排序方式： 共有76条查询结果，搜索用时 953 毫秒
51.
William A. Sands Sarah L. Smith Derek M. R. Kivi Jeni R. Mcneal Jason C. Dorman Michael H. Stone 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):197-214
The aim of this study was to characterize sprint ability, anthropometry, and lower extremity power in the US National Team Skeleton athletes. Fourteen athletes (male n = 7; mean ± SD: height 1.794 ± 0.063 m, body mass 81.2 ± 3.7 kg, age 26.9 ± 4.1 years; female n = 7; 1.642 ± 0.055 m, 60.1 ± 5.9 kg, 27.3 ± 6.9 years) volunteered to participate. Sprinting ability was measured over multiple intervals using custom infrared timing gates in both an upright and a crouched sprint. The crouched sprint was performed while pushing a wheeled‐simulated skeleton sled on rails on an outdoor skeleton and bobsleigh start track. Crouched skeleton sprint starts were able to achieve about 70% to 85% of the upright sprint times. The mean somatotype ratings for females were: 3.5‐3.5‐2.1, and males: 3.6‐4.9‐1.9. Lower extremity strength and power were measured via vertical jumps on a portable force platform using squat and countermovement jumps, and jumps with added mass. Jump height, power, rate of force development and peak force were determined from force‐time data. Lower extremity strength and power were strongly correlated with both upright and crouched sprint times. The results indicated that these athletes are strong sprinters with varying body structures, mostly mesomorphic, and that stronger and more powerful athletes tend to be better starters. 相似文献
52.
陈军 《连云港职业技术学院学报》2010,23(4):11-13
由于设备条件的限制,很多对嵌入式系统应用与开发有兴趣的人难以开展相关的学习与研究活动。针对这一问题,阐述了一种应用指令集架构层虚拟技术在PC环境中进行嵌入式系统开发实践的方法。 相似文献
53.
急、慢性缺氧刺激对训练大鼠糖原和血糖的影响 总被引：2，自引：0，他引：2
观察急、慢性缺氧刺激对训练机体糖原和血糖浓度的变化。以60只SD雄性大鼠为实验对象，人工制造缺氧φ(O2)14．5％(相当于海拔3000m)，将实验动物随机分为安静3组和训练3组(分别为常氧对照组，急性缺氧组和4周慢性缺氧组)，4周后对各组测定血糖、骨骼肌和肝脏糖原。结果显示，无论是安静组还是训练组，缺氧可使大鼠骨骼肌和肝脏糖原比常氧对照组显著或极显著性下降，但在训练组中慢性缺氧组骨骼肌和肝糖原含量仍比急性缺氧组高，血糖浓度却显著性的降低。提示慢性缺氧适应和运动训练可以提高机体糖原储备量，增强机体抗缺氧能力。 相似文献
54.
ＩＮＴＲＯＤＵＣＴＩＯＮＭｏｔｉｏｎｃａｐｔｕｒｅｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｃｒｅａｔｉｏｎｏｆｓｐｅｃｉａｌｅｆｆｅｃｔｓｉｎｍａｎｙｆｉｅｌｄｓ.Ａｓｉｄｅｆｒｏｍｕｓｅｉｎｆｉｌｍｓａｎｄａｎｉｍａｔｉｏｎｓ,ｍｏｔｉｏｎｃａｐｔｕｒｅｈａｓｃｏｍｐｒｅｈｅｎｓｉｖｅａｐｐｌｉｃａｔｉｏｎｓｉｎｔｈｅａｎａｌｙｓｉｓｏｆａｔｈｌｅｔｅｐｅｒｆｏｒｍａｎｃｅ ,ｍｅｄｉｃａｌｄｉａｇｎｏｓｔｉｃｓ,ｓｕｒｖｅｉｌｌａｎｃｅ ,ｖｉｄｅｏｒｅｔｒｉｅｖａｌ,ｅｔｃ.Ｃｏｎｖｅｎ… 相似文献
55.
线状目标的识别在很多方面具有重要应用,而目前常用的识别方法在准确性、抗干扰能力等方面有所欠缺。本文提出了一种综合利用边缘和骨架线这两个特征对线状目标进行识别的方法。方向小渡变换不仅体现了多尺度特征,而且能很好地结合图像的方向及纹理特征,反映图像的边缘信息;基于优先搜索方向的骨架线跟踪方法可以减少搜索范围,降低问题复杂度。综合利用基于方向小波变换的边缘提取方法和基于优先搜索方向的骨架线跟踪方法,有效识别出线状目标,并通过纤维的识别证明了该方法的可靠性与精确性。 相似文献
56.
The effect of recycled coarse aggregate on concrete compressive strength was investigated based on the concrete skeleton theory. For this purpose, 30 mix proportions of concrete with target cube compressive strength ranging from 20 to 60 MPa were cast with normal coarse aggregate and recycled coarse aggregate from different strength parent concretes. Results of 28-d test show that the strength of different types of recycled aggregate affects the concrete strength obviously. The coarse aggregate added to mortar matrix plays a skeleton role and improves its compressive strength. The skeleton effect of coarse aggregate increases with the increasing strength of coarse aggregate, and normal coarse aggregate plays the highest, whereas the lowest concrete strength occurs when using the weak recycled coarse aggregate. There is a linear relationship between the concrete strength and the corresponding mortar matrix strength. Coarse aggregate skeleton formula is established, and values from experimental tests match the derived expressions. 相似文献
57.
骨骼肌急性拉伤后材料力学研究进展 总被引：2，自引：0，他引：2
在查阅国内外大量相关文献资料的基础上,对肌肉急性拉伤后材料力学的研究现状进行了归纳分析,如肌肉拉伤实验研究的动物模型、拉伤肌印次复过程中材料力学特性的变化等,并对该研究中存在的问题及今后的发展,提出了看法。 相似文献
58.
通过对海南省少年儿童骨龄检查 ,分析其骨龄发育程度 ,提出海南省运动员各年龄段骨骼发育特点 ,为科学选材、育材提供依据。 相似文献
59.
西藏山溪鲵种群年龄划分的研究 总被引：2，自引：0，他引：2
采用肱骨横切片法,对西藏山溪鲵进行了年龄鉴定,并对三个地理种群进行了年龄划分。结果表明：三个地理种群均包含九个年龄组,依据骨骼年龄环带与各组头体长的相关性得出了年龄鉴定的形态学标准,供野外快速而准确地鉴定年龄参考。 相似文献
60.
Shmuel T. Klein 《Information Retrieval》2000,3(1):7-23
A new data structure is investigated, which allows fast decoding of texts encoded by canonical Huffman codes. The storage requirements are much lower than for conventional Huffman trees, O(log2 n) for trees of depth O(log n), and decoding is faster, because a part of the bit-comparisons necessary for the decoding may be saved. Empirical results on large real-life distributions show a reduction of up to 50% and more in the number of bit operations. The basic idea is then generalized, yielding further savings. 相似文献