氢键效应及对有机反应活性的影响

在有机化合物中广泛存在着分子内氢键或分子间氢键,多种因素影响着氢键效应,氢键效应对有机物的理化性质和反应活性产生较大的影响。     

应用矩阵求解化学平衡体系的组分数

本文通过实例介绍用矩阵求解化学平衡体系中的组分数的方法 ,且同时可解出独立反应数及反应方程式     

TisiW_(12)O_(40)/TiO_2的合成、表征及催化活性

本文报道了非均相固载型杂多酸盐催化剂ＴｉＳｉＷ１２Ｏ４０／ＴｉＯ２的制备方法，并用ＩＲ、ＸＲＤ谱对该催化剂进行了表征，研究了该催化剂的催化活性．实验表明，在以苯为带水剂时，催化剂的用量为反应液的０．５％，醇酸摩尔比为１．２０∶１，酯化反应时间为２ｈ，乙酸正丁酯的收率达７６．８％，超过硫酸、磷钨酸催化水平．     

化学反应速度及活化能测定实验研究

针对化学反应速度及活化能测定实验中经常遇到的困难,分析了实验失败的主要原因,是由于固体(NH4)2S2O8试剂中含有少量水而引起的,提出了用Na2SO3及以痕量碘加速过量Na2SO3氧化的方法消除其影响.     

The effect of different foot and hand set-up positions on backstroke start performance

Foot and hand set-up position effects were analysed on backstroke start performance. Ten swimmers randomly completed 27 starts grouped in trials (n = 3) of each variation, changing foot (totally immersed, partially and totally emerged) and hand (lowest, highest horizontal and vertical) positioning. Fifteen cameras recorded kinematics, and four force plates collected hands and feet kinetics. Standardised mean difference and 95% confidence intervals were used. Variations with feet immersed have shown lower vertical centre of mass (CM) set-up position (0.16 m), vertical impulse exerted at the hands, horizontal and vertical impulse exerted at the feet (0.28, 0.41, 0.16 N/BW.s, respectively) than feet emerged with hands horizontal and vertically positioned. Most variations with feet partially emerged exhibited higher and lesser vertical impulse exerted at hands than feet immersed and emerged (e.g. vertical handgrip, 0.13, 0.15 N/BW.s, respectively). Variation with feet emerged and hands on the lowest horizontal handgrip depicted shorter horizontal (0.23, 0.26 m) and vertical CM positioning at flight (0.16, 0.15 m) than the highest horizontal and vertical handgrip, respectively. Start variations have not affected 15-m time. Variations with feet partially or totally emerged depicted advantages, but focusing on the entry and underwater biomechanics is relevant for a shorter start time.     

Effect of defence response time during lunge in foil fencing

The aim of this study was to analyse the effect of stimulus change timing on reaction response time parameters, horizontal velocity of the centre of mass (CM) and precision during offensive actions in fencing. Twelve fencers from the Spanish National Foil Team were included in the study. Two 500 Hz force plates were used to register the horizontal component of the reaction force while a 3D video camera set at 250 Hz recorded the spatial position of 11 body markers and a projector connected to a programmed stopwatch projected a moving target (stimulus) on a screen. When the circle (target) appeared in the centre of the plastron, fencers had to execute a step-forward-lunge as fast as possible, trying to touch the circle with the tip of the foil. During the lunge, the position of the target could randomly shift or not to three different positions. The stimulus change was performed randomly at four different times with a progressive delay. The results show that target changes did not have any effect when they occurred at the beginning of the movement sequence. However, when the target change was delayed, reaction and movement times increased and the technical execution of the lunge changed, leading to more errors.     

催化动力学光度法测定痕量铜的综述

本文综述我国催化动力学光度法测定痕量铜的状况,提出一些尚待开发新指示反应的设想,并介绍提高催化动力学法灵敏度的两个新途径。     

一种新的动力学模型--反应类过渡态理论

反应类过渡态理论，是以过渡态理论为基础，对于与主反应同一类的其它反应的热力学速率常数仅从它们的势垒差和反应能中就可有效的预测出发，这种理论已应用于许多氢提取反应，在复杂反应的基本动力学模型设计中预测热力学速率常数将是非常有用的。     

化学平衡到达的标志和同一平衡

学生在学习《化学反应速率和化学平衡》过程中,往往对化学平衡这一概念理解不透,尤其 是判断一个可逆反应是否达到平衡,由于考虑不全面而导致判断失误。结合实例,总结化 学平衡的标志及同一平衡问题。     

谈“苍天已死,黄天当立”的由来

从文字学和历史学的角度对“苍天”和“黄天”两个词进行深入分析,考证东汉黄巾起义的“苍天已死,黄天当立”口号中“黄天”是从“皇天”一词演变来的,并结合历史和宗教典籍,考察该口号所蕴含的道教文化以及朴素辩证法思想。