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71.
油脂氢化理论研究进展 总被引:2,自引:0,他引:2
本文从下列几个方面阐明油脂氢化理论的研究状况:(1)氢化机理的研究;(2)氢化反应动力学处理;(3)氢化反应活化能的确定;(4)氢化选择性的研究。 相似文献
72.
Mohammed Nurul Afsar Hua Chi 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(7):1161-1179
The room temperature application of sapphire as window material at higher frequencies is not feasible since its absorption coefficient increases almost linearly with increasing frequency in the millimeter wavelength region. At cryogenic temperature the absorption coefficient value decreases only by a few factors (factor of 2 to 3) in the 90 – 200 GHz region. The earlier reported temperature squared dependence (decrease) in the absorption coefficient or the loss tangent value is totally absent in our broad band continuous wave data we are reporting here (at 6.5 K, 35K, 77K and 300K) and one we reported at conferences earlier. Our results are verified by another technique. We utilize our precision millimeter wave dispersive Fourier transform spectroscopic techniques at room temperature and at cryogenic temperatures The extra high resistivity single crystal compensated silicon is no doubt the lowest loss material available at room temperature in the entire millimeter wavelength region At higher millimeter wave frequencies an extra high resistivity silicon window or an window made with extra high resistivity silicon coated with diamond film would certainly make a better candidate in the future. A single free standing synthetic diamond window seems to have higher absorption coefficient values at millimeter wavelength region at this time although it is claimed that it possesses good mechanical strength and higher thermal conductivity characteristics. It certainly does not rule out the use of diamond film on a single crystal high resistivity silicon to improve its mechanical strength and thermal conductivity 相似文献
73.
张弛 《网络安全技术与应用》2007,(2):80-82
本文系统的分析了“黑客”对于ASP网站后台的入侵手段,结合我国网站管理员水平及经验参差不齐的现状,给出了简单且有效的ASP网站后台安全解决方案。使大多数编程水平不高的管理员也能杜绝网站后台的安全隐患。 相似文献
74.
Xu Zhigang Huang Kezheng Ai Xing Shan Lianye College of Mechanical Engineering Shandong University of Technology Jinan Shandong China 《计算机辅助绘图.设计与制造(英文版)》1997,(2)
SolidModelingEror:AnalysisandCompensation①XuZhigangHuangKezhengAiXingShanLianyeColegeofMechanicalEngineering,ShandongUniversi... 相似文献
75.
文章以介电测井理论为基础,借鉴感应仪的模拟刻度方法,对大庆油田的60MHz相位介电井仪的模拟刻度进行了研究。参照国内外有关资料,提出了模拟刻度器的设计模型,通过理论分析与计算,建立了一套模拟刻度方法。现场初步试验,该方法取得了一定物效果,为进一步提高仪器的测量精度提供了依据。 相似文献
76.
干粉灭火剂浅论 总被引:4,自引:0,他引:4
前言 :干粉灭火剂 (Dry fire extinguishing powder、Drychemical、Fire extinguishent)始于十九世纪末 ,二十世纪三十年代美国 Ansul公司首先开发出以碳酸氢钠为基料的干粉灭火剂 ,是最早应用于消防科技领域的干粉灭火剂。干粉灭火剂由一种或多种具有灭火能力的细微无机粉末组成 ,粉末的粒径大小及其分布对灭火效果有很大的影响 ,按照干粉灭火范围可划分为三类 :ABC类 :磷酸一铵 ;BC类 :碳酸氢钠、碳酸氢钾、氯化钾、氯化钠、硫酸钾、硫酸铵、monnex;D类 :氯化钠、碳酸氢钠、石墨灭火剂。干粉灭火剂与水、泡沫、二氧化碳等相比 ,在灭火… 相似文献
77.
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79.
Glucosamine, which enters the hexosamine pathway downstream of the rate-limiting step, has been routinely used to mimic the insulin resistance caused by high glucose and insulin. We investigated the effect of glucosamine on insulin-stimulated glucose transport in 3T3-L1 adipocytes. The Delta-insulin (insulin-stimulated minus basal) value for 2-deoxyglucose uptake was dramatically inhibited with increasing concentrations of glucosamine with an ED50 of 1.95 mM. Subcellular fractionation experiments demonstrated that reduction in insulin-stimulated 2-deoxyglucose uptake by glucosamine was due to an inhibition of translocation of both Glut 1 and Glut 4 from the low density microsomes (LDM) to the plasma membrane. Analysis of the insulin signaling cascade revealed that glucosamine impaired insulin receptor autophosphorylation, insulin receptor substrate (IRS-1) phosphorylation, IRS-1-associated PI 3-kinase activity in the LDM, and AKT-1 activation by insulin. Measurement of intracellular ATP demonstrated that the effects of glucosamine were highly correlated with its ability to reduce ATP levels. Reduction of intracellular ATP using azide inhibited Glut 1 and Glut 4 translocation from the LDM to the plasma membrane, insulin receptor autophosphorylation, and IRS-1 tyrosine phosphorylation. Additionally, both the reduction in intracellular ATP and the effects on insulin action caused by glucosamine could be prevented by the addition of inosine, which served as an alternative energy source in the medium. We conclude that direct administration of glucosamine can rapidly lower cellular ATP levels and affect insulin action in fat cells by mechanisms independent of increased intracellular UDP-N-acetylhexosamines and that increased metabolism of glucose via the hexosamine pathway may not represent the mechanism of glucose toxicity in fat cells. 相似文献
80.
Hu Chi Yang Hong-sheng Lu Zhong-zuo 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(2):401-410
Circular groove guide is a kind of waveguide for millimeter waves with low loss, large dimensions, and low dispersion. In this paper, the dominant mode characteristics of it is analysed. The technique that mode macthing method combines with point matching method is used to derive the Nth-order characteristic equation of the guide. The 1st order, 2nd order and 3rd order approximate curves that the normalized cutoff wavelength of circular groove guide varies with c/a are given. The attenuation curves are given at 1mm, 1.5mm and 3mm wavelength. The numerical results are in well agreement with the experimental results published. 相似文献