共查询到20条相似文献,搜索用时 11 毫秒
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M. Kunitz 《The Journal of general physiology》1935,18(4):459-466
The rennet activity of chymo-trypsin (or pepsin) is conveniently measured by allowing a standard solution of milk to which chymotrypsin has been added to flow slowly through a graduated pipette and observing the rate and distance of flow of the milk before it clots. The time required for chymo-trypsin to clot milk may be calculated from these observations. The rennet activity is expressed as the reciprocal of the time in minutes required for 1 ml. of enzyme solution to clot 10 ml. of standard milk powder solution. 相似文献
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A quantitative method is described which permits a determination of the relative amount of trypsin or pepsin present in a gelatin-enzyme digestion mixture, provided the gelatin and trypsin solutions are purified. This method is dependent upon the change in viscosity of such solutions. It is found that the time required to cause a given percentage change in the viscosity is nearly inversely proportional to the amount of enzyme present. It is pointed out that the particular value of the method lies in the fact that enzyme reactions which take place in the presence of "buffer" salts may be studied. 相似文献
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After treatment of cells with 5-bromodeoxyuridine (BUdR), the percentage of completely BUdR-labelled interphase nuclei is greater the longer the BUdR treatment. The labelling effect is visible after staining with the fluorochrome 33258 Hoechst and with Giemsa. Various formulae and a nomogram are presented by means of which the percentage of cells in S period, duration of the S period and the whole cell cycle can be determined by examination of a single preparation or by comparison of several preparations. The methods are tested using cell cultures of Microtus agrestis and compared with autoradiographic methods after labelling with 3H-thymidine. 相似文献
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John C. Jones 《The Western journal of medicine》1947,67(6):375-378
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Brown PK 《California and Western Medicine》1930,33(5):804-809
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1. Alkali (pH 7.6)-denatured pepsins from swine, cattle, and guinea pigs precipitate in swine pepsin antiserum. Similarly treated pepsins from the rabbit, chicken, and shark do not. 2. Pepsin antisera react with both pepsin and pepsinogen, but do not react with the serum proteins from the homologous species. 3. Pepsinogen antisera react with pepsinogen, but not with twice crystallized pepsin, nor with the serum proteins from the homologous species. Positive reactions between activated pepsinogen and pepsinogen antiserum have been observed. It was possible to remove the reacting material from either the pepsinogen or the activated pepsinogen mixture. 4. Antisera made with serum proteins do not react with the homologous pepsin or pepsinogen. 相似文献
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JIAN BI 《Journal of sensory studies》1995,10(4):325-340
Nonparametric models for sensory discrimination methods are developed. In these models, the relationship between the probability of a correct response, Pc , and the measures for sensory discriminability or sensory difference, p1 and p2 are given. On the basis of the models, different sensitivities for triadic tests were compared including 3-AFC and triangle methods with the strong stimulus as the odd sample and with the weak stimulus as the odd sample. Predictions were made which can be tested experimentally. 相似文献