| carbon-carbon lyases | <enzyme> Enzymes that catalyze the cleavage of a carbon-carbon bond by means other than hydrolysis or oxidation. This subclass contains the decarboxylases, the aldehyde-lyases, and the oxo-acid-lyases. Registry number: EC 4.1 (12 Dec 1998) |
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| colloidal silicon dioxide | A submicroscopic fumed silica prepared by the vapor-phase hydrolysis of a silicon compound; used as a tablet diluent and as a suspending and thickening agent. (05 Mar 2000) |
| hydrogen dioxide | <chemical> Hydrogen peroxide is produced by vertebrate phagocytes and is used in bacterial killing (the myeloperoxidase halide system). (05 May 1997) |
| silicon dioxide | <chemical> Silica. Transparent, tasteless crystals found in nature as agate, amethyst, chalcedony, cristobalite, flint, sand, quartz, and tridymite. The compound is insoluble in water or acids except hydrofluoric acid. Chemical name: Silica (12 Dec 1998) |
| nitrogen dioxide | <chemical> Nitrogen oxide (no2). A highly poisonous gas. Exposure produces inflammation of lungs that may only cause slight pain or pass unnoticed, but resulting oedema several days later may cause death. It is a major atmospheric pollutant that is able to absorb uv light that does not reach the earth's surface. Pharmacological action: oxidants, photochemical, poisons. Chemical name: Nitrogen oxide (NO2) (12 Dec 1998) |
| sulfur dioxide | <chemical> A highly toxic, colourless, nonflammable gas. It is used as a pharmaceutical aid and antioxidant. It is also an environmental air pollutant. Pharmacological action: air pollutants, environmental, antioxidants, pharmaceutic aid. Chemical name: Sulfur dioxide (12 Dec 1998) |
| dioxide | <chemistry> An oxide containing two atoms of oxygen in each molecule; binoxide. An oxide containing but one atom or equivalent of oxygen to two of a metal; a suboxide. Carbon dioxide. See Carbonic acid, under Carbonic. Origin: Pref. Di- + oxide. Source: Websters Dictionary (01 Mar 1998) |
| thorium dioxide | <chemical> Thorium oxide (tho2). A radiographic contrast agent that was used in the early 1930s through about 1954. High rates of mortality have been linked to its use and it has been shown to cause liver cancer. Pharmacological action: carcinogens. Chemical name: Thorium oxide (ThO2) (12 Dec 1998) |
| titanium dioxide | TiO2;contains not less than 99.0% and not more than 100.5% of TiO2, calculated on the dry basis; used in creams and powders as a protectant against external irritations and solar rays. (05 Mar 2000) |
| 1,4-diethylene dioxide | 1,4-dioxane;a colourless liquid used as a solvent for cellulose esters and in histology as a drying agent. Synonym: 1,4-diethylene dioxide. (05 Mar 2000) |
| ammonia fixation | The utilization of ammonia (or ammonium ions) in the net synthesis of nitrogen-containing molecules; e.g., glutamine synthetase. Synonym: ammonia fixation. (05 Mar 2000) |
| bifoveal fixation | A condition in which both eyes are simultaneously directed to the same target. Synonym: bifoveal fixation. (05 Mar 2000) |
| binocular fixation | A condition in which both eyes are simultaneously directed to the same target. Synonym: bifoveal fixation. (05 Mar 2000) |
| mandibulomaxillary fixation | Fixation of fractures of the mandible or maxilla by applying elastic bands or stainless steel wire between the maxillary and mandibular arch bars or other types of splint. Synonym: mandibulomaxillary fixation, maxillomandibular fixation. (05 Mar 2000) |
| genes, nitrogen fixation | Regulatory and structural genes present in certain bacteria, algae and fungi that control the conversion of atmospheric nitrogen into biologically usable compounds; include nif structural genes (e.g., nifd, nifh) for nitrogenase and nitrate reductase as well as regulator genes nifa, nifb, ntra, ntrb, ntrc. Some are responsible for regulating transcription of genes involved in the assimilation of poor nitrogen sources in enteric bacteria. (12 Dec 1998) |