在教学中对学生创造力的培养

在教学中对学生创造能力的培养,可从以下几方面进行探索。一、设置问题情景设置问题情景,激发学习兴趣和创造欲望,启发学生提出问题（或感受问题）,提出假说,检验假说,发表认识成果,开展创造性教学。创设好的问题情景能激发学生的好奇心和求知欲。问题情景的创设和...     

Changes in respiratory muscle and lung function following marathon running in man

Respiratory muscle fatigue has been reported following short bouts of high-intensity exercise, and prolonged, moderate-intensity exercise, as evidenced by decrements in inspiratory and expiratory mouth pressures. However, links to functionally relevant outcomes such as breathing effort have been lacking. The present study examined dyspnoea and leg fatigue during a treadmill marathon in nine experienced runners. Maximal inspiratory and expiratory pressure, peak inspiratory and expiratory flow, forced vital capacity, and forced expiratory volume in one second were assessed before, immediately after, and four and 24 hours after a marathon. During the run, leg effort was rated higher than respiratory effort from 18 through 42 km (P < 0.05). Immediately after the marathon, there were significant decreases in maximal inspiratory pressure and peak inspiratory flow (from 118 +/- 20 cm H(2)O and 6.3 +/- 1.4 litres x s(-1) to 100 +/- 22 cm H(2)O and 4.9 +/- 1.5 litres x s(-1) respectively; P < 0.01), while expiratory function remained unchanged. Leg maximum voluntary contraction force was significantly lower post-marathon. Breathing effort correlated significantly with leg fatigue (r = 0.69), but not inspiratory muscle fatigue. Our results confirm that prolonged moderate-intensity exercise induces inspiratory muscle fatigue. Furthermore, they suggest that the relative intensity of inspiratory muscle work during exercise makes some contribution to leg fatigue.     

The effect of crank inertial load on the physiological and biomechanical responses of trained cyclists

The existing literature suggests that crank inertial load has little effect on the responses of untrained cyclists. However, it would be useful to be aware of any possible effect in the trained population, particularly considering the many laboratory-based studies that are conducted using relatively low-inertia ergometers. Ten competitive cyclists (mean VO(2max) = 62.7 ml x kg(-1) x min(-1), s = 6.1) attended the human performance laboratories at the University of Wolverhampton. Each cyclist completed two 7-min trials, at two separate inertial loads, in a counterbalanced order. The inertial loads used were 94.2 kg x m(2) (high-inertia trial) and 2.4 kg x m(2) (low-inertia trial). Several physiological and biomechanical measures were undertaken. There were no differences between inertial loads for mean peak torque, mean minimum torque, oxygen uptake, blood lactate concentration or perceived exertion. Several measures showed intra-individual variability with blood lactate concentration and mean minimum torque, demonstrating coefficients of variation > 10%. However, the results presented here are mostly consistent with previous work in suggesting that crank inertial load has little direct effect on either physiology or propulsion biomechanics during steady-state cycling, at least when cadence is controlled.     

演示实验在物理教学中的应用——物理演示实验应用讨论会介绍之一

在初级物理课程中,有人往往试图把“经典物理学”全部包罗在内,但是“经典”一词有着几分不定的涵义。目前每本初级教科书除力学、热学、电学、声学与光学的概念外,还包括近代物理学的概念。教科书的格式随着近代题材的增加而改变,而当教科书改变时,教学方法似乎就改变了。物理教学的传统表明如何利用我们的感官来认识自然规律。许多物理定律就是直接靠我们的感觉而获得,且主要的感觉的应用导致诸如力学、声学和光学等最早题材的划分。近代物理学把我们的概念扩展到通常在显微镜下看不出的亚微观世界,我们就不再     

“痞子”阿姆

Eminem is easily the most enigmatic figure in popular musictoday. Brazenly(厚脸皮地) honest, deeply troubled, allegedlyhomophonic and misogynistic(厌恶女人的人) yet undeniably gifted and entertaining, the Detroit-based rapper has defied     

Concentric left ventricular morphology in aerobically trained kayak canoeists

The aim of the present study was to test the hypothesis that upper body aerobically trained athletes (kayak canoeists) would have greater left ventricular wall thickness, but similar left ventricular diastolic chamber dimensions, compared with recreationally active and sedentary men. Ultrasound echocardiography was used to determine cardiac structure and function in highly trained kayak canoeists (n = 10), moderately active (n = 10) and sedentary men (n = 10). The septal and posterior left ventricular walls were approximately 0.2 cm thicker in kayak canoeists (P < 0.05), and left ventricular mass was 51% and 32% greater (P < 0.05) in canoeists than in the sedentary and moderately trained participants, respectively. There were no differences in left ventricular chamber dimension, suggesting that the kayak canoeists had a concentric pattern of left ventricular adaptation to aerobic upper body training. Scaling the data to body composition indices had no effect on the outcome of the statistical analysis. There were no differences in resting Doppler left ventricular diastolic or systolic function among the groups. Ejection fraction was lower in the kayak canoeists, but the magnitude of the difference was within the normal variability for this measurement. Thus aerobically upper body trained athletes demonstrated a concentric pattern of cardiac enlargement, but resting left ventricle function was not different between athletes, moderately active and sedentary individuals.     

“表象训练”提高发球速度

2003年本刊推出了“现代网球技战术名家精华”连载专栏,其权威、前沿、专业的内容受到了广泛好评。在此基础上,本刊从2004年第1期开始,再次推出范畴更广更深的“现代网球名家精粹”连载专栏,所载内容由国际网联命题和认可,由多位世界网坛资深教练、专家执笔,相信这样的内容将会对中国网球运动的深入发展有所裨益。——编者     

宇宙的中年不辉煌

尽管宇宙已不如往昔那样活跃，但它仍然在以令人叹服的步伐形成恒星并打造黑洞。