| 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) |
| acromioclavicular joint | The joint formed by the acromion of the scapula and the acromial extremity of the clavicle. (12 Dec 1998) |
| ankle joint | The joint that is formed by the inferior articular and malleolar articular surfaces of the tibia, the malleolar articular surface of the fibula, and the medial malleolar, lateral malleolar, and superior surfaces of the talus. (12 Dec 1998) |
| anterior intraoccipital joint | Cartilaginous union in the newborn between the lateral and the basilar portions of the occipital bone. Synonym: synchondrosis intraoccipitalis anterior, anterior intraoccipital joint. (05 Mar 2000) |
| arthrodial joint | A synovial joint in which the opposing surfaces are nearly planes and in which there is only a slight, gliding motion, as in the intermetacarpal joints. Synonym: articulatio plana, arthrodia, arthrodial articulation, arthrodial joint, gliding joint. (05 Mar 2000) |
| articular disc of acromioclavicular joint | The articular disk of fibrocartilage usually found between the acromial end of the clavicle and the medial border of the acromion. Synonym: discus articularis acromioclavicularis, acromioclavicular disk, Weitbrecht's cartilage. (05 Mar 2000) |
| articular disc of distal radioulnar joint | The disk that holds together the distal ends of the radius and ulna; it is attached by its apex to a depression between the styloid process and distal surface of the head of the ulna, and by its base to the ridge separating the ulnar notch from the carpal surface of the radius. Synonym: discus articularis radioulnaris, radioulnar disk, radioulnar articular disk, triangular cartilage, triangular disk of wrist, triquetrous cartilage. (05 Mar 2000) |
| articular disc of sternoclavicular joint | The fibrocartilaginous disk that subdivides the sternoclavicular joint into two cavities. Synonym: discus articularis sternoclavicularis, sternoclavicular disk, sternoclavicular articular disk. (05 Mar 2000) |
| articular disc of temporomandibular joint | The fibrocartilaginous plate that separates the joint into upper and lower cavities. Synonym: discus articularis temporomandibularis, mandibular disk, temporomandibular articular disk. (05 Mar 2000) |
| atlantoaxial joint | <anatomy> Compound joint between first and second cervical vertebrae, the atlas and axis bones. (20 Jun 2000) |
| atlanto-occipital joint | <anatomy> A condylar synovial joint between the superior articular facets of the atlas and the condyles of the occipital bone. Synonym: articulatio atlanto-occipitalis, atlanto-occipital articulation. (05 Mar 2000) |
| ball-and-socket joint | A multiaxial synovial joint in which a more or less extensive sphere on the head of one bone fits into a rounded cavity in the other bone, as in the hip joint. Synonym: articulatio spheroidea, articulatio cotylica, cotyloid joint, enarthrodial joint, enarthrosis, socket joint, spheroid articulation, spheroid joint. (05 Mar 2000) |