| RA | radioactive; ragocyte; ragweed antigen; rapidly adapting [receptors]; reactive arthritis; reciprocal... |
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| RAIU | radioactive iodine uptake |
| RAMP | radioactive antigen microprecipitin; right atrial mean pressure |
| RAU | radioactive uptake |
| RI | radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [stra... |
| radioactive tracers | Radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., geiger counter. Compounds containing tracers are often said to be tagged or labelled. (12 Dec 1998) |
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| radioactive waste | <radiobiology> Equipment and materials from nuclear operations which are radioactive and for which there is no further anticipated use. Wastes are generally classified as high-level (having radioactivity concentrations of hundreds to thousands of curies per gallon or cubic foot), low-level (in the range of 1 microcurie per gallon or cubic foot), or intermediate (between high and low). See: curie. (09 Oct 1997) |
| gold colloid, radioactive | <chemical> A radioactive suspension of minute particles of metallic gold, made by exposure to neutrons. It is used in the pleural cavity to treat lung cancer. Pharmacological action: antineoplastic agent, radiopharmaceuticals. (12 Dec 1998) |
| rose bengal radioactive test | A test of liver function used as a means of measuring hepatic blood flow and for scintillation scanning of the liver to determine size and contour of the liver, or the presence of space-occupying masses in the liver. (05 Mar 2000) |
| water pollutants, radioactive | Pollutants, present in water or bodies of water, which exhibit radioactivity. (12 Dec 1998) |
| colloidal radioactive gold | A radioactive isotope of gold emitting negative beta particles and gamma radiation, with a half-life of 2.7 days; formerly used for irradiation of closed serous cavities in the palliative treatment of ascites and pleural effusion due to metastatic malignancies, and for liver scans. Synonym: 198Au colloid, colloidal radioactive gold. (05 Mar 2000) |
| soil pollutants, radioactive | Pollutants, present in soil, which exhibit radioactivity. (12 Dec 1998) |
| elements, radioactive | Chemical elements which spontaneously transmute into another element with corpuscular or electromagnetic radiation. The natural radioactive elements are all those with an atomic number above 83, and some other elements, such as potassium (atomic number 19) and rubidium (atomic number 7), which are very weakly radioactive. (12 Dec 1998) |
| acid dissociation constant | <chemistry> This is the equilibrium constant for the breaking apart of a weak acid into its hydrogen and conjugate base in a water solution. (09 Oct 1997) |
| Ambard's constant | <physiology> Obsolete law's for output of urea: 1. With the urinary urea concentration constant, urea output varies directly as the square of the concentration of the blood urea. 2. With the blood urea concentration constant, urea output varies inversely as the square root of its urinary concentration. (05 Mar 2000) |
| association constant | <chemistry> Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium. (18 Nov 1997) |
| Avogadro's constant | <physics> The number of molecules in a mole (gram molecular weight) of a substance, equals 6.02 x 1023 molecules. (09 Oct 1997) |
| base dissociation constant | <chemistry> This is the equilibrium constant for the reaction in which a weak base breaks apart in water to form its conjugate acid and hydroxide ion. (09 Oct 1997) |
| binding constant | <chemistry> Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium. (18 Nov 1997) |
| boltzmann constant | <radiobiology> K = 1.38 x 10^-16 erg/degree. This is the ratio of the universal gas constant to Avogadro's number. It is also used to relate temperatures (Kelvin) to energies (ergs or Joules) via E = (constant of order unity) kT. (09 Oct 1997) |