- 行业: Printing & publishing
- Number of terms: 178089
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- 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.
Graphical or textual languages that are used to build models by describing the qualities with which the models are concerned. A model represents something and includes some but not all qualities of what it represents. For example, an architect's model of a new development area concentrates on the physical appearance, while an aircraft designer's wind-tunnel model concentrates on aerodynamic qualities. When models are used in systems and software engineering, their important qualities are structure, behavior, communication, and requirements.
Industry:Science
Antarctica is the coldest, windiest, and driest continent. The lowest temperature ever measured on Earth, −89.2°C (−128.5°F), was recorded at the Russian Antarctic station of Vostok in July 1983. Katabatic (cold, gravitational) winds with velocities up to 50 km/h (30 mi/h) sweep down to the coast and occasionally turn into blizzards with 150 km/h (nearly 100 mi/h) wind velocities. Antarctica's interior is a cold desert averaging annually only a few centimeters of water-equivalent precipitation, while the coastal areas average 30 cm (12 in.).
Industry:Science
Any naturally occurring carbon-containing material which when burned with air (or oxygen) produces (directly) heat or (indirectly) energy. Fossil fuels can be classified according to their respective forms at ambient conditions. Thus, there are solid fuels (coals); liquid fuels (petroleum, heavy oils, bitumens); and gaseous fuels (natural gas, which is usually a mixture of methane, CH<sub>4</sub>, with lesser amounts of ethane, C<sub>2</sub>H<sub>6</sub>, hydrogen sulfide, H<sub>2</sub>S, and numerous other constituents in small proportions).
Industry:Science
Electric charge at rest, generally produced by friction or electrostatic induction. In the sixth century B.C., Thales of Miletus, who is usually credited with the discovery of static electricity, described experiments in which rubbed amber induced movement in nearby particles. It was not until the eighteenth century, when Benjamin Franklin carried out his kite-flying experiments in which he “captured” some thunderstorm electricity in a Leyden jar, that it was verified that thunderstorm electricity and static electricity were one and the same.
Industry:Science
Audio program broadcasting, traditionally an analog service using either amplitude or frequency modulation (AM or FM), is rapidly evolving to digital methods. Digital audio broadcasting (DAB) promises to bring to listeners an audio signal with vastly improved characteristics, accompanied by additional digital data-based services not available from the analog signals now in use. This article discusses the in-band/on-channel approach to implementing terrestrial digital audio broadcasting, and the first global satellite digital broadcasting system.
Industry:Science
Any processed, partially processed, or unprocessed substance taken into the body primarily for providing nourishment. In addition, factors such as satisfying social needs, achieving psychological ends, and satisfying hunger govern the selection and consumption of foods. Chosen carefully, foods can provide all of the essential nutrients required for the normal functioning of the human body. In this context, food is necessary to provide energy, to provide structural components for building and repairing body tissues, and to regulate body processes.
Industry:Science
Echolocation refers to an animal's use of sound reflections to localize objects and to orient in the environment. Echolocating animals transmit acoustic signals and process information contained in the reflected signals, allowing the detection, localization, and identification of objects by sound. Echolocation has been documented in bats, marine mammals, some species of nocturnal birds, and to a limited extent in blind or blindfolded humans. Specialized perceptual and neural processes for echolocation have been detailed only for bats and dolphins.
Industry:Science
Determination of the biology of extinct organisms is hampered by the fact that, except in very unusual situations, only their hard parts (teeth, skeleton, shells) fossilize. In other words, a vertebrate paleontologist studying a particular dinosaur is almost always limited to the skeleton, and often only part of that skeleton. Information about the remainder of the animal's anatomy, its behavior, and other attributes must be inferred. This information is required in order to visualize the fossil as a living organism and to consider its paleoecology.
Industry:Science
Any of the ~25 species of large fishes that comprise the family Acipenseridae in the order Acipenseriformes. These fish are found in North Temperate Zone waters, where they are almost exclusively bottom-living and feed on organisms such as mollusks, worms, and larvae. The body has five rows of bony plates, of which one is situated dorsally, two laterally, and two ventrally. The snout is elongate, and there are four barbels on its lower surface; the mouth is ventrally located, and in the adult the jaws lack teeth. The skeleton is mainly cartilaginous.
Industry:Science
Electrically powered light sources can be divided into three broad classes: (1) solid materials heated to high temperature such as incandescent lamps, (2) direct-conversion solid-state devices such as light-emitting diodes, and (3) gas-discharge systems such as fluorescent and metal halide lamps. Gas-discharge lamps operated at radio frequencies are efficient sources with interesting properties, whereas there is no advantage in operating incandescent or solid-state light sources at radio frequencies. Radio frequencies range from about 10 kHz to 30 GHz.
Industry:Science
