Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

IntroductionThestudyonthereactivitiesoflanthanidecomplexesto wardisocyanateshasattractedmuchattention .Ithasbeenre portedthatlanthanidealkoxides,1anddivalentdiaza pentadi enyllanthanidecomplexes2 canbeusedasthesinglecompo nentinitiatorsforisocyanatespolymerization .Recentlyourre searchgrouphasalsofoundthatlanthanoceneamide ,3diva lentaryloxideofsamarium4 ,5anddivalentsamarocene6 areallactivefortheoligomerizationofphenylisocyanate,andtheactivespeciesforthesethreesystemswereallsuccessfullyisolat…     

高灵敏度X光探测系统

对高灵敏度X光探测系统结构和灵敏度进行了阐述，给出了厚度差为0．1mm的铜台阶在低照射量下的透视图像及处理结果，证明了系统具有高的灵敏度。     

由Cu^2＋中介的DNA双螺旋结构

大型干涉望远镜 (theverylargetelescopeinterferometer ,VLTI )是一台具有两个望远镜头的装置 ,它可以在任何方位角将光信号组合并获得较高的角分辨率 .最近VLTI拍摄到过去从未观察到的扁平星体Achernar.Achernar星是一颗离地球约有 14 5光年距离的恒星 ,它位于地球天空的南方 ,其质量是太阳质量的 6倍 .虽然VLTI不能提供这个星体的真实图像 ,但它却给出了Achernar星的精确的剖面图 .从图上可以看出Achernar星的赤道半径要比它的极地半径大 5 0 %,这在一般天体中是属于非常扁平状的球体 .如我们地球的赤道半径只比极地半径大 0 .3%.…     

Three Stilbene Tetramers from the Roots of Caragana sinica

Three stilbene tetramers, carasinols A-C (1-3), along with three known substances, leachianol C, cararosinol A and stenophyllol B, were isolated from the roots of Caragana sinica. Their structures were elucidated by spectroscopy. It was found that compounds isolated except for stenophyllol B stimulated the proliferation of cultured osteoblasts.     

A Complexity View of Acid Deposition

We show that acid deposition is analogous to complex systems composed of a series of interconnected components. Frequency-size distributions of weekly hydrogen deposition (WHD) of precipitation are consistent with double power-law in two different regimes separated by a crossover WHD. The distribution of variations in acid deposition over a week interval is remarkably symmetrical, with long tail extending over eight orders of magnitude. The acid deposition fluctuations exhibit fractal Brown motion with two different temporal scaling regimes and long-range correlation exists in the series. The power-laws in the acid deposition dynamics are considered to be indicators of self-organization of atmosphere under environmental pollution stress.     

YBa2Cu3O7-δ体系在B∥I∥c下磁场引起的电阻耗散

基于最近提出的平面外电阻耗散模型,计算了YBa_2Cu_3O_(7-8),体系在平行于c轴的磁场下不同温度时的平面外磁阻率ρ-B和不同磁场时的平面外电阻转变ρ-T.该模型预言了文献上普遍报道的该体系在外加磁场下的Lorentz力无关的耗散行为.为确信这一点,作为例子,特别将由该模型预言的理论结果与在YBa_2Cu_5O(7-8)体系中在B//I//c下测得的电阻转变曲线进行了定量地比较. 关键词：     

流通池—介质交换—阳极溶出伏安法同时测定铜,锑,铋

本文研究了同时测定Ｃｕ（Ⅱ）Ｓｂ（Ⅲ）Ｂｉ（Ⅲ）的方法。在盐酸溶液中对Ｃｕ（Ⅱ），Ｓｂ（Ⅲ），Ｂｉ（Ⅲ）进行预电解富集，经介质交换在选定的丙二酸－盐酸溶液中进行了差示脉冲阳极溶出伏安法（ＤＰＡＳＶ）测定，相邻溶出峰的△Ｆｐ＞８０ｍＶ，波形完好。