule in mammals and other animals. It can be toxic or beneficial, depending upon the amount and where in the body it is released. Initial research into the chemistry of nitric oxide (NO) was motivated by its production in automobile emissions and other combustion processes, which results in photochemical smog and acid rain. In the late 1980s, researchers in immunology, cardiovascular pharmacology, neurobiology, and toxicology discovered that nitric oxide is a crucial physiological messenger molecule. Nitric oxide is now thought to play a role in blood pressure regulation, control of blood clotting, immune defense, digestion, neuronal signaling, the senses of sight and smell, and possibly learning and memory. Underproduction or unregulated overproduction of nitric oxide may also contribute to disease processes such as diabetes, artherosclerosis, stroke, hypertension, carcinogenesis, multiple sclerosis, transplant rejection, damage associated with reperfusion in ischemic (oxygen-deprived) tissues, impotence, septic shock, and long-term depression.
Industry:Science
An important paleontological concept that denotes temporal mixing (or age mixing) of fossils. Unlike live-collected organisms, fossils found together within a single stratum need not be contemporaneous with one another, but may represent mixed remains of organisms that lived at different times and never interacted with one another. Fossilized shells, bones, and other skeletal remains collected from the same sediment layer or the same bedding plane may represent individuals that lived centuries or even millennia apart.
Industry:Science
An important spice from the fruits of the perennial herb <i>Carum carvi</i>, of the family Apiaceae. A native of Europe and western Asia, it is now cultivated in many temperate areas of both hemispheres. The small, brown, slightly curved fruits are used in perfumery, cookery, confectionery, in medicine, and for flavoring beverages.
Industry:Science
An important vegetable, belonging to the genus <i>Lycopersicon</i>, especially <i>L</i>. <i>esculentum</i>, that is grown for its edible fruit. <i>Lycopersicon</i> species are native to South America, especially Peru, and the Galápagos Islands. The tomato was first domesticated in Mexico, and received its name from the Aztec word <i>xitomate</i>.
Industry:Science
An important way in which vehicles can be made more fuel-efficient is to make them lighter. Unfortunately, lighter vehicle structures inevitably transmit more low-frequency noise than heavier structures, and to make light-weight vehicles acceptable to passengers, this low-frequency noise has to be controlled. Conventional passive treatments for low-frequency noise tend to add weight to the structure, reducing the environmental benefits. Active noise control, in which the sound generated by an array of loudspeakers or shakers reduces vehicle noise by destructive interference, can, however, be achieved with much smaller increases in weight. There is thus a growing interest in reducing the low-frequency noise inside vehicles using active noise control.
Industry:Science
