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971.
以氢化物发生-光度比色法为基础,利用新型测砷仪并选择合适的分离测试条件,实现了高浓度铅和锑存在下微量砷的测定。建立的蓄电池铅锑合金板栅中微量砷的分析方法,使氢化物发生、分离、富集和显色在同一体系中一次完成,操作简便快速、灵敏度、准确度和精密度均满足生产工艺的要求。 相似文献
972.
毛培法 《浙江工业大学学报》1992,(4)
本文提出容差扩展的三原则,并按该原则分析了电压比较器μA710(SN52510,TEXAS),提出了改进方案.按该方案集成的电压比较器FBC_(01)与同样条件下的μA710相比,成品率提高两倍,迟延时间缩小四倍,参数一致性显著提高. 相似文献
973.
H. Mukuda K. Ishida Y. Kitaoka Z. Mao Y. Mori Y. Maeno 《Journal of Low Temperature Physics》1999,117(5-6):1587-1591
17O Knight shift measurements in Sr2RuO4 were performed over the wide range of magnetic field 3.2-11.4kOe parallel to the basal RuO2 planes. The spin susceptibility is totally unchanged through its Tc, evidencing that the spin-triplet superconducting state is realized in Sr2RuO4. The result indicates that the Cooper pairs consist of the parallel spin pairs | > and | > with their quantization axis perpendicular to the c-axis direction. The in-plane 2D nearly ferromagnetic spin fluctuations may play a role for the stabilization of this state among various representations of spin-triplet order parameter. 相似文献
974.
975.
动态系统的自适应模糊神经网络控制 总被引:1,自引:0,他引:1
Aim To build an adaptive fuzzy neural controller and simulate
it. Methods Fuzzy logic and back propagation(BP) algorithm are combined
to utilize their advantages while avoiding the disadvantages. Results and
Conclusion Simulation results of the third-order plant with disturbances and dead
times show the validity of the presented controller. The presented controller can control
cases that preceding controllers were unable to control. 相似文献
976.
977.
IDES: An Internet Distance Estimation Service for Large Networks 总被引:2,自引:0,他引:2
Mao Y. Saul L. K. Smith J. M. 《Selected Areas in Communications, IEEE Journal on》2006,24(12):2273-2284
The responsiveness of networked applications is limited by communications delays, making network distance an important parameter in optimizing the choice of communications peers. Since accurate global snapshots are difficult and expensive to gather and maintain, it is desirable to use sampling techniques in the Internet to predict unknown network distances from a set of partially observed measurements. This paper makes three contributions. First, we present a model for representing and predicting distances in large-scale networks by matrix factorization which can model suboptimal and asymmetric routing policies, an improvement on previous approaches. Second, we describe two algorithms-singular value decomposition and non-negative matrix factorization-for representing a matrix of network distances as the product of two smaller matrices. Third, based on our model and algorithms, we have designed and implemented a scalable system-Internet Distance Estimation Service (IDES)-that predicts large numbers of network distances from limited samples of Internet measurements. Extensive simulations on real-world data sets show that IDES leads to more accurate, efficient and robust predictions of latencies in large-scale networks than existing approaches 相似文献
978.
设计了一种单片集成的光电接收机芯片.在同一衬底上制作了基于同一工艺的光电二极管与接收机电路,以消除混合集成引入的寄生影响.这种单片集成接收机采用了先进的深亚微米MS/RF(混合信号/射频)CMOS工艺,利用这种新型工艺提供的新技术对原有光电二极管进行了改进,使其部分性能显著改善,并对整个光电集成芯片性能的提高有所帮助. 相似文献
979.
P Mooney M Sarmiento JM Bishop N Biswas NM Cason L Dauwe J Godfrey VP Kenney R Pemper E Rojek RC Ruchti WD Shephard G Ginther RM Edelstein CP Forsyth K Gamarnik AE Kreymer RJ Lipton JM McQuade DM Potter JS Russ L Spiegel DE Johnson D Buchholz LM Cremaldi SW Delchamps HS Mao JL Rosen W Sakumoto RA Schluter SB Sontz C Winter 《Canadian Metallurgical Quarterly》1989,39(9):2494-2498
980.
Antioxidants such as probucol and alpha-tocopherol have been shown to attenuate the oxidation of low-density lipoproteins (LDL) and atherosclerotic lesions in animal models of atherosclerosis. The purpose of this study is to determine the protection effect of antioxidants on endothelial cells when exposed to oxidized and native LDL. In a cell-free system, we found that probucol, alpha-tocopherol, and ascorbic acid inhibited copper-induced LDL oxidation by a dose-dependent fashion (from 1 microM to 10 mM). In porcine aortic endothelial cells, antioxidants alone did not change basal endothelin-1 (ET-1) secretion. When porcine aortic endothelial cells were exposed to LDL and oxidized-LDL, both of them stimulated ET-1 secretion dose-dependently, whereas oxidized-LDL elicited higher ET-1 secretion. However, probucol, alpha-tocopherol, and ascorbic acid did not prevent LDL or oxidized-LDL induced ET-1 secretion. Furthermore, nimodipine inhibited both of native and oxidized LDL induced ET-1 secretion. Since Ca2+ channel blocker reduced the elevation of induced ET-1 secretion, the [Ca2+]i is possibly involved for the regulation of ET-1 secretion. Our results suggest that antioxidants can only prevent the oxidation of LDL rather than oxidized and native LDL-induced ET-1 secretion in vascular endothelial cells. The increase in the [Ca2+]i of endothelial cells through the opening of voltage-dependent Ca2+ channels may be involved in the LDL-induced ET-1 release. 相似文献