| chemical knife | Term sometimes used for restriction endonuclease. (05 Mar 2000) |
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| Merrifield knife | A long, narrow, triangularly shaped knife used in gingival surgery. (05 Mar 2000) |
| ring-knife | A circular or oval ring with internal cutting edge, on the model of the carpenter's spoke-shave, for shaving off tumours in the nasal and other cavities. Synonym: spoke-shave. (05 Mar 2000) |
| Clark electrode | An oxygen electrode consisting of the tip of a platinum wire exposed to a thin film of electrolyte covered by a plastic membrane permeable to oxygen but not to water or the electrolyte. When a certain voltage is applied, oxygen is destroyed at the platinum surface; the flow of current is then proportional to the rate at which oxygen can diffuse to the platinum surface from the gas or liquid sample outside the membrane, and is thus a measure of the oxygen pressure in the sample; commonly used to measure oxygen pressure in arterial blood samples. (05 Mar 2000) |
| clasp-knife effect | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
| clasp-knife rigidity | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
| clasp-knife spasticity | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
| cooled-knife method | The cutting of frozen sections with a knife cooled to a few degrees below the freezing point. (05 Mar 2000) |
| positive electrode | <microscopy> The electrode to which a major flow of electrons takes place internally (as in a cathode-ray tube) or to which an external positive voltage supply is connected. (05 Aug 1998) |
| hernia knife | A slender bladed knife, with short cutting edge, for dividing the constricting tissues at the mouth of the hernial sac. Synonym: herniotome. (05 Mar 2000) |
| Humby knife | A knife with a roller and a calibration device to cut skin grafts of different thickness. (05 Mar 2000) |
| Severinghaus electrode | A glass electrode in a film of bicarbonate solution covered by a thin plastic membrane permeable to carbon dioxide but impermeable to water and electrolytes; the carbon dioxide pressure of a gas or liquid sample quickly equilibrates through the membrane and is measured in terms of the resulting pH of the bicarbonate solution, as sensed by the glass electrode; commonly used to analyze arterial blood samples. Synonym: Severinghaus electrode. (05 Mar 2000) |
| hydrogen electrode | The ultimate standard of reference in all pH determinations, limited and technically difficult to use, consisting of a piece of spongy platinum black partly immersed in a solution in a small glass tube; the tube above the solution is filled with hydrogen gas that is bubbled through the solution and absorbed by the platinum; the electrode thus measures the potential between H2 and H+, the "standard" potential of which (1 atmosphere, 1 molar) is taken as zero; hence, the hydrogen electrode potential measures [H+] or pH. (05 Mar 2000) |
| silent electrode | In unipolar electrocardiography, a remote electrode placed either upon a single limb or connected with the central terminal and paired with an exploring electrode; the indifferent electrode is supposed to contribute little or nothing to the resulting record. Synonym: dispersing electrode, silent electrode. (05 Mar 2000) |
| spalting knife | A knife used in splitting codfish. Alternative forms: spalding knife. Source: Websters Dictionary (01 Mar 1998) |