- 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.
The names associated with a great number of species of mammals in a number of different families of the order Rodentia. The rodents constitute the largest order of mammals, and they presently include 2277 species, or about 42% of the known mammalian species of the world. Most of the smaller rodents are called rats or mice. There is no fundamental taxonomic difference between mice and rats; they differ only in size. (Smaller species are generally called mice, larger ones rats.) Both mice and rats are often in the same family, and there are mice and rats in a number of different rodent families.
Industry:Science
The science of the elementary, atomic compositions of solids and the transformations that occur in and between solids and between solids and other phases to produce solids. Solid-state chemistry deals primarily with those microscopic features which are uniquely characteristic of solids and which are the causes for the macroscopic chemical properties and the chemical reactions of solids. As with other branches of the physical sciences, solid-state chemistry also includes related areas that furnish concepts and explanations of those phenomena which are more characteristic of the subject itself.
Industry:Science
The strong evidence of efficacy for the stimulants methylphenidate (Ritalin®) and amphetamine (Adderall®) in treating children and adolescents with attention deficit hyperactivity disorder (ADHD) has raised expectations that medications might be found with similar levels of efficacy to help children and adolescents with other psychiatric disorders. In the case of agents to treat depression, the results have turned out to be controversial. Confronted with equivocal data for efficacy, as well as serious questions about safety, the public has become somewhat skeptical—as have prescribing clinicians.
Industry:Science
The most common function of a key is to prevent relative rotation of a shaft and the member to which it is connected, such as the hub of a gear, pulley, or crank. Many types of keys are available, and the choice in any installation depends on such factors as power requirements, tightness of fit, stability of connection, and cost. For light power requirements a setscrew may be tightened against the round shaft or against a flat spot on the shaft. For most requirements a positive connection, such as by a key, is necessary. A setscrew is frequently used to seat the key and to prevent axial motion.
Industry:Science
The science of sound waves having frequencies above the audible range, that is, above about 20,000 Hz. Original workers in this field adopted the term supersonics. However, this name was also used in the study of airflow for velocities faster than the speed of sound. The present convention is to use the term ultrasonics as defined above. Since there is no marked distinction between the propagation and the uses of sound waves above and below 20,000 Hz, the division is artificial. In this article the emphasis is on instrumentation, engineering applications, analytical uses, and medical applications.
Industry:Science
The process whereby one or more gene alleles present in one chromosome may be exchanged with their alternative alleles on a homologous chromosome to produce a recombinant (crossover) chromosome which contains a combination of the alleles originally present on the two parental chromosomes. Genes which occur on the same chromosome are said to be linked, and together they are said to compose a linkage group. In eukaryotes, crossing-over may occur during both meiosis and mitosis, but the frequency of meiotic crossing-over is much higher. This article is concerned primarily with meiotic crossing-over.
Industry:Science
The small male reproductive bodies produced in the pollen sacs of seed plants (gymnosperms and angiosperms). The term comes unchanged from Latin, meaning fine dust or flour, and was popularized by Carl Linnaeus in 1751 (but used since 1523). Pollen is usually carried by wind or insects to the sticky stigmas of angiosperms or to the naked ovules of gymnosperms. Fertilization, which follows pollination within a wide time range—minutes, hours, a year in <i>Agathis</i>, 15 months or more in juniper, and 2 years in stone pine (<i>Pinus pinea</i>)—is usually effected only by pollen of the same species.
Industry:Science
The motion of air relative to the Earth's surface. The term usually refers to horizontal air motion, as distinguished from vertical motion, and to air motion averaged over a chosen period of 1–3 min. Micrometeorological circulations (air motion over periods of the order of a few seconds) and others small enough in extent to be obscured by this averaging are thereby eliminated. The choice of the 1- to 3-min interval has proven suitable for the study of the hour-to-hour and day-to-day changes in the atmospheric circulation pattern, and the larger-scale aspects of the atmospheric general circulation.
Industry:Science
The measuring, recording, and transmitting of data of the variable elements of weather. In the United States the National Weather Service (NWS), a division of the National Oceanic and Atmospheric Administration (NOAA), has as one of its primary responsibilities the acquisition of meteorological information. Most observations are taken by federal employees, although private citizens and private organizations such as the utilities are also involved. The data are sent by various communication methods to National Weather Service field offices and to the National Meteorological Center near Washington, D.C.
Industry:Science
The notion that thermal convection currents must exist in the Earth's mantle occupies a central position in theories which have been proposed to account for the occurrence of continental drift and sea-floor spreading. Apart from the controlling influence which these currents exert on surface geological processes such as mountain building, they also govern the rate at which heat is transferred from the hot interior of the Earth to its surface and so are crucial to understanding the thermal history of the planet. Mantle convection serves as the guiding principle in the geological and geophysical sciences.
Industry:Science
