发展男子排球运动员下肢速度力量的调查

依据当今速度力量的研究成果,制定专家问卷、教练问卷,以河南几所高校排球教研室和少年体校为调查对象,针对男子排球运动员下肢速度力量的训练方法做出综合统计分析,以期为排球教学与训练提供参考.     

2,6-二甲基-3,5-二氯-4-吡啶醇的合成及其抗球虫作用的研究

以双乙烯酮为原料,经二聚合反应,得脱氢醋酸。再由脱氢醋酸分别经水解、氨化、氯化反应(总收率26.97%)或高压氨化、氯化反应(总收率39.52%)制得文题化合物(m.p.345℃)。药理试验表明其毒性较低(LD_(50)>10g/kg)。用作饲料添加剂可明显提高鸡的增重率,降低死亡率,防治球虫病。     

Evolution and ecological correlates of uniparental reproduction in freshwater snails

We review the spatial and temporal correlates of uniparental reproduction in freshwater snails as they pertain to the ecological hypotheses for the maintenance of biparental sex. The biogeographic evidence from two species (Potamopyrgus antipodarum andBulinus truncatus) presently supports the Red Queen hypothesis that biparental reproduction is selected as a way to reduce the risk to progeny of parasite attack. Uniparental reproduction in these species is associated with low levels of infection by parasites (castrating digenetic trematodes), suggesting that parthenogenesis or self-fertilization can replace cross-fertilization when the risk of infection is low. In addition, inB. truncatus, the opportunity for cross-fertilization coincides with the season in which parasite attack is highest. In a third species (Campeloma decisum), parthenogenetic reproduction is correlated with latitude and the presence of a non-castrating trematode that may prevent cross-fertilization; these patterns suggest that parthenogenesis has been selected as a mechanism to assure reproduction. Finally, we discuss the spotty taxonomic distribution of parthenogenetic species.     

在不同水硬度下铜对草鱼、鲢和大鳞泥鳅的急性毒性

实验以草鱼、鲢和大鳞泥鳅的鱼苗为材料,测定了水硬度对铜的急性毒性的影响,水硬度在255、141、37和14mg/L(以 CaCO_3计)时铜对草鱼的48小时 LC_(50)分别是519、354、91和76μg/L,96小时 LC_(50)则分别为460、307、67和39μg/L.在同样的硬度条件下,对鲢的48小时 LC_(50)是452、393、71和40μg/L,96小时 LC_(50)分别为452、296、41和31μg/L.大鲢泥鳅鱼苗在硬度260、137、36和10μg/L(以 CaCO_3计)条件下,铜的48小时 LC_(50)为369、305、1113和67μg/L,而96小时 LC_(50)则分别是226、135、67和18μg/L.铜的急性毒性和水硬度之间的关系可用下列方程来描述:草鱼 ln96小时■_(50)=1.1345+0.9051ln 硬度 r=0.99ln96小时■_(50)=2.2118+0.7220ln 硬度 r=0.97鲢 ln96小时■_(50)=0.4564+1.0207ln 硬度 r=0.97ln96小时■_(50)=1.1371+0.9232ln 硬度 r=0.98大鳞泥鳅ln96小时■_(50)=1.2823+0.7506ln 硬度 r=0.99ln96小时■_(50)=2.8635+0.5563ln 硬度 r=0.99     

Molecular mechanisms in male determination and germ cell differentiation

Sex determination and gametogenesis are key processes in human reproduction, and any defect can lead to infertility. We describe here the molecular mechanisms of male sex determination and testis formation; defects in sex determination lead to a female phenotype despite the presence of a Y chromosome, more rarely to a male phenotype with XX chromosomes, or to intersex phenotypes. Interestingly, these phenotypes are often associated with other developmental malformations. In testis, spermatozoa are produced from renewable stem cells in a complex differentiation process called spermatogenesis. Gene expression during spermatogenesis differs to a surprising degree from gene expression in somatic cells, and we discuss here mechanistic differences and their effect on the differentiation process and male fertility.Received 23 January 2004; received after revision 30 March 2004; accepted 6 April 2004     

澎泽鲫幼鱼对盐度和碱度耐受性的研究

试验研究了盐度和碱度对澎泽鲫幼鱼的急性毒性,结果为24,48,72,96 h其盐度的半致死浓度分别是9.996,7.871,6.879,6.676 g·L-1,碱度的半致死浓度分别是71.71,69.85,60.81,59.87mmol·L-1.盐碱混合毒性试验中的AI指数表明盐度和碱度在一定程度上存在着协同作用.     

从《危舍府的倒塌》看男性人格自我完善的趋势

在爱伦·坡众多女性受害题材的作品中 ,《危舍府的倒塌》是比较典型的一篇。本文试图通过该文男主角性格转变的过程 ,从一个侧面说明坡作品中男性人格自我完善的一种趋势。这种趋势也显示了坡描写的接受女人既是“其他的人”又是“自己的一部分”的能力是人类自我完善的一种尝试。     

离子液体的毒性及其潜在风险评估

组成离子液体的结构和纯度对其毒性有较大的影响.综述离子液体的纯度,阳离子、阴离子组成对其毒性的影响以及离子液体的生态学设计方案和多维风险分析的研究进展.     

基于AMD和爆破荷载耦合作用下的深凹露天矿边坡失稳研究

AMD是化工(金属)矿边坡体破坏的一种特殊方式,与爆炸应力波共同对边坡体产生作用.新桥深凹露天矿边坡岩体的原位剪切试验、点载荷试验、室内模拟AMD作用试验表明:AMD蚀化后的石英砂岩,岩体层面间的抗剪强度和粘聚力减小的幅值约为13.2%～21.3%;层面间内摩擦角减小幅值在5.0%～7.5%之间;AMD一般影响垂直边坡体内部在60～100 m范围内的岩体力学性质.数值分析表明:(1)AMD对边坡体的作用主要集中在弱化区域内,边坡体的底脚和AMD作用中心区域的剪切应力减少了52.0%和64.7%;(2)随着边坡体高度和距离的增加,远场爆炸应力波对边坡扰动幅值的增加趋势明显,边坡顶部和断层部位的响应突出,损伤效应明显;边坡底脚扰动幅值最小,临空面附近台阶的扰动幅值明显大于边坡体内部;(3)AMD与爆破荷载耦合作用后,边坡体内部的应力分布主要呈现出爆炸应力场的特征,AMD影响区域形成了一个剪切应力弱区.台阶顶部最大剪切应力比单一爆炸应力场增加了1.63倍,形成了一个不稳定的弱区.图12,表3,参14.