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991.
Gilles Tiraboschi Nohad Gresh Claude Giessner‐Prettre Lee G. Pedersen David W. Deerfield 《Journal of computational chemistry》2000,21(12):1011-1039
In this study we compare the binding energies of polycoordinated complexes of Zn2+ within cavities composed of model “hard” (H2O, OH−) or “soft” (CH3SH, CH3S−) ligands. Ab initio supermolecule computations are performed at the HF and MP2 levels using extended basis sets to determine the binding energies and their components as a function of: the number of ligands, ranging from three to six; the net charge of the cavity; and the “hard” versus “soft” character of the ligands. These ab initio computations are used to test the reliability of the SIBFA molecular mechanics procedure, originally formulated and calibrated on the basis of ab initio computations, for such charged systems. The SIBFA intermolecular interaction energies match the corresponding ab initio values using a coreless effective potential split‐valence basis set with a relative error of ≤3%. Extensions to binuclear Zn2+ complexes, such as those that occur in the Zn‐binding sites of Gal4 and β‐lactamase proteins, are performed to test the applicability of the methodology for such systems. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 1011–1039, 2000 相似文献
992.
Anne Veyland Laurent Dupont Jean Rimbault Jean‐Claude Pierrard Michel Aplincourt 《Helvetica chimica acta》2000,83(2):414-427
The interactions between carbonate ions and zirconium oxychloride are studied by potentiometry, dialysis, and 13C‐ and 17O‐NMR spectroscopy in aqueous media. The nature of the soluble carbonatohydroxo complexes depends on the proportions of hydrogencarbonate and carbonate ions in solution before the addition of zirconium oxychloride. Carbonate media lead to polynuclear entities containing no more than two complexed carbonate ions per Zr4+. The presence of hydrogencarbonate favors the formation of less condensed and more carbonated complexes such as [Zr(CO3)4]4−. The polycondensation degree of the species decreases when the number of carbonates linked per Zr4+ increases. In all complexes, the carbonate is bidentate, and the metal atoms are linked via hydroxo bridges. The complexation of carbonate with Zr4+ occurs for a total carbonate concentration higher than 0.1M . Consequently, in natural medium, the speciation of this metal is governed only by the formation of hydroxo complexes. 相似文献
993.
Narcis Avarvari Pascal Le Floch Claude Charrier Franois Mathey 《Heteroatom Chemistry》1996,7(5):397-402
1-Alkynyl-1,2-dihydrophosphetes, as prepared by reaction of the appropriate titanacyclobutenes with alkynyldichlorophosphines, rearrange to the corresponding phosphinines via an original 4π-cycloreversion-6π-electrocyclization mechanism. The reaction of dimethyltitanocene with 1,4-diphenylbutadiyne affords a new 3-vinyltitanacyclobut-3-ene that can serve to prepare a 3-vinylphosphinine 6 by the same route. © 1996 John Wiley & Sons, Inc. 相似文献
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Pseudo‐Spectral Methods for the Laplace‐Beltrami Equation and the Hodge Decomposition on Surfaces of Genus One 下载免费PDF全文
Lise‐Marie Imbert‐Gérard Leslie Greengard 《Numerical Methods for Partial Differential Equations》2017,33(3):941-955
The inversion of the Laplace‐Beltrami operator and the computation of the Hodge decomposition of a tangential vector field on smooth surfaces arise as computational tasks in many areas of science, from computer graphics to machine learning to computational physics. Here, we present a high‐order accurate pseudo‐spectral approach, applicable to closed surfaces of genus one in three‐dimensional space, with a view toward applications in plasma physics and fluid dynamics. © 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 941–955, 2017 相似文献
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Yves Claude Guillaume Lydie Lethier Claire André 《Biomedical chromatography : BMC》2015,29(9):1338-1342
In a previous paper Guillaume's group demonstrated that magnesium (Mg2+ concentration range 0.00–2.60 mm ) increased the passive diffusion of statins and thus played a role in their potential toxicity. In order to confirm an increase in this passive diffusion by divalent salt cations, the role of calcium chloride (CaCl2) on the statin–immobilized artificial membrane (IAM) association was studied. It was demonstrated that calcium supplementation (Ca2+ concentration range 0.00–3.25 mm ) increases the statin passive diffusion. In addition, it was shown that the Ca2+ effect on the statin–IAM association is higher than that of Mg2+. These results show that Ca2+ enhances the passive diffusion of drugs into biological membranes and thus their potential toxicity. Also, addition of H2O2 to the medium showed a hyperbolic response for the statin passive diffusion and this effect was enhanced for the highest Ca2+ or Mg2+ concentrations in the medium. H2O2 is likely to interact with the polar head groups of the IAM through dipole–dipole interactions. The conformational changes in H2O2–IAM result in a higher degree of exposure of hydrophobic areas, thus explaining why the binding of pravastatin, which showed the lowest logP value, was less affected by H2O2. This result shows the significant contribution of H2O2 and thus the oxidative stress on the statin passive diffusion. Much of the sensitivity derives from the action of Ca2+ or Mg2+, in turn supported the idea that H2O2 may serve a Ca2+ or Mg2+ sensing function in statin passive diffusion Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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