蟾蜍组织LDH同工酶的比较研究

本文采用聚丙烯酰胺盘电泳法,对中华大蟾蜍(Bufo gargarizans)在冬眠期与活动期的肝、骨骼肌、心肌和脑组织进行了乳酸脱氢酶(LDH)同工酶的比较生化研究。结果表明,冬眠期蟾蜍与活动期蟾蜍的LDH同工酶是不同的,向一种组织LDH同工酶谱显示的区带数,在冬眠期较活动期多,相对活力也不同,心肌的LDH_5区带,在冬眠期还出现了两条亚带。     

Avian flu: isolation of drug-resistant H5N1 virus

The persistence of H5N1 avian influenza viruses in many Asian countries and their ability to cause fatal infections in humans have raised serious concerns about a global flu pandemic. Here we report the isolation of an H5N1 virus from a Vietnamese girl that is resistant to the drug oseltamivir, which is an inhibitor of the viral enzyme neuraminidase and is currently used for protection against and treatment of influenza. Further investigation is necessary to determine the prevalence of oseltamivir-resistant H5N1 viruses among patients treated with this drug.     

Transcriptional regulation of a metastasis suppressor gene by Tip60 and beta-catenin complexes

Defining the molecular strategies that integrate diverse signalling pathways in the expression of specific gene programmes that are critical in homeostasis and disease remains a central issue in biology. This is particularly pertinent in cancer biology because downregulation of tumour metastasis suppressor genes is a common occurrence, and the underlying molecular mechanisms are not well established. Here we report that the downregulation of a metastasis suppressor gene, KAI1, in prostate cancer cells involves the inhibitory actions of beta-catenin, along with a reptin chromatin remodelling complex. This inhibitory function of beta-catenin-reptin requires both increased beta-catenin expression and recruitment of histone deacetylase activity. The coordinated actions of beta-catenin-reptin components that mediate the repressive state serve to antagonize a Tip60 coactivator complex that is required for activation; the balance of these opposing complexes controls the expression of KAI1 and metastatic potential. The molecular mechanisms underlying the antagonistic regulation of beta-catenin-reptin and the Tip60 coactivator complexes for the metastasis suppressor gene, KAI1, are likely to be prototypic of a selective downregulation strategy for many genes, including a subset of NF-kappaB target genes.     

Polyalanine expansion and frameshift mutations of the paired-like homeobox gene PHOX2B in congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome (CCHS or Ondine's curse; OMIM 209880) is a life-threatening disorder involving an impaired ventilatory response to hypercarbia and hypoxemia. This core phenotype is associated with lower-penetrance anomalies of the autonomic nervous system (ANS) including Hirschsprung disease and tumors of neural-crest derivatives such as ganglioneuromas and neuroblastomas. In mice, the development of ANS reflex circuits is dependent on the paired-like homeobox gene Phox2b. Thus, we regarded its human ortholog, PHOX2B, as a candidate gene in CCHS. We found heterozygous de novo mutations in PHOX2B in 18 of 29 individuals with CCHS. Most mutations consisted of 5-9 alanine expansions within a 20-residue polyalanine tract probably resulting from non-homologous recombination. We show that PHOX2B is expressed in both the central and the peripheral ANS during human embryonic development. Our data support an essential role of PHOX2B in the normal patterning of the autonomous ventilation system and, more generally, of the ANS in humans.     

塔里木盆地12000年来的环境变迁

本文综合分析了地层、考古、树轮等方面的考察资料，认为新疆塔里木盆地在最近１２０００年中，一直是在干旱的荒漠环境控制之下，与现代自然环境的特征基本相似。尽管塔里木盆地干旱多风、水源短缺、植被稀少等环境条件是生存环境恶化的潜在因素，但历史时期发生的河水断流、湖泊变干、沙漠扩张等环境劣变主要是人类活动改变了地表水的地域分配造成的。因此，合理用水、平衡水土是我们今后开发塔里木盆地自然资源应当吸取的历史教训。     

加筋微型钢管桩配筋优化及受力特征

为了节约加筋钢管抗滑桩的建造成本,缩短施工周期,通过理论推导,在达到相同抗滑效果的同时,对钢筋的布置角度进行优化设计。根据工程实例从钢管规格型号以及混凝土强度等级等因素,探讨了最优的材料组合和配筋角度,并通过数值模拟验证,研究了加筋钢管抗滑桩优化配筋后的受力特征以及钢管、钢筋和混凝土在抵抗滑坡推力过程中的抗剪分担比。结果表明：(1)从理论推导的过程来看,钢管直径和钢管厚度对配筋影响最大,本文所提出最优配筋公式相比较常规圆形抗滑桩配筋公式节约钢材约60%;(2)通过数值模拟可以得出,加筋钢管抗滑桩配筋之后抗滑能力相比较未配钢筋提高约20%;(3)优化配筋相对于常规配筋滑坡治理效果差距不大,但是节约钢筋约60.37%,更加符合经济效益,说明优化配筋更加符合工程经济价值;(4)优化配筋之后单根钢筋所承受应力比常规配筋提高约50%,将钢筋自身受力特性发挥更加充分。综上,研究成果可以进一步节约实际工程的建造成本,具有实际的工程参考价值。     

500kV超高压交流变电站分裂导线间隔棒优化设计

内蒙古地区17座500 kV超高压交流变电站电晕放电的观测结果表明,变电站内分裂导线间隔棒表面电晕放电最为剧烈。为有效抑制分裂导线间隔棒表面电晕放电,本文首先建立分裂导线间隔棒有限元模型进行仿真计算,然后提出分裂导线间隔棒结构优化设计方案。研究结果表明,内蒙古地区500 kV变电站现用的曲率半径R1=40mm, R2=10mm 的间隔棒表面最大电场强度位于线夹头部曲率半径R2 圆弧段处,且大于起晕场强,为降低间隔棒表面的电场强度,采取改变间隔棒线夹头部曲率半径R1和R2的方法。仿真结果表明,相比增大R1,增大R2对于降低间隔棒线夹头部电场强度的效果更加显著。因此,将间隔棒线夹头部曲率半径R2由10 mm增大至20 mm时,可以满足内蒙古地区500 kV超高压交流变电站分裂导线间隔棒防晕要求。为对计算结果进行验证,在中国电力科学研究院开展分裂导线间隔棒起晕特性试验,验证间隔棒线夹头部曲率半径分别为R1=40mm 、R2=10mm和R1=40mm、R2=20mm时的起晕特性,所得试验结果与计算结果一致。因此可说明,经过优化后的分裂导线间隔棒具有较好的电晕特性。     

可挥发性有机化合物废气治理技术及其新进展

从经济学的一般均衡理论角度,分析了政府对食品安全进行监管的有效边界和稳定的均衡条件。需求和供给分析表明,食品安全监管的供给和需求存在一个合理的度,也就是说当食品安全监管供给边界曲线的斜率绝对值大于食品安全监管需求边界曲线的斜率绝对值时,食品安全监管便达到动态稳定均衡。