有机反应中稳定与不稳定的辩证关系

阐述了有机反应中稳定与不稳定的各种辩证关系,归纳总结了有机反应中各种不稳定和稳定因素,对理解和解释有机反应进行方向,反应机理和反应活性都有很大的帮助。     

基于案例分析的国外在华“微传播”政府应对研究--以新浪微博为例

以国外政府机构和政要入驻新浪微博的典型案例为研究对象,利用内容分析法和案例分析法,探析国外在华“微传播”现象并总结相应政府应对策略。研究发现,国外政府机构和政要善用自媒体社交工具展开全方位的信息传播与价值输出,对此,我国一方面要关注、警惕,另一方面也要学习、借鉴。     

整理活动的生理效应

整理活动做为运动训练过程中一个重要的环节,已为许多教练员和运动员所认同,然而,也有许多教练员和运动员由于不完全了解它的生理机制以及给训练所带来的好处,引起足够的重视。本文旨在通过对整理活动的分析,阐述其对人体各器官的机能的影响,从而帮助教练员和运动员以及体育爱好者掌握和有效地运用这种方法,使它贯穿于训练和比赛之中,促进运动员疲劳的消除和机体的快速恢复。     

Impact absorption of tennis shoe-surface combinations

The aim of this study was to investigate, for typical shoes and surfaces used in tennis, the relative role of the shoe and surface in providing cushioning during running. Five test surfaces ranging from concrete to artificial turf were selected, together with two shoe models. Impact absorbing ability was assessed mechanically using drop test procedures and biomechanically using peak magnitude and rate of loading of impact force and peak in-shoe pressure data at the lateral heel. Differences in biomechanical variables between shoe-surface combinations were identified using a two-way ANOVA (p < 0.05). Mechanical test results were found to rank the surfaces in the same order regardless of the shoe model, suggesting that the surface is influential in providing cushioning. However, for all mechanical and biomechanical (p < 0.05) variables representing impact absorbing ability, it was found that the difference between shoes was markedly greater than the differences between surfaces. The peak heel pressure data were found to rank the surfaces in the same order as the mechanical tests, while impact force data were not as sensitive to the changes in surface. Correlations between mechanical and biomechanical impact absorption highlighted the importance of testing the shoe-surface combination in mechanical tests, rather than the surface alone. In conclusion, mechanical testing of the shoe-surface combination was found to provide a strong predictor of the impact absorbing ability during running if pressure data were used. In addition, for typical shoe-surface combinations in tennis, the shoe was found to have more potential than the surface to influence impact loading during running. Finally, in-shoe pressure data were found to be more sensitive than force plate data to changes in material cushioning.     

固体酸催化剂在酯化反应中的应用

固体酸包括杂多酸、沸石型分子筛、固体超强酸、金属氧化物及阳离子交换树脂等，具有很强的酸性。它作为一类新型催化剂材料替代浓硫酸催化合成酯类物质，具有易分离，可再利用及不腐蚀设备等优点，且反应活性和选择性都很高。     

ε-己内酯合成方法的改进研究

以乙酸酐和双氧水合成出过氧乙酸,经与环己酮进行Baeyer-V illiger氧化反应,制备ε-己内酯,在最佳合成反应条件下,其收率达到61.3%.并对其做了IR、MS、折光率等鉴定.     

Postural stability,clicker reaction time and bow draw force predict performance in elite recurve archery

Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers.     

Role of Nitric Oxide in Salmonella Infection

Nitric oxide (NO) derivative of l-arginine is an important signaling molecule that mediates a variety of essential physiological processes including vasodilation neurotransmission, and host cell defense. Many types of cells produce NO e.g., smooth muscle cell, endothelial cell, and leukocytes. Host defense functions are known for many bacterial and parasitic infections. In the present study we estimated the levels of serum NO in cases of salmonellosis and in controls. The nitric oxide was estimated by cadmium reduction method, Griess reaction. We observed that in controls the level of NO was (22 ± 2.06) μmol/l and in cases the level was (137.49 ± 29.84) μmol/l. The level of NO was significantly higher than controls (p < 0.001). The raised level of NO could be accounted for by host response to the infection. The host rapidly expresses iNOS, which in turn produces an excess amount of NO. Its cytotoxic effect is by its reactive nitrogen oxide derivative e.g., peroxynitrite. Apart from this it also has anti apoptotic functions. In future one can do follow up study of typhoid cases by bacterial culture.     

Structure characterization for the geopolymer of sodium silicate and metakaolin

1 Introduction 1 During the last decade a new kind of material called geopolymer has emerged as a viable alternative for many conventional cements and plastics. Geopolymer is inorganic polymer derived from metakaolin and sodium silicate solution. It can be synthesized at low temperature and have useful properties such as high compressive strength. It is stable at temperatures up to 800 °C and even 1150 °C while ordinary Portland cement loses its strength at 500 °C [1]. Several microstruct…     

对女子幼儿体操运动员四项心理特征的研究

对经过一定阶段体操训练的和未经训练的６岁幼儿进行了四项心理指标的测试与对比分析，结果证明，参加训练的幼儿各项心理指标明显高于未经训练的普通幼儿。通过综合成绩的评定与有关幼儿性格特征的调查统计，发现具有综合类性特征的幼儿较多，而且她们的成绩较好。