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901.
Corrosion-induced stress and susceptibility to stress corrosion cracking (SCC) of brass in an ammonia solution with various pH values have been studied. pH value dependence of corrosion-induced stress measured by two different methods showed a good agreement, and was correspondent to that of susceptibility to SCC. When pH?8, with increasing pH value, the corrosion-induced tensile stress had a maximum value and hardly changed; at the same time, the susceptibility to SCC exhibited a maximal value and a slight change. However, when pH?6, with decreasing pH value, both the corrosion-induced tensile stress and the susceptibility to SCC reduced rapidly. So, the SCC of brass in an ammonia solution was in close relationship with the corrosion-induced stress. 相似文献
902.
在微波/毫米波频段,高电平载波泄漏是制约数字直接变频调制器(如QPSK)性能、产生调制矢量误差的一个重要因素。在直接变频接收方式中,二阶交调失真(IM2)及本振噪声是制约动态范围的关键因素之一。偶次分谐波混频可有效地抑制载波泄漏、二次混频失真及本振噪声,是提高调制器精确度及直接解调器动态范围的有效技术。 相似文献
903.
D Desaulniers R Poon W Phan K Leingartner WG Foster I Chu 《Canadian Metallurgical Quarterly》1997,13(5):627-638
It has been reported that suramin, an anthelminthic, trypanocidal agent and an inhibitor of P2 receptors, may antagonise N-methyl-D-aspartate (NMDA) subtype of the excitatory amino acid receptors. Both NMDA receptors and P2X subclass of P2 receptors are ligand-gated Ca2+-selective channels and, since the increased influx of Ca2+ into neurons has been linked to neurotoxicity, simultaneous inhibition of P2X and NMDA receptors in vivo by suramin could represent an effective neuroprotective treatment. We have found that suramin inhibited the binding of [3H]CGP 39653 to NMDA receptor binding sites in vitro and reduced the frequency of NMDA channel openings in patch-clamp studies. Suramin (1 mM) had no effect on [3H]kainate binding in vitro. In vivo, intracerebroventricular (I.C.V.) injections of suramin (70 nmol/brain) antagonised convulsive effects of the NMDA agonist (RS)-(tetrazol-5-yl)-glycine (TZG, LY 285265). Suramin, however, did not prevent neurotoxic lesions in the hippocampus caused by I.C.V. administration of TZG. Increasing the dose of suramin resulted in death from severe respiratory depression. 相似文献
904.
905.
906.
Greenstein L.J. Amitay N. Ta-Shing Chu Cimini L.J. Jr. Foschini G.J. Gans M.J. Chih-Lin I. Rustako A.J. Jr. Valenzuela R.A. Vannucci G. 《Communications Magazine, IEEE》1992,30(12):76-88
Research projects involving fiber-connected microcell base units, measurements and models of propagation in urban microcells, and radio link performance in urban microcells are summarized. Developments in microcell system issues, such as channel assignments and handoff in microcells and architectures for combining microcells with traditional macrocells, are discussed. Research on both indoor radio propagation and wireless indoor systems is reviewed 相似文献
907.
908.
用二氧化硅片作为模拟岩石,以椭圆偏振法测量癸烷在其表面形成的油膜厚度,通过长度测量法测定水在二氧化硅表面的接触角来判断润湿性及润湿性的变化。亲水的二氧化硅表面难以形成油膜,而疏水的二氧化硅表面能形成较厚而稳定的油膜。疏水或近中性的二氧化硅表面在经碱水作用或吸附表面活性剂后,在特定的条件下能变成弱亲水或亲水,从而将油膜破坏。 相似文献
909.
Wen-Ting Chu Hao-Hsiung Lin Yu-Hsiung Wang Chia-Ta Hsieh Hung-Cheng Sung Yung-Tao Lin Wang C.S. 《Electron Device Letters, IEEE》2004,25(7):498-500
A high source-coupling ratio design for full-featured EEPROM composed of one-transistor split-gate cells with a cell area of less than 22 F/sup 2/ is proposed. This is in contrast to a traditional cell that requires an extra select transistor and is not area economic when compared to the new design cell. In this design, the cell adopts poly-poly Fowler-Nordheim tunneling to erase, and an inhibited source voltage is used for the unselected cell to achieve bit erase. It has demonstrated excellent program and erase disturb margins and passed 300 k program/erase (P/E) cycling test. It was found that after P/E cycling stress, the cell gains a better erase disturb immunity. 相似文献
910.
In this study, different molecular weight PEEK materials were used to determine the effect of spherulite size on fracture. Melt processing of the PEEK at different temperatures produced samples of different average spherulite size. A permanganic etching technique was used to reveal the spherulites. It was found that for low molecular weight 150P PEEK, the spherulite size increased with melt processing temperature; but, for the higher molecular weight 450G PEEK, the spherulite size remained approximately constant. Also, the average spherulite size was markedly lower for the material of higher molecular weight. The failure behaviour of these samples was studied using a compact tension test. It was found that the fracture toughness of PEEK varied with processing temperature. Also, the average spherulite size of this material had a profound influence on the fracture mechanism. 相似文献