表面承受常静水载荷的谐和弹性半无限体的表面不稳定性

本文应用小变形叠加到大变形上的分析方法,考察了表面受常静水载荷作用下,谐和弹性半无限体的表面平面应变失稳问题。分析表明,对于标准材料情形,压缩方向的临界主伸缩比随静水载荷值的增大而减小,相应的临界载荷则随之增大。     

催化合成氯化石蜡-42的研究

本文论述固态石蜡催化氯化的新技术。重点考察 PC-04催化剂对固态石蜡氯化反应的催化效能和各因素对催化反应的影响规律,进行工艺方案的优化研究,并与现行工艺进行技术经济比较。研究结果表明,催化氯化新技术比热氯化工艺,具有反应速度快、生产周期短、工艺与设备简单、产品质量好、对原料适应性强、单耗能耗低、污染少、生产效率高和经济效益显著等特点。     

浅谈篮球运动员早期选材与训练

篮球运动是技术、战术、心理的较量，也是身体素质的对抗．篮球运动水平要一步提高，必须要从早期选材，从小就把有篮球先天优越条件的人才选拔出来，从事训练要结合儿童特点采取有程序训练，主要抓身体训练、基本功训练、基本技术训练．     

光亮铅—锡合金电镀

光亮Pb-Sn合金电镀液系采用K_4P_2O_7作为Sn~(2+)、Pb~(2+)的主络合剂,NTA为辅助络合剂,以DTL-1和DTL-2作为光亮添加剂,在pH为7～8,液温为40～50℃,阴极电流密度在1.5 A/dm~2左右,以铅锡合金板作为阳极的条件下施镀,可得含Ph 40%、含锡60%左右的全光亮合金镀层.另外,文中还对赫尔槽试片的特性、极化曲线的测量、镀液的组成及作用机理等作了探讨。     

医院手术室局部层流净化装置的研究

本文介绍了国内外手术室微生物控制标准及其设施的现状。针对手术室细菌浓度大、感染率高的问題,在现有研究成果的基础上,设计了一种新的手术室用局部层流净化装置——可调方向气幕保护的局部层流净化机组。从理论和实验两方面证明了该装置的优越性。装置的各项性能指标——速度场、尘埃浓度场、细菌浓度场及噪声均达到较先进的水平。     

VEGF links hippocampal activity with neurogenesis, learning and memory

An enriched environment is associated with hippocampal plasticity, including improved cognitive performance and increased neurogenesis. Here, we show that hippocampal expression of vascular endothelial growth factor (VEGF) is increased by both an enriched environment and performance in a spatial maze. Hippocampal gene transfer of VEGF in adult rats resulted in approximately 2 times more neurogenesis associated with improved cognition. In contrast, overexpression of placental growth factor, which signals through Flt1 but not kinase insert domain protein receptors (KDRs), had negative effects on neurogenesis and inhibited learning, although it similarly increased endothelial cell proliferation. Expression of a dominant-negative mutant KDR inhibited basal neurogenesis and impaired learning. Coexpression of mutant KDR antagonized VEGF-enhanced neurogenesis and learning without inhibiting endothelial cell proliferation. Furthermore, inhibition of VEGF expression by RNA interference completely blocked the environmental induction of neurogenesis. These data support a model in which VEGF, acting through KDR, mediates the effect of the environment on neurogenesis and cognition.     

Juxtaposed regions of extensive and minimal linkage disequilibrium in human Xq25 and Xq28

Linkage disequilibrium (LD), or the non-random association of alleles, is poorly understood in the human genome. Population genetic theory suggests that LD is determined by the age of the markers, population history, recombination rate, selection and genetic drift. Despite the uncertainties in determining the relative contributions of these factors, some groups have argued that LD is a simple function of distance between markers. Disease-gene mapping studies and a simulation study gave differing predictions on the degree of LD in isolated and general populations. In view of the discrepancies between theory and experimental observations, we constructed a high-density SNP map of the Xq25-Xq28 region and analysed the male genotypes and haplotypes across this region for LD in three populations. The populations included an outbred European sample (CEPH males) and isolated population samples from Finland and Sardinia. We found two extended regions of strong LD bracketed by regions with no evidence for LD in all three samples. Haplotype analysis showed a paucity of haplotypes in regions of strong LD. Our results suggest that, in this region of the X chromosome, LD is not a monotonic function of the distance between markers, but is more a property of the particular location in the human genome.     

Online uniform machine covering with the known largest size

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2 matches the overall lower bound.