- 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 variety of organic compounds which contain two adjacent atoms bearing formal positive and negative charges, and in which both atoms have full octets of electrons. Heteroatoms most commonly utilized as the positive atom are phosphorus, nitrogen, sulfur, selenium, and oxygen, and the negative atom usually involves carbon, nitrogen, oxygen, or sulfur. The ylide may be in an alicyclic or cyclic environment, and in the latter the ylide function may be endocyclic or exocyclic. Ylides most useful in organic synthesis are those containing phosphorus or sulfur and an adjacent carbanion.
Industry:Science
A variety of peridotite, an igneous rock containing at least 35% olivine. The full definition is unusually complex for an igneous rock, with many qualifications. Briefly, kimberlite is richer in carbon dioxide than most peridotites, and has crystals larger in diameter than 0.5 mm of olivine, garnet, clinopyroxene, phlogopite, and orthopyroxene. All of these silicate minerals have high Mg/Fe ratios in kimberlites. In addition, there can be 0.5 mm or larger crystals of magnesian ilmenite and titanium-poor chromite. The matrix (crystals less than 0.5 mm) contains olivine plus one or more of monticellite, phlogopite, perovskite, spinel, apatite, serpentine, and carbonate minerals. Melilite, leucite, kalsilite, and alkali feldspar do not crystallize from kimberlite magma. In part, the complexity of this definition is caused by the complicated processes of generation and emplacement of kimberlites and, in part, a restrictive definition is imposed as a defense against wishful thinking, because kimberlite was long thought to be the only rock that brought diamonds to the Earth's surface. However, in the 1970s other diamond-bearing rocks (lamproites) were found in western Australia and elsewhere, and in the 1980s R. H. Mitchell distinguished orangeite and kimberlite as separate hosts for diamonds in South Africa. Some eclogites have recently been found to contain diamonds also.
Industry:Science
A vast body of literature supports the idea that early adversities, such as childhood sexual abuse (CSA), physical abuse, and witnessing domestic violence, are major risk factors for psychopathology, accounting for 50–75% of the population-attributable risk for depression, suicide attempts, and drug abuse. The powerful relationship between childhood abuse and psychopathology may be best understood as a cascade. Exposure to early adversity alters trajectories of brain development, which in turn leads to social, emotional, and cognitive impairment, followed by the adoption of health-risk behaviors.
Industry:Science
A vast reservoir of icy bodies in the region of the solar system beyond the orbit of the planet Neptune. The trans-Neptunian region of the solar system was thought to be home only to the small planet Pluto and its satellite Charon until the discovery of the Kuiper Belt object 1992 QB<sub>1</sub> in 1992 by David Jewitt and Jane Luu. Members of the belt (Kuiper Belt objects, or KBOs) are part of the original building blocks (planetesimals) of the outer planets, left behind simply because they were not incorporated into planets or ejected from the solar system. They are thus relics from the solar nebula, the original disk of gas and dust that gave rise to everything in the solar system. As such, Kuiper Belt objects should preserve records of the early stages of the solar system's evolution.
Industry:Science
A vector quantity equal in magnitude to the instantaneous rate of flow of electric charge, perpendicular to a chosen surface, per unit area per unit time. If a uniform wire of cross-sectional area <i>A</i> carries a current <i>I</i>, the current density <i>J</i> is <i>I/A</i>. The units of <i>J</i> in the International System (SI) are amperes per square meter.
Industry:Science
A vector quantity representing the electric dipole moment per unit volume of a dielectric material.
Industry:Science
A vegetation formation characterized by woody plants of low stature (3–9 ft or 1–3 m tall), impenetrable because of tough, rigid, interlacing branches, with small, simple, waxy, evergreen, thick leaves. The term refers to evergreen oak, Spanish <i>chapparo</i>, and therefore is uniquely southwestern North American. This type of vegetation has its center in California and occurs continuously over wide areas of mountainous to sloping topography. The Old World Mediterranean equivalent is called maquis or macchie, with nomenclatural and ecological variants in the countries ranging from Spain to the Balkans. Physiognomically similar vegetation occurs also in South Africa, Chile, and southwestern Australia in areas of Mediterranean climates, that is, with very warm, dry summers and maximum precipitation during the cool season.
Industry:Science
A versatile solvent, abbreviated DMSO, used industrially and in chemical laboratories as a medium for carrying out chemical reactions. Its uses have been extended to that of a chemical reagent with DMSO as a reactant undergoing a chemical change. DMSO has also gained popularity as a medicinal compound; however, its efficacy as a curative agent is not well established.
Industry:Science
A vertical hollow structure of masonry, steel, or reinforced concrete, built to convey gaseous products of combustion from a building or process facility. A chimney should be high enough to furnish adequate draft and to discharge the products of combustion without causing local air pollution. The height and diameter of a chimney determine the draft.
Industry:Science
A vertical sequence of several different kinds of distinctive sedimentary rock units that is repeated upward through the stratigraphic succession. Originally defined in the rock succession of Pennsylvanian age in the Illinois Basin in the 1930s, the rock types include coal, limestone, sandstone, and several types of shale and mudstone. Cyclothems were soon recognized elsewhere in rocks of this age in the central and eastern United States. Those in the Midcontinent (Kansas and states to the northeast) are dominated by several types of limestone and shale, with less coal and sandstone. Those in the Appalachian region are dominated by coal, mudstone, shale, and sandstone, with less limestone. Some workers generalized the term, and simple cyclothems became recognized in coal-bearing successions of other ages, but the term never achieved wide usage outside of rocks of Pennsylvanian age.
Industry:Science
