- 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 nonenzymatic chemical reaction involving condensation of an amino group and a reducing group, resulting in the formation of intermediates which ultimately polymerize to form brown pigments (melanoidins). It was named for the French biochemist Louis-Camille Maillard, who published initial studies of the reaction between 1912 and 1916. The reaction is of extreme importance to food chemistry, especially because of its ramifications in terms of food quality.
Industry:Science
A nonfatal viral disease that occurs naturally in cottontail rabbits in states bordering the Mississippi River as well as in Oklahoma and Texas, and in brush rabbits in California. Cottontail rabbits from other parts of the United States and domestic rabbits (<i>Oryctolagus</i>) are also susceptible. The disease is caused by infection with Shope papilloma virus, one of a number of papilloma viruses that infect a range of animals, including humans; it is spread naturally by contamination of broken skin or by the rabbit tick.
Industry:Science
A noninvasive technique for imaging subsurface tissue structure with micrometer-scale resolution. The principles of time gating, optical sectioning, and optical heterodyning are combined to allow cross-sectional imaging. Depths of 1–2 mm (0.04–0.08 in.) can be imaged in turbid tissues such as skin or arteries; greater depths are possible in transparent tissues such as the eye.
Industry:Science
A nonlinear circuit component that allows more current to flow in one direction than in the other. An ideal rectifier is one that allows current to flow in one (forward) direction unimpeded but allows no current to flow in the other (reverse) direction. Thus, ideal rectification might be thought of as a switching action, with the switch closed for current in one direction and open for current in the other direction. Rectifiers are used primarily for the conversion of alternating current (ac) to direct current (dc).
Industry:Science
A nonmetallic element, symbol I, atomic number 53, relative atomic mass 126.9045, the heaviest of the naturally occurring halogens. Under normal conditions iodine is a black, lustrous, volatile solid; it is named after its violet vapor.
Industry:Science
A nonporous envelope of thin material filled with a lifting gas and capable of lifting any surrounding material and usually a suspended payload into the atmosphere. A balloon which is supported chiefly by buoyancy imparted by the surrounding air is often referred to as an aerostat. The balloon rises because of a differential displacement of air according to Archimedes' principle, which states that the total upward buoyant force is equal to the weight of the air displaced. The upper practical limit for useful ballooning is approximately 34 mi (55 km). Beyond this, the exponential nature of the atmosphere would require balloons of enormous size and delicately thin skin.
Industry:Science
A normal galaxy like the Milky Way produces a few new stars each year. Starburst galaxies create new stars much more frequently, especially in the central regions, at rates tens or even hundreds of times higher. This phenomenon is still a mystery; a large supply of dense gas collected around the nucleus of the galaxy can supply the raw material for star formation, but it is not clear why or how the gas piles up in this way. Some likely causes include the formation of a galactic bar, with stars and gas following elliptical orbits that pass near the nucleus, or an interaction with another passing galaxy that perturbs the orbital motions. A third influence may be a magnetic field; since interstellar gas is partially ionized and ionic particles tend to move with magnetic field lines, this can ease the flow of gas toward the nucleus. In the last few years, astronomical techniques have been developed that allow the magnetic field to be imaged in starburst galaxies.
Industry:Science
A northern constellation named for a Greek hero (see <b>illustration</b>). Perseus and adjacent Cassiopeia are prominently located in the northern Milky Way. In Johan Bayer's (1603) star atlas, the bright star Mirfak marks Perseus' shoulder.
Industry:Science
A north-seeking form of gyroscope used as a directional reference in navigation. The first practical gyrocompasses were developed by H. Anschütz (Germany) in 1908, E. A. Sperry (United States) in 1911, and S. G. Brown (England) in 1916. Modern gyrocompasses are so reliable and so much more accurate than magnetic compasses that they are now used as the prime navigational instrument on nearly every ship and on major aircraft and missiles.
Industry:Science
A nuclear fusion reaction which occurs between various nuclei of the light elements when they are constituents of a gas at very high temperatures. Thermonuclear reactions, the source of energy generation in the Sun and the stable stars, are utilized in the fusion bomb.
Industry:Science
