- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- 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 chemical element, symbol Am, atomic number 95. The isotope <sup>241</sup>Am is an alpha emitter with a half-life of 433 years. Other isotopes of americium range in mass from 232 to 247, but only the isotopes of mass 241 and 243 are important. The isotope <sup>241</sup>Am is routinely separated from “old” plutonium and sold for a variety of industrial uses, such as 59-keV gamma sources and as a component in neutron sources. The longer-lived <sup>243</sup>Am (half-life 7400 years) is a precursor in <sup>244</sup>Cm production.
Industry:Science
A chemical element, symbol As, atomic number 33. Arsenic is found widely distributed in nature (approximately 5 × 10<sup>−4</sup> of the Earth's crust). It is one of the 22 known elements composed of only one stable nuclide, <sub>33</sub><sup>75</sup>As; the atomic weight is 74.92158. There are 17 other radioactive arsenic nuclides known.
Industry:Science
A chemical element, symbol Bh, atomic number 107. Bohrium was synthesized and identified in 1981 by using the Universal Linear Accelerator (UNILAC) of the Gesellschaft für Schwerionenforschung (GSI) at Darmstadt, West Germany, by a team led by P. Armbruster and G. Müzenberg. The reaction used to produce the element was proposed and applied in 1976 by Y. T. Oganessian and colleagues at Dubna Laboratories in Russia. A <sup>209</sup>Bi target was bombarded by a beam of <sup>54</sup>Cr projectiles.
Industry:Science
A chemical element, symbol Db, atomic number 105. It was synthesized and identified unambiguously in March 1970 at the heavy-ion linear accelerator (HILAC) at the Lawrence Radiation Laboratory, Berkeley, University of California. The discovery team consisted of A. Ghiorso and colleagues.
Industry:Science
A chemical element, symbol Hs, atomic number 108. It was synthesized and identified in 1984 by using the Universal Linear Accelerator (UNILAC) at Darmstadt, West Germany, by the same team (led by P. Armbruster and G. Müzenberg) which first identified bohrium and meitnerium. The isotope <sup>265</sup>Hs was produced in a fusion reaction by bombarding a <sup>208</sup>Pb target with a beam of <sup>58</sup>Fe projectiles.
Industry:Science
A chemical element, symbol Lr, atomic number 103. Lawrencium, named after E. O. Lawrence, is the eleventh transuranium element; it completes the actinide series of elements.
Industry:Science
A chemical element, symbol Na, atomic number 11, and atomic weight 22.9898. Sodium is between lithium and potassium in group I of the periodic table. The element is a soft, reactive, low-melting metal with a specific gravity of 0.97 at 20°C (68°F). Sodium is commercially the most important alkali metal. It was named by Humphry Davy, who first isolated it by electrolysis in 1807.
Industry:Science
A chemical element, symbol Np, atomic number 93. Neptunium is a member of the actinide or 5<i>f</i> series of elements. It was synthesized as the first transuranium element in 1940 by bombardment of uranium with neutrons to produce neptunium-239. The lighter isotope <sup>237</sup>Np, a long-lived alpha emitter with half-life 2.14 × 10<sup>6</sup> years, is particularly important chemically.
Industry:Science
A chemical element, symbol Rb, atomic number 37, and atomic weight 85.47. Rubidium is an alkali metal in group 1 of the periodic table. It is a light, low-melting, reactive metal. Little is known about rubidium because it has never been available in quantity at a reasonable price. In 1958 rubidium salts became much more readily available and at lower prices as by-products of lithium chemicals manufacture, and knowledge of the properties and reactions of rubidium metal have developed accordingly. Rubidium was discovered in 1861 by R. Bunsen and G. R. Kirchhoff by interpretation of its spectral lines. Bunsen first prepared free rubidium metal that same year, using an electrolytic method.
Industry:Science
A chemical element, symbol Rf, atomic number 104. Rutherfordium is the first element beyond the actinide series, and the twelfth transuranium element. In 1964 G. N. Flerov and coworkers at the Dubna Laboratories in the Soviet Union claimed the first identification of rutherfordium (element 104). A. Ghiorso and coworkers made a definitive identification at the University of California, Berkeley, in 1969 and suggested the name rutherfordium (symbol Rf).
Industry:Science
