New use of BCG for recombinant vaccines

BCG, a live attenuated tubercle bacillus, is the most widely used vaccine in the world and is also a useful vaccine vehicle for delivering protective antigens of multiple pathogens. Extrachromosomal and integrative expression vectors carrying the regulatory sequences for major BCG heat-shock proteins have been developed to allow expression of foreign antigens in BCG. These recombinant BCG strains can elicit long-lasting humoral and cellular immune responses to foreign antigens in mice.     

宾汉流体偏心环空轴向层流流场的研究

本文对宾汉流体偏心环空轴向层流流场进行了理论分析,导出了速度分布、视粘度分布、分层雷诺数分布和流量的计算公式。大量实验数据与理论计算结果吻合。由此证明这些公式是正确的,可以作为定向井水力参数设计的理论依据。     

产品竞争能力评价

本文剖析了影响产品竞争能力的主要因素,建立了有49个子项目的产品竞争能力指标体系及结构模型。利用层次分析法计算出严品竞争能力综合评价指标,使生产同类产品的竞争对手之间,可以方便地进行产品竞争能力的定量对比分析。最后,给出了实例,来说明此方法的应用.     

物理学、化学论文的写作特点和要求

本文从物理学和化学这两门学科的一些共性特点出发,着重从科学实验的角度,分析这种类型论文的写作原则、表达方法和由学科自身特点所提出的一些特殊要求。     

科技论文英文摘要写作浅谈

本文简述了撰写科技论文英文摘要的必要性;英文摘要的类型与格式;各组成部分的写作要求、表达方式及应注意的有关事项。     

三相流态化浸出锑精炼渣的研究

本文对锑精炼渣进行了三相流态化浸出的小型及扩大试验研究,探讨了锑精炼渣水浸分离砷锑的控制环节。考察了锑精炼渣浆的流变特性,讨论了温度、粒度、时间液固比等因素对浸出过程的影响。小型及扩大试验均表明,在常温和液固比为2.0的条件下浸出30min,砷浸出率可达97%。三相流态化浸出可在低液固比下进行,能强化浸出过程,缩短浸出时间。     

Phenotypic differences between alpha beta versus beta T-cell receptor transgenic mice undergoing negative selection

T-cell differentiation in the thymus is thought to involve a progression from the CD4-CD8- phenotype through CD4+CD8+ intermediates to mature CD4+ or CD8+ cells. There is evidence that during this process T cells bearing receptors potentially reactive to 'self' are deleted by a process termed 'negative selection' One example of this process occurs in mice carrying polymorphic Mls antigens, against which a detectable proportion of T cells are autoreactive. These mice show clonal deletion of thymic and peripheral T-cell subsets that express the autoreactive V beta 3 segment of the T-cell antigen receptor, but at most a two-fold depletion of thymic cells at the CD4+CD8+ stage. By contrast, transgenic mice bearing both alpha and beta chain genes encoding autoreactive receptors recognizing other ligands, show severe depletion of CD4+CD8+ thymocytes as well, suggesting that negative selection occurs much earlier. We report here the Mls 2a/3a mediated elimination of T cells expressing a transgene encoded V beta 3-segment, in T-cell receptor alpha/beta and beta-transgenic mice. Severe depletion of CD4+CD8+ thymocytes is seen only in the alpha/beta chain transgenic mice, whereas both strains delete mature V beta 3 bearing CD4+ and CD8+ T cells efficiently. We conclude that severe CD4+CD8+ thymocyte deletion in alpha/beta transgenic mice results from the premature expression of both receptor chains, and does not reflect a difference in the timing or mechanism of negative selection for Mls antigens as against the allo- and MHC class 1-restricted antigens used in the other studies.