全文获取类型
收费全文 | 66篇 |
免费 | 7篇 |
国内免费 | 172篇 |
专业分类
化学 | 232篇 |
物理学 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2020年 | 1篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 47篇 |
2012年 | 9篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 5篇 |
排序方式: 共有245条查询结果,搜索用时 31 毫秒
151.
在甲醇中氧化双[三(2-甲基-2-苯基)丙基锡]分别与吡嗪-2-甲酸、吲唑-3-甲酸反应,合成了2个三(2-甲基-2-苯基丙基)锡含N杂环羧酸酯(PhCMe2CH2)3Sn[O2C(C4N2H3)](1)和(PhCMe2CH2)3Sn[O2C(C7N2H5)](2)。经IR、1H和13CNMR、元素分析和X-射线单晶衍射表征结构。配合物1属单斜晶系,空间群P21/n,晶体学参数:a=1.20931(7)nm,b=1.81815(11)nm,c=1.49139(9)nm,β=93.567(3)°,Z=4,V=3.2728(3)nm3,Dc=1.302Mg·m-3,μ(MoKα)=0.812mm-1,F(000)=1328,R1=0.0275,wR2=0.0670。配合物2属三斜晶系,空间群P1。晶体学参数:a=1.15310(7)nm,b=1.81973(11)nm,c=2.62040(16)nm,α=86.866(2)°,β=87.063(2)°,γ=73.332(2)°,Z=6,V=5.2559(6)nm3,Dc=1.288Mg·m-3,μ(MoKα)=0.762mm-1,F(000)=2112,R1=0.0374,wR2=0.0925。1和2的中心锡原子均为畸变四面体构型。通过分子间C-H…O和N-H…N氢键作用,配合物2形成环状三聚体结构;两相邻三聚体间,经C-H…π作用进一步扩展成为六聚体。热重分析结果表明,1和2具有良好的热稳定性,分别在210、240℃以下可以稳定存在。毒性测试的初步结果表明,配合物1、2对石螺急性毒性较小,具有较好的环境相容性,且1的毒性低于2和苯丁锡。 相似文献
152.
以3,5-二甲基苄基氯和间氰基苄基氯在适当的溶剂中与锡粉反应,合成了三(3,5-二甲基苄基)氯化锡(1)和四(间氰基苄基)锡(2),经X射线衍射方法测定了化合物的晶体结构。化合物1属单斜晶系,空间群为P21/m,晶体学参数:a=0.584 03(4) nm,b=1.966 37(14) nm,c=0.856 46 (5) nm, β=95.138(3), V=0.979 62(11) nm3,Z=2,Dc=1.735 g·cm-3,μ(Mo Kα)=14.53 cm-1,F(000)=524,R1=0.043 7,wR2=0.1232。化合物2属单斜晶系,空间群为C2/c,晶体学参数:a=1.692 21(12) nm,b=1.167 41(8) nm,c= 1.539 41(11) nm,β=116.615(10)°,V=2.718 9(3) nm3,Z=4,Dc=1.424 g·cm-3,μ(Mo Kα)=9.67cm-1,F(000)=1 176,R1=0.017 5,wR2=0.046 1;中心锡原子为畸变四面体构型。对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。 相似文献
153.
三环己基氢氧化锡分别与辛二酸和壬二酸进行甲醇溶剂热反应,合成了2个双(三环已基锡)二元酸酯(CH2)n(CO2SnCy3)2[(n:6(1),7(2)],并用IR、1H和13C NMR、元素分析和X射线单晶衍射表征结构。化合物1、2均属单斜晶系,空间群分别为P21/n和P21/c,在化合物的晶体中,1通过Sn-O共价键,2通过Sn-O和Sn…O弱作用,分别形成了四锡核30元(1)和32元(2)二维大环网状结构。化合物1、2对人癌细胞Colo205、HepG2、MCF-7、Hela、NCI-H460均具有良好的体外抑制活性,对S. Aureus、B. Subtilis、E. Coli和S. Typhi具有选择性的抑菌作用。 相似文献
154.
Tricyclohexyltin 4-amino-3-methyl-benzoate(1) and tricyclohexyltin 3,4-dimethoxybenzoate(2) were synthesized and their crystal structures were determined by X-ray diffraction. Compound 1 belongs to the monoclinic system, space group P21/c with a = 14.0554(15), b = 11.6947(13), c = 16.2720(17) , Z = 4, V = 2565.7(5) 3, Dc = 1.341 g·cm-3, μ(MoKα) = 1.016 mm-1, F(000) = 1080, R = 0.0833 and wR = 0.2964. Compound 2 is of monoclinic system, space group C2/c with a = 17.8712(6), b = 8.4433(3), c = 35.5783(13) , Z = 8, V = 5366.8(3) 3, Dc = 1.360 g·cm-3, μ(MoKα) = 0.980 mm-1, F(000) = 2288, R = 0.0549, wR = 0.1279. In compounds 1 and 2, the central Sn atom is coordinated in a tetradentate manner to assume a distorted tetrahedral configuration. Preliminary biological tests showed that these two compounds have strong acaricidal activity. 相似文献
155.
Two dinuclear organotin complexes C8H14(CO2SnCy3)2(1)(Cy = cyclohexyl group) and C8H14[CO2Sn(CH2CMe2Ph)3]2(2) were synthesized by the reactions of camphoric acid with tricyclohexyltin hydroxide and bis[tri(2-methyl-2-phenyl)propyltin] oxide under solvothermal conditions, and these complexes were characterized by infrared spectra, elemental analyses, and H NMR spectra. The crystal of 1 belongs to the monoclinic system, space group P21/c with a = 1.83478(19), b = 1.52707(18), c = 1.9849(2) nm, β = 122.515(7), Z = 4, V = 4.6896(9) nm3, Dc = 1.324 g/cm3, μ(MoKα) = 1.103 mm-1, F(000) = 1952, R = 0.0697 and wR = 0.2040. In addition, thermal stability and quantum chemical calculation of 1 were also studied. 相似文献
156.
在甲醇中三苄基氯化锡与3,4-二甲氧基苯甲酸发生脱烃基反应,合成了梯形四核有机锡氧簇合物[(μ-O)(μ-OMe)(L)Sn2(CH2Ph)4]2(HL=(MeO)2C6H3CO2H),经UV、IR、元素分析及X-射线单晶衍射表征结构。该晶体属三斜晶系,空间群P1,晶体学参数:a=1.225 6(5)nm,b=1.229 4(5)nm,c=1.378 0(5)nm,α=69.784(7)°,β=68.568(7)°,γ=72.926(7)°,V=1.780 1(12)nm3,Z=1,Dc=1.549 g·cm-3,μ(Mo Kα)=1.447 mm-1,F(000)=832,R1=0.0261,wR2=0.060 6。晶体结构分析表明:整个分子是以Sn2O2四元环为中心的对称结构,中心锡原子呈五配位畸变三角双锥构型。晶体中,两相邻的配合物分子经C-H…π作用组成一维带状结构。利用量子化学G03W软件,在LANL2DZ基组对配合物的稳定性、前沿分子轨道组成及能量进行研究。热重分析表明,配合物在128℃以下能稳定存在。此外,还研究了该配合物的荧光性质。 相似文献
157.
158.
鼓形有机锡氧簇合物[nBuSn(O)(NNA)]6的合成、晶体结构及生物活性 总被引:2,自引:2,他引:0
The title complex [nBuSn(O)(NNA)]6(1), was synthesized by the reaction of nBuSn(O)OH with naphthalene acetic acid in 1∶1 molar radio, where HNNA=naphthalene acetic acid. The complex was characterized by IR, 1H NMR spectra and elemental analysis. The crystal structure was determined by X-ray diffraction method. It crystallizes in monoclinic system with space group P21/n. The crystal data are: a=2.647 1(5) nm, b=1.412 9(3) nm, c=2.805 7(6) nm, β=116.185(3)°, Z=4, V=9.417(3) nm3, Dc=1.595 g·cm-3, μ=1.632 mm-1, F(000)=4 512, R1=0.050 3, wR2=0.131 2. The structure shows a distorted octahedral configuration with six-coordination for the central tin atom. The bioactivity test shows that the Sn(Ⅳ) complex has selective antibacterial property. CCDC: 752497. 相似文献
159.
The title compound,[Ag4(L)4](PMBS)4·2H2O (1),where L=2,5-bis (4-pyridyl)-3,4-diaza-2A-hexadiene,PMBS =p-methylbenzenesulfonate was synthesized and its crystal structure was determined by X-ray diffraction structure analysis.The crystal is of triclinic,space group P1 with a=0.820 3(2) nm,b=1.3227(3) nm,c=2.0610(3) nm,α=76.155(2)°,β=78.651 (4)°,γ=89.993(3)°,V=2.126 2(8) nm3,Z=2,Dc= 1.644 g·cm-3,F(000)= 1068,R=0.052 4,wR=0.113 6.The Ag atoms are linear coordinated by two N atoms of two L ligands,while the p-methylben-zenesulfonate molecules are included in the lattice and connected to [Ag(L)]n by hydrogen bonding interactions to form a three-dimensional supramoleculur structure.CCDC:727587. 相似文献
160.
A novel organotin hydration dibenzyltin dichloride has been synthesized and its crystal structure was determined by X-ray diffraction. The crystal belongs to monoclinic, space group Pc with a = 1.1918(5), b = 0.6199(2), c = 1.1074(5)nm, β = 106.899(7)°, V= 0.7828(8)nm3, Z = 2, Dc = 1.654 g/cm3,μ(MoKa) = 19.59 cm^-1, F(000) = 384, R = 0.0564 and RwR = 0.1427. The Sn-C bonds are 0.2140(9) and 0.2152(5) nm, Sn-Cl are 0.2385(4) and 0.2497(3) nm, and Sn-O is 0.2388(7) nm. The tin atom is five-coordinated in a distorted trigonal bipyramidal configuration. The study on the title complex has been performed with quantum chemistry calculation by means of G98W package on the Lanl2dz basis set. The stability of the complex as well as the orbital energies and composition characteristics of some frontier molecular orbitals has been investigated. 相似文献