| emission-computed tomography | <radiology> Tomography using emissions from radionuclides and a computer algorithm to reconstruct the image. (20 Jun 2000) |
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| emission electron | <physics>? A beta particle resulting from radioactive decay. (05 Mar 2000) |
| emission offset | <chest medicine> A reduction in the air pollution emissions of existing sources to compensate for emissions from new sources. (05 Dec 1998) |
| emission standard | This regulatory value is a quantitative limit on the emission or discharge of a potentially toxic substance from a source. The simplest form for regulatory purposes is a uniform emission standard (UES) where the same limit is placed on all emissions of a particular contaminant. (09 Oct 1997) |
| field-emission microscope | <instrument, microscopy> Either one of two kinds of point-projection microscopes, both invented by E. W. Muller: (1) The older device (1936) is a specialised cathode-ray tube, employing field-emission of electrons from a negatively charged tip of a very sharp needle in a vacuum, by point-projection of the image onto a positively charged, fluorescent screen. (2) A later device (field-ion-mission microscope, 1950) emits absorbed helium ions from an anode. (05 Aug 1998) |
| field emission tube | An X-ray tube that uses a cold cathode, relying on the tube voltage to pull electrons from it to the anode. (05 Mar 2000) |
| flame emission spectrophotometry | Determination of the concentration of an element by measurement of light emitted when the element is excited by energy in the form of heat. (05 Mar 2000) |
| absorption spectrum | <chemistry> A graph of the amount of light a substance absorbs, plotted as a fuction of energy, frequency or wavelength. (15 Jan 1998) |
| antimicrobial spectrum | See: spectrum. (05 Mar 2000) |
| broad spectrum | <pharmacology> Often used to describe an antibiotic that is effective against a wide range of microorganisms. (13 Nov 1997) |
| broad spectrum antibiotic | An antibiotic having a wide range of activity against both Gram-positive and Gram-negative organisms. (05 Mar 2000) |
| Raman spectrum | The characteristic array of light produced by the Raman effect. (05 Mar 2000) |
| visible spectrum | That part of electromagnetic radiation that is visible to the human eye; it extends from extreme red, 7606 A |
| chromatic spectrum | The continuum of colours that white light forms on passing through a prism or diffraction grating. Synonym: colour spectrum. (05 Mar 2000) |
| colour spectrum | The continuum of colours that white light forms on passing through a prism or diffraction grating. Synonym: colour spectrum. (05 Mar 2000) |