电导法测定乙酸乙酯皂化反应速度常数的简化

本文介绍了一种只需要氢氧化钠的准确浓度，不需要乙酸乙酯的准确浓度测定皂化反应速度常数的方法。此法避免了酯溶液浓度不易配准。且测定的数据个数较少。测定的速度常数值在实验误差范围内与文献值符合较好。     

正电子素络合形成研究(英文)

本文讨论了正电子素与在30％(v/v)乙醇—水及20％(v/v)二氧六环—水溶剂中的N—(对位取代苯基)氨基乙酸、N—(间位取代苯基)氨基乙酸间的络合形成。描述了应用BaF_2闪烁记数器的正电子湮没寿命谱仪。藉助于这个新型的正电子湮没寿命谱仪,测量了正电子素与溶液中的氨基乙酸衍生物的络合形成的反应速度常数。结果表明,其反应速度常数值依赖于苯环的共轭效应、取代苯基的诱导效应及溶剂的性质。在反应速度常数与N—取代苯基氨基乙酸的碱性离解常数的负对数值间存在着线性自由能关系。这表明,正电子素与分子的瞬态络合形成很象通常的化学反应,遵守经典的规律。     

利用加速量热仪(ARC)研究热分析动力学反应机理

从动力学基础方程推导出绝热条件下ARC热分析动力学方程,与传统的DTA动力学方程比较,ARC理论模型更接近于化学过程工业.以SM型和RM型含能材料为样品进行热分析测试,运用新的理论模型分别计算出了SM型和RM型两种样品的活化能ESM=247.55kJ.mol-1,ERM=138.46kJ.mol-1和指前因子ASM=4.26×1023S-1,ARM=4.20×1012S-1.     

微分-积分法确定反应速率常数

介绍微分-积分法确定反应速率常数的原理以及利用MATLAB语言设计了微分．积分法求反应级数的计算机处理过程。处理时先对在实验测定中不同时刻测定的浓度C数据，利用三次样条插值法和差分法求出各浓度C对应的速率V，再利用线性回归法求出反应级数，最后利用动力学积分方程计算反应速率常数。本以一级、二级反应和分数级反应实验测定结果为例进行验证，结果表明，利用所编程序确定的反应级数与常规方法能很好的吻合。在化学动力学中这种数据处理方法将使实验过程得到简化，实验结果更准确、更可靠。     

中老年人健身运动前后安静心电图的分析研究

对59名进行3个月健身运动(如太极拳、木兰扇、新编五禽戏和健身走等)的中老年人跟踪调查,测试他们3个月前后两次的安静心电图并分析,结果显示:前后两次的异常心电图的例数分别为30例和25例,分别占总人数的50.20%和42.40%,异常心电图中ST—T段改变占受测者异常心电图的绝大部分,分别为70.00%和68.00%;3个月的健身运动对ST—T改变和PR间期延长、窦性心动过缓的影响较明显;对两次测试的异、正常心电图例数进行卡方检验,结果为X2=0.851,p>0.05,无显著性差异,从例数来看,有5例转为正常,有好转趋势。说明3个月的健身运动使中老年人的异常心电图有好转趋势的表现,但不是很明显,建议应长期坚持健身运动。     

镁缺乏对充血性心力衰竭的影响

目的：研究镁缺乏对充血性心力衰竭的影响。方法：回顾性分析了227例充血性心力衰竭患者（CHF）,其中137例加用硫酸镁治疗（Ⅰ组）,140例未加用硫酸镁治疗（Ⅱ组）。结果：Ⅰ组总有效率92．7％,显效率64．2％,均显著高于Ⅱ组（P＜0.01）。疗效出现时间显著短于Ⅱ组（P＜0．01）,并且死亡率显著低于Ⅱ组（P＜0．01）低钾、室性心律失常、洋地黄中毒等并发症也显著低于Ⅱ组（P＜0．01、P＜0．01,P＜0．01）。结论：在CHF患者的治疗中,应重视镁缺乏的影响,及时加用镁剂治疗,可能对提高CHF患者的生存率,减少室性心律失常,猝死等并发症的发生率,降低死亡率有重要意义。     

Relationship between action potential, contraction-relaxation pattern, and intracellular Ca2+ transient in cardiomyocytes of dogs with chronic heart failure

Abnormalities of contractile function have been identified in cardiomyocytes isolated from failed human hearts and from hearts of animals with experimentally induced heart failure (HF). The mechanism(s) responsible for these functional abnormalities are not fully understood. In the present study, we examined the relationship between action potential duration, pattern of contraction and relaxation, and associated intracellular Ca²⁺ transients in single cardiomyocytes isolated from the left ventricle (LV) of dogs (n = 7) with HF produced by multiple sequential intracoronary microembolizations. Comparisons were made with LV cardiomyocytes isolated from normal dogs. Action potentials were measured in isolated LV cardiomyocytes by perforated patch clamp, Ca²⁺ transients by fluo 3 probe fluorescence, and cardiomyocyte contraction and relaxation by edge movement detector. HF cardiomyocytes exhibited an abnormal pattern of contraction and relaxation characterized by an attenuated initial twitch (spike) followed by a sustained contracture ('dome') of 1 to 8 s in duration and subsequent delayed relaxation. This pattern was more prominent at low stimulation rates (58% at 0.2 Hz, n = 211, 21% at 0.5 Hz, n = 185). Measurements of Ca²⁺ transients in HF cardiomyocytes at 0.2 Hz manifested a similar spike and dome configuration. The dome phase of both the contraction/relaxation pattern and Ca²⁺ transients seen in HF cardiomyocytes coincided with a sustained plateau of the action potential. Shortening of the action potential duration by administration of saxitoxin (100 nM) or lidocaine (30 μM) reduced the duration of the dome phase of both the contraction/relaxation profile as well as that of the Ca²⁺ transient profile. An increase of stimulation rate up to 1 Hz caused shortening of the action potential and disappearance of the spike-dome profile in the majority of HF cardiomyocytes. In HF cardiomyocytes, the action potential and Ca²⁺ transient duration were not significantly different from those measured in normal cells. However, the contraction-relaxation cycle was significantly longer in HF cells (314 ± 67 ms, n = 21, vs. 221 ± 38 ms, n = 46, mean ± SD), indicating impaired excitation-contraction uncou pling in HF cardiomyocytes. The results show that, in cardiomyocytes isolated from dogs with HF, contractile abnormalities and abnormalities of intracellular Ca²⁺ transients at low stimulation rates are characterized by a spike-dome configuration. This abnormal pattern appears to result from prolongation of the action potential. Received 22 January 1998; received after revision 16 March 1998; accepted 27 March 1998     

二元概率型算子族的收敛定理

利用随机向量构造了一类二元概率型算子族，并利用量化的Ｐｏｉｓｏｎ极限定律和概率分布的性质给出这类算子族的收敛阶估计     

PtCl4^2—／PtCl6^2—体系电子自交换速率常数的测定

本文研究了籍静电引力接着ＰｔＣｌ４＾２－／ＰｔＣｌ６＾２－的ＰＶＰ修饰电极，采用动电势扫描法、旋转圆盘电极法和电位阶跃法等测定了不同Ｈ２ＰｔＣｌ６溶液浓度、ＰＶＰ膜厚度和支持电解质条件下ＰｔＣｌ４＾２－／ＰｔＣｌ６＾２－体系的Ｋｅｘ值。     

亚硒酸钠对麦穗鱼的遗传毒性效应研究

４ｐｐｍ的Ｎａ２ＳｅＯ３对麦穗鱼的微核率有显的影响（Ｐ＜０．０５），所以ｓｅ在定浓度下是致突变剂，而０．１ｐｐｍ的ＮａＳｅＯ３对麦穗鱼的核异常率有极显的影响（Ｐ＜０．０１），因此，０．１ｐｐｍ应视为有毒效应浓度。麦穗鱼可用作淡水水体致突变物污染的监测生物。