- 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 clock that makes use of the piezoelectric property of a quartz crystal. When a quartz crystal vibrates, a difference of electric potential is produced between two of its faces. The actual displacement of the surface is generally only a few atomic diameters. The crystal has a natural frequency of vibration that depends on its size and shape. If it is placed in an oscillating electric circuit having nearly the same frequency as the crystal, it is caused to vibrate at its natural frequency, and the frequency of the entire circuit becomes the same as the natural frequency of the crystal. The first quartz clock was invented by Warren Marrison in 1927.
Industry:Science
A closely spaced structure of the spectrum lines forming a multiplet component in the spectrum of an atom or molecule, or of a liquid or solid. In the emission spectrum for an atom, when a multiplet component is examined at the highest resolution, this component may be seen to be resolved, or split, into a group of spectrum lines which are extremely close together. This hyperfine structure may be due to a nuclear isotope effect, to effects related to nuclear spin, or to both.
Industry:Science
A cloud comprising waterdroplets or (less commonly) ice crystals formed near the ground and resulting in a reduction in visibility to below 0.6 mi (1 km). This is lower than that occurring in mist, comprising lower concentration of waterdroplets, and haze, comprising smaller-diameter aerosol particles.
Industry:Science
A cluster compound containing both carbon (C) and boron (B) atoms as well as hydrogen (H) atoms external to the framework of the cluster. A cluster compound is one with insufficient electrons to allow for classical two-center two-electron bonds between all adjacent atoms. Sometimes the term carborane is used as a synonym for <i>closo-</i>1,2-C<sub>2</sub>B<sub>10</sub>H<sub>12</sub>, commonly referred to as <i>ortho-</i>carborane. Carboranes are of interest because of their nonclassical bonding, their relatively high thermal stability, and their ability, when containing the <sup>10</sup>B isotope, to capture neutrons efficiently.
Industry:Science
A coherent, cellular, carbonaceous residue remaining from the dry (destructive) distillation of a coking coal. It contains carbon as its principal constituent, together with mineral matter and residual volatile matter. The residue obtained from the carbonization of a noncoking coal, such as subbituminous coal, lignite, or anthracite, is normally called a char. Coke is produced chiefly in chemical-recovery coke ovens (see <b>illus.</b>), but a small amount is also produced in beehive or other types of nonrecovery ovens.
Industry:Science
A coiled, tubular gland found in mammals. There are two kinds, merocrine (or eccrine) and apocrine. The latter are generally associated with hair follicles (see <b>illus.</b>). Merocrine glands are distributed extensively over the body in the human, whereas the apocrine variety is restricted to the scalp, nipples, axilla, external auditory meatus, external genitals, and perianal areas. Apocrine sweat glands are more numerous in mammals, with the exception of the chimpanzee and human, in which the merocrine variety predominates. The mammary glands probably represent modified apocrine sweat glands which grow inward and increase in complexity. In association with adipose tissue, they eventually form pendant structures, the mammae, which project outward from the general contour of the skin's surface. The secretion process is apocrine with a considerable portion of the cell being discharged. The discharged portion of such a gland cell disintegrates to free fat droplets and albuminous substances. A mammary gland is complex and represents an association of lobes. Each lobe contains a compound alveolar (acinous) gland with a separate lactiferous duct which opens on the nipple in the human. The glands of Moll associated with the eyelashes are relatively large modified apocrine glands as are the ceruminous or wax glands in the external auditory meatus. The anal sacs of the skunk presumably are apocrine glands modified by the addition of muscle fibers from the levator ani muscle which enables the pungent contents to be ejected with force.
Industry:Science
A cold metalworking process in a press-type die. Coining is used to produce embossed parts, such as badges and medals, and for minting of coins. It is also used on portions of a blank or workpiece to form corners, indentations, or raised sections, frequently as part of a progressive die operation. The work is subjected to high pressure within the die cavity and thereby forced to flow plastically into the die details. The absence of overflow of excess metal from between the dies is characteristic of coining and is responsible for the fine detail achieved. However, because this action requires highly accurate dies and higher-than-usual die pressures, only essential surfaces are coined.
Industry:Science
A collection of pressed and dried plant specimens, and a description of when, where, and by whom they were collected, arranged in a systematic manner, and serving as a permanent physical record of the occurrence of an individual plant at a specific place and time. Herbaria may contain specimens from the full range of organisms that have classically been considered plants: fungi, lichens, algae, bryophytes, ferns and their allies, gymnosperms, and angiosperms. Many herbaria also accumulate and manage special collections such as liquid-preserved parts for anatomical studies, wood, seeds, or specially preserved material suitable for extraction of deoxyribonucleic acid (DNA) or other chemical constituents. Many groups of plants, especially those with succulent or fleshy parts, are not suitable for preservation as dry, flat specimens because they lose many of their important features in the drying process. Consequently, these plants are often preserved in liquid.
Industry:Science
A collection of specialized cells (neurons) in the head that regulates behavior as well as sensory and motor functions. Neurons grow long threadlike structures—an axon and a dendritic tree—from their cell bodies, which provide them with a rapid communication network throughout the body. The axon uses pulses to transmit a signal to thousands of other neurons or to muscle or gland cells. The dendritic tree uses waves of electric current to integrate the pulses from thousands of other neurons. Groups of neurons form ganglia in chains along both sides of the body axis from “head to tail.” The largest of these paired groups, the brain, is in the head, where the distance receptors (nose, eyes, and ears) are located. These receptors respond to smells, sights, and sounds coming so far from the collective that the collective has time to receive the inputs, interpret them as signals, plan an action before being overtaken by circumstance, and act while monitoring and correcting its action. These are the minimal functions of a brain. The power of a brain lies not in its size but in the complexity of the connections among its functional parts.
Industry:Science
A collection of strategies and statistical methods for ensuring high-quality results in manufacturing and service processes. Traditionally, the statistical methods associated with statistical process control (SPC) have focused on process monitoring. As a result, some experts argue that statistical process control is a misnomer and that the term statistical process monitoring is more appropriate. Others argue that statistical quality control methods have become so entwined with strategic decisions and daily operations that the term statistical process control is entirely appropriate. Regardless, statistical process control methods and philosophies are essential tools for survival in today's highly competitive environment.
Industry:Science
