基于面阵传感器的固体表面速度二维相关测量

提出一种非接触二维实时相关检测物体瞬时速度新方法,具有适应性强、精度高等特点.介绍了相关测速理论与实现方法,并给出初步实验结果.     

Effects of myocardial ischemia and reperfusion on mitochondrial function and susceptibility to oxidative stress

We investigated the effects of ischemia duration on the functional response of mitochondria to reperfusion and its relationship with changes in mitochondrial susceptibility to oxidative stress. Mitochondria were isolated from hearts perfused by the Langendorff technique immediately after different periods of global ischemia or reperfusion following such ischemia periods. Rates of O₂ consumption and H₂O₂ release with complex I- and complex II-linked substrates, lipid peroxidation, overall antioxidant capacity, capacity to remove H₂O₂, and susceptibility to oxidative stress were determined. The effects of ischemia on some parameters were time dependent so that the changes were greater after 45 than after 20 min of ischemia, or were significantly different to the nonischemic control only after 45 min of ischemia. Thus, succinate-supported state 3 respiration exhibited a significant decrease after 20 min of ischemia and a greater decrease after 45 min, while pyruvate malate-supported respiration showed a significant decrease only after 45 min of ischemia, indicating an ischemia-induced early inhibition of complex II and a late inhibition of complex I. Furthermore, both succinate and pyruvate malate-supported H₂O₂ release showed significant increases only after 45 min of ischemia. Similarly, whole antioxidant capacity significantly increased and susceptibility to oxidants significantly decreased after 45 min of ischemia. Such changes were likely due to the accumulation of reducing equivalents, which are able to remove peroxides and maintain thiols in a reduced state. This condition, which protects mitochondria against oxidants, increases mitochondrial production of oxyradicals and oxidative damage during reperfusion. This could explain the smaller functional recovery of the tissue and the further decline of the mitochondrial function after reperfusion following the longer period of oxygen deprivation. Received 18 May 2001; received after revision 17 July 2001; accepted 24 July 2001     

几种释放因素对紫杉醇合成与释放的影响

比较研究了几种释放因素对红豆杉细胞生长和紫杉醇合成与释放的影响,结果表明,在中国红豆杉细胞悬浮培养过程中,在细胞生长对数期（14d)加入φ＝5％二甲亚砜及0．2mol/L甘露醇,能显著提高紫杉醇的合成及释放,紫杉醇总产量达到16mg/L,在细胞生长在对数期（14d)加入0．04mol/L氯化钠时,紫杉醇总产量达到7．3mg/L,在细胞生长对数期（14d）加入2mg/L硫酸铈铵时,紫杉醇总产量达到24mg/L。     

庆大霉素-聚酸酐缓释制剂的制备及释药特性

以聚（二聚酸－癸二酸）共取物[P(DA-SA),wDA;WSA=50:50]为药物缓释材料,庆大霉素为模型药物,采用热熔法制备庆大霉素－聚酸酐缓释药棒,初步的制剂稳定性研究表明,在室温干燥条件下,该缓释药棒具有良好的制剂稳定性,体外释药结果表明,在37度时质量分数为0．9％的生理盐水体系中,该缓释药棒的体外释药时间为25d,释药动力学符合一级动力学方程,其体外释药程为：Y＝9．1826＋6．690lt-0.1272t2,R2=0.9874,上述结果表明庆大霉素－聚酸酐缓释药棒是一类具有明显缓释作用的释药体系。     

bFGF药物缓释系统的构建

此研究的目的是为药物bFGF构建一个缓释系统,此系统可用于修复损伤的外周神经、损伤脊髓,或作为某些需要长效释放的药物的载体．制备此载药系统的方法是：先制备含bFGF的明胶微球,再在此微球表面包覆一层疏水材料PLGA（聚乳酸乙醇酸）,采用此方法制备的复合微球的直径在5—18μm,bFGF封载率达到80．5％,释药实验显示该复合系统能持续长时间的释放bFGF并保护其生物活性．     

基于瞬时无功理论的检测方法中低通滤波器的优化设计

针对瞬时无功理论的检测方法中Butterworth低通滤波器存在动、静态特性难以兼顾的弱点,选用Butterworth滤波器和均值滤波器串联的形式作为优化低通滤波器,通过均值滤波器抑制Butterworth滤波器的输出纹波,选用2阶Butterworth滤波器以加快检测速度.实验表明,该优化低通滤波器既可以保证畸变电流的检测精度,又具有较快的响应速度.     

采用检测电源电流控制方式的串联型电力有源滤波器

分析了与并联型电力有源滤波器原理完全不同的、适用于补偿电压型谐波源的串联型电力有源滤波器的工作原理,阐明了其基于瞬时无功功率理论的检测电源电流控制方式,并据此提出了直流电压和ＰＷＭ 逆变器的控制方法．在此基础上研制了实验样机．实验结果验证了所提出的控制方法是有效的,并且表明串联型电力有源滤波器对电压型谐波源具有良好的谐波补偿能力．     

瞬态弱信号采样系统的设计

阐述了被测对象是幅值小、持续时间短的瞬态信号这类采样系统的设计难点和要求．在频谱分析和瞬态分析的基础上,分析了被测信号及采样系统的各环节,并合理地确定了采样频率．     

真空管式太阳热水器热性能研究（二）—瞬时效率、日平均效率的比较分析

利用模型计算值和实验值对真空管式太阳热水器的瞬时效率、日平均效率进行了比较分析,结果表明所建立的计算模型总体上是成功的。还利用计算数据对真空管式太阳热水器和平板式太阳热水器的瞬时效率进行了比较分析,指出了两类热水器在非稳态效率曲线上的重要差别。     

电压型PWM整流器功率控制策略研究

基于功率控制策略的三相电压型PWM整流器控制系统的组成与原理,通过建立基于MATLAB/Simulink环境下的仿真模型,对系统进行了仿真研究,结果表明DPC系统具有良好的动态性能,并具有结构简单、无PWM调制模块、高功率因数、低谐波干扰等优点。