- 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.
A gas of atoms, generally ultracold, in which the individual atoms possess half-integer spin (that is, are fermionic). Since the 1980s, researchers have developed powerful new techniques for cooling atoms to ultralow temperatures. Among the most significant achievements made possible by these technical developments was the creation in 1995 of the long-sought Bose-Einstein condensate. In a Bose-Einstein condensate, atoms are cooled to such a low temperature that they collect in the quantum-mechanical ground state of their confinement volume. Bose-Einstein condensation is possible only in the class of particles known as bosons. Particles of the other class, fermions, are forbidden to occupy the same quantum state and are thus prevented from directly condensing.
Industry:Science
A gas turbine power plant producing shaft power to drive a propeller or propellers for aircraft propulsion. Because of its high propulsive efficiency at low flight speeds, it is the power plant of choice for short-haul and low-speed transport aircraft where the flight speeds do not exceed Mach 0.5–0.6. Developments in high-speed, highly loaded propellers have extended the range of propellers to flight speeds up to Mach 0.8–0.9, and there are prospects of these extremely efficient prop-fans assuming a much larger role in powering high-speed transport aircraft.
Industry:Science
A gas, liquid, or solid used to prevent contact of parts in relative motion, and thereby reduce friction and wear. In many machines, cooling by the lubricant is equally important. The lubricant may also be called upon to prevent rusting and the deposition of solids on close-fitting parts.
Industry:Science
A gaseous chemical element, He, atomic number 2 and atomic weight 4.0026. Helium is one of the noble gases in group 18 of the periodic table. It is the second lightest element. The world's chief source of helium is a group of natural gas fields in the United States.
Industry:Science
A gaseous chemical element, Kr, atomic number 36, and atomic weight 83.80. Krypton is one of the noble gases in group 18 of the periodic table. Krypton is a colorless, odorless, and tasteless gas. The table gives some physical properties of krypton. The principal use for krypton is in filling electric lamps and electronic devices of various types. Krypton-argon mixtures are widely used to fill fluorescent lamps.
Industry:Science
A gaseous chemical element, Ne, with atomic number 10 and atomic weight 20.183. Neon is a member of the family of noble gases. The only commercial source of neon is the Earth's atmosphere, although traces of neon are found in natural gas, minerals, and meteorites.
Industry:Science
A gaseous chemical element, O, atomic number 8, and atomic weight 15.9994. Oxygen is of great interest because it is the essential element both in the respiration process in most living cells and in combustion processes. It is the most abundant element in the Earth's crust. About one-fifth (by volume) of the air is oxygen.
Industry:Science
A gaseous layer that envelops the Earth and most other planets in the solar system. Earth, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Titan (Saturn's largest satellite) are all known to possess substantial atmospheres that are held by the force of gravity. The structure and properties of the various atmospheres are determined by the interplay of physical and chemical processes. Structural features of Earth's atmosphere detailed below can often be identified in the atmospheres of other planetary bodies.
Industry:Science
A gaseous, liquid, or solid fuel, also known as synfuel, that does not occur naturally. Synthetic fuel can be made from tar sand, coal, or oil shale. Included in the category are various fuel gases, such as substitute natural gas and synthesis gas.
Industry:Science
A gas-filled sac found in the body cavities of most bony fishes (Osteichthyes). The swim bladder has various functions in different fishes, acting as a float which gives the fish buoyancy, as a lung, as a hearing aid, and as a sound-producing organ. In many fishes it serves two or three of these functions, and in the African and Asiatic knife fishes (Notopteridae) it may serve all four. The swim bladder contains the same gases that make up air, but often in different proportions.
Industry:Science
