Synthesis and Crystal Structure of 1＇-Methyl-4＇-（4-chlorophenyl）-1H-indole-3-spiro-2＇-pyrrolidine-3＇-spiro-4＂-（2＂-phenyloxazole）-2,5＂（3H,4＂H）-dione

The title compound （C26H20ClN3O3） has been synthesized by 1,3-dipolar cycloaddition reaction from isatin, sarcosine and （Z）-4-（4-chlorobenzylidene）-2-phenyloxazol-5（4H）-one through a one-pot procedure, and its structure was confirmed by IR, IH NMR, elemental analysis and single-crystal X-ray diffraction analysis. The crystal belongs to the triclinic system, space group PI, with a = 9.3903（19）, b = 11.398（2）, c = 12.603（3） A, α = 83.495（3）, β = 68.988（3）, γ = 67.178（3）^o, V= 1160.1（4）A^3 Z = 2, Mr= 457.90, Dc= 1.311 g/cm^3, p = 0.198 mm ^-1, F（000） = 476, the final R = 0.0489 and wR = 0.1144 for 3109 observed reflections with I 〉 2σ（I）.     

等比数列的项不能为零

<正>《普通高中课程标准实验教科书（人教B版）·数学5必修》第54页练习B第3题:已知数列{a_n}是等比数列,S_n是其前n项和,试问S_n,S_2n—S_n,S_3n—S_2n,S_4n—S_3n,…（?）成等比数列吗?证明你的结论.这是一道开放性题目,需要给出严格的证明.     

The CDF Date Acquisition System for Tevatron Run Ⅱ

The CDF experiment at the Fermilab Tevatron has been significantly upgraded for the collider Run Ⅱ,which started in march 2001 and is scheduled to alst until 2006,Instantaneous luminosities of 10^32cm^-2S^-1 and above are expected.A data acquisition system capable of efficiently recording the data has been one of the most critical elements of the upgrade.Key figures are the abilitity to deal with the short bunch spacing of 132ns.event sizes of the order of 250kB,and permanent logging of 20MB/s ,The design of the system and experience from the first months of data-taking operation are discussed.     

电磁学教学必须重视演示实验

阐述了电磁学演示实验的重要性及提高高校电磁学演示实验水平的途径.     

浅议怎样做好中学物理静电实验

中学物理静电实验是物理老师感到最难做好的实验之一,有时在实验室准备时能做成功,一上讲台就莫名其妙地不灵了.因此,有些老师很怕做静电演示实验,特别是在阴雨天气.影响静电实验成败的因素很多,但归纳起来关键因素是"绝缘"、"环境条件"、"实验装置与方法".