中国乒乓球队制胜因素的实证研究

中国乒乓球队之所以能够长胜不衰,雄踞世界乒坛,是与多年来乒乓球队技战术的精彩演绎及强有力的后备人才培养分不开的。中国乒乓球队制胜因素即“三件宝”是指技术组合的多样化、击球点的全面性以及反方向技术的应用能力,这三个方面对取得比赛的胜利起着关键的作用。主要通过观察法和数理统计法对这"三件宝"在优秀运动员比赛过程中的应用情况进行了研究,力求发现其中的规律,为运动员今后的训练提供参考依据。     

企业家先验知识、治理模式与创新策略选择

本文以2012年科技型中小企业为样本,实证分析了企业家的教育背景和从业经历等对企业创新策略的影响,以及公司治理模式在企业家先验知识对创新策略选择的调节关系;研究结果表明企业家的高学历和理工科背景对企业的创新决策和创新风险偏好有着显著的正向影响;此外,在公司治理模式调节变量作用下,企业家从业经历对企业创新策略选择有显著影响。     

解读未注册商标在我国的法律保护——以我国2013新《商标法》为视角

文章从未注册商标在我国商标法中的法律地位谈起,根据现行商标法分析了未注册商标的三重保护机制,对于新商标法中未注册商标的保护加以肯定的同时仍然就其在转让和许可使用方面效力规定的缺失、未注册商标使用和管理的混乱、先用权制度的不足方面提出了自己的建议。     

Effects of changing speed on knee and ankle joint load during walking and running

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s^?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.     

中美首位城市与首府城市对比与思考

本文对比了中美两国首府城市(包括首都)与该地区首位城市的重叠比率,并在此基础上讨论其中的社会管理体制和文化传统,这个差异不仅反映了社会发育的不同阶段,尤其反映了不同的历史根基。     

约化弦EKR理论背景方程的二重逆散射方法

文章首先构造了约化弦EKR理论背景方程的二重形式,然后给出了适合于该理论的二重逆散射方法,并利用此方法求取了该理论的二重孤子解族。     

Largest Silurian Vertebrate Discovered from Yunnan,China

<正>An apparent absence of Silurian fishes more than half-a-metre in length has been viewed as evidence that gnathostomes(jawed vertebrates)were restricted in size and diversity prior to the Devonian.A team led by Professor ZHU Min,Institute of Vertebrate Paleontology and Paleoanthropology(IVPP)of the Chinese Academy of Sciences has unearthed a bony fi sh with an estimated length of about 1 meter from the Silurian Kuanti Formation in Yunnan Province of southwestern China,revealing that pre-Devonian gnathostomes could attain comparatively large sizes.The study published on June 12 in the journal of Scientifi c Reports adds     

反三角函数是怎样产生的？

三角函数学了正弦、余弦和正切,没学余切、正割和余割;更没学反三角函数了!这就是今年某些大专新生在初等数学方面的薄弱之处;读懂本文后,新生们一定能有所弥补,在进校后的高等数学学习中扎实地迈进一大步。     

Lower extremity power during the squat jump with various barbell loads

The purpose of this study was twofold: (1) to determine the barbell load that maximised the system power as well as the ankle, knee, and hip joint powers during the squat jump, and (2) to compare the system powers computed from two different methods: the centre of mass (COM) method and the barbell method. Seven male throwers were recruited in this study. The system power (COM method) and the ankle, knee, and hip joint powers were determined with the load incrementally set at 0%, 10%, 30%, 50%, 70%, and 90% of one repetition maximum. The largest system power was observed at the load of 30% (p < 0.008) while the largest ankle and knee powers were observed at 70% and 0% (p < 0.05). The barbell method overestimated the system power (p < 0.001) when compared to the COM method. It was concluded that the barbell method could influence load optimisation in squat jump. The optimal barbell load which maximised the system power did not maximise the ankle, knee, or hip power simultaneously.