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研究表明，在一场长达90min的激烈比赛中，足球运动员的一般活动距离为8000～10000m，冲刺距离2000～3000m，冲刺以8～50m居多，其中尤以15～30m为最多；平均每45s～1min就要完成一次攻防转换，并伴有激烈的身体接触以及急停、急转、起动、弹跳、不规则的变向跑等。这就对运动员的身体能力提出了较高的要求。从生化角度看，足球是一项有氧和无氧代谢混合供能的运动。 相似文献
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A rectangular thin plate vibration model subjected to inplane stochastic excitation is simplified to a quasinonintegrable Hamiltonian system with two degrees of freedom. Subsequently a one-dimensional Ito? stochastic differential equation for the system is obtained by applying the stochastic averaging method for quasi-nonintegrable Hamiltonian systems. The conditional reliability function and conditional probability density are both gained by solving the backward Kolmogorov equation numerically. Finally, a stochastic optimal control model is proposed and solved. The numerical results show the effectiveness of this method. 相似文献
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运用“自然数码奇象记忆法”记忆100句英语的实验 总被引：1，自引：0，他引：1
本实验考察了硕士生运用自然数码数序形象挂钩法记忆30-100句常用英语句子的记忆效果，并首次公开介绍了运用此法记牢上百句英语句子的奥秘。结果表明：（1）硕士生运用数序形象挂钩法识记和回忆30-100句常用英语句子，能达到按其顺序排列倒背、顺背、随点随背，随点随背其中任何一句的平均反应时不超过2秒。（2）数序形象挂钩法能使人的识记很快通过短时记忆而快速地顺利进入长时记忆，能有效防止前摄和倒摄抑制，且在以后的较长时间里遗忘较少较慢。（3）数序形象挂钩法对于顺序性强、数量大、难记住的材料，能达到快速高效，是一套具有特殊效果的高效记忆方法，是值得在英语常用句子的学习和记忆中进行运用和推广的实用高效的记忆方法。（4）良好的记忆储存技术、储存方法和记忆线索是提高记忆效率的关键。 相似文献
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The active control of rotor vibration was studied while shape memory alloy (SMA) spring component was chosen as bearing of rotor system. The vibration of rotor system was controlled by the phase transformation of SMA with electric heating method. The SMA spring component has nonlinear coupling problem of thermal stress and thermal elasticity, because thermal constants α,β and elasticity constants γ, G vary with temperature when temperature changes sharply. Because δ,ε were both small parameters, their square items could be ignored and approximate results were obtained by perturbation. The characters of α,β, γ, G changing with temperature were analyzed. Results show that the character of thermal diffusivity ot changes with temperature, which cannot influence U,Ψ,So the nonlinearity of ot can be ignored; the character of,β changes with temperature,which cannot influence U, but influences Ψ at high temperature; the character of γ, G change with temperature, which cannot influence Ψ, but influences U with U^(01) ε. The more γ ,G, the more their influence on U;the nonlinearity of βT/pcvεkk influences U and Ψ, which must be calculated. 相似文献
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In a hybrid system, the subsystems with discrete dynamics play a central role in a hybrid system. In the course of engineering machinery of cluster construction, the discrete control law is hard to obtain because the construction environment is complex and there exist many affecting factors. In this paper, hierarchically intelligent control, expert control and fuzzy control are introduced into the discrete subsystems of engineering machinery of cluster hybrid system, so as to rebuild the hybrid system and make the discrete control law easily and effectively obtained. The structures,reasoning mechanism and arithmetic of intelligent control are replanted to discrete dynamic, continuous process and the interface of the hybrid system. The structures of three types of intelligent hybrid system are presented and the human experiences summarized from engineering machinery of cluster are taken into account. 相似文献
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王洪礼 《沈阳教育学院学报》2000,(2)
有些报纸杂志扩展的版面 ,外表像肥皂泡沫一样极为华丽 ,而细观则内容空洞 ,我们谓之曰“泡沫版面”。“泡沫版面”干扰党的新闻媒体的运行 ,有碍社会主义精神文明建设 ;严重伤害人民群众对党报的感情 ;加重群众负担 ,冲击党报的征订 ,影响党的政策、方针的宣传和落实 相似文献
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采用《大学生面众恐惧调查量表》调查贵州省苗族、布依族和侗族等少数民族大学生的面众恐惧现状和探讨影响因素,结果显示：1.贵州省少数民族大学生面众恐惧现象低于贵州省普通大学生;2.贵州省少数民族大学生面众恐惧年级、性别和专业方面差异不显著;3.贵州省少数民族大学生家庭经状况对面众恐惧的形成有显著影响。 相似文献