关于短跑运动员服用甲壳素提高运动能力的研究

观察了短跑运动员服用甲壳素(Chitin)前后,机体在激烈运动后血乳酸浓度的变化。实验表明:通过服用甲壳素短跑运动员在运动过程中血乳酸浓度有显著的降低、运动成绩有所提高,短跑运动员服用甲壳素后能提高运动能力。     

Body composition of English Premier League soccer players: Influence of playing position,international status,and ethnicity

Abstract

Body composition is a key consideration in the physical make-up of professional soccer players. The aims of the present study were to determine whether the body composition of professional soccer players varied according to playing position, international status or ethnicity, and to establish which variables best distinguished the soccer players from a reference group. Body composition was assessed using dual-energy X-ray absorptiometry in 64 male professional soccer players. Measured variables included bone mineral density and the relative amounts of lean and fat mass. Data were analysed using analysis of variance and stepwise discriminant function. The soccer players recorded better values than a reference group (n = 24) for all body composition compartments. Percent lean mass and bone mineral density were the variables best able to identify the soccer players (95.5% correctly classified). Differences in body composition were evident between goalkeepers and outfield players, but not between outfield playing positions. No differences were found on the basis of international status. The non-Caucasian players demonstrated significantly lower percent body fat (9.2 ± 2.0%) than the Caucasian players (10.7 ± 1.8%). It was concluded that body composition is important for elite soccer players, but that homogeneity between players at top professional clubs results in little variation between individuals.     

突触后致密物、突触可塑性与运动

突触可塑性是学习、记忆的细胞分子学基础,突触后致密物在突触可塑性中对揭示学习和记忆的分子机制有非常重要的意义。突触后致密物的可塑性变化易受突触前传入信息和机体内部或外界环境因素影响,而运动可以改变突触后致密物可塑性变化进而影响学习记忆。本文综述了突触后致密物的结构及功能与突触可塑性的重要关系,探讨运动训练对突触结构和功能可塑性的影响,进一步从分子水平上揭示运动训练对学习记忆促进作用的机制。     

The density of social networks moderates effects of intergroup contact

This study tests how the density of the social network in which intergroup contact takes place might affect the extent to which contact improves intergroup attitudes. Having contact with more outgroup members in dense social networks, in which everybody knows each other, may reinforce contact's positive effect. In this case, outgroup contact is shared with ingroup members, which suggests positive ingroup norms toward the outgroup. Alternatively, more contact in denser networks may improve intergroup attitudes less because density may increase subtyping or reduce the salience of ethnic group memberships. These competing hypotheses are tested among white American adults in a nonprobability online sample (N = 305) and in a representative national sample (N = 1270). In both studies, contact is associated with more positive attitudes toward racial outgroups but the positive contact effect is weakened if that contact takes place in a denser social network.     

路基土的击实试验研究

路基施工的质量以压实度为主要控制指标，它与干密度有重要的关系，通过对路基土的击实试验研究，提出经济、合理的压实功能，对提高道路工程施工质量有极其重要的意义。     

反应挤出制备HDPE/PA 6/MMT复合材料研究

通过反应挤出制备了高密度聚乙烯/聚酰胺6/蒙脱土(HDPE/PA 6/MMT)复合材料,研究了MMT在HDPE/PA 6共混物中的分散和分布情况,及其对共混物相态结构的影响。从XRD和TEM的结果中可以看出,有机化蒙脱土(OMMT)选择性地分布在PA 6相内以及两相的界面上,钠基蒙脱土(Na+MMT)则主要分布在PA 6相内;大部分OMMT得到较好的剥离或插层,而Na+MMT出现明显的团聚。FE-SEM分析结果表明,增大MMT的含量会导致PA 6的相态尺寸变大,粒径分布变宽。流变分析结果表明,由于OMMT部分分布于两相界面处,从而增强了界面结合,对共混物起到了增容作用。     

密度与施肥对白肋烟香味物及品质的影响

采用同时蒸馏萃取、顶空分离前处理方法及气相色谱一质谱联用分析鉴定技术，对不同种植密度与施肥水平组合生产的原烟进行了定量测定，并对其主要化学成分和鲜叶的腺毛密度也做了测定，结果表明：密度与施肥对香味物质的成分与含量、主要化学成分和腺毛密度都具有一定影响，以A：B。处理的较好，其次是A2B3，A1B2和A1B3．因此，在当地TN86以种植密度18000株／hm^2．施氮300kg／hm^2，N：P2O5：K2O=1：1：1．5的栽培组合，有利于烟叶香吃味的形成．     

论钙对人体健康的影响及合理补钙

钙在人体中起着重要的生理调节功能，它几乎参与了人体的所有代谢过程，体内缺钙会影响健康，甚至引起疾病，而如何补钙又是很多人所未知的，所以出现了很多盲目补钙的现象。应全面认识缺钙的原因及危害，并了解如何合理而经济的补钙，把握补钙的正确途径。     

三能级原子中相对位相阻尼引起的消相干

本文对量子纯态演化为混合态进行探讨。利用密度矩阵和Kraus理论对相对位相阻尼引起的消相干进行研究,计算出三能级原子相对位相阻尼引起消相干的密度矩阵,根据密度矩阵非对角元衰变规律,得出三能级原子的消相干特性。     

关于一个平面1-集的不规则性

一个S-集必定是不规则集,除非S是整数.但S是整数的时候这个S-集可能是规则的,也可能是不规则的.为此,利用上密度和下密度来证明一个平面1-集的不规则性.