首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   85篇
  免费   3篇
  国内免费   9篇
化学   64篇
力学   5篇
数学   16篇
物理学   12篇
  2022年   1篇
  2017年   1篇
  2015年   1篇
  2014年   4篇
  2013年   13篇
  2012年   2篇
  2011年   3篇
  2010年   7篇
  2009年   3篇
  2008年   2篇
  2007年   7篇
  2006年   5篇
  2005年   4篇
  2004年   1篇
  2003年   3篇
  2002年   8篇
  2001年   3篇
  2000年   6篇
  1999年   3篇
  1992年   4篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1979年   1篇
  1977年   2篇
  1975年   1篇
  1970年   1篇
排序方式: 共有97条查询结果,搜索用时 15 毫秒
21.
Abstract

Among the new compounds of N-(thio)phosphorylthiómides. the copper(II) complex with N-diisopropoxyphosphorylthiohenzamide (Cul. 2) exhibits series of unusual properties which have been extcnsively investigated in the present work. The X-ray structure of CuL2 has been determined Crystals of CuL2 are monoclinic. P21/c, a = 15.610, b = 11.880, and c = 18.320 Å, β = 106.74°. Z = 4. The CuL2 complex has the cis-structure with Cu-S distances ranging from 2.238 to 2.253 Å and Cu-O distances being from 1.919 to 1.937 Å (Figure).  相似文献   
22.
23.
The first part of this report describes the data reduction of non-merohedrally twinned crystals measured on Bruker and Agilent area-detector diffractometers. The image frames of methyl-2-aminopyrazine-3-carboxylate were processed with APEX2 to furnish a set of overlapping diffraction indices that were used for solution and refinement. CrysAlisPRO was used for processing the frames of bis(diethyldicarbamato)nickel, which exists in monoclinic and tetragonal polymorphs, and in untwinned and twinned forms. In the second part, the crystal structure of [(3-formyl-4- hydroxyphenyl)methyl]triphenylphosphanium chloride was refined through the ‘HKLF 5'(based on a combined set of diffraction indices) and PLATON(based on one set of diffraction indices) routes to give identical outcomes because the amount of overlap of the twin domains is small. For the third part, in a proof-of-concept investigation, the diffraction pattern of untwinned and twinned 4-{(E)-(4-aminophenyl)diazenyl]phenylamine was recorded simultaneously in one run; the three domains could be indexed and the crystal structure satisfactorily refined. The refinement was identical to those derived from independent measurements; the crystal structure features two independent centrosymmetric molecules, one of which is ordered and the other whole-molecule-disordered. This two-in-one run opens up the possibility that two or more crystals having different atomic compositions can be measured simultaneously if their reciprocal lattices do not overlap significantly.  相似文献   
24.
Abstract

The analysis of all known synthesis methods of N-(thio)phosphorylthiómides of the common formula RC(S)NHP(X)R'2 (1), where R=Alk, Ar; R'=óIk, ór, SAIk, SAr. Alk, Ar; X=O,S has been gave in this report. We worked out the simple and convenient syntheses methods of this class compounds.  相似文献   
25.
26.
NG Seik Weng 《结构化学》2010,29(10):1584-1586
Dimethyltin dichloride-dibenzyl sulfoxide,((CH3)2SnCl2·O=S(CH2C6H5)2),crystallizes in the orthorhombic space group P212121 with a superstructure of dimensions a = 11.9290(1),b = 19.50490(1),c = 55.7390(6) ; Z = 28. The geometry of the five-coordinated tin atom in each of the seven independent adduct molecules is a square pyramid that is displaced towards a cis-trigonal bipyramid; the extent of displacement along the Berry pseudorotation pathway ranges from 20 to 45%.  相似文献   
27.
研究了酚醛型吸附树脂JDW 2在非水体系中对吡啶和N ,N 二甲基苯胺的静态吸附 .由实验结果推论正己烷中树脂对吡啶和N ,N 二甲基苯胺的吸附是以氢键吸附机理为主进行的 ,JDW 2酚醛型吸附树脂在正己烷中 ,等温吸附吡啶和N ,N 二甲基苯胺的平衡吸附数据符合Langmuir方程 ,相关系数在 0 99以上 ,因此 ,酚醛型吸附树脂在正己烷中吸附吡啶和N ,N 二甲基苯胺属单分子层吸附 ;同时对非水体系中乙醇或乙酸乙酯的含量对树脂吸附吡啶和N ,N 二甲基苯胺的影响进行了研究  相似文献   
28.
The title compound,[Cu2(CH3COO)4(C8H10N2)]n·nCH3CN1 (C8H10N2,4,4'-bipy = 4,4'-bipyridine),has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction.The crystal is of monoclinic,space group Cc with a = 22.626(6),b = 14.012(4),c =15.106(4) (A),β = 107.610(3)°,V = 4565(2) (A)3,C20H23Cu2N3O8,Mr = 560.49,Z = 8,Dc = 1.631 g/cm3,μ = 1.914 mm-1,Flack parameter = 0.48(1),F(000) = 2288,R = 0.042 and wR = 0.)98 for 8887 observed reflections (I > 2σ(I)).It consists of nearly linear one-dimensional chains [Cu2(CH3COO)4(C8H10N2)]n derived from paddle-wheel [Cu2(CH3COO)4] unit linked by 4,4'-bipy,and CH3CN as guest molecule regularly decorates between the chains.  相似文献   
29.
Complexing processes in MII-N-diisopropoxythiophosphorylthiobenzamide binary systems (M = Co, Ni, Cu) in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices upon contact with aqueous–alkaline (pH = 12.0 ± 0.1) solutions of organic compounds have been studied. It has been shown that, in CoII and CuII, the initial act of complexing involves destruction of the CoII and CuII hexacyanoferrates(II) by OH ions, leading to formation of the corresponding hydroxides which react with the ligand indicated. In the both systems, successive addition of two ligand molecules per M(OH)2 fragment occurs and [MB(OH)(OH2)] and [MB2] coordination compounds are formed (B-a singly deprotonated ligand form). In the NiII-N-diisopropoxythiophosphorylthiobenzamide system, the formation of three complexes, (Ni2BOH)2[Fe(CN)6], [NiB(OH)(OH2)] and [NiB2] occurs.  相似文献   
30.
In this study, a variational approach to the settlement analysis of an axially loaded pier embedded in a multi-layered soil profile is presented. In this method, the soil profile and the embedded pier are divided into a number of sub-layers according to the actual number of soil layers observed in the field. The displacement shape function of each soil layer is given as a product of an exponential equation along the pier depth and the Bessel's solution in the radial direction. The displacement relationship among the layers can be derived through the transformation matrices. One of the major features of this method is that the total number of pier elements is the same as that of soil sub-layers. All the field components, such as the displacement, stress, and strain in the soil, can be calculated by closed-form solutions except that the only unknown variable is the value β which can be determined by iteration techniques. Comparisons were made with the results of finite element analysis and the field observation in pile-loaded tests.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号