- 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.
An organic compound required in very small amounts for the normal functioning of the body and obtained mainly from foods. Vitamins are present in food in minute quantities compared to the other utilizable components of the diet, namely, proteins, fats, carbohydrates, and minerals. The average human adult eats about 600 g (21 oz) of food per day on a dry-weight basis, of which less than a gram is vitamins.
Industry:Science
An organic compound that contains a large ring. In the organic chemistry of alicyclic compounds, a closed chain of 12 carbon (C) atoms is usually regarded as the minimum size for a large ring; crown ethers are similarly defined. Macrocyclic compounds may be a single, continuous thread of atoms, as in cyclododecane ((CH<sub>2</sub>)<sub>12</sub>), or they may incorporate more than one strand or other ring systems (subcyclic units) within the macrocycle or macroring. In addition, macrocycles may be composed of aromatic rings that confer considerable rigidity upon the cyclic system. These aromatic rings may be joined together or coupled by spacer units consisting of one or more carbon atoms. The compounds generally thought of as macrocycles include crown ethers, cryptands, spherands, carcerands, cyclodextrins, cyclophanes, and calixarenes.
Industry:Science
An organic compound that contains one or more closed rings of carbon atoms. The term alicyclic specifically excludes carbocyclic compounds with an array of π-electrons characteristic of aromatic rings. Compounds with one to five alicyclic rings of great variety and complexity are found in many natural products such as steroids and terpenes. By far the majority of these have six-membered rings.
Industry:Science
An organic compound with the formula C<sub>2</sub>H<sub>2</sub> or HC≡CH. The first member of the alkynes, acetylene is a gas with a narrow liquid range; the triple point is −81°C (−114°F). The heat of formation (Δ<i>H</i>°<sub><i>f</i></sub>) is +227 kilojoules/mole, and acetylene is the most endothermic compound per carbon of any hydrocarbon. The compound is thus extremely energy-rich and can decompose with explosive force. At one time acetylene was a basic compound for much chemical manufacturing. It is highly reactive and is a versatile source of other reactive compounds.
Industry:Science
An organic compound with the general formula C<sub>n</sub>H<sub> 2n +2</sub>. Alkanes are open-chain (aliphatic or noncyclic) hydrocarbons with no multiple bonds or functional groups. They consist of tetrahedral carbon atoms, up to 10<sup>5</sup> carbons or more in length. The C-C σ bonds are formed from <i>sp</i><sup>3</sup> orbitals, and there is free rotation around the bond axis.
Industry:Science
An organic heterocyclic compound containing a diunsaturated ring of four carbon atoms and one sulfur atom.
Industry:Science
An organic substance with low electrical resistance. Two major classes of organic conductors are charge-transfer compounds and conducting polymers.
Industry:Science
An organism that belongs to the Kingdom Plantae (plant kingdom) in biological classification. The term is also loosely used to indicate any organism that is not an animal. In the most commonly accepted modern classification (the five-kingdom system), fungi, bacteria, and algae belong to the kingdoms Fungi, Monera, and Protista, respectively, rather than to the plant kingdom as they did in the outmoded two-kingdom system. The study of plants is called botany.
Industry:Science
Equipment designed to reduce the amount of water vapor in the atmosphere.
Industry:Science
