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181.
H Meves Y Pichon 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(14):1325-1328
Most of the effects of 4-aminopyridine on the potassium conductance of the giant axon of the Squid can be explained in terms of a simple model based on the physicochemical properties of the molecule and what is known about the structure of the potassium "channels". 相似文献
182.
183.
Molecular analysis of spontaneous somatic mutants. 总被引:17,自引:0,他引:17
Eukaryotic structural gene mutations occurring spontaneously in a mouse myeloma cell line offer the opportunity to study somatic mutation in animal cells at the molecular level. Studies on the myeloma protein and on mRNA have enabled us to characterise four such mutants representing four different mutation mechanisms. The results may have some bearing on the origin of antibody diversity. 相似文献
184.
185.
During serial structure analysis of cobaloxime derivatives, aimed at interpreting the catalytic capability of the asymmetric hydrogenation, we have found that the crystal of R-alpha-cyanoethyl (S-alpha-methylbenzylamine)-cobaloxime changes its unit cell dimensions by X-ray exposure without degradation of a single crystal form. The rate of the change was so slow that it was possible to collect the intensity data for several intermediate stages. We have proved, by calculating electron density in each stage, that the change reflects the racemisation of the cyanoethyl group. 相似文献
186.
An effect which appeared to be pulsating aurora was observed to be associated with explosive releases of barium vapour near 250 km altitude, but only when the explosions were in the path of precipitating electrons associated with the visible aurora. 相似文献
187.
Summary Using the Fell technique of organ culture of cartilage in a chemically defined medium, it has been shown that prostaglandin A1 at a concentration of 25 g/ml caused chondrocyte death in chick embryonic limb rudiments. An equimolar concentration of PGE2 was not toxic to the cells.Acknowledgments. We are grateful for the support of C. J. K. by the Medical Research Council and of D. L. G. by the Arthritis and Rheumatism Council for Research. Our thanks are due to Dame Honor Fell, F. R. S. for invaluable advice and guidance, to Dr J. Pike (Upjohn Co.) for supplies of prostaglandin A1, and to Dr Sylvia Fitton-Jackson for the gift of culture medium. 相似文献
188.
S. Y. Dike Meera Kamath J. R. Merchant 《Cellular and molecular life sciences : CMLS》1977,33(8):985-985
Summary A one-step synthesis of hexahydrocannabinoid analogs (HHC) is described making use of the condensation of phenolic ketones and aldehydes with citronellal in the presence of pyridine.Grateful thanks are accorded to Drs L. Chopard and S. Selvavinayakam for spectral measurements and Dr I. Fleming for useful discussion.R. Mechoulam and Y. Gaoni, Recent advances in the chemistry of Hashish, in: Progress in the Chemistry of Organic natural products, vol. 25, p. 175. Ed. L. Zechmeister. Springer Verlag, Wien 1967; R. Mechoulam, Marijuana Chemistry and Pharmacology, metabolism and clinical effects. Academic Press, New York 1973; R. Mechoulam, N. K. McCallum and S. Burstein, Chem. Rev.76, 75 (1976). 相似文献
189.
Immunoglobulin diversity seems to arise largely by three mechanisms: (1) the existence of several germ-line genes, which must be rearranged before expression--that is, V and J for the light (L) chains, V, D and J for the heavy (H) chains; (2) somatic events, including mutations and gene conversion; and (3) combinatorial association of heavy and light chains, leading to the proposal that random pairing of p X H and q X L chains might generate p X q antibody molecules expressing discrete specificities. As heavy and light chains derived from the same immunoglobulin molecule would frequently reassociate preferentially, it is likely that only a fraction of potential heavy--light pairs actually provides "valid' antibodies. As a consequence of combinatorial heavy--light chain pairing, antibodies of discrete specificities sharing the same VH region, associated with distinct light chains (or vice versa) should be encountered. We report here that two heavy chains, derived from the same VH germ-line gene, may be present in anti-NP or anti--GAT antibodies, depending on their association with a specific lambda or kappa light chain, respectively. 相似文献
190.