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101.
Tatiana Murakhtina Jasper Heuft Evert Jan Meijer Daniel Sebastiani 《Chemphyschem》2006,7(12):2578-2584
A combined experimental and ab initio study is presented of the 1H NMR chemical shift distribution of aqueous hydrogen chloride solution as a function of acid concentration, based on Car-Parrinello molecular dynamics simulations and fully periodic NMR chemical-shift calculations. The agreement of computed and experimental spectra is very good. From first-principles calculations, we can show that the individual contributions of Eigen and Zundel ions, regular water molecules, and the chlorine solvation shell to the NMR line are very distinct and almost independent of the acid concentration. From the computed instantaneous NMR distributions, it is further possible to characterize the average variation in hydrogen-bond strength of the different complexes. 相似文献
102.
Marie‐Claire Giel Christopher J. Smedley Emily R. R. Mackie Taijie Guo Jiajia Dong Tatiana P. Soares da Costa John E. Moses 《Angewandte Chemie (International ed. in English)》2020,59(3):1181-1186
The boom in growth of 1,4‐disubstituted triazole products, in particular, since the early 2000’s, can be largely attributed to the birth of click chemistry and the discovery of the CuI‐catalyzed azide–alkyne cycloaddition (CuAAC). Yet the synthesis of relatively simple, albeit important, 1‐substituted‐1,2,3‐triazoles has been surprisingly more challenging. Reported here is a straightforward and scalable click‐inspired protocol for the synthesis of 1‐substituted‐1,2,3‐triazoles from organic azides and the bench stable acetylene surrogate ethenesulfonyl fluoride (ESF). The new transformation tolerates a wide selection of substrates and proceeds smoothly under metal‐free conditions to give the products in excellent yield. Under controlled acidic conditions, the 1‐substituted‐1,2,3‐triazole products undergo a Michael addition reaction with a second equivalent of ESF to give the unprecedented 1‐substituted triazolium sulfonyl fluoride salts. 相似文献
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Ion-Pair Reversed-Phase Thin-Layer Chromatography and High-Performance Liquid Chromatography of Benzoic Acids 总被引:1,自引:0,他引:1
The separation of benzoic acids by ion-pair reversed-phase thin-layer chromatography and high-performance liquid chromatography was studied. In the optimization of separation conditions, the effect of the nature and concentration of the organic solvent, acidity of the mobile phase, concentration of salts of quaternary ammonium bases, and the length of their hydrocarbon radical on the retention of benzoic acids was studied. Conditions of the separation of a mixture of benzoic, hydroxybenzoic, aminobenzoic, and nitrobenzoic acids on Silufol plates impregnated with cetyltrimethylammonium bromide were selected; the mobile phase was isopropanol–ammonium acetate buffer solution with pH 5–dodecyltrimethylammonium bromide. 相似文献
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Tatiana N. Drebushchak Nikita V. Chukanov Elena V. Boldyreva 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(12):o623-o625
The ɛ‐form of chlorpropamide [systematic name: 4‐chloro‐N‐(propylaminocarbonyl)benzenesulfonamide], C10H13ClN2O3S, has been obtained as single crystals from solution (and not as a polycrystalline sample by heating the α‐, γ‐ or δ‐forms). The results of anisotropic structure refinements for the ɛ‐ and δ‐forms are reported. The density of the δ‐polymorph is the highest, and that of the ɛ‐polymorph the lowest, among the five known chlorpropamide polymorphs. The main intermolecular hydrogen‐bonding pattern in polymorphs δ and ɛ is the same as in polymorphs α, β and γ, but the conformations differ. The densities of the polymorphs were found to depend on the molecular conformations. 相似文献
107.
Ernest M. Asani Victor N. Khrustalev Rachel M. Williamson Rodolfo A. Martinez Clifford J. Unkefer Tatiana V. Timofeeva 《Journal of chemical crystallography》2007,37(10):663-667
[1,2,3-13C3]-1-(Phenylsulfinyl)-3-benzyloxyacetone, C16H16O3S, (3) has been synthesized and its crystal structure has been determined by a single-crystal X-ray diffraction analysis. The X-ray diffraction study revealed that compound 3 crystallizes in the monoclinic crystal system in the acentric space group Pc, with cell constants at T = 100 K: a = 16.073(5), b = 5.5079(16), c = 7.949(2) Å, β = 100.221(4)°, V = 692.6(3) Å3, Z = 2, d calc = 1.383 g/cm3. Compound 3 contains the chiral tetravalent three-coordinated sulfur atom, which has a distorted tetrahedral configuration with a lone electron pair occupying one of the tetrahedron vertices. In the crystal, the molecules are packed in stacks along the b axis; the stacks consist of the molecules of the same chirality. Furthermore, the stacks of the molecules of the opposite chirality alternate along the c axis. The molecules in neighboring stacks are arranged by head-to-tail orientations. There are no short intermolecular contacts in the crystal of 3. 相似文献
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