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991.
992.
李飨民 《科技情报开发与经济》2006,16(11):287-289
结合乐温高速公路工程,详细介绍了水泥稳定碎石基层的施工工艺、质量管理及检查验收,提出了施工过程中应注意的问题。 相似文献
993.
994.
Summary Phosphate uptake inClaviceps sp. strain SD-58 was found to be linear for 20 min, proportional to cell density in mg/ml, energy dependent, and taking place against a concentration gradient with a Km value of 45.45×10–5 M. Osmotic shock treatment to the cell caused a reduction in phosphate uptake associated with the release of binding protein. Partial restoration of uptake was observed on incubation of osmotically shocked cells with shock fluid. The results are discussed with reference to the effect of phosphate on alkaloid synthesis inClaviceps sp. strain SD-58. 相似文献
995.
996.
D. A. Powis 《Cellular and molecular life sciences : CMLS》1985,41(8):1048-1051
Summary The effect of calcium on Na, K-ATPase activity of rat brain homogenates and its modification by the chelating agent EDTA has been investigated. In the absence of EDTA, free calcium (approximately 10–6mol/l) stimulates Na,K-ATPase activity; in the presence of EDTA the same concentration of free calcium is without effect on the enzyme. In the absence of EDTA the stimulation by calcium of Na,-K-ATPase activity is enhanced by the additional presence of calmodulin but in the presence of EDTA, even when calmodulin is added to excess, calcium still fails to stimulate the enzyme. The possibility that EDTA interferes with an interaction between a calcium-calmodulin complex and Na,K-ATPase is discussed.The expert technical assistance of Mrs Paula Jarvie is gratefully acknowledged. Thanks are due also to Professor Philip Kuchel for assistance with the calculations to determine the concentrations of metal-ligand complexes in the experimental media. 相似文献
997.
Multiple prismatic calcium phosphate layers in the jaws of present-day sharks (Chondrichthyes; Selachii) 总被引:1,自引:0,他引:1
Summary Jaws of large individuals, over 2 m in total length, of the shark speciesCarcharodon carcharias (great white shark) andIsurus oxyrinchus (mako shark) of the family Lamnidae, andGaleocerdo cuvieri (tiger shark) andCarcharhinus leucas (bull shark) of the family Carcharhinidae were found to have multiple, up to five, layers of prismatic calcium phosphate surrounding the cartilages. Smaller individuals of these species and other known species of living chondrichthyans have only one layer of prismatic calcium phosphate surrounding the cartilages, as also do most species of fossil chondrichthyans. Two exceptions are the fossil shark generaXenacanthus andTamiobatis. Where it is found in living forms, this multiple layered calcification does not appear to be phylogenetic, as it appears to be lacking in other lamnid and carcharhinid genera and species. Rather it appears to be functional, only appearing in larger individuals and species of these two groups, and hence may be necessary to strengthen the jaw cartilages of such individuals for biting. 相似文献
998.
5′-磷酸吡哆醛(PLP)与经β-硫酸酯乙砜基苯胺活化的聚乙二醇(PEG)或右旋糖酐(Dx)共价结合,得可溶性5′-磷酸吡哆醛衍生物。用PLP-PEG和PLP-Dx衍生物代替PLP作为谷氨酸脱羧酶的辅酶,谷氨酸脱羧酶活力回复率达18%左右;用甘氨酸封闭的PLP-PEG代替PLP作为辅酶,谷氨酸脱羧酶活力回复率达44%。 相似文献
999.
1000.
全麻剂通过干扰膜的结构与功能而起作用,研究了四种全麻剂(氯仿、乙醚、乙醇及辛醇)对3mmolCa2+诱导融合影响用PS:DMPC:Cholesterol=5:3:2的人工膜脂质体进行实验,脂质体融合用荧光共振能量转移监测,初步实验表明:在临床浓度范围内,氯仿,乙酸及辛醇能轻微地抑制膜融合,而乙醇在临床浓度附近能促进膜融合,并且随着乙醇浓度的提高其促融合效应变得十分明显,这可能是乙醇分子的极性及通过氢键与磷脂头缔结,并取代部份结构水,减弱水化排斥力而促使膜融合。 相似文献