| ISA | Instrument Society of America; intracarotid sodium amytal; intrinsic simulating activity; intrinsic ... |
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| SA | salicylic acid; saline [solution]; salt added; sarcoidosis; sarcoma; scalenus anticus; secondary ame... |
| EC | effective concentration; ejection click; electrochemical; electron capture; embryonal carcinoma; eme... |
| MCC | mean corpuscular hemoglobin concentration; medial cell column; Medical Council of Canada; metacerebr... |
| MEC | median effective concentration; middle ear canal; middle ear cell; minimum effective concentration |
| critical concentration | <chemistry> The minimum concentration of units needed before a biological polymer will form. Examples of biopolymers are microtubules from tubulin units, polypeptides from amino acid units, polysaccharides from simple sugar units, etc. (09 Oct 1997) |
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| critical dissolved oxygen concentration | <biology> The minimum concentration of oxygen in the water needed for the growth of a culture which has been submerged, where oxygen is the limiting factor to the growth of the culture. (09 Oct 1997) |
| critical micelle concentration | The concentration at which an amphipathic molecule (e.g., a phospholipid) will form a micelle. (05 Mar 2000) |
| immediately dangerous to life concentration | <radiobiology> This is a regulatory value defined as the maximum exposure concentration in the workplace from which one could escape within 30 minutes without suffering symptoms which would interfere with escaping and without suffering any irreversible health effects. (04 Nov 1997) |
| osmolar concentration | The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent. (12 Dec 1998) |
| urinary concentration test | A test of renal tubular function whereby the patient is dehydrated for a measured period of time and the specific gravity of the urine is subsequently determined. (05 Mar 2000) |
| Fishberg concentration test | A test of renal water conservation; after overnight fluid deprivation, morning urine samples are collected and specific gravity is measured. (05 Mar 2000) |
| activity | 1. The state of being active, the ability to produce some effect, the extent of some function or action. 2. <chemistry> A thermodynamic quantity that represents the effective concentration of a solute in a nonideal solution, if concentrations are replaced by activities, the equations for equilibrium constants, electrode potentials, osmotic pressure, boiling point elevation, freezing point depression and vapour pressures of volatile solutes are converted from approximations that hold only for dilute solutions to exact equations that hold for all concentrations. The activity is equal to the product of the concentration and the activity coefficient, a dimensionless number measuring deviation from nonideality. Symbol a. The potential or true thermodynamic activity of a substance, as opposed to its molar concentration. 3. <radiobiology> The number of nuclear transitions or disintegrations occurring in a given quantity of radioactive material per unit time. The SI unit of activity is s-1. The special name for the unit of activity is becquerel (Bq). The previously used special unit of activity, curie (Ci), is being replaced by the becquerel. 1 Bq = 2.7 x E-11 Ci. 1 Ci = 3.7 x E10 Bq. 4. Optical activity. (16 Dec 1997) |
| activity coefficient | <chemistry> The factor by which the value of a concentration of a solute must be multiplied to determine its true thermodynamic activity. (06 May 1997) |
| activity cycles | Bouts of physical irritability or movement alternating with periods of quiescence. It includes biochemical activity and hormonal activity which may be cellular. These cycles are shorter than 24 hours and include sleep-wakefulness cycles and the periodic activation of the digestive system. (12 Dec 1998) |
| activity, drug | A measure of the physiological response a drug produces in the body. A less active drug produces less response (and visa versa). (12 Dec 1998) |
| blocking activity | The repression or elimination of electrical activity in the brain by the arrival of a sensory stimulus. (05 Mar 2000) |
| blood bactericidal activity | Native bactericidal property of blood due to normally occurring antibacterial substances such as beta lysin, leukin, etc. (12 Dec 1998) |
| melanoma growth stimulatory activity | Cytokine of the C X C subfamily. Potent mitogen. Activates and is chemotactic for, neutrophils. (18 Nov 1997) |
| water activity | <chemistry> An expression of the relative availability of water in a substance. Pure water has an water activity of 1.000. The water activity of a solution is one-hundredth its relative humidity. (09 Oct 1997) |