| first-order kinetics | A term describing the reaction rate of a chemical reaction in which the rate is proportional to the concentration (in moles) of only one of the reactants. Such a reaction might have an equation like rate = k[A], where k is the reaction rate constant and [A] is the concentration of a reactant A. (09 Oct 1997) |
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| first-order reaction | A reaction the rate of which is proportional to the concentration of the single substance undergoing change; radioactive decay is a first-order process, defined by the equation -(dN/dt)=kN, where N is the number of atoms subject to decay (reaction), t is time, and k is the first-order decay (reaction) constant, i.e., the fraction of all atoms decaying per unit of time. See: decay constant, order. (05 Mar 2000) |
| first parallel pelvic plane | The upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. Synonym: apertura pelvis superior, aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic inlet, pelvic plane of inlet, plane of inlet. (05 Mar 2000) |
| first rank symptoms | Those symptom's that, when present, indicate that the diagnosis of schizophrenia is likely, provided that organic or toxic aetiology is ruled out: delusion of control, thought broadcasting, thought withdrawal, thought insertion, hearing one's thoughts spoken aloud, auditory hallucinations that comment on one's behaviour, and auditory hallucinations in which two voices carry on a conversation. Synonym: first rank symptoms, schneiderian first rank symptoms. (05 Mar 2000) |
| first-set rejection | Allograft transplantation between two organisms not previously sensitised to the graft tissue. Necrosis of the graft usually occurs within 10 days of transplantation. (05 Mar 2000) |
| first stage of labour | The part of labour when the cervix dilates fully (to 10 centimeters). The first stage of labour is also called the stage of dilatation. (12 Dec 1998) |
| first temporal convolution | A longitudinal gyrus on the lateral surface of the temporal lobe between the lateral (sylvian) fissure and the superior temporal sulcus. Synonym: gyrus temporalis superior, first temporal convolution, superior temporal convolution. (05 Mar 2000) |
| first visceral cleft | <anatomy> The cleft between the hyoid and mandibular arches of the embryo; the external auditory meatus is developed from its dorsal portion. Synonym: first visceral cleft. (05 Mar 2000) |
| adenoidal-pharyngeal-conjunctival virus | <virology> An icosahedral (20-sided) virus that contains DNA, there are over 40 different adenovirus varieties, some of which cause the common cold. (10 May 1997) |
| ascending pharyngeal artery | <anatomy, artery> Origin, external carotid; distribution, wall of pharynx and soft palate, posterior cranial fossa. Synonym: arteria pharyngea ascendens. (05 Mar 2000) |
| ascending pharyngeal plexus | An autonomic plexus on the artery of the same name, formed of fibres from the superior cervical ganglion. Synonym: plexus pharyngeus ascendens. (05 Mar 2000) |
| buccopharyngeal part of superior pharyngeal constrictor | See: superior constrictor muscle of pharynx. Synonym: pars buccopharyngea musculi constrictoris pharyngei superioris. (05 Mar 2000) |
| caudal pharyngeal complex | The ultimobranchial body associated with the embryonic fourth and transitory fifth pharyngeal pouches. (05 Mar 2000) |
| glossopharyngeal part of superior pharyngeal constrictor | See: superior constrictor muscle of pharynx. Synonym: pars glossopharyngea musculi constrictoris pharyngis superioris. (05 Mar 2000) |
| ceratopharyngeal part of middle pharyngeal constrictor | See: middle constrictor muscle of pharynx. Synonym: pars ceratopharyngea musculi constrictoris pharyngis medii. (05 Mar 2000) |