MC^2电缆介质结构及阻抗分析

本文将用数学和实验两种方法证实MC～2电缆不仅能保证特性阻抗变化不超出电缆技术规范。而且能保证在设计频率范围内电缆结构反射损耗最小。     

化学镀Ni—P镀层的X射线衍射研究

根据X射线衍射分析结果,对化学镀高P(含P>11wt％或19at％)Ni-P镀层加热时效时,镀层成分和加热温度对结构转变的影响作了研究,结果表明,高P共晶、过共晶(含P>11wt％或19at％)合金的结构转变有如下特征:(1)相同加热时效条件下,Ni-P合金的结构转变与成分有密切关系:(2)对同一成分的过共晶合金,Ni-P合金的结构转变与时效温度密切相关;(3)过共晶合金在290～360℃温度范围内时效处理,出现Ni_xP_y介稳相,X射线衍射分析认为Ni_xP_y为Ni_(12)P_5。     

Endothelium-dependent effect of perindopril and enalaprilat in rat thoracic aorta

AIM: To study the effect of the angiotensin-converting enzyme (ACE) inhibitors perindopril (Per) and enalaprilat (Ena) on the reactivity of the endothelium in normal rats. METHODS: Male rats were treated intragastrically with Per (2 mg.kg-1.d-1) or placebo (n = 18) for 6 wk. Aorta was isolated for experiment. Another set of isolated aortic rings with and without endothelium were incubated with Ena (0.1 mumol.L-1) for 30 min. Responses to acetylcholine, serotonin, phenylephrine, sodium nitroprusside (SN), and nitroglycerin (Nit) were observed. RESULTS: Endothelium-dependent relaxation to acetylcholine was augmented in aortic rings from rats treated with Per in comparison with control. The IC50 value (95% confidence limits) decreased from 3.8 (0.56-26.1) mumol.L-1 (control group) to 0.98 (0.28-3.41) mumol.L-1 (Per-treated group). The maximal relaxation was augmented from 62 +/- 9% to 78 +/- 10% (P < 0.01). However, the responses to the endothelium-independent vasodilators, SN and Nit, were similar. Serotonin- and phenylephrine-induced contractions were decreased, which were influenced by basal release of endothelium-derived relaxing factor (EDRF). EC50 values was 6.1 (2.6-14.4) nmol.L-1 vs 8.3 (3.6-18.8) nmol.L-1 in comparison with control group and Per-treated group. The maximal contraction was decreased from 2.42 +/- 0.29 g (control group) to 1.96 +/- 0.25 g (treated group) (P < 0.01). Similar results were found in incubation with Ena. CONCLUSION: Ena and Per enhanced the basic release of EDRF from vascular endothelium.     

激光诱导H_2S催化裂解制备H_2的研究

在室温常压静态条件下研究了以Ｖ２Ｏ５／ＴｉＯ２为催化剂，紫外脉冲激光诱导Ｈ２Ｓ催化分解为Ｈ２和Ｓ的反应及其机理。考察了产氢量与激光不同照射条件之间的关系。     

贝氏体铁素体片条的超微亚结构研究

首次采用扫描隧道显微镜(STM)在大气环境下直接观察了Fe-1.0C-2.0Si-4.0Cr钢中下贝氏体铁素体片条的组织结构,在下贝氏体亚单元内部首次观察到以前从未发现的,尺寸更小、形状规则、排列整齐的结构单元——超亚单元,并初步提出下贝氏体铁素体由以下四个结构层次组成:即下贝氏体铁素体片条由亚片条组成,亚片条由亚单元组成,亚单元由超亚单元组成。     

北京谱仪Ⅱ（BESⅡ）顶点探测器数据获取系统

北京谱仪（ＢＥＳⅡ）顶点探测器数据获取系统是北京谱仪数据获取系统的一部分，该子系统电子学采用快总线标准，本文描述了该系统的硬件结构和软件系统，软件包括快总线系统的微码软件和上层控制软件，该系统的死时间为１．５ｎｓ，对ＢＥＳⅡ系统总死时间的贡献小于０．５ｍｓ。     

FD—TD在分析FSS中的应用

本文讨论了用FD TD分析FSS的有关问题,提出了一种适合于在任意入射角情况下分析FSS的有效吸收边界条件,分别以单层、双层FSS为例进行了计算.数值结果和矢量模式法、谱域法的结果非常一致.     

喷气客机涡轮风扇发动机的振动诊断与改进

通过动态分析和现场测试对一喷气客机的发动机振动作出诊断，发现涡轮叶轮的变柔导致其极转动惯量显著下降，因而改变发动机的动态特性，使其临界转速接近飞机的巡航转速，产生不应有的振动和噪声。文章提出了具体改进方案，已为研制单位采用。