顺(反)-4,4''''-双(4-羟基苯基偶氮)二苯并冠醚的合成与表征

以顺(反)-二氨基二苯并-14-冠-4、顺(反)-二氨基二苯并-18-冠-6和苯酚为原料,通过重氮化和偶联反应合成了4个新的顺(反)-4,4′-双(4-羟基苯基偶氮)二苯并-14-冠-4(化合物1和2)和顺(反)-4,4'-双(4-羟基苯基偶氮)二苯并-18-冠-6(化合物3和4).化合物的结构通过元素分析、紫外光谱、红外光谱和核磁共振波谱等手段确证.发现反式-构型的化合物2和4的熔点高于顺式-构型的化合物1和3的熔点.     

Positive correlation between δ~(18)O in monsoon precipitation and atmospheric wind speed

Analyzed results of the atmospheric wind speedand stable isotopic data (δ^18O) in summer precipitation atBangkok, Bombay, New Delhi, Kunming and Lhasa, the IAEA/WMO stations, indicate that δ^18O in monsoon pre-cipitation correlate positively to wind speed and that thereexists a monsoonal vapor layer over these monsoon-controlled areas during monsoon seasons. The isotopic ex-change happens between monsoon vapors and failing rain-drops in the layer, resulting in this correlation between δ^18O and wind speed. This suggests that wind speed is probablyone of key factors affecting the δ^18O variation besides air temperature and rainfall in the southwest monsoon domain.     

电冰箱数字温度检测仪的设计

介绍了一种采用ATMEL公司的AT89C2051单片机和DALLAS公司的DS18B20数字温度传感器为主要元件，设计的电冰箱数字温度检测仪．该设计方案给出了详细的电路原理图和部分用C51编写的AT89C2051单片机与DS18B20数字温度传感器通信的源程序．     

Phylogenetic position of Ephedra rhytidosperma, a species endemic to China： Evidence from chloroplast and ribosomal DNA sequences

The chloroplast genes matK and rbcL, ribosomal gene 18S and ITS regions of nuclear ribosomal DNA from Ephedra rhytidosperma, a species endemic to China, were sequenced and its phylogenetic position was investigated. Independent and combined phylogenetic analyses for the DNA sequences from 16 taxa representing 15 species of the genus Ephedra were performed using the maximum parsimony （MP）, neighbor-joining （N J）, minimum evolution （ME） and maximum likelihood （ML） methods. The results indicate that E. rhytidosperma is closely related to E. equisetina. The divergence time between them is estimated to be 10.85±2.44 Ma based on the results of the relative-rate tests and the evolutionary rate of rbcL gene.     

Effects of isoxazolyl-naphthoquinoneimines on growth and oxygen radical production inTrypanosoma cruzi andCrithidia fasciculata

Several 4-(aminomethylisoxazolyl)-1,2-naphthoquinones inhibited growth and DNA synthesis inTrypanosoma cruzi and stimulated O₂ uptake and generation by the parasite epimastigotes and their mitochondrial and microsomal membranes; these results support the idea that oxygen radicals play a role in quinone toxicity. Maximal effects on respiration and generation were observed with antimycin-inhibited cells. Similar results as well as stimulation of H₂O₂ production were obtained withCrithidia fasciculata despite the presence of catalase in this organism.Acknowledgments. This work was aided by grants from the University of Buenos Aires, the Scientific Office of the American States Organization and CEDIQUIFA (Buenos Aires). S.G.G. and M.P.M.P. are Research Fellows and A.O.M.S. is Career Investigator of CONICET (Argentina). L. T. Viñas and M. G. Gutierrez lent able technical assistance.     

基于KYN18-12高压开关柜事故原因及相应措施

随着配电网自动化的迅速发展和供电可靠性的日益提高，对开关柜的要求也愈来愈高了，特别是变电所在逐步实现综合自动化进而为无人值守时，对开关及开关柜运行状态的无事故提出了更多的要求。文章阐述了高压开关柜的概念、并结合KYN18-12开关柜具体论述了常见的事故及原因，并针对事故做出了具体的技术改善对策。     

Dawson结构磷钨酸钕制备、表征及催化合成四氢呋喃

通过复分解法制备Dawson结构Nd₂P₂W₁₈O₆₂催化剂,并通过XRD、EDS、SEM和FT-IR等方法表征催化剂.以催化1,4-丁二醇液相脱水环化合成四氢呋喃为探针反应,通过正交实验确定了反应的最佳条件:w(催化剂)=2.6%(相对于1,4-丁二醇质量),反应温度为190 ℃,反应时间为40 min,四氢呋喃的平均产率为97.6%,催化剂重复使用到第3次时,四氢呋喃收率为87.9%.本工艺具有绿色、安全、操作简单、收率高等优点.     

泥鳅和黄鳝18S rRNA基因的克隆与序列分析

通过自行设计引物, 扩增且测定了泥鳅和黄鳝18S rRNA基因部分序列, 并讨论了后生动物18S rRNA基因的碱基含量变化情况. 结果表明, 泥鳅和黄鳝的18S rRNA基因部分序列长度均为1 204 bp, 泥鳅该基因序列GC含量为53.74%, 黄鳝该基因序列GC skew为0.082, 两条序列同源性为99.67%. 将它们和大西洋鲑3个物种的18S rRNA基因与其线粒体12S rRNA,16S rRNA,Cyt b和D loop区4基因进行序列比较, 发现核18S rRNA最保守, 而线粒体D loop区基因进化速率最快. 从GenBank中选择已测定的4种鱼纲动物和11种脊索动物的同源序列, 分别运用NJ法、 MP和ML法, 构建6种鱼纲动物和13种脊索动物的分
子系统树, 结果均显示, 在鱼纲动物系统树中, 6种鱼纲动物被分为软骨鱼类和硬骨鱼类两大支; 在脊索动物的系统树中, 鱼纲与脊椎动物的四足类形成姐妹群, 表明它们在系统发育过程中具有同等重要地位.     

基于nRF401芯片的温度无线数据采集系统设计

介绍了基于nRF401芯片的温度无线数据采集系统的设计.给出了无线数据采集系统的硬件具体电路及通信协议的具体格式,上位机采用查询的方式对多个测温点进行查询.系统具有数据传输速度快、可靠性高、功能易扩展等特点,适用于多种工业领域.     

煤堆温度远程监控系统的设计与实现

为了预测煤堆自燃可能性,利用在煤堆中布设温度传感器,通过准确及时的监控煤堆温度分布与变化,从而达到预防预报煤堆自燃的目的.通过硬件设计,在地面煤堆中埋入多个ds18b20数字温度传感器,利用STC89C52单片机采集温度数据,并通过RS-485串口传回主控计算机,实现对煤堆温度的实时监测;在软件方面:采用Visual C++和数据库技术编写的上位机软件实现了温度的实时显示、曲线绘制、高温报警、数据存储、分析等功能.煤堆温度远程监控系统能够用于测量煤堆温度场分布,是预报煤堆自燃发火的有力工具.