酯水解的动力学常数测定实验的改进

对酯水解的动力学常数测定实验进行改进,通过使用带恒温装置的紫外可见分光光度计,在一定pH值和恒温条件下测定具有三脚架型的二乙烯三胺锌配合物催化磷酸双酯BNPP水解的吸光度随时间的变化,进一步求算出催化磷酸双酯水解的二级速率常数,有助于学生掌握测定配合物催化酯水解的动力学参数。     

Identification of types of landings after blocking in volleyball associated with risk of ACL injury

Landing with a low knee flexion angle after volleyball block jumps may be associated with an increased risk of anterior cruciate ligament (ACL) injury. The aim of the present study was to identify the types of volleyball landings after blocks where the knee flexion angle is found to be under a critical knee flexion angle value of 30° at the instant of the first peak of the ground reaction force (GRF). Synchronized kinematic and kinetic data were collected for each trial. T-tests were used to determine if each knee flexion angle at the instant of the peak GRF was significantly different from the critical value of 30°. A repeated measures ANOVA was used to compare knee flexion angle, time to first peak and the magnitude of the first peak of the resultant GRF and knee stiffness. Significantly lower knee flexion angles were found in the “go” landing (p?=?.01, ES?=?0.6) and the “reverse” landing (p?=?.02, ES?=?0.6) only. The results for knee flexion angle and GRF parameters indicated a significant difference between a “reverse” and “go” and other types of landings, except the “side stick” landing for GRF. The “reverse” and “go” landings may present a risk for ACL injury due to the single-leg landing of these activities that have an associated mediolateral movement.     

Horizontal ground reaction forces to stationary running performed in the water and on dry land at different physiological intensities

The aim of the present study was to compare the peak anterior–posterior (Fy) and medio–lateral (Fx) ground reaction forces (GRFs) of women performing stationary running at different intensities in aquatic and dry land environments. Fourteen young women performed the stationary running exercise at three cadences (first ventilatory threshold, second ventilatory threshold and maximum effort, as determined during exercise in water) in aquatic and dry land environments. Two-way repeated measures ANOVA was used to analyse the data (α?=?.05). As a result, significantly lower peak Fy anterior, Fy posterior, Fx medial and Fx lateral values were observed for the aquatic environment, except for the Fy posterior at the first ventilatory threshold. Significant differences were observed between cadences in the peak Fy anterior, Fy posterior, Fx medial and Fx lateral values, with higher values for the cadence corresponding to maximum effort compared to the first ventilatory threshold, except for the Fy posterior and Fx medial in the aquatic environment. The results indicate that the horizontal GRFs are reduced in the aquatic environment and depend on the intensity of stationary running exercise performance.     

微波场中甲壳素非均相碱法脱乙酰反应动力学研究

比较了微波场中密闭式及开放式条件下,甲壳素非均相碱法脱乙酰反应的动力学情况。研究表明:在密闭条件下,温度为120℃时,1.5m in~24m in内,脱乙酰反应是一级反应,反应速率常数为7.69×10-2.m in-1,动力学方程为:[-ln(1-D.D)]=7.62×10-2t+0.7659。在开放式处理条件下,甲壳素脱乙酰反应过程比较复杂,反应不符合一级化学反应规律。     

Adsorption of 2,4-Dichlorophenol from Aqueous Solution onto Microwave Modified Activated Carbon： Kinetics and Equilibrium

Batch experiments were conducted to investigate the adsorption of 2,4-dichlorophenol (2,4-DCP) onto microwave modified activated carbon (AC) at three different temperatures (303 K, 313 K and 323 K). Adsorption isotherms, kinetics, and thermodynamics of the adsorption process were explored. Equilibrium data were fitted into Langmuir and Freundlich equations, and the result reveals that the Freundlich isotherm model fits better than the Langmuir model. Three simplified kinetic models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations were adopted to examine the mechanism of the adsorption process, and the pseudo-second-order kinetic model proved to be the best in describing the adsorption data. The thermodynamic parameters of the adsorption process were estimated, showing that the adsorption of 2,4-DCP was exothermic and spontaneous, and the adsorption studied in this paper can be assigned to a physisorption mechanism.     

几种不同产量水平水稻品种光合特性的比较

研究几种不同产量水平的水稻品种的光合特性,结果表明,高产品种的水稻具有较高的PSⅡ原初光能转化效率、PSⅡ潜在活性和光合电子传递速率。Mg~(2 )能较大幅度地提高高产品种的Fv/Fm和Fv/Fo的比值,并对高产品种叶绿体的PSⅡ和PSⅠ之间激发能分配的调节能力也较高,这可能与高产品种叶绿体的内部结构有助于外加Mg~(2 )更充分发挥提高它们原初光能转化效率、PSⅡ潜在活性和调节两个光系统之间激发能分配的作用有关。 Ch1a荧光诱导动力学的技术,有可能运用于早期检测水稻(或其他作物)的生产潜力。     

中、外优秀男子百米途中跑运动学研究及模型的构建

通过文献资料调研、影片解析等方法对中、外优秀男子短跑运动员途中跑最高速度时一个单步的技术结构进行运动学研究。通过对着地瞬间、后蹬瞬间、腾空瞬间的运动学指标分析，总结出男子优秀运动员共性的技术原理，运用灰色关联分析中关联度的大小，建立优秀男子百米专项运动技术模型。     

我国优秀女子撑竿跳高运动员悬垂摆体技术的运动学特征

通过对10名优秀女子撑竿跳高运动员的悬垂摆体进行运动学研究,结果表明:我国优秀女子撑竿跳高运动员在竿上支撑阶段时间的分配上存在问题;运动员都能很稳定地保持合理的身体姿势;悬垂时下握手的肘关节角度偏大;我国优秀选手在竿弦最短时竿弦与地面的夹角过大,竿子的弯曲度不够,造成竿子的能量储备不够.我国运动员的摆体技术基本上是以"高髋摆体"技术为主.