| atomic theory | That chemical compounds are formed by the union of atoms in certain definite proportions; in its modern form, first advanced in 1803 by John Dalton. (05 Mar 2000) |
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| atomic volume | The atomic weight of an element divided by its density in the solid state; the volume of the gram-atomic weight of a solid element. (05 Mar 2000) |
| atomic weight | <chemistry> The average weight of an atom of an element, i.e. The total mass of protons and neutrons in an atom. (09 Oct 1997) |
| gram-atomic weight | Atomic weight expressed in grams. Compare: mole. (05 Mar 2000) |
| microscopy, atomic force | Microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. A microcomputer keeps track of the vertical excursions as a function of the position of the probe in the horizontal plane and presents the sample's image. (12 Dec 1998) |
| spectrophotometry, atomic absorption | A highly sensitive technique used to analyze various elements, especially metals, including aluminum, arsenic, beryllium, calcium, copper, iron, lead, and lithium, which are present in trace amounts. The atoms are excited above a ground state by flame vaporization, and the radiation emitted as the molecules return to a ground state is measured in unexcited non-ionised molecules. (12 Dec 1998) |
| advanced multiple-beam equalization radiography | A variant of scanning equalization radiography using several X-ray beams. (05 Mar 2000) |
| Balkan beam | An overhead frame, supported on uprights attached to the bedposts or to a separate stand, from which a splinted limb is slung in the treatment of fracture or joint disease. Synonym: Balkan beam, Balkan splint. (05 Mar 2000) |
| beam | <radiobiology> Stream of particles or electromagnetic radiation travelling in a single direction. (09 Oct 1997) |
| beam dump | <radiobiology> A mass of shielding material which absorbs the energy of a beam of particles or electromagnetic radiation. (09 Oct 1997) |
| beam-plasma reaction | <radiobiology> Fusion reaction which occurs from the collision of a fast beam ion with a thermal plasma ion. (09 Oct 1997) |
| beam splitter | <radiobiology> Optical device for dividing a beam of electromagnetic radiation into two or more separate beams. (09 Oct 1997) |
| beam tree | <botany> A tree (Pyrus aria) related to the apple. Origin: AS. Beam a tree. See: Beam. Source: Websters Dictionary (01 Mar 1998) |
| beam-wall reaction | <radiobiology> Fusion reaction which occurs from the collision of a fast beam ion with an ion embedded in or adsorbed onto the reactor wall. (09 Oct 1997) |
| cantilever beam | In dentistry, a beam that is supported by only one fixed support at only one of its ends. (05 Mar 2000) |