- 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.
A small, aberrant subclass of Crustacea within the class Maxillopoda. These animals are cryptic meiobenthos (small benthic animals ranging in size between macrofauna and microfauna), and were first found living in the interstices of the intertidal sands at Nobska Beach, Woods Hole, Massachusetts, in 1939. In subsequent years, related species were uncovered along the Atlantic coast of Europe and in the Mediterranean, as well as along the northwest coast of Africa. Later still, collections were made in southern Africa. In all, some eight species were assigned to the single genus <i>Derocheilocaris</i>. At first, the evolution of mystacocarids was thought to be relatively recent and linked with the post-Cretaceous opening of the Atlantic. However, a second genus, <i>Ctenocheilocaris</i>, was discovered along the coast of Chile, and then several species of that genus came to light in Brazil. The definitive end of the circum-Atlantic scenario for mystacocarid evolution ended, though, when a fifth species of <i>Ctenocheilocaris</i> was described from the coast of Western Australia, near Perth. Mystacocarids are now perceived as a relict group of ancient origins.
Industry:Science
A small, opaque nebula seen in silhouette against a rich star field or a bright nebula. Globules were first cataloged in the 1920s. In 1947, B. J. Bok called attention to their potential significance for star formation, and since then they have been commonly known as Bok globules. A globule is a region of the interstellar medium containing a high density of interstellar grains that obscure the more distant background stars and cause the region to appear as a dark nebula in optical photographs. Only relatively nearby globules can be identified, because if there are many stars in front of the nebula the contrast with the background is too weak. The distances to such nebulae have been estimated by counting the number of stars photographed in the line of sight and comparing this count with an analogous star count in a clearer comparison field. Comparative star counts have also been used to evaluate the degree of extinction produced by the grains in the nebula; if the optical properties of the grains are known, the total number of grains in a cut through the nebula can be estimated.
Industry:Science
A smooth, semisolid blend of mineral oil with waxes crystallized from the residual type of petroleum lubricating oil. The wax molecules contain 30–70 carbon atoms and are straight chains with a few branches or naphthene rings. They are microneedles and hold a large amount of oil in a gel. Petrolatums are useful because they cling, lubricate, and resist both moisture and oxidation. They serve as lubricants in baking and candymaking; as carriers in polishes, cosmetics, and ointments; as rust preventives; as waterproofing agents for paper; and in other uses calling for an inert greaselike material.
Industry:Science
A smooth, streamline type of viscous fluid motion characteristic of flow at low-to-moderate deformation rates. The name derives from the fluid's moving in orderly layers or laminae without the formation of small eddies or irregular fluctuations.
Industry:Science
A smooth-skinned, fuzzless form of peach, <i>Prunus persica</i>, probably brought to the Middle East from Central Asia by Alexander the Great. The nectarine's lack of pubescence is a simple recessive genetic characteristic. Classically, the fruits were thought of as being somewhat smaller, softer, and richer in flavor than those of the peach. More recently developed cultivars, however, approximate fresh-market peaches in size and firmness but are not usually superior in flavor. Propagation and cultivation are the same as for the peach, but because of its susceptibility to brown rot (<i>Sclerotinia fructicola</i>) in humid growing areas, the nectarine is primarily grown in irrigated peach-growing areas where atmospheric humidity is low.
Industry:Science
A sodium-rich plagioclase feldspar mineral whose composition extends over the range Ab<sub>100</sub>An<sub>0</sub> to Ab<sub>90</sub>An<sub>10</sub>, where Ab (= albite) is NaAlSi<sub>3</sub>O<sub>8</sub> and An (= anorthite) is CaAl<sub>2</sub>Si<sub>2</sub>O<sub>8</sub> (see <b>illus.</b>). Albite occurs in crustal igneous rocks as a major component of pegmatites and granites, in association with quartz, mica (usually muscovite), and potassium feldspar (orthoclase or microcline). Sodium and potassium feldspars usually occur as distinct mineral grains, sizes varying from millimeter to meter scale. However, they are frequently intergrown, having exsolved from a single phase at high temperatures. If the intergrowth is visually observable in a hand specimen, the composite material is known as macroperthite; if visible only in a microscope, microperthite; and if submicroscopic in scale, cryptoperthite. In metamorphic rocks albite is found in granitic gneisses, and it may be the principal component of arkose, a feldspar-dominant, sedimentary rock. Cleavelandite, a platy variety, is sometimes found in lithium-rich pegmatites.
Industry:Science
A soft talc-rich rock. Soapstones are rocks composed of serpentine, talc, and carbonates (magnesite, dolomite, or calcite). They represent original peridotites which were altered at low temperatures by hydrothermal solutions containing silicon dioxide, SiO<sub>2</sub>; carbon dioxide, CO<sub>2</sub>; and other dissolved materials (products of low-grade metasomatism). Among the rock products thus formed are antigorite schists, actinolite-talc schists, and talc-carbonate rocks. To the last belongs the true soapstone, but the whole group of rocks may loosely be referred to as soapstones because of their soft, soapy consistency. Such rocks were selected by prehistoric humans for making primitive vessels and pots, and for making rough carvings for ornamental purposes.
Industry:Science
A soft, waxy material derived from the greasy coating on raw wool. In the processing of wool, the fleece is scoured with an aqueous alkaline solution to remove debris, wax, water-soluble material, and free acids. The insoluble fraction, which constitutes about 15–20% of the weight of the original wool, is crude lanolin.
Industry:Science
A soft-iron core that is magnetized by passing a current through a coil of wire wound on the core. Electromagnets are used to lift heavy masses of magnetic material and to attract movable magnetic parts of electric devices, such as solenoids, relays, and clutches.
Industry:Science
A software-controlled means of directing digitally encoded information in a communication network from a source to a destination, in which information messages may be divided into smaller entities called packets. Switching and transmission are the two basic functions that effect communication on demand from one point to another in a communication network, an interconnection of nodes by transmission facilities (see <b>illustration</b>). Each node functions as a switch in addition to having potentially other nodal functions such as storage or processing.
Industry:Science
