网球运动员反应判断与自信心的研究

网球技术动作的结果或运动成绩取决于若干因素--运动员对对方技术的感知、判断和运动员对自己动作的控制等环节,这些环节又直接与自信心和行为控制相关.研究专业网球运动员和业余网球运动员在这些环节中的反应时、反应准确度和信心程度.研究结果表明,专业网球运动员和业余网球运动员在反应时方面没有明显差异,但在反应准确度和信心程度上专业运动员显著高于业余运动员;左强势手运动员的反应时、反应准确度和信心程度略胜于右强势手运动员;反应时与反应准确度的相关关系大于反应时与信心程度的相关关系.     

脂肪酶催化硬脂酸酯化反应的研究

用脂肪酶在四氢呋喃中催化合成硬脂酸酯.研究了反应温度、时间、加水量、加酶量、不同的醇以及原料摩尔比对硬脂酸转化率的影响.最佳反应条件为:反应温度35℃,硬脂酸与乙醇的摩尔比为1∶1.3,加水量为0.4%,加酶量为600μg/g硬脂酸,反应时间24 h,硬脂酸转化率达72.4%.     

室温固相法合成纳米层状双金属氢氧化物

首次报道了通过室温固相法,合成纳米层状双金属氢氧化物(简称LDH).考察了反应物配比、反应时间分别对试样物相的影响.采用X-射线衍射仪(XRD)、透射电镜(TEM)分别对样品的物相、形貌、粒径等进行了表征.结果表明,反应物配比、反应时间对产物物相有很大影响,镁铝比为3:1,反应时间控制在60min制备的样品分散性好,晶型单一,粒子呈针状,长120nm,宽20nm.     

再造与复古的辩难:整理国故与文化复古之关系的历史考察

整理国故的主要内容是校勘古籍、考辨史事。整理的对象当然包括那些传统的"高文典册",本身就有沉迷于故纸堆的"嫌疑",再加上整理国故的领军人物胡适等人一再强调其与清代汉学家在研究方法等方面的种种内在关联,事实上未能严格划清与旧学的界限,遂使整理国故与当时社会上出现的种种复古现象之间产生了难以厘清的干系,引起了思想文化界关于整理国故与文化复古现象之间关系的争论。作为"再造文明"的重要手段,整理国故对于复古现象的出现起了推波助澜的作用,但不能因此简单地目之为复古和反动。     

基于LifeMoD对体操运动员踏跳过程的仿真研究

摘要：目的：旨在探讨人-器械相互作用过程中的动力学关系为后期优化踏板技术提供理论基础。方法：在LifeMoD中建立19个环节的多体动力学模型和助跳板,并展开助跳板力学特性的仿真研究。结果：踏跳过程中体操运动员受到的踏板反作用力峰值随着助跳板弹簧的刚度、阻尼以及板面体刚度的增加而增大,而随着板面体阻尼的增加而减小;增加助跳板弹簧的刚度能有效地提高体操运动员踏板后的垂直起跳速度,而改变助跳板弹簧的阻尼以及板面体的刚度和阻尼则影响不明显;增加助跳板面体的阻尼虽能减小踏板反作用力的峰值,但其负载率也明显增大。建议在满足人体肌骨系统能够承载的生理范围内,适当地增加助跳板的刚度有助于完成更高难度的技术动作。     

N-heterocyclic carbene-stabilized metal nanoparticles within porous organic cages for catalytic application

Tuning the surface-embellishing ligands of metal nanoparticles (NPs) is a powerful strategy to modulate their morphology and surface electronic and functional features, impacting their catalytic activity and selectivity. In this work, we report the design and synthesis of a polytriazolium organic cage PIC-T, capable of stabilizing PdNPs within its discrete cavity. The obtained material (denoted Pd@PCC-T) is highly durable and monodispersed with narrow particle-size distribution of 2.06 ± 0.02 nm, exhibiting excellent catalytic performance and recyclability in the Sonogashira coupling and tandem reaction to synthesize benzofuran derivatives. Further investigation indicates that the modulation of N-heterocyclic carbene sites embedded in the organic cage has an impact on NPs’ catalytic efficiency, thus providing a novel methodology to design superior NP catalysts.     

Shoe collar height and heel counter-stiffness for shoe cushioning and joint stability in landing

ABSTRACT

This study examined the effects of shoe collar-height and counter-stiffness on ground reaction force (GRF), ankle and knee mechanics in landing. Eighteen university basketball players performed drop landing when wearing shoes in different collar height (high vs. low) and counter-stiffness (stiffer vs. less stiff). Biomechanical variables were measured with force platform and motion capturing systems. Two-way repeated measures ANOVA was performed with α = 0.05. Wearing high collar shoes exhibited smaller peak ankle dorsiflexion and total sagittal RoM, peak knee extension moment, but larger peak knee varus moment than the low collar shoes. Stiffer counter-stiffness shoes related to smaller ankle inversion at touchdown and total coronal RoM, but larger peak knee flexion and increased total ankle and knee sagittal RoM than the less stiff counter-stiffness. Furthermore, wearing stiffer counter-stiffness shoes increased forefoot GRF peak at high collar condition, while no significant differences between counter-stiffness at low collar condition. These results suggest that although higher collar height and/or stiffness heel counter used can reduce ankle motion in coronal plane, it would increase the motion and loading at knee joint, which is susceptible to knee injuries. These findings could be insightful for training and footwear development in basketball.     

影响不对称烯烃加成反应的因素

影响不对称烯烃加成反应方向有三个因素：①取代基;②亲电试剂;③其它试剂（如引发剂）．     

石油化工中的绿色化学与经济原子

该文主要介绍石油化工中的绿色化学与经济原子的概念、发展现状,并归纳分类出目前已有研究基础又较为值得研究发展的导向性研究课题。     

从C_2H_3F到C_2H_2途径的IRC和哈密顿理论讨论

介绍了IRC和反应途径的哈密顿理论研究反应机理的方法,同时讨论从C2H3F到C2H2过程的反应机理．