| HEIS | high-energy ion scattering |
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| RHEED | reflection high-energy electron diffraction |
| HCD | health care delivery; heavy-chain disease; high-calorie diet; high-carbohydrate diet; homologous can... |
| HD | Haab-Dimmer [syndrome]; Hajna-Damon [broth]; Hansen disease; hearing distance; heart disease; helix ... |
| HFD | hemorrhagic fever of deer; high-fiber diet; high forceps delivery; hospital field director; human fa... |
| Reichstein's compound | One of several steroids; e.g., Reichstein's substance F (cortisone), Reichstein's substance H (corticosterone), Reichstein's substance M (cortisol), Reichstein's substance Q (cortexone), and Reichstein's substance S (cortexolone). Synonym: Reichstein's compound. (05 Mar 2000) |
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| renewable energy resource | <ecology> An energy resource replenished continuously or that is replaced after use through natural means. Sustainable energy. Renewable energy resources include bioenergy, solar energy, wind energy, geothermal power, and hydropower. (25 Jun 1999) |
| resonance energy transfer | <technique> Transfer of energy from one fluorochrome to another. The emission wavelength of the fluorochrome excited by the incident light must approximately match the excitation wavelength of the second fluorochrome. If light at the second emission wavelength is detected, it implies that the two fluorochromes were physically within a few nanometres. Used as a technique to probe protein or cell interactions. (25 Jun 1999) |
| glycosyl compound | The compound formed between a sugar and another organic substance in which the OH of the reducing (hemiacetal) group of the former is removed; e.g., the natural nucleosides, in which a heterocyclic N becomes linked directly to the C-1 of ribose (or deoxyribose) to yield ribosyl compounds. Compare: glycoside. (05 Mar 2000) |
| gold compound | <pharmacology> A group of medications which act to suppress inflammation in synovial tissue. Examples include gold sodium thiomalate, auranofin and aurothioglucose. These medications are indicated in the treatment of rheumatoid arthritis, psoriatic arthritis, Felty's syndrome and juvenile rheumatoid arthritis. (27 Sep 1997) |
| chemical energy | Energy liberated or absorbed by a chemical reaction, e.g., oxidation of carbon, or absorbed in the formation of a chemical compound. (05 Mar 2000) |
| 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) |
| 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) |