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Tohru Ueda 《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):67-75
Abstract Methods for the synthesis of carbon-bridged 6,5′-, 6,6′-, 6,3′-, and 6,2′-cyclopyrimidine and 8,2′-cycloadenine nucleosides and some of their phosphates are described. The 6,5′- and 6,6′-cyclouridine 2′,3′-cyclic phosphates were the substrates and their 3′-phosphates were strong inhibitors of pancreatic ribonuclease. 相似文献
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A Study of Some Properties of the Cytoplasmic Factor, "Kappa," in Paramecium Aurelia,Variety 2 总被引:6,自引:0,他引:6
Preer JR 《Genetics》1948,33(4):349-404
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Sumner FB 《Genetics》1917,2(3):291-300
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COLLIER HB 《The Journal of general physiology》1952,35(4):617-628
1. Lysolipid was prepared by the action of snake venom on egg yolk, and a study was made of the factors affecting its hemolytic action upon rabbit erythrocytes. 2. Lysis proceeded very rapidly at first, then ceased within a few minutes at room temperature. A given amount of lysin appeared to hemolyze a fixed number of cells, under specified conditions. 3. The more dilute erythrocyte suspensions required relatively more lysin per cell, for 50 per cent hemolysis of the suspension. There may be an equilibrium between the lysin dissolved in the medium and that adsorbed on the cells. 4. The degree of hemolysis for varying lysin concentrations was measured, and the cells showed a typical distribution of resistance to hemolysis. 5. As the temperature was lowered lysis was more extensive. Adsorption of the lysin on the cell surface was apparently increased. 6. The resistance of the erythrocytes to lysis increased slightly as the pH was raised from 5.5 to 7.8. 7. Resistance to lysis was independent of the tonicity of the medium and of initial cell volume. The magnitude of the cell surface was probably the determining factor. 8. A marked shrinkage of the erythrocytes was observed in the presence of calcium ions and lysin, but not in the absence of the lysin. 9. Hemolytic resistance curves obtained by the Wilbrandt technique were of the "colloid-osmotic" type. However, there was no evidence of prolytic loss of potassium ions. 10. Hypotonic fragility of the cells was slightly increased in the presence of the lysin. The rate of penetration of thiourea was greatly increased. 相似文献
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An Electrokinetic Interpretation of the Functioning of Biological Systems and its Application to the Study of Mineral Salts Absorption 总被引:1,自引:0,他引:1
An attempt has been made to apply an electrokinetic approachto describe the functioning of biological systems. Using anohmic expression, it is possible to construct models as effectiveas those of Michaelis-Menten kinetics to interpret experimentaldata. While retaining the notions of competitive and non-competitiveinteractions it replaces the parameters Km and Vm by log (B/[P])and A/r which have simple biological meanings. In addition,the approach is well adapted to the analysis of problems presentedby complex systems working in series or parallel, coupled systemsand networks of reactions. By the use of a non-ohmic expressionthe electrokinetic approach attributes a semi-conductor-likecomponent to catalytic systems in the cell. The approach isconsistent with the data of quantum mechanics and it predictsthe existence of a third type of interaction, perhaps equivalentto allosteric interactions. Applied to the problem of absorptionit leads to an explanation of experimental results without thenecessity of invoking the presence of two carrier systems. 相似文献
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《生命科学研究》2016,(2):135-139
比较分析了不同水域刀鲚的分类地位,生殖洄游时间、路线和所需外界条件以及其分布现状和资源状况。同时,于2015年对鄱阳湖、赣江和抚河下游的刀鲚进行了现场调查,并与1982年采自鄱阳湖的刀鲚标本进行了生物学特性比较。研究发现,1982年鄱阳湖短颌鲚(定居型刀鲚)体长范围为5.0~30.0 cm,优势组体长为6~20 cm,体重范围是0.90~105.08 g;2015年调查的短颌鲚体长范围为11.6~28.0 cm,优势组体长为11~20 cm,体重范围为5.99~81.31 g。1982年鄱阳湖洄游型刀鲚占总尾数的3.86%,体长范围为15.0~33.0 cm,体重范围为10.24~151.63 g;而2015年调查的洄游型刀鲚仅占总尾数的0.97%,体长范围是25.5~28.0 cm,体重范围是60.62~78.00 g。结果分析表明,江西上述水域均以短颌鲚为主,洄游型刀鲚难已形成渔汛。 相似文献
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