浅议《歇马山庄的两个女人》的社会文化内涵     

尼楣 《大连教育学院学报》2006,22(2):38-39

孙惠芬的小说除了揭示农民“现代化”的渴望与觉醒外,更深入到切实的社会问题,即农民在“城市化”、“现代化”过程中的现实生活与精神情感的苦难和困惑。  相似文献   

A Theoretical Study the Effect of Openings in Infill Wall Panels on the Behavior of Structures     

Umary Jamal * 《东南大学学报》1998,(1)

ＡＴｈｅｏｒｅｔｉｃａｌＳｔｕｄｙｔｈｅＥｆｅｃｔｏｆＯｐｅｎｉｎｇｓｉｎＩｎｆｉｌＷａｌＰａｎｅｌｓｏｎｔｈｅＢｅｈａｖｉｏｒｏｆＳｔｒｕｃｔｕｒｅｓＵｍａｒｙＪａｍａｌ（ＣｏｌｅｇｅｏｆＣｉｖｉｌＥｎｇｉｎｅｒｉｎｇ,ＳｏｕｔｈｅａｓｔＵｎｉｖ...  相似文献   

The effect of sex and localised fatigue on triceps surae musculoarticular stiffness     

Aurélio Faria  Ronaldo Gabriel  Helena Moreira  Tanya Camacho  Rui Brás  Massimiliano Ditroilo 《European Journal of Sport Science》2018,18(4):483-490

Purpose: The main purpose of this study was to investigate the influence of fatigue on musculoarticular stiffness (MAS) of the ankle joint across sexes. Methods: Twenty-seven males and 26 females participated in the study. After baseline assessment of MAS and related variables, localised fatigue was induced in triceps surae using the standing heel-rise test during which the subjects were instructed to lift and drop the heel at a frequency of 0.5?Hz. When subjects were unable to continue due to exhaustion the test was terminated and another MAS test was performed soon after. Results: Significant higher triceps surae MAS was found in men compared to women (p?p??1 and from 14.5 to 13.9?KN?m^?1 in men and women, respectively. Percentage changes revealed, however, that in relative terms the changes in all the variables evaluated were similar (p?>?.01) between sexes, with MAS less than 5%. Conclusion: Despite the sex-related differences at baseline, fatigue seems to affect biomechanical properties of the ankle joint similarly in men and women.  相似文献   

Effects of viscoelastic properties of tendon structures on stretch – shortening cycle exercise in vivo     

Keitaro Kubo  Hiroaki Kanehisa  Tetsuo Fukunaga 《Journal of sports sciences》2013,31(8):851-860

The aim of the present study was to examine the effects of viscoelastic properties of human tendon structures during stretch?–?shortening cycle exercise. The elongation of tendon and aponeurosis of the medial gastrocnemius muscle of 26 participants was measured by ultrasonography while they performed ramp isometric plantar flexion up to the voluntary maximum, followed by a ramp relaxation. The relationship between estimated muscle force and tendon elongation during the ascending phase was fitted to a linear regression, the slope of which was defined as stiffness. The percentage of the area within the muscle force?–?tendon elongation loop relative to the area beneath the curve during the ascending phase was defined as hysteresis. In addition, maximal voluntary concentric contractions at 2.09 and 3.14 rad?·?s^?1 with and without prior eccentric contractions were performed. The difference in the concentric torque at equivalent joint angles with and without prior eccentric contractions (i.e. pre-stretch augmentation) was negatively correlated with stiffness (P <?0.05) and hysteresis (P <?0.05). Furthermore, there was a higher correlation between the pre-stretch augmentation and the viscoelastic properties index – that is, the sum of normalized score values of stiffness and hysteresis (P <?0.01) – than with either stiffness or hysteresis alone. The results of this study suggest that performance during stretch?–?shortening cycle exercise is significantly affected by the viscoelastic properties of the tendon structures.  相似文献   

Recovery of pulmonary diffusing capacity after maximal exercise     

Jess Rasmussen  Birgitte Hanel  Kari Saunamaki  Niels H. Secher 《Journal of sports sciences》2013,31(6):525-531

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.  相似文献   

Tensiomyography parameters and jumping and sprinting performance in Brazilian elite soccer players     

Saulo Gil  Irineu Loturco  Valmor Tricoli  Carlos Ugrinowitsch  Ronaldo Kobal  Cesar Cavinato Cal Abad 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):340-350

Tensiomyography has been suggested as an indirect marker of muscle stiffness, which is associated with strength/power performance. Therefore, it is reasonable to suggest that tensiomyography parameters could be associated with power-related motor tasks. The purpose of this study was to investigate the association between tensiomyography parameters (from rectus and biceps femoris) and jumping and sprinting abilities in elite soccer players. In addition, we used tensiomyography parameters to compare the lateral symmetry between dominant and non-dominant legs. Twenty elite soccer players (age: 23.3 ± 4.8 years; height: 183.5 ± 6.6 cm; weight: 77.8 ± 7.5 kg) volunteered to participate in the study. Significant moderate negative correlations between biceps femoris displacement and contact time (r = –0.5, p = 0.03), rectus femoris displacement and contact time (r = –0.51, p = 0.02), and a significant moderate correlation between biceps femoris displacement and reactive strength index (r = 0.5, p = 0.03) were found. There were no correlations between tensiomyography parameters and power-related motor tasks. In addition, no differences in tensiomyography parameters between dominant and non-dominant legs were found. Our data suggest that tensiomyography parameters are not associated with power-related motor tasks performance in elite soccer players.  相似文献   

Sex differences in lower extremity stiffness and kinematics alterations during double-legged drop landings with changes in drop height     

I-Lin Wang  Shi-Yi Wang 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):404-412

The aim of this study was to determine whether sex differences and effect of drop heights exist in stiffness alteration of the lower extremity during a landing task with a drop height increment. Twelve male participants and twelve female participants performed drop landings at two drop heights (DL40 and DL60; in cm). The leg and joint stiffnesses were calculated using a spring–mass model, and the joint angular kinematics were calculated using motion capture. Ground reaction forces (GRFs) were recorded using a force plate. The peak vertical GRF of the females was significantly increased when the drop height was raised from 40 to 60 cm. Significantly less leg and knee stiffness was observed for DL60 in females. The ankle, knee, and hip angular displacement during landing were significantly increased with drop height increment in both sexes. The knee and hip flexion angular velocities at contact were significantly greater for the 60 cm drop height relative to the 40 cm drop height in males. These sex disparities regarding the lower extremity stiffness and kinematics alterations during drop landing with a drop height increment would predispose females to lower extremity injury.  相似文献   

基于Morph功能的改款车模态刚度分析     

温立志  魏健  郑明锋 《天津工程师范学院学报》2013,23(2):13-15

基于ANSA中的Morph功能,在某改款车型的概念设计阶段,对标杆车的有限元模型进行快速的结构调整,通过仿真手段,对改款车的模态刚度进行分析;然后,对原型车白车身结构进行模态实验,获取其模态频率及对应振型,进而与改款车进行对比,提前对改款车结构的合理性做出评价。  相似文献   

Effect of different loading conditions on running mechanics at different velocities     

Germán Carretero-Navarro  Doménico Cherubini  Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602

Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.  相似文献   

Metabolic cost of running is greater on a treadmill with a stiffer running platform     

James A. H. Smith  Alexander D. McKerrow  Tertius A. Kohn 《Journal of sports sciences》2017,35(16):1592-1597

Exercise testing on motorised treadmills provides valuable information about running performance and metabolism; however, the impact of treadmill type on these tests has not been investigated. This study compared the energy demand of running on two laboratory treadmills: an HP Cosmos (C) and a Quinton (Q) model, with the latter having a 4.5 times stiffer running platform. Twelve experienced runners ran identical bouts on these treadmills at a range of four submaximal velocities (reported data is for the velocity that approximated 75–81% VO_2max). The stiffer treadmill elicited higher oxygen consumption (C: 46.7 ± 3.8; Q: 50.1 ± 4.3 ml·kg^?1 · min^?1), energy expenditure (C: 16.0 ± 2.5; Q: 17.7 ± 2.9 kcal · min^?1), carbohydrate oxidation (C: 9.6 ± 3.1; Q: 13.0 ± 3.9 kcal · min^?1), heart rate (C: 155 ± 16; Q: 163 ± 16 beats · min^?1) and rating of perceived exertion (C: 13.8 ± 1.2; Q: 14.7 ± 1.2), but lower fat oxidation (C: 6.4 ± 2.3; Q: 4.6 ± 2.5 kcal · min^?1) (all analysis of variance treadmill comparisons P < 0.01). This study confirms that caution is required when comparing performance and metabolic results between different treadmills and suggests that treadmills will vary in their comparability to over-ground running depending on the running platform stiffness.  相似文献