无穷时滞一阶脉冲积分微分方程温和解的存在性

利用预解算子理论,结合不动点定理,证明了无穷时滞一阶脉冲积分微分方程温和解的存在性.     

Dynamics of visual feedback in a laboratory simulation of a penalty kick

Sport scientists have devoted relatively little attention to soccer penalty kicks, despite their decisive role in important competitions such as the World Cup. Two possible kicker strategies have been described: ignoring the goalkeeper action (open loop) or trying to react to the goalkeeper action (closed loop). We used a paradigm simulating a penalty kick in the laboratory to investigate the dynamics of the closed-loop strategy in these controlled conditions. The probability of correctly responding to the simulated goalkeeper motion as a function of time available followed a logistic curve. Kickers on average reached perfect performance only if the goalkeeper committed him or herself to one side about 400 ms before ball contact and showed chance performance if the goalkeeper motion occurred less than 150 ms before ball contact. Interestingly, coincidence judgement?-?another aspect of the laboratory responses?-?appeared to be affected for a much longer time (>500 ms) than was needed to correctly determine laterality. The present study is meant as groundwork for experiments in more ecological conditions applicable to kickers and goalkeepers.     

需求弹性的精确计算

采用定积分方法给出了需求弹性的一个精确计算公式,使点弹性和弧弹性的表达得到统一,对弹性所表达的经济含义给出了直观且精确的解释.     

半p-拟凸函数的一些性质及应用

本文在半P-不变凸集和半（P,r）-前-不变凸函数的基础上,提出了与半（p,r）-前-不变凸函数相关的一类广义凸函数——半P-拟凸函数,探讨了它与一些熟知的广义凸函数间的关系和它的有关性质,以及这类广义函数的局部极小点与全局极小点的关系．     

Menger概率度量空间中的广义压缩映象原理

文中在概率度量空间的框架下,证明了一个新的广义压缩映象定理．     

关于切点单形几个结果的改进

最近文献〔1〕、〔2〕中获得了切点单形的几个重要几何不等式，本文给出了〔1〕、〔2〕中结果的改进，从而获得切点单形几个更强的几何不等式。     

关于教育技术学逻辑起点研究的一点探讨

教育学以"教育"活动作为逻辑起点具有研究对象与逻辑起点重合的缺陷,相应地教育技术学以"借助于技术的教育"活动作为逻辑起点也具有同样的问题。对教育技术学的逻辑起点的认识只有当教育技术学发展到一定阶段之后才成为可能,在这个过程中,需要处理好逻辑起点与研究起点、历史起点的关系。最后,作者提出了重新认识逻辑起点的问题及其重要性。     

西点军校体育运动的开展及启示

西点军校德、智、军、体等多育并举,其体育运动对学员能力素质的培养起到了重要作用。在查阅文献的基础上,结合实地参观访问,阐述了西点体育运动的开创与发展的历程、体育课程设置、体育活动、体育工作人员与场馆设施等方面的经验与做法。西点军校体育运动的宝贵经验对我国军事体育教育具有重要的借鉴和启迪意义。     

On the Points of View Used in Mansfield’ s “Miss Brill”

Point of view has been a big playground for study in fiction for about a century.Mansfield’ s "Miss Brill" is featured by its successful use of points of view.This paper will discuss how Mansfield’ s choice of a particular point of view helps to communicate the central theme of the story.