| nereid | Origin: L. Nereis, -idis, gr, a daughter of Nereus, a nymph of the sea, fr. Nereus, an ancient sea god; akin to wet, Skr. Nara water, cf. Gr. To flow. 1. A sea nymph, one of the daughters of Nereus, who were attendants upon Neptune, and were represented as riding on sea horses, sometimes with the human form entire, and sometimes with the tail of a fish. 2. <zoology> Any species of Nereis. The word is sometimes used for similar annelids of other families. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| nereidian | <zoology> Any annelid resembling Nereis, or of the family Lycoridae or allied families. Source: Websters Dictionary (01 Mar 1998) |
| nereis | Origin: L. 1. A Nereid. See Nereid. 2. <zoology> A genus, including numerous species, of marine chaetopod annelids, having a well-formed head, with two pairs of eyes, antennae, four pairs of tentacles, and a protrusile pharynx, armed with a pair of hooked jaws. Source: Websters Dictionary (01 Mar 1998) |
| nereites | <paleontology> Fossil tracks of annelids. Source: Websters Dictionary (01 Mar 1998) |
| nereocystis | <botany> A genus of gigantic seaweeds. Nereocystis Lutkeana, of the North Pacific, has a stem many fathoms long, terminating in a great vesicle, which is crowned with a tuft of long leaves. The stem is used by the Alaskans for fishing lines. Origin: NL. See Nereid, and Cyst. Source: Websters Dictionary (01 Mar 1998) |
| nerfling | <zoology> The id. Source: Websters Dictionary (01 Mar 1998) |
| Neri's sign | <clinical sign> In hemiplegia, the knee bends spontaneously when the leg is passively extended. (05 Mar 2000) |
| neriine | Roquessine; 3b-(dimethylamino)con-5-enine; 3b-dimethylamino-18a:20a-methylimino-5-pregnene;a steroid alkaloid derived from Holarrhena antidysenterica (conessi); a yellow astringent, used in the treatment of amoebic dysentery and vaginal trichomoniasis. Synonym: neriine, wrightine. (05 Mar 2000) |
| nerita | <zoology> A genus of marine gastropods, mostly natives of warm climates. Origin: L, a sort of sea mussel, gr. Source: Websters Dictionary (01 Mar 1998) |
| nerite | <marine biology> Any mollusk of the genus Nerita. (19 Mar 1998) |
| neritina | <zoology> A genus including numerous species of shells resembling Nerita in form. They mostly inhabit brackish water, and are often delicately tinted. Source: Websters Dictionary (01 Mar 1998) |
| Nernst equation | <physics> A basic equation of biophysics that describes the relationship between the equilibrium potential difference across a semipermeable membrane and the equilibrium distribution of the ionic permeant species. It is described by: E = (RT/zF).ln[C1/C2 Where E is the potential on side 2 relative to side 1 in volts), R is the gas constant (8.314 J Kexp 1 molexp 1), T is the absolute temperature, z is the charge on the permeant ion, f is the Faraday constant (96500 C molexp 1) and C1 and C2 are the concentrations (more correctly activities) of the ions on sides 1 and 2 of the membrane. It can be seen that this equation is a solution of the more general equation of electrochemical potential, for the special case of equilibrium. The equation described the voltage generated by ion selective electrodes, like the laboratory pH electrode and approximates the behaviour of the resting plasma membrane (see resting potential). (13 Nov 1997) |
| Nernst potential | See: Nernst equation and ion selective electrodes. (18 Nov 1997) |
| Nernst's equation | The equation relating the equilibrium potential of electrodes to ion concentrations; the equation relating the electrical potential and concentration gradient of an ion across a permeable membrane at equilibrium: E = [RT / nF Origin: Ln (C1/C 2)], where E = potential, R = absolute gas constant, T = absolute temperature, n = valence, F = the Faraday, ln = the natural logarithm, and C1 and C2 are the ion concentrations on the two sides; in nonideal solutions, concentration should be replaced by activity. See: Nernst's theory, activity. (05 Mar 2000) |
| Nernst's theory | That the passage of an electric current through the tissues causes a dissociation of the ions, with consequent concentration of salts in the solution bathing the cell membranes, the electric stimulus being thereby effected. (05 Mar 2000) |