- 行业: Printing & publishing
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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 relatively new order of flightless insects first described from Sulphur Mountain near Banff, Canada, in 1914 by entomologist E. M. Walker. There are now 26 described species of living Grylloblattodea in five genera. Called ice crawlers, they are typically found at high elevations in East Asia, Japan, Siberia, and western North America.
Industry:Science
A relatively primitive subclass of the class Liliopsida (monocotyledons) of the division Magnoliophyta (Angiospermae), the flowering plants, consisting of 4 orders, 16 families, and less than 500 species. Typically they are aquatic or semiaquatic, with apocarpous flowers and nonendospermous seeds. They have trinucleate pollen, and the stomates usually have two subsidiary cells. The orders Alismatales, Hydrocharitales, and Najadales are closely related among themselves and have often been treated as a single order, Helobiae or Helobiales. The Triuridales differ from the other orders in being terrestrial and mycotrophic, without chlorophyll, and in having abundant endosperm in the seeds.
Industry:Science
A relatively rare chemical element, symbol Cd, atomic number 48, closely related to zinc, with which it is usually associated in nature. It is a silvery-white ductile metal with a faint bluish tinge. It is softer and more malleable than zinc, but slightly harder than tin. It has an atomic weight of 112.40 and a specific gravity of 8.65 at 20°C (68°F). Its melting point of 321°C (610°F) and boiling point of 765°C (1410°F) are lower than those of zinc. There are eight naturally occurring stable isotopes, and eleven artificial unstable radio isotopes have been reported. Cadmium is the middle member of group 12 (zinc, cadmium, and mercury) in the periodic table, and its chemical properties generally are intermediate between zinc and mercury. The cadmium ion is displaced by zinc metal in acidic sulfate solutions. Cadmium is bivalent in all its stable compounds, and its ion is colorless.
Industry:Science
A relatively small and generally rather compact group of protozoa in the subphylum Sporozoa. Authorities differ as to the group's taxonomic status; that assigned it by the Committee on Taxonomy and Taxonomic Problems of the Society of Protozoologists is followed here: a suborder of the order Eucoccida, subclass Coccidia, class Telosporea, subphylum Sporozoa. The Haemosporina are common protozoan parasites of vertebrates, and some of them are important as causes of illness and death. The best known of the group are the four species of malarial parasites of humans. Not so well known are at least 60 other species of malarial parasites, with a wide host distribution among terrestrial vertebrates, as well as numerous species of <i>Haemoproteus</i> and <i>Leucocytozoon</i>, and some species of <i>Hepatocystis</i>. All three genera are closely related to the genus <i>Plasmodium</i>, in which all the true malarial parasites are placed (see <b>table</b>).
Industry:Science
A relatively small body orbiting a larger one that in turn orbits a star. In the solar system, all of the planets except Mercury and Venus have satellites. Well over 100 planetary satellites are known to exist, of which a total of 101 were definitely established by March 1, 2004, distributed as follows: Earth, 1; Mars, 2; Jupiter, 38; Saturn, 30; Uranus, 21; Neptune, 8; and Pluto, 1. Additional satellites have been observed in all four giant systems (Jupiter, Saturn, Uranus, and Neptune); more observations are needed to define their orbits. The close flyby of the <i>Galileo</i> spacecraft (enroute to Jupiter) of the asteroid 243 Ida in 1993 revealed the presence of a 0.9-mi-diameter (1.5-km) satellite, now known as Dactyl. This unexpected discovery has been followed by the detection of several other asteroid satellites by Earth-based observers. Several Kuiper Belt objects (distant comet nuclei) have also been observed to be binaries.
Industry:Science
A relatively small group of extinct South American ungulates, ranging from the late Paleocene to the late Miocene. They are customarily divided into two suborders: the late Paleocene–Eocene Trigonostylopoidea, and the early Eocene–late Miocene Astrapotheroidea. Eocene members of the order, such as <i>Albertogaudrya</i>, tended to be large animals and exhibited the enlargement of the canines characteristic of later astrapotheres.
Industry:Science
A relatively small subclass of the class Magnoliopsida (dicotyledons) of the division Magnoliophyta (Angiospermae), the flowering plants, consisting of 3 orders, 14 families, and about 11,000 species. They have mostly trinucleate pollen and ovules with two integuments (bitegmic) and a nucellus that is more than one cell thick (crassinucellate). Also, the ovules are often distorted by unequal growth so that the micropyle is brought near the funiculus and the chalazal end (campylotropous), or half inverted so the funiculus is attached near the middle (amphitropous) and these are usually borne on a free-central or basal placenta.
Industry:Science
A relief valve set to open at a pressure safely below the bursting pressure of a container, such as a boiler or compressed air receiver. Typically, a disk is held against a seat by a spring; excessive pressure forces the disk open (see <b>illus.</b>). Construction is such that when the valve opens slightly, the opening force builds up to open it fully and to hold the valve open until the pressure drops a predetermined amount, such as 2–4% of the opening pressure. This differential or blow-down pressure and the initial relieving pressure are adjustable. Adjustments must be set by licensed operators, and settings must be tamperproof. The ASME Boiler Construction Code gives typical requirements for safety valves.
Industry:Science
A remote sensing technique or device that uses sound waves to detect, locate, and sometimes identify objects in water. The term is an acronym for sound navigation and ranging. There are many applications, using a wide variety of equipment. Naval uses include detection of submarines, sea mines, torpedoes, and swimmers; torpedo guidance; acoustic mines; and navigation. Civilian uses include determining water depth; finding fish; mapping the ocean floor; locating various objects in the ocean, such as pipelines, wellheads, wrecks, and obstacles to navigation; measuring water current profiles; and determining characteristics of ocean bottom sediments. Sound waves rather than electromagnetic waves (for example, radar and light) are used in these applications because their attenuation in seawater is much less. Some marine mammals use sound waves to find food and to navigate.
Industry:Science
A remote-sensing device that transmits and receives microwave radiation for the purpose of detecting and measuring weather phenomena. Radar is an acronym for radio detection and ranging. Today, many types of sophisticated radars are used in meteorology, ranging from Doppler radars, which are used to determine air motions (for example, to detect tornadoes), to multiparameter radars, which provide information on the phase (ice or liquid), shape, and size of hydrometeors. Airborne Doppler radars play a vital role in meteorological research. Additionally, weather radar is now orbiting the Earth on the NASA <i>Tropical Rainfall Measuring Mission</i> satellite, launched in November 1997. Radars are also used to detect hail, estimate rainfall rates, probe the clear-air atmosphere to monitor wind patterns, and study the electrification processes in thunderstorms that generate lightning discharges.
Industry:Science
