| meso compound | <chemistry> A compound that has two or more chiral centres but does not rotate plane-polarized light because it has an internal plane of symmetry. These compounds are identical to their mirror images. (09 Jan 1998) |
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| chiral compound | <chemistry> A molecule that has an asymmetric centre and can be found in twonon-superimposable mirror-image forms (enantiomers). (05 Jan 1998) |
| ring 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) |
| microscope, compound | A microscope that consists of two microscopes in series, the first serving as the ocular lens (close to the eye) and the second serving as the objective lens (close to the object to be viewed). Credit for creating the compound microscope goes usually to the dutch spectaclemakers hans and zacharias janssen who in 1590 invented an instrument that could be used as either a microscope or telescope. The compound microscope evolved into the dominant type of optical microscope today. (12 Dec 1998) |
| closed chain 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) |
| modeling compound | A thermoplastic material usually composed of gum damar and prepared chalk, used especially for making dental impressions. Synonym: impression compound, modeling composition, modeling compound. (05 Mar 2000) |
| compound | <chemistry> A material made up of two or more elements. <botany> Of a leaf, having the blade divided into two or more distinct leaflets, of an inflorescence, made up of an aggregate of smaller inflorescences. (09 Oct 1997) |
| compound 48-80 | <chemical> A potent mast cell degranulator. It is involved in histamine release. Chemical name: Phenethylamine, p-methoxy-N-methyl- (12 Dec 1998) |
| compound aneurysm | An aneurysm in which some of the coats of the artery are ruptured, others intact. (05 Mar 2000) |
| compound articulation | A joint composed of three or more skeletal elements, or in which two anatomically separate joints function as a unit. For example, the telonavicular and calcaneocuboid joints act together as the compound transverse tarsal joint. Synonym: articulatio complexa, articulatio composita, composite joint, compound articulation. (05 Mar 2000) |
| compound bone fracture | <orthopaedics> A fractured bone that is exposed to potential bacterial contamination through a laceration or puncture wound in the soft tissues overlying the fracture site. (05 Jan 1998) |
| compound caries | Caries involving more than one surface of a tooth, two or more carious lesions joined to form one cavity. (05 Mar 2000) |
| compound character | An inherited character dependent upon two or more distinct genes. (05 Mar 2000) |
| compound cyst | A cyst containing several compartments formed by membranous septa. Synonym: compound cyst. (05 Mar 2000) |
| compound dislocation | Synonym: open dislocation. (05 Mar 2000) |