全文获取类型
收费全文 | 103篇 |
免费 | 10篇 |
国内免费 | 13篇 |
专业分类
化学 | 87篇 |
晶体学 | 9篇 |
力学 | 4篇 |
综合类 | 5篇 |
物理学 | 21篇 |
出版年
2020年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 10篇 |
2013年 | 6篇 |
2012年 | 7篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 8篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有126条查询结果,搜索用时 0 毫秒
1.
A new mixed-valence heterometal cluster Mo8VW2VIO26(C5H5N)8·2H2O has been synthesized under solvothermal conditions and characterized by X-ray single-crystal diffraction, IR, UV-vis and XPS spectroscopy. The title compound crystallizes in the triclinic system, space group P1 with a = 11.708(3), b = 12.018(4), c = 13.316(4) , a = 112.184(4), β = 97.844(4), r = 110.043(3)o, V = 1551.9(8) 3 and Z = 1 at 293(2) K. The final full-matrix least-squares refinement converged to R = 0.0414 for 4460 observed unique reflections with I 2σ(I) and w R = 0.1290 for all data(5352) and S = 1.015. In addition, its thermal stability and fluorescent property have also been investigated. 相似文献
2.
Two complexes, [Cu2(Htdb)4(H2O)2] (1) and [Cd(bipy)2(Hmcmbc)2] (2) (H2tdb = 2,2-thiodibenzoic acid, H2mcmbc = m-(carboxyl-methyloxy)-benzenecarboxylic acid, bipy = 4,4'-bipyridine), have been prepared, and were characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction. Structures indicate that complex 1 is a single molecule, and 2 is a one-dimensional chain. Their two-and three-dimensional frameworks are constructed through hydrogen bonding, π…π or C–H…π stacking, and such other weak interactions. The cyclic voltametric behavior of complex 1 and luminescence property of complex 2 were investigated. 1 belongs to the triclinic system, space group P with a = 7.8607(6), b = 11.7619(9), c = 15.3481(12) , α = 109.3670(10), β = 92.4420(10), γ = 92.0450(10)°, V = 1335.65(18) 3, Mr = 1256.26, Dc = 1.5619(2) g/cm3, F(000) = 642, μ = 1.029 mm–1, Z = 1, the final R = 0.0289 and wR = 0.0763 for 5199 observed reflections with I > 2σ(I). Complex 2 crystallizes in triclinic, space group P with a = 9.6378(10), b = 9.7508(10), c = 19.055(2) , α = 88.7020(10), β = 80.5260(10), γ = 69.2000(10)o, V = 1649.9(3) 3, Mr = 815.07, Dc = 1.641 g/cm3, μ = 0.732 mm-1, F(000) = 828, Z = 2, the final R = 0.0511 and wR = 0.1149 for 4729 observed reflections (I > 2σ(I)). 相似文献
3.
用XRD、IR和TPR等技术研究了钙钛矿型复合氧化物的晶体结构及其反应性能.整个组成范围内,LaNi_(i-x)Mn_xO_3(0.0≤x≤1.0)体系都生成单一钙钛矿相;x=0.0,0.6≤X≤1.0时为菱形晶系,0.2≤x≤0.5为立方晶系.IR和TPR研究表明,晶体结构对B—O键合作用存在较大影响.CO微反考察表明,本体系的催化活性与晶系存在密切关系,晶体对称性越高,反应活性越低.说明钙钛矿型复合氧化物的催化活性与体系活性中心的B—O键合作用能力有关. 相似文献
4.
This paper gives the general expressions for the compliance s′ijkl, Young's modulus E(hkl) and Poisson's ratio v(hkl, θ) along arbitrary loading direction [hkl] for tetragonal crystals. The representation surface for which the length of the radius vector in the [hkl] direction equals E(hkl) and representation curve for which the length of the radius vector with angle θ deviated from the reference directions [001^-], [100], [001^-], [101^-] and [112^-] equals v(100, θ), v(001, θ), v(110,θ), v(101,θ) and v(111, θ) respectively, are constructed for nine tetragonal crystals (ammonium dihydrogen arsenate, ammonium dihydrogen phosphate, barium titanate, indium, nickel sulfate, potassium dihydrogen arsenate, potassium dihydrogen phosphate, tin and zircon). The characteristics of them are analysed in detail. 相似文献
5.
本文论述了应用lotus 123软件确定立方晶系Miller指数的方法.这个方法具有简单、直观、迅速、精度高等特点,而且同时也确定出晶格常数α值。对于晶系的确定也具有一定的指导意义。 相似文献
6.
新矿物柴达木石(ZnFe(SO_4)_2(OH)·4H_2O)属三斜晶系,空间群P1.最小二乘法修正的晶胞参数:a=7.309(2) ,b=7.202(2) ,c=9.691(3) ,α=89.64(3)°,β=105.89(3)°,γ=91.11(2)°。晶体结构经Patterson法和Fourier合成法测定;2833个独立衍射全矩阵最小二乘修正,R因子为0.032。结构中,[Fe(1)O_5(OH)]和[Fe(2)O_5(OH)]两种配位八面体通过共用OH角顶,组成‘Z’字形链;链的这一侧和另一侧的4对八面体角顶被[SO_4]四面体共用。这种八面体-四面体链又被孤立的[Zn(1)O_2(H_2O)_4]和[Zn(2)O_2(H_2O)_4]八面体连接成平行(100)面的波状层;层间通过水分子以氢键相连。 相似文献
7.
合成了N,N′-二(5-氯水杨醛)缩乙二胺合铜配合物([Cu(5-ClSalen)]),用单晶X射线衍射法测定了晶体结构.其晶体属三斜晶系,空间群P-1,晶胞参数a=0.83285(1)nm,b=0.95170(4)nm,c=1.09304(4)nm,α=115.130(2)°,β=94.694(2)°,γ=101.127(2)°,V=0.75642(4)nm3,分子式C16H12Cl2CuN2O2,Mr=398.72,Z=2,Dc=1.751g/cm3.在配合物中,Cu处于两个氮原子和两个酚氧原子形成的平面四方场中. 相似文献
8.
9.
用硝酸盐分解法(N-法)和柠檬酸络合法(L-法)合成了La-Sr-Ni-O系复合氧化物.用XRD技术考察了样品组成、制备条件及灼烧气氛等对产物结构的影响.结果表明:按La_(1-x)Sr_xNiO_3计量比,用N-法合成只能形成四方体心K_2NiF_4结构的A_2BO_4型复合氧化物.而采用L-法,通过改变条件,在0.0≤x≤0.2范围内可形成菱形晶系钙钛矿结构的复合氧化物.另外,用L-法合成La_(2-x)Sr_xNiO_4系列样时发现,制备条件及灼烧温度、气氛对样品结晶态存在较大的影响,高温、空气氛下可形成高结晶态的K_2NiF_4结构复合氧化物.La_(2-x)Sr_xNiO_4体系CO催化氧化活性研究表明,随x(Sr~(2+)取代量)增加,CO的转化率增加. 相似文献
10.
Reaction of [(μ-SCH2)2NPh]Fe2(CO)6 with Ph2PCH2PPh2 in the presence of Me3NO·2H2O gave the title complex [(μ-SCH2)2NPh]Fe2(CO)5(Ph2PCH2PPh2)(1)in 78% yield.The new complex 1 was characterized by elemental analysis,spectroscopy and X-ray crys-tallography.It crystallizes in triclinic,space group P1 with a = 10.832(2),b = 12.003(2),c = 15.579(3),V = 1785.6(6)3,Z = 2,C32H26Fe2NO5PS2,Mr = 819.40,Dc = 1.524 g/cm3,μ(MoKα)= 1.064 mm-1,F(000)= 840,T = 113(2)K,the final R = 0.0543 and wR = 0.1218 for 6203 observed reflections(I > 2σ(I)).The Ph2PCH2PPh2 ligand resides in an axial position of the square-pyramidal coordination sphere of the Fe atom and trans to the benzene ring in order to reduce the steric repulsion between Ph2PCH2PPh2 and the benzene ring. 相似文献