- 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.
The development of microwave heating was preceded by work with radio waves, which were experimentally produced by Heinrich Hertz at Karlsruhe Polytechnic in Germany between 1885 and 1889. Hertz measured the wavelength and velocity of these waves. His first oscillator operated between 500,000 and 1,500,000 Hz (cycles per second), and the waves were tested on animals. He concluded that the only effect of these waves was that owing to heat. This work led to the first example of high-frequency heating therapy on humans at a Paris hospital in 1895.
Industry:Science
The Dryolestida (formerly known as the Pantotheria or Eupantotheria) are an extinct order of mammals related to the living marsupials and eutherian (placental) mammals. Along with the closely related symmetrodonts, they were the most diverse group of mammals during the Jurassic. They are often found in some of the same quarries that yield the giant sauropod dinosaurs. Most were about the size and shape of a shrew or mouse, with teeth adapted for chopping up a diet of insects, and they apparently were adapted for living in trees like squirrels.
Industry:Science
The conversion of most types of coal (with the exception of anthracite) primarily to petroleumlike hydrocarbon liquids which can be substituted for the standard liquid or solid fuels used to meet transportation, residential, commercial, and industrial fuel requirements. Coal liquids contain less sulfur, nitrogen, and ash, and are easier to transport and use than the parent (solid) coal. These liquids are suitable refinery feedstocks for the manufacture of gasoline, heating oil, diesel fuel, jet fuel, turbine fuel, fuel oil, and petrochemicals.
Industry:Science
That property of an electron which gives rise to its angular momentum about an axis within the electron. Spin is one of the permanent and basic properties of the electron. Both the spin and the associated magnetic dipole moment of the electron were postulated by G. E. Uhlenbeck and S. Goudsmit in 1925 as necessary to allow the interpretation of many observed effects, among them the so-called anomalous Zeeman effect, the existence of doublets (pairs of closely spaced lines) in the spectra of the alkali atoms, and certain features of x-ray spectra.
Industry:Science
The high-energy, charged particles that are trapped into orbits by the geomagnetic field, forming radiation belts that surround the Earth. The belts consist primarily of electrons and protons and extend from a few hundred kilometers above the Earth to a distance of about <i>8</i> <i>R<sub>e</sub></i> (<i>R<sub>e</sub></i> = radius of Earth = 6371 km = 3959 mi). James Van Allen and coworkers discovered them in 1958 using radiation detectors carried on satellites <i>Explorer 1</i> and <i>3</i>, and they are often referred to as the Van Allen belts.
Industry:Science
The intelligible images organized into readable text of various styles and sizes. Type used in printing on paper or in video display is divided into four categories: foundry, machine-cast, photocomposed, and digitized type. In the first two the face of the letter is raised on one end of a piece of metal. It is from that surface, when inked, that the impression of type was made from its invention until the 1970s. In photocomposition, the type is reproduced photographically. Digitized methods assemble dots into typographic letters, lines, or pages.
Industry:Science
The glacial history of the Earth is complex and extends back in geological time to the Proterozoic and possibly the Archean. Global glaciations have occurred during every geological period except the Jurassic. This persistence of global glaciation, as well as repeated and continuing glaciation in high mountainous areas, wherever altitudes exceed the local snowline, is so consistent that one might argue that the Earth is essentially a glacial planet. Evidence suggests that glacial epochs have repeatedly occurred almost every 100,000 to 150,000 years.
Industry:Science
Substances formed by the addition of one or more elements, usually metals, to aluminum. The principal alloying elements in aluminum-base alloys are magnesium (Mg), silicon (Si), copper (Cu), zinc (Zn), and manganese (Mn). In wrought products, which constitute the greatest use of aluminum, the alloys are identified by four-digit numbers of the form NXXX, where the value of N denotes the alloy type and the principal alloying element(s) as follows: 1 (Al; at least 99% aluminum by weight), 2 (Cu), 3 (Mn), 4 (Si), 5 (Mg), 6 (Mg + Si), 7 (Zn), 8 (other).
Industry:Science
The closest distance which a satellite, revolving around a parent body, can approach the parent without being pulled apart tidally. The simplest formal definition is that the Roche limit is the minimum distance at which a satellite can be in equilibrium under the influence of its own gravitation and that of the central mass about which it is describing a circular orbit. If the satellite is in a circular orbit and has negligible mass, the same density as the primary, and zero tensile strength, the Roche limit is 2.46 times the radius of the primary.
Industry:Science
The division of forestry concerned with taxonomy of trees and other woody plants. Dendrology, called forest botany in some countries, usually is limited to taxonomy of trees but may also include shrubs and woody vines. This basic subject in the training of foresters teaches how trees are named (nomenclature), described (morphology), and grouped (classification); how to find the name of an unknown tree and recognize important forest species (identification); and where trees occur both by geographic ranges of species and by forest types (distribution).
Industry:Science
