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991.
股骨头负重区松质骨的压缩力学特性   总被引:6,自引:0,他引:6  
本文对19具新鲜青年(30左右)尸体股骨负重区的松质骨进行了压缩测试,测算并提供了一组松质骨弹性模量,极限应力,应变,屈服载荷及能量吸收值。试验表明松质骨力学性能主要缓解外力冲击加压。  相似文献   
992.
The bioactivity screening of fractions from two inter-tidal sponges collected from the north of China Yellow Sea and one sponge collected from the South Chinese Sea was reported in this study. In sponge Hymeniacidon perleve there were 9 fractions out of 15 from CHCl3 extract with anti Staphylococcus aureus activity, 9 fractions out of 19 from BuOH extract with anti Escherichia coli activity, and three fractions from CHCl3 extract which had moderate to strong activity in inhibiting Bacillus subtilis, Candida albicans, and Aspergilus niger. The fractions of Reniochalina sp. showed bioactivity against bacteria and fungi. The fractions of Acanthella acuta Schmidt showed bioactivity against S. aureus and fungi. One compound from H. perleve obtained by the bioactively directing isolation was tested for bioactivity against the human hepatoma cell line Qgy7701 (IC50 10.1 μg/ml), Burkitt's lymphoma cell line Raji (IC50 9.76 μg/ml) and chronic myelogenous leukemia K562 (IC50 1.90 μg/ml).  相似文献   
993.
[目的]利用分子生物学手段探索裳卷蛾变形孢虫的遗传发育地位.[方法]微孢子虫的SSUrRNA序列是构建系统发育进化树的重要工具.试验通过T-A克隆法对裳卷蛾变形孢虫(Vairimorphaceraces)SSU rRNA核心序列进行了克隆,并采用近邻法构建了系统发育进化树.[结果]克隆得到了长为1228bp的核苷酸序列(GenBank EU267796).系统发育分析结果表明:裳卷蛾变形孢虫与分离于小菜蛾(Plutella xylostella)的Vairimorpha sp.Germany(GenBank AF124331)和Vairimorphaimperyecta(GenBank AJ131645)相似性最高,它们在系统发育进化树中与寄主为鳞翅目昆虫的Nosema属聚为一类,与纳卡变形孢虫(Vairimorpha necatrix)为代表的Vairimorpha属为相邻集.[结论]结合其生物学特征,裳卷蛾变形孢虫确实为Vairimorph a属的成员,但根据系统发育分析归入Nosematidae科可能更为合适.  相似文献   
994.
995.
Lebanon is an eastern Mediterranean country inhabited by approximately four million people with a wide variety of ethnicities and religions, including Muslim, Christian, and Druze. In the present study, 926 Lebanese men were typed with Y-chromosomal SNP and STR markers, and unusually, male genetic variation within Lebanon was found to be more strongly structured by religious affiliation than by geography. We therefore tested the hypothesis that migrations within historical times could have contributed to this situation. Y-haplogroup J*(xJ2) was more frequent in the putative Muslim source region (the Arabian Peninsula) than in Lebanon, and it was also more frequent in Lebanese Muslims than in Lebanese non-Muslims. Conversely, haplogroup R1b was more frequent in the putative Christian source region (western Europe) than in Lebanon and was also more frequent in Lebanese Christians than in Lebanese non-Christians. The most common R1b STR-haplotype in Lebanese Christians was otherwise highly specific for western Europe and was unlikely to have reached its current frequency in Lebanese Christians without admixture. We therefore suggest that the Islamic expansion from the Arabian Peninsula beginning in the seventh century CE introduced lineages typical of this area into those who subsequently became Lebanese Muslims, whereas the Crusader activity in the 11(th)-13(th) centuries CE introduced western European lineages into Lebanese Christians.  相似文献   
996.
The human UGT2B17 gene varies in copy number from zero to two per individual and also differs in mean number between populations from Africa, Europe, and East Asia. We show that such a high degree of geographical variation is unusual and investigate its evolutionary history. This required first reinterpreting the reference sequence in this region of the genome, which is misassembled from the two different alleles separated by an artifactual gap. A corrected assembly identifies the polymorphism as a 117 kb deletion arising by nonallelic homologous recombination between ~4.9 kb segmental duplications and allows the deletion breakpoint to be identified. We resequenced ~12 kb of DNA spanning the breakpoint in 91 humans from three HapMap and one extended HapMap populations and one chimpanzee. Diversity was unusually high and the time to the most recent common ancestor was estimated at ~2.4 or ~3.0 million years by two different methods, with evidence of balancing selection in Europe. In contrast, diversity was low in East Asia where a single haplotype predominated, suggesting positive selection for the deletion in this part of the world.  相似文献   
997.
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) that places a heavy strain on public health. Host susceptibility to Mtb is modulated by macrophages, which regulate the balance between cell apoptosis and necrosis. However, the role of molecular switches that modulate apoptosis and necrosis during Mtb infection remains unclear. Here, we show that Mtb‐susceptible mice and TB patients have relatively low miR‐342‐3p expression, while mice with miR‐342‐3p overexpression are more resistant to Mtb. We demonstrate that the miR‐342‐3p/SOCS6 axis regulates anti‐Mtb immunity by increasing the production of inflammatory cytokines and chemokines. Most importantly, the miR‐342‐3p/SOCS6 axis participates in the switching between Mtb‐induced apoptosis and necrosis through A20‐mediated K48‐linked ubiquitination and RIPK3 degradation. Our findings reveal several strategies by which the host innate immune system controls intracellular Mtb growth via the miRNA‐mRNA network and pave the way for host‐directed therapies targeting these pathways.  相似文献   
998.
西宁大黄小碎片加到20%硫酸溶液和氯仿的混合液中,在水浴中回流以水解,提取,氯仿提取液相继以5%碳酸氢钾溶液,5%氢氧化钾溶液振荡提取,提取液分别以盐酸酸化,即分离得大黄酸,大黄素,芦荟大黄素及大黄酚和大黄素甲醚混合物等黄色沉淀物,后者再以硅胶柱层析分离,可得大黄酚和大黄素甲醚单体,上述五种蒽醌衍生物再经结晶即得纯品。  相似文献   
999.
加拿大自然保护区规划的启迪   总被引:5,自引:0,他引:5  
许学工 《生物多样性》2001,9(3):306-309
为了更好地国际接轨,搞好自然保护区的管理工作,我们需要学习其他国家的先进经验,本文重点介绍加拿大自然保护区规划方面的典型经验,包括系统规划,综合管理规划,资源管理规划,服务规划,行动规划,以及各种规划之间的关系,并提出了对我们的启迪与可借鉴之处。  相似文献   
1000.
氨肽酶N的表达及其与结石形成的关系(英文)   总被引:6,自引:0,他引:6  
 为研究大鼠高胆固醇饮食时 ,肝脏氨肽酶N(APN)在实验结石形成中可能的结石发生作用 ,采用 1.2 %胆固醇饮食 4周 ,诱发新西兰兔胆囊结石形成 .根据兔APN基因cDNA序列设计引物 ,提取肝脏总RNA .利用RT PCR检测肝脏APNmRNA水平的变化 ,用组织化学方法观察肝脏毛细胆管膜上APN的表达 .观察新西兰兔胆囊结石形成过程中肝脏APN的mRNA水平的变化、APN表达及胆汁中APN活性、胆脂、总蛋白含量的变化 ,探讨APN在胆石形成中可能的作用 .经成石饲料饲养后 ,随着胆汁饱和度增加和APN活性加强 ,胆囊结石组肝脏APNmRNA水平较对照组明显增高 ,胆囊结石组胆汁中总胆固醇、CSI、总蛋白浓度及APN活性均明显高于对照组 ,且胆汁中APN活性与肝脏APN的表达及胆汁CSI增高呈正相关 .结果提示 ,当存在胆汁过饱和的情况下 ,APN很可能作为促成核因子在胆结石形成早期发挥重要作用  相似文献   
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