| molecular weight ratio | The sum of the atomic weight's of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units. See: atomic weight. Synonym: molecular mass, molecular weight ratio, relative molecular mass. (05 Mar 2000) |
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| weight | 1. The quality of being heavy; that property of bodies by which they tend toward the center of the earth; the effect of gravitative force, especially when expressed in certain units or standards, as pounds, grams, etc. Weight differs from gravity in being the effect of gravity, or the downward pressure of a body under the influence of gravity; hence, it constitutes a measure of the force of gravity, and being the resultant of all the forces exerted by gravity upon the different particles of the body, it is proportional to the quantity of matter in the body. 2. The quantity of heaviness; comparative tendency to the center of the earth; the quantity of matter as estimated by the balance, or expressed numerically with reference to some standard unit; as, a mass of stone having the weight of five hundred pounds. "For sorrow, like a heavy-hanging bell, once set on ringing, with his own weight goes." (Shak) 3. Hence, pressure; burden; as, the weight of care or business. "The weight of this said time." "For the public all this weight he bears." (Milton) "[He] who singly bore the world's sad weight." (Keble) 4. Importance; power; influence; efficacy; consequence; moment; impressiveness; as, a consideration of vast weight. "In such a point of weight, so near mine honor." (Shak) 5. A scale, or graduated standard, of heaviness; a mode of estimating weight; as, avoirdupois weight; troy weight; apothecaries' weight. 6. A ponderous mass; something heavy; as, a clock weight; a paper weight. "A man leapeth better with weights in his hands." (Bacon) 7. A definite mass of iron, lead, brass, or other metal, to be used for ascertaining the weight of other bodies; as, an ounce weight. 8. <mechanics> The resistance against which a machine acts, as opposed to the power which moves it. <chemistry> See Atomic, and cf. Element. Dead weight, Feather weight, Heavy weight, Light weight, etc. See Dead, Feather, etc. <astronomy> Weight of observation, a number expressing the most probable relative value of each observation in determining the result of a series of observations of the same kind. Synonym: Ponderousness, gravity, heaviness, pressure, burden, load, importance, power, influence, efficacy, consequence, moment, impressiveness. Origin: OE. Weght, wight, AS. Gewiht; akin to D. Gewigt, G. Gewicht, Icel. Vaett, Sw. Vigt, Dan. Vaegt. See Weigh. 1. To load with a weight or weights; to load down; to make heavy; to attach weights to; as, to weight a horse or a jockey at a race; to weight a whip handle. "The arrows of satire, . . . Weighted with sense." (Coleridge) 2. <astronomy> To assign a weight to; to express by a number the probable accuracy of, as an observation. See Weight of observations, under Weight. Origin: Weighted; Weighting. Source: Websters Dictionary (01 Mar 1998) |
| weight-bearing | The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot. (12 Dec 1998) |
| weight gain | Increase in body weight over existing weight. (12 Dec 1998) |
| weight lifting | A sport in which weights are lifted competitively or as an exercise. (12 Dec 1998) |
| weight loss | Decrease in existing body weight. (12 Dec 1998) |
| weight perception | Recognition and discrimination of the heaviness of a lifted object. (12 Dec 1998) |
| weight sense | The faculty of discriminating various degrees of pressure on the surface. Synonym: baresthesia, piesesthesia, weight sense. (05 Mar 2000) |
| combining weight | The weight in grams of an element that combines with or replaces 1 gram of hydrogen, the atomic or molecular weight in grams of an atom or group of atoms involved in a chemical reaction divided by the number of electrons donated, taken up, or shared by the atom or group of atoms in the course of that reaction, the weight of a substance contained in 1 liter of 1 normal solution; a variant of. Synonym: combining weight, equivalent weight. (05 Mar 2000) |
| wet weight | <botany> Weight of plants after the outer surface covering of water has been removed. Wet weight is not a reliable measurement since methods to prepare plants prior to weighing vary considerably. (09 Oct 1997) |
| heparin, low-molecular-weight | <chemical> Heparin fractions with a molecular weight usually between 4000 and 6000 kD. These low-molecular-weight fractions are effective antithrombotic agents. Their administration reduces the risk of haemorrhage, they have a longer half-life, and their platelet interactions are reduced in comparison to unfractionated heparin. They also provide an effective prophylaxis against postoperative major pulmonary embolism. Pharmacological action: anticoagulant, fibrinolytic agent. (12 Dec 1998) |
| dry weight | The weight of material remaining after removing the water (e.g., after heating above 100캜). (05 Mar 2000) |
| equivalent weight | The weight in grams of an element that combines with or replaces 1 gram of hydrogen, the atomic or molecular weight in grams of an atom or group of atoms involved in a chemical reaction divided by the number of electrons donated, taken up, or shared by the atom or group of atoms in the course of that reaction, the weight of a substance contained in 1 liter of 1 normal solution; a variant of. Synonym: combining weight, equivalent weight. (05 Mar 2000) |
| kininogen, high-molecular-weight | A plasma protein, molecular weight of 110 kD, that normally exists in plasma in a 1:1 complex with prekallikrein. Hmwk is split by plasma kallikrein to produce bradykinin. The complex is a cofactor in the activation of coagulation factor xii. The product of this reaction, xiia, in turn activates prekallikrein to kallikrein. (12 Dec 1998) |
| kininogen, low-molecular-weight | A protein, molecular weight 50 kD, located in various normal tissues. Upon cleavage by kallikrein or other kallikreins, it forms kallidin. Kallidin, in turn, is converted into bradykinin. (12 Dec 1998) |