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991.
Nick Wright 《Journal of Functional Analysis》2003,197(2):469-488
In this paper we introduce an alternative form of coarse geometry on proper metric spaces, which is more delicate at infinity than the standard metric coarse structure. There is an assembly map from the K-homology of a space to the K-theory of the C∗-algebra associated to the new coarse structure, which factors through the coarse K-homology of the space (with the new coarse structure). A Dirac-type operator on a complete Riemannian manifold M gives rise to a class in K-homology, and its image under assembly gives a higher index in the K-theory group. The main result of this paper is a vanishing theorem for the index of the Dirac operator on an open spin manifold for which the scalar curvature κ(x) tends to infinity as x tends to infinity. This is derived from a spectral vanishing theorem for any Dirac-type operator with discrete spectrum and finite dimensional eigenspaces. 相似文献
992.
J.K. BrooksKazuyuki Saitô J.D.Maitland Wright 《Journal of Mathematical Analysis and Applications》2002,276(1):160-167
Let (φn) be a norm bounded sequence in the pre-dual of a von Neumann algebra M. In general it is not true that this sequence has a weakly convergent subsequence. But given a normal state ψ, then, for any ε>0, there exists a projection e such that ψ(1−e)?ε and the restriction of (φn) to eMe has a subsequence which converges weakly to a normal functional on eMe. 相似文献
993.
Richard A. Layfield Carole A. Morrison Dominic S. Wright 《Journal of organometallic chemistry》2002,650(1-2):75-76
The isolation of a tetragonal, helical phase of plumbocene, Cp2Pb, provides a rare example of a helical metallocene and the opportunity to shed light on the relationship between the modes of aggregation found in its various polymorphs. 相似文献
994.
A new finite volume method for the incompressible Navier–Stokes equations, expressed in arbitrary Lagrangian–Eulerian (ALE) form, is presented. The method uses a staggered storage arrangement for the pressure and velocity variables and adopts an edge‐based data structure and assembly procedure which is valid for arbitrary n‐sided polygonal meshes. Edge formulas are presented for assembling the ALE form of the momentum and pressure equations. An implicit multi‐stage time integrator is constructed that is geometrically conservative to the precision of the arithmetic used in the computation. The method is shown to be second‐order‐accurate in time and space for general time‐dependent polygonal meshes. The method is first evaluated using several well‐known unsteady incompressible Navier–Stokes problems before being applied to a periodically forced aeroelastic problem and a transient free surface problem. Published in 2003 by John Wiley & Sons, Ltd. 相似文献
995.
Wang B Wright D Cliffel D Haglund R Pantelides ST 《The journal of physical chemistry. A》2011,115(28):8142-8146
The unimolecular decomposition reaction of TNT can in principle be used to design ways to either detect or remove TNT from the environment. Here, we report the results of a density functional theory study of possible ways to lower the reaction barrier for this decomposition process by ionization, so that decomposition and/or detection can occur at room temperature. We find that ionizing TNT lowers the reaction barrier for the initial step of this decomposition. We further show that a similar effect can occur if a positive moiety is bound to the TNT molecule. The positive charge produces a pronounced electron redistribution and dipole formation in TNT with minimal charge transfer from TNT to the positive moiety. 相似文献
996.
997.
Less RJ Naseri V McPartlin M Wright DS 《Chemical communications (Cambridge, England)》2011,47(21):6129-6131
Reaction of the redox-active base Sn(NMe(2))(2)/(n)BuLi with o-phenylene diamine leads to oxidative dehydrocoupling and rearrangement into the triazolyl anion. 相似文献
998.
Haywood J Stokes FA Less RJ McPartlin M Wheatley AE Wright DS 《Chemical communications (Cambridge, England)》2011,47(14):4120-4122
The reaction of chromocene, Cp(2)Cr, with dilithiated 2,3-diphenylguanidine [(PhNH)(2)C=NH = L(2)H(3)] gives the novel, quadruply-bonded tetraanion [Cr(2)(L(2)H)(4)](4-). 相似文献
999.
Wright WR Berkeley ER Alden LR Baker RT Sneddon LG 《Chemical communications (Cambridge, England)》2011,47(11):3177-3179
Significant advantages result from combining the disparate hydrogen release pathways for ammonia-borane (AB) dehydrogenation using ionic liquids (ILs) and transition metal catalysts. With the RuCl(2)(PMe(3))(4) catalyst precursor, AB dehydrogenation selectivity and extent are maximized in an IL with a moderately coordinating ethylsulfate anion. 相似文献
1000.
Kaziannis S Wright JA Candelaresi M Kania R Greetham GM Parker AW Pickett CJ Hunt NT 《Physical chemistry chemical physics : PCCP》2011,13(21):10295-10305
The vibrational dynamics of (μ-propanedithiolate)Fe(2)(CO)(4)(CN)(2)(2-), a model compound of the active site of the [FeFe]-hydrogenase enzyme, have been examined via ultrafast 2D-IR spectroscopy. The results indicate that the vibrational coupling between the stretching modes of the CO and CN ligands is small and restricted to certain modes but the slow growth of off-diagonal peaks is assigned to population transfer processes occurring between these modes on timescales of 30-40 ps. Analysis of the dynamics in concert with anharmonic density functional theory simulations shows that the presence of CN ligands alters the vibrational relaxation dynamics of the CO modes in comparison to all-carbonyl model systems and suggests that the presence of these ligands in the enzyme may be an important feature in terms of directing the vibrational relaxation mechanism. 相似文献