| diffusion shell | A small vessel made of a semipermeable membrane through which peptone, but not serum albumin, can pass; used in performing the Abderhalden test. (05 Mar 2000) |
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| facilitated diffusion | <physiology> A process by which substances are conveyed across cell membranes faster than would be possible by diffusion alone. This is generally achieved by proteins that provide a hydrophilic environment for polar molecules throughout their passage through the plasma membrane, acting as either shuttles or pores. See: symport, antiport, uniport. (18 Nov 1997) |
| lateral diffusion | Diffusion in two dimensions, usually referring to movement in the plane of the membrane, such as the motion of fluorescently labelled lipids or proteins measured by the technique of fluorescent recovery after photobleaching (FRAP). (18 Nov 1997) |
| least diffusion circle | In the configuration of rays emerging from a spherocylindrical lens system, the place where diverging rays of the lens first forming a line image are balanced by converging rays of the second lens. (05 Mar 2000) |
| burns, first degree | A first degree burn is superficial and has similar characteristics to a typical sun burn. The skin is red in colour and sensation is intact. In fact, it is usually somewhat painful. (12 Dec 1998) |
| ventriculography, first-pass | Radionuclide ventriculography where a bolus of radionuclide is injected and data are recorded from one pass through the heart ventricle. Left and right ventricular function can be analyzed independently during this technique. First-pass ventriculography is preferred over gated blood pool imaging for assessing right ventricular function. (12 Dec 1998) |
| mirror, first or front surface | <microscopy> An optical mirror on which the reflecting surface is applied to the front surface of the mirror instead of to the back, that is, to the first surface of incidence. (05 Aug 1998) |
| pregnancy trimester, first | Period of pregnancy from the first day of the last normal menstrual period through the completion of 14 weeks (98 days) of gestation. (12 Dec 1998) |
| healing by first intention | Healing by fibrous adhesion, without suppuration or granulation tissue formation. Synonym: primary adhesion, primary union. (05 Mar 2000) |
| schneiderian 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) |
| Schneider's 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) |
| double first | <engineering> A degree of the first class both in classics and mathematics. One who gains at examinations the highest honor both in the classics and the mathematics. Source: Websters Dictionary (01 Mar 1998) |
| error of the first kind | See: Error, alpha. (12 Dec 1998) |
| tuberosity of first metatarsal | A tubercle at the base of the bone to which is attached the tendon of the peroneus longus muscle. Synonym: tuberositas ossis metatarsalis primi. (05 Mar 2000) |
| first | 1. Preceding all others of a series or kind; the ordinal of one; earliest; as, the first day of a month; the first year of a reign. 2. Foremost; in front of, or in advance of, all others. 3. most eminent or exalted; most excellent; chief; highest; as, Demosthenes was the first orator of Greece. at first blush. See Blush. At first hand, from the first or original source; without the intervention of any agent. "It is the intention of the person to reveal it at first hand, by way of mouth, to yourself." (Dickens) First coat The first year's whole profits of a benefice or spiritual living. The earliest effects or results. "See, Father, what first fruits on earth are sprung From thy implanted grace in man!" (Milton) First mate, an officer in a merchant vessel next in rank to the captain. First name, same as Christian name. See Name, First officer, the watch from eight to twelve at midnight; also, the men on duty during that time. First water, the highest quality or purest luster; said of gems, especially of diamond and pearls. Synonym: Primary, primordial, primitive, primeval, pristine, highest, chief, principal, foremost. Origin: OE. First, furst, AS. Fyrst; akin to Icel. Fyrstr, Sw. & Dan. Forste, OHG. Furist, G. Furst prince; a superlatiye form of E. For, fore. See For, Fore, and cf. Formeer, Foremost. Source: Websters Dictionary (01 Mar 1998) |