论篮球运动员防守观念和素质的培养

文章运用文献资料法、观察统计法和逻辑分析法的研究方法,对篮球运动中运动员的防守观念、防守技术、身体素质、心理素质进行分析,以期为提高篮球运动员防守观念和素质能力提供理论参考。     

太原师范学院开展定向运动的可行性研究

定向运动是一项有趣味性、大众性、竞争性的户外体育运动,是智力与体力相结合的运动项目。在高校开展定向运动有利于培养学生的野外生存能力、创新能力,提高学生的智能,锻炼学生顽强的意志,促进学生良好道德品质和集体主义精神。文章对太原师范学院在学生中开展定向运动的可行性研究发现,定向运动可以缓解体育资源的不足,丰富学生业余生活,对于增强学生综合身体素质、开发学生智力、增强社会适应能力以及野外生存能力方面都有着重要的意义。     

网络外部性下传统码头与自动化码头的博弈

为研究不同网络外部性下传统码头与自动化码头的博弈问题,建立基于网络外部性和码头服务质量的Hotelling模型,使用Nash博弈和Stackelberg博弈得出两种码头的最优定价、市场需求和市场收益这3个变量值。结果表明:在Stackelberg博弈下传统码头和自动化码头的这3个变量值均大于在Nash博弈下的这3个变量值。在码头服务质量差异化不变时,传统码头的市场需求与边际成本呈正相关,自动化码头的市场需求与边际成本呈负相关。在自动化码头网络外部性较小时,传统码头应提升自身服务质量;在自动化码头网络外部性较大时,传统码头不应提升自身服务质量。网络外部性使码头在选择定价时有更多空间,不再仅受码头位置和服务质量的影响。     

Direct observation of nodeless superconductivity and phonon modes in electron-doped copper oxide Sr1−xNdxCuO2

The microscopic understanding of high-temperature superconductivity in cuprates has been hindered by the apparent complexity of crystal structures in these materials. We used scanning tunneling microscopy and spectroscopy to study the electron-doped copper oxide compound Sr_1−xNd_xCuO₂, which has only bare cations separating the CuO₂ planes and thus the simplest infinite-layer structure of all cuprate superconductors. Tunneling conductance spectra of the major CuO₂ planes in the superconducting state revealed direct evidence for a nodeless pairing gap, regardless of variation of its magnitude with the local doping of trivalent neodymium. Furthermore, three distinct bosonic modes are observed as multiple peak-dip-hump features outside the superconducting gaps and their respective energies depend little on the spatially varying gaps. As well as the bosonic modes, with energies identical to those of the external, bending and stretching phonons of copper oxides, our findings reveal the origin of the bosonic modes in lattice vibrations rather than spin excitations.