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1.
高水平跳远运动员起跳过程中摆动腿作用的研究   总被引:3,自引:0,他引:3  
本文研究证明,跳远起跳过程中缓冲阶段拉动腿的摆动效果对上板速度、腾起初速度和跳远成绩有显著影响,起跳蹬伸阶段摆动腿的摆动制动加速度与腾起初速度和跳远成绩有高度的相关关系。  相似文献   
2.
研究了室温、缓冲液两种pH值、显色时间、显色剂量对食品中铝测定的铬天青-S显色的影响;铝含量和吸光度之间的线性关系.结果显示:室温从21℃升高到33℃,吸光度相应增加;pH5.7缓冲液较pH5.5的吸光度轻微增加;加入铬天青-S20分钟后至45分钟内显色稳定;将显色剂量减半后吸光度稍微降低,显色效果改善;铝含量在0.5-6μg/ml范围内与吸光度之间线性关系良好;铝含量增至8μg/ml时失去线性关系;方法的重复性较好.  相似文献   
3.
ABSTRACT

This study examined the effect of wearing time on comfort perception and landing biomechanics of basketball shoes with different midsole hardness. Fifteen basketball players performed drop landing and layup first step while wearing shoes of different wearing time (new, 2-, 4-, 6- and 8-week) and hardness (soft, medium and hard). Two-way ANOVA with repeated measures was performed on GRF, ankle kinematic and comfort perception variables. Increased wearing time was associated with poorer force attenuation and comfort perception during landing activities (p < 0.05). The new shoes had significantly smaller forefoot (2- and 4-week) and rearfoot peak GRF impacts (all time conditions) in drop landing and smaller rearfoot peak GRF impact (6- and 8-week) in layup; shoes with 4-week of wearing time had significantly better perceptions of forefoot cushioning, forefoot stability, rearfoot cushioning, rearfoot stability and overall comfort than the new shoes (p < 0.05). Compared with hard shoes, the soft shoes had better rearfoot cushioning but poorer forefoot cushioning (p < 0.05). Shoe hardness and wearing time would play an influential role in GRF and comfort perception, but not in ankle kinematics. Although shoe cushioning performance would decrease even after a short wearing period, the best comfort perception was found at 4-week wearing time.  相似文献   
4.
运动鞋缓冲避震研究进展   总被引:1,自引:0,他引:1  
运用文献资料法和归纳与演绎等方法,阐述了运动鞋避震的重要意义、评价运动鞋避震性能的指标(足底压力和地面反作用力相关指标、负加速度峰值和冲量)和评价运动鞋避震性能的测试方法。  相似文献   
5.
结合现有传统鞋底方案及多胞结构特征,设计了菱形和正六边形两种多胞结构的鞋底方案,并用有限元法对不同鞋底的静力学性能进行分析,得出最优的鞋底结构方案。结果表明,同一工况下正六边形多胞鞋底结构平均变形量最大,减振缓冲性能最优越。同时,对正六边形多胞尺寸参数进行影响分析,得出当正六边形边长5mm,凹槽深度为2.5mm时,鞋底结构具有最佳的缓冲性能。  相似文献   
6.
In this study, we evaluated the protective functions of cloth sport shoes, including cushioning and lateral stability. Twelve male students participated in the study (mean ± s: age 12.7 ± 0.4 years, mass 40.7 ± 5.9 kg, height 1.50 ± 0.04 m). Cloth sport shoes, running shoes, basketball shoes, cross-training shoes, and barefoot conditions were investigated in random sequence. Human pendulum and cutting movement tests were used to assess cushioning performance and lateral stability, respectively. For cushioning, the running shoes (2.06 body weight, BW) performed the best, while the cross-training shoes (2.30 BW) and the basketball shoes (2.37 BW) both performed better than the cloth sport shoes (2.55 BW) and going barefoot (2.63 BW). For the lateral stability test, range of inversion–eversion was found to be from 3.6 to 4.9°, which was far less than that for adult participants (> 20°). No significant differences were found between conditions. All conditions showed prolonged durations from foot-strike to maximum inversion (66–95 ms), which was less vigorous than that for adult participants ( < 40 ms) and was unlikely to evoke intrinsic stability failure. In conclusion, the cloth sport shoe showed inferior cushioning capability but the same lateral stability as the other sports shoes for children.  相似文献   
7.
Abstract

Ethylene vinyl acetate and polyurethane are widely used materials for shoe midsoles. The present study investigated the durability of running shoes made from ethylene vinyl acetate and one type of polyurethane (polyurethane-1), which have similar hardness and density, and another type of polyurethane (polyurethane-2), which has high hardness/density. All shoes differed from one another only in terms of the midsole material used. Eight male runners participated in the present study and used the shoes to run 500 km (10 × 50 km). The cushioning and energy return characteristics of each shoe were measured using an impact tester before and after each 50-km run. The results showed that as the running distance increased, the peak force of midsole materials changed with different patterns. Ethylene vinyl acetate and polyurethane-1 showed greater cushioning than polyurethane-2 over 500 km (ethylene vinyl acetate, 918.2–968.0 N; polyurethane-1, 909.6–972.9 N; polyurethane-2, 983.0–1105.6 N). Polyurethane-1 showed greater cushioning from 200 km to 300 km compared with 0 km (0 km, 972.9 ± 66.3 N; 200 km, 909.6 ± 61.2 N; 250 km, 921.9 ± 51.2 N; 300 km, 924.6 ± 51.9 N). The cushioning of ethylene vinyl acetate shoes was diminished after 500 km compared with that at 0 km (968.0 ± 25.9 N vs. 921.1 ± 20.1 N). Ethylene vinyl acetate resulted in greater energy returns than polyurethane. Both foam category and hardness/density affected the critical biomechanical properties of running shoes.  相似文献   
8.
9.
目的:测试静态拉伸训练前、后男性青年排球运动员踝关节跖-背屈动作和落地缓冲动作生物力学参数,分析静态拉伸对踝关节动力学及下肢缓冲特征影响的机制及意义。方法:22名健康男性青年高水平排球运动员随机分为实验组和对照组,对实验组进行36组下肢静态拉伸训练。分别于训练前、12组训练后、24组训练后、36组训练后、停训4周恢复期后测试踝关节跖-背屈动力学和缓冲期下肢及下肢各关节动力学、运动学数据,同步测试小腿后肌群影像学。结果:12组训练后至恢复期踝关节跖-背屈范围增加非常显著(P<0.01),小腿后肌群被动刚度显著降低(P<0.05),二者的增加/降低率%于36组训练后改变最明显(P<0.05),且变化率%之间呈非常显著正相关(P<0.01)。训练后小腿后肌群滞后%明显降低(P<0.05),肌腱弹性回缩率%明显升高(P<0.05),且二者之间呈显著负相关(P<0.05)。下肢刚度显著降低(P<0.05),髋、膝、踝关节做功均显著增加(P<0.05),训练各阶段踝关节做功贡献度均最大(P<0.05)。结论:静态拉伸训练早期即可通过降低肌肉-肌腱复合体被动刚度而增加关节活动范围和通过降低滞后而提高肌腱弹性回缩率并保持至恢复期,提示,静态拉伸训练急性期和慢性期均能提高肌肉-肌腱复合体的柔韧性及肌腱的弹性能利用率,从而有利于提高拉长-缩短周期运动表现。训练后各阶段下肢刚度降低的同时各关节缓冲吸能增加且踝关节是吸能的主要部位,提示,静态拉伸可通过调整缓冲模式、提高关节能量吸收、增效踝关节作用降低排球运动员下肢损伤的风险。  相似文献   
10.
ABSTRACT

While foot orthoses are commonly used in running, little is known regarding biomechanical risk potentials during uphill running. This study investigated the effects of arch-support orthoses on kinetic and kinematic variables when running at different inclinations. Sixteen male participants ran at different inclinations (0°, 3° and 6°) when wearing arch-support and flat orthoses on an instrumented treadmill. Arch-support orthoses induced longer contact time, larger initial ankle dorsiflexion, maximum ankle eversion, and knee sagittal range of motion (RoM) (p < 0.05). As incline slopes increased, vertical impact peak and loading rate, stride length, and ankle coronal RoM decreased, but contact time, stride frequency, initial ankle dorsiflexion and inversion, maximum dorsiflexion, initial knee flexion, and ankle sagittal RoM increased (p < 0.05). Furthermore, knee sagittal RoM was lowest when running at an inclination of 3°. The interaction effect indicated that in arch-support condition, participants running at 6° induced higher maximum ankle eversion than running at 0° (p < 0.05), while no differences were found in flat orthosis condition. These findings suggest that the use of arch-support orthoses would influence running biomechanics that is related to injury risks. Running at higher inclination led to more alterations to biomechanical variables than at lower inclination.  相似文献   
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