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排序方式: 共有142条查询结果,搜索用时 15 毫秒
91.
介绍了活塞外圆加工的一种软靠模车床中使用的直流永磁圆筒型直线伺服电机系统 ,对其组成部分直线电动机 ,速度检测电路 ,位置检测电路及具有高频响数模混合控制器进行了分析 ,并针对该设备在使用中的损坏情况 ,提出了一些维修建议。 相似文献
92.
关于社会主义新农村精神文明建设方法的思考 总被引:1,自引:0,他引:1
库占福 《科技情报开发与经济》2008,18(31):103-104
论述了加强农村精神文明建设的必要性,分析了目前面临的困难,提出了解决问题的方法。 相似文献
93.
为了揭示无线传感器信号在下水道内的传播规律,采用混合方法,把电磁波在下水道内的传播空间分为了近场区和远场区两个不同的区域,推导出了电磁波传播的信道模型。结果表明:下水道内的介电常数越大,衰减率越小;频率越高,电磁波衰减越小;半径越大,越有利于电磁波的传播。研究结果初步解决了信号在下水道内的传播规律,有助于污水流量计的进一步投入使用。 相似文献
94.
库晓慧 《沈阳大学学报:自然科学版》2009,21(6):83-85
介绍了汉初诸帝剪除异姓王、分封同姓王,削藩、平定七国之乱,实行“推恩令”“左官律”“附益法”等事件;说明了汉代中央集权逐步加强的过程;总结了中国历代分封、削藩对地方政区制度的影响。 相似文献
95.
Petrified leaf and pericarpic tissues from the Eocene Deccan Intertrappean beds of India were studied using light and transmission electron microscopy. Degradated cytoplasm with organellelike bodies are present in cells of the leaf tissues. TEM of these cells revealed wall structure and cytoplasmic residues. Microfibril distribution of pericarpic cells resembles fiber cells in extant angiosperms. 相似文献
96.
Mast cells in the skin of normal,hairless and athymic mice 总被引:3,自引:0,他引:3
Summary The skin of congenitally athymicnu/nu mice is rich in mast cells which stain metachromatically, contain histamine and 5-hydroxytryptamine, and participate in the PCA reaction. Mast cells of athymic mice have thus the attributes of normal mast cells.This work was supported by grants from the Swiss National Science Foundation (No. 3.516.71 and 3.234.74) and the Fritz Hoffmann-La-Roche-Stiftung.The skilful technical assistance of MissR. Keist is gratefully acknowledged. 相似文献
97.
Summary The microfluorimetrical investigation showed that in the principal perikarya of the rat superior cervical ganglion, after inhibition of noradrenaline-synthesis and unilateral preganglionic axotomy, the fluorescence of newly synthesized noradrenaline was most intense at the periphery of the perikarya of the intact side.The authors are deeply indebted to Mr H. Petermann, and to Mr B. Rombach, Ciba-Geigy Ltd. for their mathematical support. 相似文献
98.
Direct measurement of proton transfer rates to a group controlling the dihydropyridine-sensitive Ca2+ channel 总被引:1,自引:0,他引:1
Protons participate in most biologically important reactions, as substrates, products, cofactors and modulators, and proton transport is an essential step in energy transduction. The dynamics of protonation reactions have been studied extensively in solution and in model systems involving lipid-water interfaces, but have never been resolved at the timescale of the elementary molecular event. Here we show that, under appropriate conditions, binding and unbinding reactions of single protons and deuterium ions to a single site on the L-type calcium channel can be resolved and the protonation and deprotonation rates quantified. The protonation rate constant considerably exceeds previous estimates obtained in simpler systems. The functional consequences of channel protonation is a threefold reduction of the channel conductance, independent of the applied voltage. The data are consistent with the presence of a single protonatable group with pK in the physiological pH range, close to the external mouth of the channel. The two conductance levels of the open channel might be explained by greatly differing local potentials associated with the protonated and deprotonated state of the group. 相似文献
99.
H J Hess J S Bindra J W Constantine W Elger O Loge E Schillinger W Losert 《Experientia》1977,33(8):1076-1077
N-methanesulfonyl 16-phenoxy-omega-tetranor PGE2 is a prostaglandin analog which is markedly more tissue selective than PGE2. This compound is 10-30 times more potent than PGE2 in animal models which are considered relevant to antifertility effects in humans. In pharmacological tests which are believed to be predictive for side effects in humans, the compound has potency either equal to or less than that of PGE2. 相似文献
100.
H. Dransfeld K. Greeff D. Hess A. Schorn 《Cellular and molecular life sciences : CMLS》1967,23(5):375-377
Summary In isolated mitochondria of heart muscle from rabbits and oxen there is, under suitable conditions, an accumulation of Ca++, which is significantly enhanced by elevating the K+/Na+ quotient of the incubation medium. K-strophanthine (10–5–10–7) does not influence the accumulation of Ca++ by the mitochondria of heart muscle. Therefore the intracellular increase in exchangeable Ca++ observed after digitalis-glycosides could be explained by a decrease of the intracellular K+/Na+ quotient, which is caused by inhibition of the membrane ATPase and diminishes the capacity for Ca++ accumulation in mitochondria. 相似文献