- 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.
A combination of two or more gears used to transmit motion between two rotating shafts or between a shaft and a slide. In theory two gears can provide any speed ratio in connecting shafts at any center distance, but it is often not practical to use only two gears. If the ratio is large or if the center distance is relatively great, the larger of the two gears may be excessively large. Moreover, an additional gear may be necessary simply to give the proper direction to the output gear. Belt, rope, and chain drives are frequently used in conjunction with gear trains.
Industry:Science
A combustible gas that occurs beneath the surface of the earth, often found in conjunction with petroleum deposits. Its main use is for fuel, but it is also used to make carbon black, certain chemicals, and liquefied petroleum gas.
Industry:Science
A combustion chamber in which oil is the heat-producing fuel. Fuel oils, having from 18,000 to 20,000 Btu/lb (42 to 47 megajoules/kg), which is equivalent to 140,000 to 155,000 Btu/gal (39 to 43 MJ/liter), are supplied commercially. The lower flash-point grades are used primarily in domestic and other furnaces without preheating. Grades having higher flash points are fired in burners equipped with preheaters. The ease with which oil is transported, stored, handled, and fired is advantageous in small installations. The fuel burns almost completely so that, especially in a large furnace, combustible losses are negligible.
Industry:Science
A commercial dairy food made by freezing while stirring a pasteurized mix of suitable ingredients. The product may include milk fat, nonfat milk solids, or milk-derived ingredients; other ingredients may include corn syrup, water, flavoring, egg products, stabilizers, emulsifiers, and other non-milk-derived ingredients. Air incorporated during the freezing process is also an important component.
Industry:Science
A common asymptomatic infection caused by cytomegalovirus, which can produce life-threatening illnesses in the immature fetus and in immunologically deficient subjects.
Industry:Science
A common definition of temperature, as stated by one dictionary, is: “Degree of hotness or coldness measured on a definite scale based on some physical phenomenon (as the expansion of mercury in a thermometer).” However, to rigorously define the concept of temperature, one can use the idea of operationalism, which asserts that a concept is synonymous with a corresponding set of operations. Thus, “temperature” can be defined by the five operations needed to construct a temperature scale. There are many arbitrary decisions in doing this.
Industry:Science
A common disorder of premature (or preterm) birth, defined by respiratory difficulty, which requires oxygen or assisted ventilation, and characteristic changes on chest xray. It is primarily the result of deficiency in surface-active lipids (contained within pulmonary surfactant) which serve to stabilize the air spaces (alveoli) within the lung. Although most cases of infant respiratory distress syndrome rarely result in a fatal outcome in developed countries, all require specialized care in a neonatal intensive care unit.
Industry:Science
A common group of fossil organisms that lived during the Ordovician, Silurian, and Devonian periods. They are preserved in rocks of these systems as large (cabbage-sized) calcium carbonate fossils in the shape of crusts, plates, domes, fingers, bulbs, cylinders, and bushes consisting internally of a three-dimensional network of regularly repeating structural elements such as pillars, laminae, cyst plates, and walls (<b>illus. <i>a</i>,<i>b</i>,<i>c</i></b>). Although recognized as a class, or subclass, of sponges, these fossils, unlike most sponges, are lacking in siliceous or calcareous spicules (spikelike supporting structures). The term stromatoporoid has been used for a very similar group of Mesozoic fossils that are discussed here as sphaeractinids. Unlike the Paleozoic stromatoporoids, some of the sphaeractinids show the remains of siliceous spicules and can be assigned to several subclasses of the sponge class Demospongiae. Stromatoporoid has also been used as a descriptive term to apply to a grade of evolution of a wide range of different groups of sponges in which a calcareous basal skeleton of stromatoporoid-like architecture was secreted. The implication of such usage is that the Paleozoic fossils are not a natural group but a collection of disparate lineages of sponges that are at a similar stage of evolution. The term stromatoporoid is best restricted to the fossils of Ordovician, Silurian, and Devonian age defined by their lack of spicules and characteristic internal structures that can be grouped as the class Stromatoporoidea of the Porifera.
Industry:Science
A common hydrous aluminum silicate mineral found in sediments, soils, hydrothermal deposits, and sedimentary rocks. It is a member of a group of clay minerals called the kaolin group minerals, which include dickite, halloysite (7 Å and 10 Å), nacrite, ordered kaolinite, and disordered kaolinite. These minerals have a theoretical chemical composition of 39.8% alumina, 46.3% silica, and 13.9% water (Al<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>), and they generally do not deviate from this ideal composition. They are sheet silicates comprising a single silica tetrahedral layer joined to a single alumina octahedral layer. Although the kaolin group minerals are chemically the same, each is structurally unique as a result of how these layers are stacked on top of one another. Kaolinite is the most common kaolin group mineral and is an important industrial commodity used in ceramics, paper coating and filler, paint, plastics, fiberglass, catalysts, and other specialty applications.
Industry:Science
A common mineral in the upper oxidized zone of ore deposits containing galena (PbS). It is usually associated with anglesite, smithsonite, malachite, and other secondary minerals. Normally cerussite is close in composition to PbCO<sub>3</sub> with only minor amounts of zinc (Zn) and strontium (Sr) in place of lead (Pb).
Industry:Science
