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131.
Barbazán P Carballo R Casas JS García-Martínez E Pereiras-Gabián G Sánchez A Vázquez-López EM 《Inorganic chemistry》2006,45(18):7323-7330
The reaction of [ReX(CO)5] with thiosemicarbazones H2L(R) derived from beta-keto esters (X = Cl, Br; R = Me, Ph) allowed the isolation of cyclic trimeric complexes [Re3(pyz(R))3(CO)9], where pyz(R) is the pyrazolonate corresponding to the thiosemicarbazone. Electron spray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) monitoring of the reactions of H2L(Ph) in toluene confirmed that the trimer was formed in the reaction mixture and no higher oligomer was detected. These studies, together with the X-ray structures of the trimeric complexes, afford new insight into the factors influencing the self-assembly of pyrazolonaterhenium(I) complexes. 相似文献
132.
Vicente J Chicote MT Guerrero R Vicente-Hernández I Alvarez-Falcón MM 《Inorganic chemistry》2006,45(1):181-188
[Rh(Cp)Cl(mu-Cl)](2) (Cp = pentamethylcyclopentadienyl) reacts (i) with [Au(NH=CMe(2))(PPh(3))]ClO(4) (1:2) to give [Rh(Cp)(mu-Cl)(NH=CMe(2))](2)(ClO(4))(2) (1), which in turn reacts with PPh(3) (1:2) to give [Rh(Cp)Cl(NH=CMe(2))(PPh(3))]ClO(4) (2), and (ii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:2 or 1:4) to give [Rh(Cp)Cl(NH=CMe(2))(2)]ClO(4) (3) or [Rh(Cp)(NH=CMe(2))(3)](ClO(4))(2).H(2)O (4.H(2)O), respectively. Complex 3 reacts (i) with XyNC (1:1, Xy = 2,6-dimethylphenyl) to give [Rh(Cp)Cl(NH=CMe(2))(CNXy)]ClO(4) (5), (ii) with Tl(acac) (1:1, acacH = acetylacetone) or with [Au(acac)(PPh(3))] (1:1) to give [Rh(Cp)(acac)(NH=CMe(2))]ClO(4) (6), (iii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:1) to give 4, and (iv) with (PPN)Cl (1:1, PPN = Ph(3)P=N=PPh(3)) to give [Rh(Cp)Cl(imam)]Cl (7.Cl), which contains the imam ligand (N,N-NH=C(Me)CH(2)C(Me)(2)NH(2) = 4-imino-2-methylpentan-2-amino) that results from the intramolecular aldol-type condensation of the two acetimino ligands. The homologous perchlorate salt (7.ClO(4)) can be prepared from 7.Cl and AgClO(4) (1:1), by treating 3 with a catalytic amount of Ph(2)C=NH, in an atmosphere of CO, or by reacting 4with (PPN)Cl (1:1). The reactions of 7.ClO(4) with AgClO(4) and PTo(3) (1:1:1, To = C(6)H(4)Me-4) or XyNC (1:1:1) give [Rh(Cp)(imam)(PTo(3))](ClO(4))(2).H(2)O (8) or [Rh(Cp)(imam)(CNXy)](ClO(4))(2) (9), respectively. The crystal structures of 3 and 7.Cl have been determined. 相似文献
133.
134.
Three model dyads have been synthesized by esterification of beta- and alpha-cholesterol (Ch) with (S)- and/or (R)-ketoprofen (Kp). The alpha-dyads are efficient photogenerators of the 7-allyl Ch radicals by intramolecular H abstraction. Subsequent cyclization via C-C coupling occurs in a stereoselective way. 相似文献
135.
136.
Eligius M.T. Hendrix Leocadio G. Casado Inmaculada García 《European Journal of Operational Research》2008
The semi-continuous quadratic mixture design problem (SCQMDP) is described as a problem with linear, quadratic and semi-continuity constraints. Moreover, a linear cost objective and an integer valued objective are introduced. The goal is to deal with the SCQMD problem from a branch-and-bound perspective generating robust solutions. Therefore, an algorithm is outlined which identifies instances where decision makers tighten requirements such that no ε-robust solution exists. The algorithm is tested on several cases derived from industry. 相似文献
137.
A previously proposed procedure for generating approximate valence, Rydberg, and continuum orbitals from spectral data is extended to two-valence electron systems. Oscillator strengths and photoionization cross sections are reported for the respective 1s22s2 →1s22s np and 1s22s2→1s22s ep transitions of Be, B+, C++, N+++, 0+4, Ne+6, Mg+8, Al+9, and Si+10. Comparisons show a high level of agreement with Hartree-Fock oscillator strengths, but the accuracy of the cross sections is uncertain. 相似文献
138.
José S. Casas Eduardo E. Castellano Javier Ellena Ionel Haiduc Agustín Sánchez José Sordo 《Journal of chemical crystallography》1999,29(7):831-836
The crystal structure of the title compound, Hg[S2P(OPri)2]2, has been determined by single-crystal X-ray diffraction. The compound crystallizes in the centrosymmetric P21/c space group with a = 11.800(1), b = 8.925(2), c = 22.167(2) Å, = 94.988(7)°, and Z = 4. The same compound has been previously reported but the structure is described there in the space group C2/c. In both cases, one phosphorodithioate moiety acts as a chelating group and the other as a bridging group between neighboring mercury atoms (related to one another by the twofold screw axis), giving rise to an infinite polymer along the direction of the b axis. It turns out that in spite of the difference in space group symmetry, the structures are remarkable similar in that they are formed from infinite polymers of similar geometry. The coordination around the Hg ion shows, however, significant differences, mainly for the bridging Hg—S(4) bond length, which is 0.16 Å smaller than that previously reported. 相似文献
139.
J.S. Casas E.E. Castellano M.S. García-Tasende A. Sánchez J. Sordo J. Zukerman-Schpector 《Journal of chemical crystallography》1999,29(6):725-727
2-S-Methylthiouracil crystallizes in the triclinic space group P
with unit cell dimensions a = 5.508(4), b = 7.175(3), c = 8.522(2) Å, = 80.83(2), = 80.43(3), = 76.86(3)°, and Z = 2. The molecule exists in the crystal in the lactam form and is essentially planar. The molecular packing consists of molecules linked in centrosymmetric hydrogen-bonded pairs. The effects of methylation and subsequent metallation on the 2-thiouracil structure are discussed. 相似文献
140.