| base of renal pyramid | The outer broad part of a renal pyramid that lies next to the cortex. Synonym: basis pyramidis renis. (05 Mar 2000) |
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| base of sacrum | The upper end of the sacrum that articulates with the body of the fifth lumbar vertebra in the midline and the alae on either side. Synonym: basis ossis sacri. (05 Mar 2000) |
| base of skull | The sloping floor of the cranial cavity. It comprises both the external base of skull (external view) and the internal base of skull (internal view). See: internal base of skull. Synonym: basis cranii, cranial base. (05 Mar 2000) |
| base of stapes | The flat portion of the stapes that fits in the oval window. Synonym: basis stapedis, footplate, foot-plate. (05 Mar 2000) |
| base of tongue | The posterior attached portion of the tongue. Synonym: radix linguae, base of tongue. (05 Mar 2000) |
| base pair | <molecular biology> Two nitrogenous bases (adenine and thymine or guanine and cytosine) held together by weak bonds. Two strands of DNA are held together in the shape of a double helix by the bonds between base pairs. (09 Oct 1997) |
| base pairing | <molecular biology> The specific hydrogen bonding between purines and pyrimidines in double stranded nucleic acids. In DNA the pairs are adenine and thymine and guanine and cytosine, while in RNA they are adenine and uracil and guanine and cytosine. Base pairing leads to the formation of a DNA double helix from two complementary single strands. (15 Nov 1997) |
| base projection | Radiographic projection devised to obtain direct visualization of the base of the skull. Synonym: axial view, base projection, submental vertex projection, submentovertical projection, verticosubmental view. (05 Mar 2000) |
| base sequence | <molecular biology> The order of nucleotide bases in a DNA molecule. (09 Oct 1997) |
| base sequence analysis | <molecular biology> A method, sometimes automated, for determining the base sequence. (09 Oct 1997) |
| base-stacking | A clustering of DNA or RNA bases in which the rings lie on top of each other. (05 Mar 2000) |
| base substitution | <molecular biology> One nucleotide base is replaced by another in a DNA molecule. This is also called a point mutation. (09 Oct 1997) |
| base units | The fundamental unit's of length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity in the International System of Units (SI); the names and symbols of the unit's for these quantities are meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd). See: International System of Units. (05 Mar 2000) |
| Bronsted base | Any molecule or ion that combines with a proton; e.g., OH-, CN-, NH3; this definition replaces the older and more limited concepts of base. (05 Mar 2000) |
| vegetable base | <chemistry, pharmacology> One of a large group of nitrogenous substances found in naturally in plants. They are usually very bitter and although the plant may be poisonous, many have extracts that are pharmacologically active. Examples are atropine, caffeine, coniine, morphine, nicotine, quinine, strychnine. The term is also applied to synthetic substances which have structures similar to plant alkaloids, such as procaine. (29 Sep 1997) |