| unidirectional block | Block that prevents passage of an impulse when it approaches from one direction but not from the other, as when block in the A-V node prevents anterograde conduction to the ventricles while retrograde conduction to the atria remains intact. (05 Mar 2000) |
|---|---|
| unidirectional flux | The flux of a substance from one surface of a boundary layer or membrane to the other, disregarding any counterbalancing flux in the other direction, as measured by tracer technique. (05 Mar 2000) |
| unidirectional replication | Replication in which there is movement by a single replication fork. (05 Mar 2000) |
| unifamilial | Relating to or occurring in a single family; denoting especially a nervous disease attacking several of the children in the same family in which no hereditary trait is apparent. (05 Mar 2000) |
| unified medical language system | A research and development program initiated by the national library of medicine to build an intelligent automated system that can understand biomedical concepts, words, and expressions and their interrelationships, and use this understanding to help users retrieve and organise information from a variety of machine-readable sources. The goal of the umls is to compensate for differences in the terminology of the disparate systems and for variations in user modes of expression. The umls project has produced four knowledge sources meant to be used by user interface programs. These are the metathesaurus, the semantic network, the information sources map, and the specialist lexicon. (12 Dec 1998) |
| unifilar | Having only one thread; involving the use of only one thread, wire, fibre, or the like; as, unifilar suspension. <physics> Unifilar magnetometer, an instrument which consists of a magnetic bar suspended at its center of gravity by a long thread, constituting a delicate means for accurately measuring magnetic intensities, also for determining declinations of the magnetic needle. Origin: Uni- + L. Filum a thread. Source: Websters Dictionary (01 Mar 1998) |
| uniflagellate | <biology> Having but one flagellum; as, uniflagellate organisms. Origin: Uni- + flagellate. Source: Websters Dictionary (01 Mar 1998) |
| uniflorous | <botany> Bearing one flower only; as, a uniflorous peduncle. Origin: Uni- + L. Flos, floris, a flower: cf. F. Uniflore. Source: Websters Dictionary (01 Mar 1998) |
| unifoliate | <botany> Having one leaf. (09 Oct 1997) |
| unifoliolate | <botany> Of a leaf, basically compound, but reduced to only one leaflet. (09 Oct 1997) |
| unifolliate | <botany> Having only one leaf. Origin: Uni- + foliate. Source: Websters Dictionary (01 Mar 1998) |
| unifollilate | <botany> Having only one leaflet, as the leaves of the orange tree. Origin: Uni- + foliolate. Source: Websters Dictionary (01 Mar 1998) |
| uniforate | Having but one foramen, pore, or opening of any kind. (05 Mar 2000) |
| uniform | Marked by lack of variation, diversity, change in form, degree or character in all occurrences or manifestations. (18 Nov 1997) |
| uniform mechanical code | (UMC) A code sponsored by the International Association of Plumbing and Mechanical Officials and the International Conference of Building Officials, adopted and amended by the Oregon Department of Commerce. The UMC contains requirements for the installation and maintenance of heating, ventilating, cooling, and refrigeration systems. (05 Dec 1998) |