密立根油滴实验中油滴大小的选择和下落计时起点的确定

从理论上给出了密立根油滴实验中油滴下落达到终极速度前的下落距离与速度之间的函数关系 ;并讨论了油滴下落计时起点的确定和油滴大小的选择问题。     

壮阳春滴丸中黄芪甲苷质量控制方法研究

通过高效液相色谱法对黄芪中的黄芪甲苷进行含量测定,建立了黄芪甲苷HPLC含量测定方法,并对壮阳春滴丸中的黄芪甲苷进行定量检测．结果准确,方法简便．此方法可用于壮阳春滴丸中的黄芪甲苷的质量控制．     

油滴实验数据的数值分析法

本文讨论一种基于最小二乘原理求取最大公约数的数值方法,它是处理密立根油滴实验数据较为理想的方法。     

The impact phase of drop punt kicking for maximal distance and accuracy

Impact is an important aspect of the kicking skill. This study examined foot and ball motion during impact and compared distance and accuracy punt kicks. Two-dimensional high-speed video (4000 Hz) captured data of the shank, foot and ball through impact of 11 elite performers kicking for maximal distance and towards a target 20 m in distance. Four phases were identified during impact, with an overall reduction in foot velocity of 5.0 m · s^?1 (± 1.1 m · s^?1) and increase in ball velocity of 22.7 m · s^?1 (± 2.3 m · s^?1) from the start to end of contact. Higher foot velocity was found in distance compared to accuracy kicks (22.1 ± 1.6 m · s^?1 vs. 17.7 ± 0.9 m · s^?1, P < 0.05), and was considered to produce the significant differences in all impact characteristics excluding foot-to-ball speed ratio. Ankle motion differed between the kicking tasks; distance kicks were characterised by greater rigidity compared to accuracy kicks evident by larger force (834 ± 107 N vs. 588 ± 64 N) and smaller change in ankle angle (2.2 ± 3.3° vs. 7.2 ± 6.4°). Greater rigidity was obtained by altering the position of the ankle at impact start; distance kicks were characterised by greater plantarflexion (130.1 ± 5.8° vs. 123.0 ± 7.9°, P < 0.05), indicating rigidity maybe actively controlled for specific tasks.     

挺举中下蹲式与上挺利弊分析

通过对 7名现国家男子举重队优秀运动员进行挺举的“箭步式”和“下蹲式”两种上挺技术的比较研究 ,用实地测量的数据经过计算 ,证明了“下蹲式”上挺的突出优点。举重的整个过程是一个作功的过程 ,简而言之是一个力乘以距离的问题。假如能在举重中缩短杠铃的行程 ,就会用有限的力量举起更大的重量。本文不仅从正反两个方面对此问题进行了论述 ,同时从举重技术演变的历史 ,进一步阐明了“下蹲式”上挺的先进性。从发展的观点来看 ,“下蹲式”上挺将来成为上挺的主要潮流是有可能的。     

高考生源持续下降背景下招生工作的策略——以内蒙古自治区高职院校为例

针对内蒙古自治区高考生源下降对高职院校招生工作造成一定冲击的现实,分析高考生源下降的原因及对高职院校发展所带来的危害,提出要积极制定自治区高职院校招生工作的策略,确保高职院校能够健康稳定的发展。     

555压控振荡器振荡周期计算公式的修正

由555时基电路组成的压控振荡器,经实验得出的ux-T曲线中有一个极小值,这和理论计算值有较大差异。分析了产生这种现象的原因是控制信号ux较小时,受放电管V的饱和压降uces影响所致,并对理论计算公式进行了修正。     

对高职院校学生退学试读的分析与思考

高职院校学生退学试读的原因主要有学习态度不端正,对所学的专业没兴趣,沉迷于网络游戏等。退学试读对学风建设产生负面影响,给学生和家庭带来心理上和经济上的压力,给学校管理带来诸多不便。学校要加强理想、人生观教育,重视学风建设,加强专业指导和专业教育,发挥家庭教育的作用,加强校园文化建设。     

浮顶罐内原油温降计算方法研究

目前国家石油战略储备库工程已陆续启动和建成。浮顶罐内原油的凝结问题是制约储备库安全经济储油的瓶颈之一。本文在研究国内外各种浮顶罐内原油温度计算方法的基础上建立了一套计算方法体系,为了方便工程应用,还编制了原油温降计算软件,在已知气象数据、原油物性参数和储罐技术参数的前提下,可计算原油的温度变化。实际算例表明,计算结果与实际值较接近,能够反映原油随储存时间等因素变化的趋势。     

The sidestep cutting manoeuvre requires exertion of lumbosacral lateral flexion torque to avoid excessive pelvic obliquity

During sidestep cutting, the pelvis is supported only on one side; this affects the athlete’s posture. This study investigated the mechanism to avoid excessive pelvic obliquity during sidestep cutting. Ten physically active men performed sidestep cutting with maximal effort, and we captured the kinematics and kinetics with force platforms and an eight-camera motion capture system. Our results indicated that the stance hip exerted little abduction torque; however, lumbosacral lateral flexion torque was exerted towards the free-leg side (peak value: 3.39 ± 0.91 N m/kg). Although bilateral hip joint forces acted to drop the free-leg side of the pelvis, the net torque around pelvic elevation/drop axis was nearly zero during the entire stance phase and the change in the angular momentum around the pelvic elevation/drop axis from touchdown to toe-off was negligible (?0.004 ± 0.003 N m s/kg). The integrated components of lateral flexor for elevating the free-leg side of the pelvis (0.220 ± 0.072 N m s/kg) were significantly larger than any other integrated components, which were all negligible (<0.010 N m s/kg). Thus, sidestep cutting requires the lumbosacral lateral flexion torque exertion to neutralise the passive action that drops the free-leg side of the pelvis.