| isocyclic compound | Any compound in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous compound's contain rings of carbon atoms (carbocyclic compound's) or carbon atoms plus one or more atoms of other types (heterocyclic compound's), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic compound); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic compound), the compound is similar in properties to the corresponding acyclic compound (e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalised π electrons (Huckel's rule) (aromatic compound; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic compound's. These aromatic compounds have the ability to sustain an induced ring current. Synonym: closed chain compound, ring compound. (05 Mar 2000) |
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| open chain compound | An organic compound in which the chain does not form a ring. Synonym: aliphatic compound, open chain compound. (05 Mar 2000) |
| organic compound | <chemistry> A compound containing carbon. (11 Jan 1998) |
| lens, compound | <microscopy> A lens composed of two or more separate pieces of glass or other optical maternal. These component pieces or elements may or may not be cemented together. A common form of compound lens is a two-element objective, one element being a converging lens of crown glass and the other a diverging lens of flint glass. The combination of suitable glasses or other optical materials (plastics, minerals) properly ground and polished reduces aberrations normally present in a single lens. (05 Aug 1998) |
| benzoylpas calcium | 4-Benzamidosalicylic acid calcium salt;an antituberculous agent. (05 Mar 2000) |
| calcium | <element> An element taken in through the diet that is essential for a variety of bodily functions, such as neurotransmission, muscle contraction and proper heart function. Imbalances of calcium can lead to many health problems and excess calcium in nerve cells can cause their death. (22 May 1997) |
| calcium-45 | <radiobiology> Most easily available of the radioactive calcium-45 isotopes; beta-emitter with a half-life of 162.7 days; used as a tracer. (05 Mar 2000) |
| calcium-47 | <radiobiology> A radioisotope of calcium with a half-life of 4.54 days, used in the diagnosis of disorders of calcium metabolism. (05 Mar 2000) |
| calcium alginate | A topical haemostatic. (05 Mar 2000) |
| calcium aminosalicylate | The calcium salt of p-aminosalicylic acid, with the same uses. (05 Mar 2000) |
| calcium antagonist | calcium channel-blocking agent |
| calcium ATPase | <enzyme> Usually used of the calcium pumping ATPase present in high concentration as an integral membrane protein of the sarcoplasmic reticulum of muscle. This pump lowers the cytoplasmic calcium level and causes contraction to stop. Normal function of the pump seems to require a local phospholipid environment from which cholesterol is excluded. (18 Nov 1997) |
| calcium benzoylpas | Calcium 4-benzamidosalicylate;an antituberculous agent. (05 Mar 2000) |
| calcium-binding protein | <biochemistry> There are two main groups of calcium binding proteins, those that are similar to calmodulin and are called EF hand proteins and those that bind calcium and phospholipid (e.g. Lipocortin) and that have been grouped under the generic name of annexins. Many other proteins will bind calcium, although the binding site usually has considerable homology with the calcium-binding domains of calmodulin. They can act as transport proteins, regulator proteins or activator proteins. There is also a vitamin D-dependent variant which is a protein that plays a fundamental role in the vitamin d mediated transport of calcium in reptiles, amphibians, birds and mammals. It is found in the intestine, kidneys, egg shell gland, brain, and possibly other organs. Its molecular weight is species dependent. (12 May 2002) |
| calcium bromide | Used to meet the same indications as potassium bromide. (05 Mar 2000) |