| arrhenic | Relating to arsenic. Origin: G. Arrhenikon (var.), arsenic (05 Mar 2000) |
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| arrhenic medication | Treatment of disease by means of the organic preparations of arsenic, the cacodylates, and methylarsinates. (05 Mar 2000) |
| Arrhenius doctrine | The theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution (e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. Synonym: Arrhenius law. (05 Mar 2000) |
| arrhenius equation | This equation expresses the logarithmic relationship between the rate constant of a reaction and the reciprocal of the temperature (expressed in K). (09 Oct 1997) |
| Arrhenius law | The theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution (e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. Synonym: Arrhenius law. (05 Mar 2000) |
| Arrhenius plot | A plot of the logarithm of reaction rate against the reciprocal of absolute temperature. For a single stage reaction this gives a straight line from which the activation energy and the frequency factor can be determined. Often applied to data from complex biological systems when the form observed is frequently a series of linear portions with sudden changes of slope. Great caution must be observed in interpreting such slopes in terms of activation energies for single processes. (18 Nov 1997) |
| Arrhenius, Svante | <person> Swedish chemist and Nobel laureate, 1859-1927. See: Arrhenius doctrine, Arrhenius equation, Arrhenius law, Arrhenius-Madsen theory. (05 Mar 2000) |
| Arrhenius-Madsen theory | That the reaction of an antigen with its antibody is a reversible reaction, the equilibrium being determined according to the law of mass action by the concentrations of the reacting substances. (05 Mar 2000) |
| arrhenoblastoma | <oncology, tumour> A type of ovarian tumour whose sells secrete a male sex hormone (testosterone) causing virilisation in women. (27 Sep 1997) |
| arrhinencephaly | Congenital absence or rudimentary state of the rhinencephalon, or olfactory lobe of the brain, on one or both sides, with a corresponding lack of development of the external olfactory organs. Origin: G. A-priv. + rhis (rhin-), nose, + enkephalos, brain (05 Mar 2000) |
| arrhinia | Synonym: arhinia. Origin: G. A-priv. + rhis (rhin-), nose (05 Mar 2000) |
| arrhizous | <botany> Destitute of a true root, as a parasitical plant. Origin: Gr. Not rooted; priv. + a root. Source: Websters Dictionary (01 Mar 1998) |
| arrhythmia | <cardiology, physiology> Any variation from the normal rhythm of the heart beat, including sinus arrhythmia, premature beat, heart block, atrial fibrillation, atrial flutter, pulsus alternans and paroxysmal tachycardia. Origin: Gr. Rhythmos = rhythm (18 Nov 1997) |
| arrhythmia, sinus | Irregularity of the heart rate related to functioning of the sinoatrial node. (12 Dec 1998) |
| arrhythmias | Abnormal heart rhythms. The heartbeats may be too slow, too rapid, irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than 60 beats per minute) are called bradycardias. Irregular heart rhythms are called fibrillations (as in atrial fibrillation). When a single heartbeat occurs earlier than normal, it is called a premature contraction. (12 Dec 1998) |