BX_3与C=C之间p-π作用的量子化学研究

用量子化学计算方法对BX3(X=H,F,Cl)与C‖C之间通过p-π作用形成的复合物进行了研究.计算结果表明,各复合物中BX3均位于π键的上方,并且偏向于氢原子数较多的碳原子一侧.BH3与C‖C的作用是由π键中的电子通过向B的空p轨道转移而形成,但BF3和BCl3与C‖C的作用只是通过微弱的分子间作用力结合,复合物的形成使分子的振动光谱随作用的强弱而出现一定的红移现象.     

钒对遗传性Ⅱ型糖尿病ＫＫ小鼠降糖作用的实验研究

以遗传性非胰岛素依赖型糖尿病ＫＫ小鼠为动物模型,研究钒对雌雄性糖尿病小鼠的降糖作用．实验选择３周龄的ＫＫ小鼠,雌雄各半,通过自由饮水方式给予雌雄性小鼠０ｍｇ/Ｌ、０.１ｍｇ/Ｌ和１００ｍｇ/Ｌ的钒酸铵,实验周期为１７周,观察不同剂量钒酸铵对血糖、甘油三酯和总胆固醇代谢的影响．研究结果表明,０１ｍｇ?Ｌ钒酸铵对雌雄性小鼠的血糖水平和血液生化指标没有明显的影响,高剂量钒酸铵（１００ｍｇ?Ｌ）明显降低雄性糖尿病小鼠的饮水量、血糖水平、糖基化血红蛋白、甘油三酯和总胆固醇等,葡萄糖耐量水平得到显著改善,对糖尿病小鼠的肝肾功能没有影响．结果提示钒酸铵对雌性小鼠和雄性小鼠具有降血糖作用,其作用效果有明显的性别差异．     

无线传感器网络中基于能效的最优数据包长

在无线传感器网络中,传感器节点的能效一直是非常关键的问题．当设定的数据包长度较大时,数据包在网络中传输出错的概率就会较大,而采用较小的数据包时,又会导致过多的控制包．如何通过设定数据包的最优长度进而提高节点能效是一个值得研究的问题．以往对数据包长度的设定一般是基于大量的数值、实物模拟,本文则尝试通过构造最优化模型来揭示数据包长度与无线电收发部件、通信信道、通信协议等因素的内在关系．最后,通过数值分析,说明了数据传输量与最优包长之间的联系．     

Mixed control of uncertain jumping time-delay systems

In this paper, we investigate a class of linear continuous-time systems with Markovian jump parameters. An integral part of the system dynamics is a delayed state with time-varying and bounded delays. The jumping parameters are modeled as a continuous-time, discrete-state Markov process. Employing norm-bounded parametric uncertainties and utilizing the second-method of Lyapunov, we examine the problem of designing a mixed controller which minimizes a quadratic performance measure while satisfying a prescribed -norm bound on the closed-loop system. It is established that sufficient conditions for the existence of the mixed controller and the associated performance upper bound could be cast in the form of linear matrix inequalities.     

s=1／2xxz反铁磁链的Spin—Peierls相变研究

应用玻色化的自洽微扰论方法,给出了ｓ＝１／２ｘｘｚ反铁磁链的Ｓｐｉｎ－Ｐｅｉｅｒｌｓ系统的基态能量和准粒子元激发能谱的解析近似式,了模型基态能量密度与基态准粒子激发能隙随晶格畸变大小的关系受各向异性作用参量的影响。     

The biomechanical effect of warm-up stretching strategies on landing mechanics in female volleyball athletes

ABSTRACT

Female volleyball athletes incorporate dynamic and static stretching into a warm-up, with evidence generally supporting dynamic stretching to improve performance. However, the effects of these stretching practices on injury risk during subsequent volleyball manoeuvres have yet to be fully elucidated in the warm-up literature. Three-dimensional kinematic data associated with non-contact, lower extremity injury were recorded on 12 female collegiate club volleyball athletes during unilateral landing tasks on the dominant and non-dominant limb. Participants performed landings as part of a volleyball-simulated manoeuvre prior to and post-dynamic (DWU) and combined dynamic-static (CDS) warm-ups. A significant reduction in non-dominant hip adduction angle was found at 15 min post CDS warm-up (p = 0.016; d = 0.38), however, no other warm-up differences were detected. The non-dominant limb demonstrated greater knee abduction (p = 0.006; d = 0.69) and internal rotation angle (p = 0.004; d = 0.88), suggesting that this limb demonstrates more risky landing patterns that are potentially due to altered trunk positioning upon landing. The results show that the majority of selected landing kinematics are unaffected by additional static stretching to a dynamic warm-up and that the non-dominant limb may be at a higher injury risk in female volleyball athletes.     

编程语言教学模式探索

提高学生的程序设计能力的途径是：首先,要把程序性知识作陈述性知识处理;其次,把模式识别程序和动作步骤程序相结合;然后,科学合理地组织练习与反馈.形成“知识转化、模仿修改、练习反馈、深化讨论”的过程教学模式,逐步提高提高学生的编程应用能力.     

（La,A）（Zn,Mn）SbO（A=Ca，Sr，Ba）稀磁半导体的制备与研究

通过LaZnSbO在La3+的位置用A=Ca2+, Sr2+, Ba2+进行变价替换引入P型载流子,使用Mn2+替换Zn2+引入自旋,可使ZrCuSiAs结构单相(La,A)(Zn,Mn)SbO (A=Ca, Sr, Ba)同时兼具半导体和铁磁性能,居里温度可达到40 K。居里温度以下呈现类似玻璃磁性的磁性特征,(La0.95Ca0.05)(Zn0.9Mn0.1)SbO的翻转时间(τ*)和动态临界指数(zγ)分别为：τ*=2.64×10-7s, zγ=1.91。     

簇合物（Me2BN3）n（n=1～3）结构和性质的理论研究

采用密度泛函理论B3LYP／6—311＋G^6方法,计算研究了（Me2BN3）n（n=1～3）簇合物的结构和性质．研究表明,环状多聚体（Me2BN3）n（n=1～3）的优化构型均为由不同子体系的叠氮基0-N和B原予相连形成的环状结构．讨论几何参数随聚合度的变化关系,同时对所有优化构型进行振动频率计算,对其IR谱进行归属,并与实验值进行了比较,结果发现计算值均可信．簇合物的热力学函数均随簇合物的聚合度n以及温度的增加而呈线性增加．由聚合反应的焓变可知,在298．2K下单体形成三聚体在热力学上是有利的,而形成二聚体则是不利的．     

物体受到F=kv的力时的归类解析

本文对物体受到F=kv的力时的运动规律和特点进行了归类解析,并用例题展示这些规律在处理一些较复杂的物理问题中的作用.