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柔韧素质的重要性及训练要点 总被引：3，自引：0，他引：3
学生喜欢体育锻炼,但往往忽视基础素质训练。人的柔韧素质对掌握体育技能至关重要。没有柔韧性,不可能顺利准确地完成运动项目所要求的动作。所以应大力加强柔韧素质训练,训练时要注意循序渐进、强度适中、动静结合、整体训练等几个方面。 相似文献
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本文简要报导位于北京西山房山岩体以西约15km左右的南窖闪长岩脉形成的锆石U-Pb年龄,以及区内变形岩层中同变形的白云母和绢云母矿物的40Ar/39Ar年龄.在野外构造研究、室内岩石及显微构造分析基础上,获得细粒闪长岩岩脉锆石U-Pb年龄为136±1Ma,并且该岩脉受到后期构造片理化的改造.区内变形岩层中所发育的南东东110°～120°矿物拉伸线理及相关的“褶叠层”中同变形的白云母、绢云母的^40Ar/^39Ar坪年龄为133±1～127±1Ma.显然这些变形并非形成于三叠纪或“印支期”,而是形成于大规模的向北西方向强烈的挤压变形之后,与相邻区域的岩浆热作用同期或稍晚.这些构造-热年代学证据对于区内构造格局的形成与演化是一个重要的约束. 相似文献
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SAHOO Bikash SHARMA H.G. 《浙江大学学报(A卷英文版)》2007,8(5):766-771
Analysis is carried out to study the existence, uniqueness and behavior of exact solutions of the fourth order nonlinear coupled ordinary differential equations arising in the flow and heat transfer of a viscoelastic, electrically conducting fluid past a continuously stretching sheet. The ranges of the parametric values are obtained for which the system has a unique pair of solutions, a double pair of solutions and infinitely many solutions. 相似文献
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SAR运动参数估计是SAR成像技术研究中的一项关键技术,目前国际上普遍采用的方法是GPS INS导航系统进行运动参数估计。国内由于技术等方面的原因导航参数的估计精度远远不能满足SAR成像要求,目前只能从回波中提取平台运动参数,其中较为典型的方法是PGA、子孔径相关法等,而DCFT作为一种新的CHIRP信号参数估计方法能快速、精确的估计CHIRP信号的相关参数。本文提出利用DCFT方法估计SAR运动参数,并以此为基础对传统的RD成像算法加以改进,提出了一种基于DCFT变换的改进RD成像算法。 相似文献
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María Rodriguez-Ayllon Pedro Acosta-Manzano Irene Coll-Risco Lidia Romero-Gallardo Milkana Borges-Cosic Fernando Estvez-Lpez Virginia A. Aparicio 《运动与健康科学(英文)》2021,10(3):379
PurposeThis study was aimed to analyze the associations of objectively measured physical activity (PA), sedentary time, and physical fitness with mental health in the early second trimester (16 ± 2 gestational weeks) of pregnancy.MethodsFrom 229 women initially contacted, 124 pregnant women participated in the present cross-sectional study. Data were collected between November 2015 and March 2017. The participants wore Actigraph GT3X+ Triaxial accelerometers for 9 consecutive days to objectively measure their PA levels and sedentary time. A performance-based test battery was used to measure physical fitness. Self-report questionnaires assessed psychological ill-being (i.e., negative affect, anxiety, and depression), and psychological well-being (i.e., emotional intelligence, resilience, and positive affect). Linear regression analyses were adjusted for age, educational level, accelerometer wear time, miscarriages, and low back pain.ResultsModerate-to-vigorous PA was negatively associated with depression (β = –0.222, adjusted R2 = 0.050, p = 0.041). Higher levels of sedentary time were negatively associated with positive affect (β = –0.260, adjusted R2 = 0.085, p = 0.017). Greater upper-body flexibility was positively associated with better emotional regulation (β = 0.195, adjusted R2= 0.030, p = 0.047). The remaining associations were not significant (all p > 0.05).ConclusionAn active lifestyle characterized by higher levels of moderate-to-vigorous PA and lower levels of sedentary time during pregnancy might modestly improve the mental health of pregnant women. Although previous research has focused on the benefits of cardiorespiratory exercise, the present study shows that only upper-body flexibility is related to emotional regulation in early pregnant women. If the present findings are corroborated in further experimental research, physical exercise programs should focus on enhancing flexibility to promote improvements in emotional regulation during early second-trimester of pregnancy. 相似文献
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武术旋风脚720°接跌叉稳定性的研究 总被引：12，自引：0，他引：12
武术旋风脚 72 0°接跌叉是九运会武术指定动作之一。通过对该组动作落地技术的动力学以及构成稳定性条件的分析 ,提出合理的落地技术和训练中需解决的问题。 相似文献
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目的:研究人体前臂肌腱的生物力学特征,可为其损伤的防治、修复、人工材料替换等提供理论依据.方法:用专门仪器完成58例成人新鲜前臂肌腱"一维拉伸破坏试验",并对实验数据进行统计学处理;结果:1)前臂多数肌腱在0%～5%应变内,拉伸应力随应变缓慢增加,曲线平坦,属于曲线的"坡脚区",在8%～16%应变段,拉伸应力随应变增大而增大,变形达到20%左右,拉伸应力不再随应变增长,并且各肌腱之间极限应力与极限应变没有显著性差异;2)前臂肌腱中有部分肌腱的拉伸刚度与弹性响应两项指标,相互之间有显著性差异.结论:前臂多数肌腱在承受拉伸负荷时,应力变化特点相似,最大载荷的能力差异不大,但是抵抗变形的能力与变形的难易程度等方面有一定的差异. 相似文献
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动静态伸展运动在高校田径技术教学中的实验研究 总被引：2，自引：0，他引：2
本研究以普通高校与体育学院大学生为教学实验对象，在田径运动教学中结合跑、跳、投类三个运动项目着重对静态与动态伸展运动提高柔韧性预防与运动损伤的效果进行了对比实验，结果表明静态伸展运动在这两方面的效果均明显优于动态性伸展运动，并阐明了其优越性。 相似文献
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The steady two-dimensional stagnation point flow toward a stretching/shrinking sheet with the bottom surface of the sheet heated by convection from a hot fluid is considered. The governing partial differential equations are transformed into ordinary differential equations, before being solved numerically. Results for the skin friction coefficient and the local Nusselt number as well as the temperature profiles are presented for different values of the governing parameters. Effects of the governing parameters on the heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. 相似文献
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讨论了固定模板用的拉片,同时兼拉结墙体用的拉筋的技术,从而解决了柱中砼(混凝土)振捣困难、拉筋设置困难、造成钢筋浪费等问题. 相似文献
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