| DD | dangerous drug; data definition; day of delivery; degenerated disc; degenerative disease; delusional... |
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| DIFF, diff | difference, differential; diffusion |
| DL | danger list; De Lee [catheter]; deep lobe; developmental level; difference limen; diffusion lung [ca... |
| DLCO | carbon monoxide diffusion in the lung; single-breath diffusing capacity |
| DLCO2 | carbon dioxide diffusion in the lungs |
| diffusion hypoxia | Abrupt transient decrease in alveolar oxygen tension when room air is inhaled at the conclusion of a nitrous oxide anaesthesia, because nitrous oxide diffusing out of the blood dilutes the alveolar oxygen. (05 Mar 2000) |
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| diffusion limitation | The boundary layer hypothesis, that the proliferation of cells in culture is limited by the rate at which some essential component (almost certainly a growth factor) diffuses from the bulk medium into the layer immediately adjacent to the plasma membrane. By spreading out, a cell obtains a supra threshold level of the factor and can divide, if unable to spread (because of crowding or poor adhesion) then the cell will remain in the G0 stage of the cell cycle. (18 Nov 1997) |
| diffusion method | A method for the study of bacterial enzymes in which agar is mixed with the material (e.g., starch or milk) which is to serve as an indicator of the enzyme action and is inoculated and plated; if the bacteria produce enzymes digesting the admixed material, there will be a zone of clearing in the medium about each colony. Synonym: diffusion method. (05 Mar 2000) |
| diffusion of innovation | The broad dissemination of new ideas, procedures, techniques, materials, and devices and the degree to which these are accepted and used. (12 Dec 1998) |
| diffusion potential | Potential arising from different rates of diffusion of ions at the interface of two dissimilar fluids, a junction potential. (18 Nov 1997) |
| diffusion respiration | Maintenance of oxygenation during apnea by intratracheal insufflation of oxygen at high flow rates. Synonym: apneic oxygenation. (05 Mar 2000) |
| diffusion shell | A small vessel made of a semipermeable membrane through which peptone, but not serum albumin, can pass; used in performing the Abderhalden test. (05 Mar 2000) |
| ion exchange chromatography | <procedure> Separation of molecules by absorption and desorption from charged polymers. An important technique for protein purification. For small molecules the support is usually polystyrene, but for macromolecules, cellulose, acrylamide or agarose supports give less non-specific absorption and denaturation. Typical charged residues are CM carboxymethyl) or DEAE (diethylaminoethyl). (27 Oct 1998) |
| thin layer chromatography | <technique> Chromatography using a thin layer of powdered medium on an inert sheet to support the stationary phase. Faster than paper chromatography, gives higher resolution and requires smaller samples. (18 Nov 1997) |
| thin-layer chromatography | Chromatography through a thin layer of cellulose or similar inert material supported on a glass or plastic plate. (05 Mar 2000) |
| two-dimensional chromatography | Paper chromatography in which a spot, located originally in one corner of a sheet, is developed in one direction along one side of the sheet, after which the sheet is rotated 90 |
| facilitated diffusion | <physiology> A process by which substances are conveyed across cell membranes faster than would be possible by diffusion alone. This is generally achieved by proteins that provide a hydrophilic environment for polar molecules throughout their passage through the plasma membrane, acting as either shuttles or pores. See: symport, antiport, uniport. (18 Nov 1997) |
| fick's law of diffusion | The principle that a substance put into solution will tend to diffuse towards constant concentration throughout the solution. (09 Oct 1997) |
| Fick's laws of diffusion | The direction of movement of solutes by diffusion is always from a higher to a lower concentration and the diffusive flux JA of solute A across a plane at x is proportional to the concentration gradient of A at x; i.e., JA = -D(CA/x), the increase of concentration of solute A with time, CA/t, is directly proportional to the change in the concentration gradient, i.e., CA/t = D(fl2/x2). (05 Mar 2000) |
| lateral diffusion | Diffusion in two dimensions, usually referring to movement in the plane of the membrane, such as the motion of fluorescently labelled lipids or proteins measured by the technique of fluorescent recovery after photobleaching (FRAP). (18 Nov 1997) |