The biologically active conformation of ergot alkaloids

Summary Molecular mechanics and NMR studies of the D ring conformation of ergot alkaloids demonstrate that both D₁ and D₂ forms may exist in solution. The comparison of the geometric parameters defining the spatial relations between the aromatic moieties and the basic nitrogen of conformationally restricted dopamine analogs, and that of ergolene, shows the D₁ conformation to be the bioactive one.     

我校张喜光教授研究论文在《NATURE》上发表

2007年10月4日,我校云南省古生物研究重点实验室张喜光教授研究论文《早寒武世带上肢的冠群甲壳动物》(An epipodite-bearing crown-group crustacean from the Lower Cambrian)在自然科学学术期刊《NATURE》(Vol449|4 October 2007)上发表.这是新中国成立后我校教授首次在该刊物上发表文章,对促进我校科研发展具有重要意义.       

原子核磁共振显微检测芯片的磁路设计

基于磁路设计理论首先设计了一种适用于原子核磁共振显微检测芯片的永磁磁路;然后根据磁路磁通折射定理和基尔霍夫第一定律对设计的磁路模型进行理论分析,提出了单一匀场环磁路性能优化方法;最后利用有限元方法分别计算了优化前的磁路、单一匀场环优化后磁路和传统的双匀场环优化后磁路.计算结果表明:相比优化前和采用传统的双匀场环优化后的...     

Characteristics of the Middle-Late Triassic sedimentary facies assemblages in the Songpan-Ruoergai area

The Middle-Late Triassic sedimentary rocks in the Songpan-Ruoergai area mainly consist of calcareous siltstone, muddy limestone, lithic arkose, feldspathic litharenite, mudstone, wormkalk, oolithic limestone, and conglomerate. Except for limestone bed increasing eastward longitudinally and vertically, the calcareous component of the sandstones increases obviously. Abundant benthic and plant fossils and their clasts occur within these rocks. The sedimentary structures predominately contain flaser, parallel, tabular, wavy, and herringbone cross beddings. These data coevally imply that the Middle-Late Triassic sediments deposited in the fluvial, lake and tide environments. Additionally, the rocks display graded, parallel, hummocky beddings, and sandy lamination, a feature characteristic of storm deposits.     

(Sr,Ca)TiO_3电容-压敏复合功能陶瓷材料的制备和性质研究

SrTiO_3基电容－压敏复合功能陶瓷材料具有优良性能．本文通过草酸盐化学共沉淀法制备（Sr,Ca）TiO3陶瓷的超微细粉末;对不同烧成温度、中温氧化温度和氧化时间及不同烧成气氛对材料的介电性能的影响作了综合讨论与分析．     

炉顶布料方式对高炉长寿的影响

分析了高炉长寿与炉顶布料的关系，中心加焦可促进中心气流发展，减轻煤气对炉墙的冲刷；环布碎焦可有效隔热且避免矿石粘结墙，使炉墙免侵蚀并消除吉厚，结瘤，采用此二项技术可使高炉长寿，热损失减少故亦有利节能。     

环向约束条件下高强混凝土早期开裂

为研究环向约束条件下高强混凝土早期开裂趋势,在单面干燥条件下应用非接触式混凝土收缩变形测定仪测试了水灰比为0.26,0.31和0.40试件的早期自由收缩变形.通过静压试验测试了试件早期弹性模量发展,通过改进环向约束试验观测了环向约束条件下各试件内部的收缩应力及应力梯度.结果表明,水灰比越小,单面干燥条件下受约束高强混凝土早期开裂危险性越高,开裂发生时间越早;开裂时间、开裂时弹性模量在很大程度上决定了早期开裂特点.     

硫酸中有机胺对碳钢的缓蚀及与I~-的协同效应

采用稳态极化法研究了硫脲等有机胺在硫酸介质中对 4 5# 碳钢的缓蚀作用及与 I-的协同效应 ,并与 Cl-的协同效应进行了对比。结果表明 :硫脲的缓蚀性能最佳 ;几种有机胺与 I-有明显的协同效应 ;乙二胺与 I-复配使用比单独使用时缓蚀效率提高了一倍 ;尿素与 I-为负协同效应。     

DNA sequence and analysis of human chromosome 18

Chromosome 18 appears to have the lowest gene density of any human chromosome and is one of only three chromosomes for which trisomic individuals survive to term. There are also a number of genetic disorders stemming from chromosome 18 trisomy and aneuploidy. Here we report the finished sequence and gene annotation of human chromosome 18, which will allow a better understanding of the normal and disease biology of this chromosome. Despite the low density of protein-coding genes on chromosome 18, we find that the proportion of non-protein-coding sequences evolutionarily conserved among mammals is close to the genome-wide average. Extending this analysis to the entire human genome, we find that the density of conserved non-protein-coding sequences is largely uncorrelated with gene density. This has important implications for the nature and roles of non-protein-coding sequence elements.     

次酉矩阵及次酉变换

本文在酉空间中引进了次酉矩阵和次酉变换，推广了酉矩阵和酉变换的定义，并得到一些结果，这些结果推广了文[4]中的相应定理。