- 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 bearing used in quality timekeeping devices, gyros, and instruments; usually made of synthetic corundum (crystallized Al<sub>2</sub>O<sub>3</sub>), which is more commonly known as ruby or sapphire. The extensive use of such bearings in the design of precision devices is mainly due to the outstanding qualities of the material. Sapphire's extreme hardness imparts to the bearing excellent wear resistance, as well as the ability to withstand heavy loads without deformation of shape or structure. The crystalline nature of sapphire lends itself to very fine polishing and this, combined with the excellent oil- and lubricant-retention ability of the surface, adds to the natural low-friction characteristics of the material. Sapphire is also nonmagnetic and oxidization-resistant, and has a very high melting point (3685°F or 2029°C). Ruby has the same properties as sapphire; the red coloration is due to the introduction of a small amount of chromium oxide.
Industry:Science
A bed of sediment or sedimentary rock that was deposited from a turbidity current. A turbidity current is an underwater flow produced by movement of a turbid mass of water downslope as a result of the excess weight of the turbid water as compared with the surrounding clear water. Turbidity currents are therefore a type of gravity (or density) current; such currents are kept in motion by gravity acting on relatively small differences in density between different fluids (gases or liquids) or between different parts of the same fluid mass. In some gravity currents the density difference results from a difference in temperature or salinity (for example, fresh water flowing above salt water), but in turbidity currents it results from the presence of dispersed sediment.
Industry:Science
A benign, infectious virus disease of humans characterized by coldlike symptoms and transient, generalized rash. This disease, also known as German measles, is primarily a disease of childhood. However, maternal infection during early pregnancy may result in infection of the fetus, giving rise to serious abnormalities and malformations. The congenital infection persists in the infant, who harbors and sheds virus for many months after birth.
Industry:Science
A biennial umbellifer (<i>Apium graveolens</i> var. <i>dulce</i>) of Mediterranean origin and belonging to the plant order Apiales. Celery is grown for its petioles or leafstalks, which are most commonly eaten as a salad but occasionally cooked as a vegetable (see <b>illus.</b>). Celeriac or knob celery (<i>A. graveolens</i> var. <i>rapaceum</i>) is grown for its enlarged rootlike stem and is commonly eaten as a cooked vegetable in Europe.
Industry:Science
A biennial umbellifer (<i>Daucus carota</i>) of Asiatic and Mediterranean origin belonging to the plant order Umbellales. The carrot is grown for its edible roots which are eaten raw or cooked (<b>Fig. 1</b>).
Industry:Science
A biennial, <i>Petroselinum crispum</i>, of European origin belonging to the plant order Umbellales. Parsley is grown for its foliage and is used to garnish and flavor foods. It contains large quantities of vitamins A and C and has been grown for 2000 years or more. Two types, plain-leafed and curled, are grown for their foliage; Hamburg parsley (<i>P</i>. <i>crispum</i> var. <i>tuberosum</i>), also called turnip-rooted parsley, is grown for its edible parsniplike root. Propagation is by seed. Harvesting begins 70–80 days after planting for foliage varieties, and 90 days after planting for Hamburg parsley.
Industry:Science
A binary compound of hydrogen and oxygen, empirical formula H<sub>2</sub>O<sub>2</sub>, used mostly in dilute aqueous solutions as an oxidizing agent. It was discovered in 1818 by the French chemist Louis-Jacques Thenard, who named it <i>eau oxygénée</i>. Its most remarkable feature is its tendency to decompose readily into water and oxygen, the first observed instance of contact catalysis.
Industry:Science
A binary compound of oxygen with another element. Oxides have been prepared for essentially all the elements, with the exception of the noble gases. Often, several different oxides of a given element can be prepared; a number exist naturally in the Earth's crust and atmosphere: silicon dioxide (SiO<sub>2</sub>) in quartz; aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) in corundum; iron oxide (Fe<sub>2</sub>O<sub>3</sub>) in hematite; carbon dioxide (CO<sub>2</sub>) gas; and water (H<sub>2</sub>O).
Industry:Science
A binary digit. In the computer, electronics, and communications fields, “bit” is generally understood as a shortened form of “binary digit.” In a numerical binary system, a bit is either a 0 or 1. Bits are generally used to indicate situations that can take one of two values or one of two states, for example, on and off, true or false, or yes or no. If, by convention, 1 represents a particular state, then 0 represents the other state. For example, if 1 stands for “yes,” then 0 stands for “no.”
Industry:Science
A binary star system in the Milky Way Galaxy consisting of a neutron star or a black hole accreting matter in the form of a disk from an early-type companion star. The most remarkable feature of the system is the presence of bipolar narrow outflows of matter (jets), with a velocity of 26% the speed of light, whose ejection axes change with time.
Industry:Science
