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131.
草酸二乙酯气相催化加氢合成乙二醇的研究 总被引:12,自引:0,他引:12
对草酸二乙酯气相催化加氢生成乙二醇反应进行了实验研究。研制了不含铬的铜基催化剂,并考察了催化剂的制备条件对反应结果的影响。结果表明,Cu/SiO_2质量比为0.67,活化温度为350℃时最佳。在上述催化剂制备的基础上,提出了最佳反应条件。 相似文献
132.
133.
Li Xi Zuoyan Peng Wei Fan Kui Guo Gu Jianmin Muyu Zhao Wu Guoqiang 《Materials Science and Engineering: B》1996,40(2-3):147-152
SrMgxTi1 - xO3 nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere. 相似文献
134.
步进式加热炉炉温优化设定模型及软件开发 总被引:1,自引:0,他引:1
针对线材厂步进式加热炉实际工况,提出了基于经验规则的炉温优化设定模型和在线自学习获取知识的思想,并以炉温优化设定模型为核心,开发出加热炉计算机控制系统的优化运行软件。 相似文献
135.
本文提出了一种基于拓扑法的多关节机械手无碰路径规划方法,文中重点讨论了三关节机械手路径规划时如何划分状态空间、判别各连通块之间的连通性以及路径搜索等问题,最后我们给出了一个实验结果以示该方法的有效性。 相似文献
136.
基于i860的存储器子系统设计 总被引:1,自引:0,他引:1
微处理机系统中的存储器子系统设计对整个系统性能的高低有重要的影响,尤其当微处理器的主频越来越高时。本文结合实际例子,给出了一个基于i860处理器(40MHz)的主存设计方案,讨论了实际中需仔细考虑的因素。该设计可为其它高性能RISC系统设计提供参考。 相似文献
137.
The purpose of this clinical trial is to evaluate the efficacy and safety of fleroxacin and to compare with those of lomefloxacin. A randomized controlled study was carried out to treat sixty patients with urinary tract and respiratory tract bacterial infections, thirty in each group with one of the two drugs, and fifty cases were treated with fleroxacin in an open trial. Altogether there were one hundred and ten cases. Both fleroxacin and lomefloxacin were given orally, the dosage was 200 mg every 12 hours or 400 mg every 24 hours for 7-14 days. The clinical efficacy rate was 93.3%; the culturing rate in the fleroxacin group was 83.3%; the bacterial clearance rate was 92.3%, the incidence of adverse reactions was 9.4%, while in the lomefloxacin group they were 90.0%, 80.0%, 87.5% and 6.7% respectively, with no statistically significant difference between the two groups (P > 0.05). In the open and randomized trials, fleroxacin cured eighty cases of bacterial infections, the overall clinical efficacy rate was 90.0%, the culturing rate in the flero-xacin group was 83.8%, the bacterial clearance rate was 88.2% and the incidence of adverse reactions was 9.6%. It is shown that fleroxacin is an antibiotic of broad-spectrum, high efficacy and safety. 相似文献
138.
139.
多媒体音频设备驱动程序的结构和原理 总被引:4,自引:2,他引:2
李国辉 《小型微型计算机系统》1994,15(5):8-12
本文以波形音频输入输出为样本,剖析了Windows音频设备驱动程序的结构和原理。Windows设备驱动程序为应用提供了可扩展,设备无关,一致的接口。本文给出了数字波形数据I/O的处理过程,以及应用程序,驱动程序和音频硬件的层次关系。 相似文献
140.
Responses of cytotoxic T-cells (Tc) to human cytomegalovirus (CMV) represent the predominant mechanism by which hosts resist CMV infection. The CMV major immediate-early protein (IE) is present throughout the virus replicative cycle. Studies were performed to determine whether Tc specific for IE effectively lyse CMV-infected targets and are thus capable of providing protective immunity against infection. After in vitro stimulation of peripheral blood mononuclear cells with CMV-infected autologous fibroblasts, Tc specific for IE were not readily detectable in CMV-reactive polyclonal Tc lines. However, after stimulation of peripheral blood mononuclear cells with cells selectively expressing IE, weak but detectable IE-specific Tc responses were observed. The frequency of IE-specific Tc clones derived from cultures stimulated with IE-expressing cells was 50 to 100 times lower than the frequency of Tc clones specific for other CMV proteins isolated from cultures stimulated with CMV-infected cells. All of the IE-specific Tc clones, which efficiently lysed targets selectively expressing IE, demonstrated minimal lysis of CMV-infected fibroblasts, despite abundant IE expression in these target cells. In contrast to these results with IE, other viral proteins were efficiently presented during all phases of CMV infection. These data suggest that CMV has evolved a unique mechanism for selectively limiting the presentation of the potentially immunogenic IE protein, which may preclude IE-specific Tc from providing protective immunity to CMV infection. 相似文献