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991.
992.
Andreas W. W. Ludwig Hermann Schulz-Baldes Michael Stolz 《Journal of statistical physics》2013,152(2):275-304
A random phase property is proposed for products of random matrices drawn from any one of the classical groups associated with the ten Cartan symmetry classes of non-interacting disordered Fermion systems. It allows to calculate the Lyapunov spectrum explicitly in a perturbative regime. These results apply to quasi-one-dimensional random Dirac operators which can be constructed as representatives for each of the ten symmetry classes. For those symmetry classes that correspond to two-dimensional topological insulators or superconductors, the random Dirac operators describing the one-dimensional boundaries have vanishing Lyapunov exponents and almost surely an absolutely continuous spectrum, reflecting the gapless and conducting nature of the boundary degrees of freedom. 相似文献
993.
Kirk A. Peterson Christine Krause Hermann Stoll J. Grant Hill 《Molecular physics》2013,111(22):2607-2623
A benchmark of explicitly correlated CCSD(T)-F12 methods for the dimers Ga2, As2, Br2 and diatomic molecules AsN, BrO, HBr, GaF, GaCl, GaBr, AsF, AsCl, BrF, and BrCl is presented. Equilibrium distances, harmonic vibrational frequencies, and dissociation energies are compared with extensive conventional CCSD(T) calculations using a variety of orbital basis sets and different ansätze for the explicitly correlated wavefunctions. Correlation of the 3d electrons has a strong effect, in particular on the equilibrium distances, and it is shown that this can be recovered very efficiently by the explicit correlation treatment. It is found that CCSD(T)-F12 calculations with new F12-specific cc-pVnZ-F12 basis sets give comparable accuracy to standard CCSD(T) calculations with very much larger aug-cc-pwCV(n+2)Z basis sets. The effects of higher order valence electron correlation (up to CCSDTQP) are also investigated in conventional calculations and are found to be significant in some cases. 相似文献
994.
Hermann Schulz-Baldes 《Communications in Mathematical Physics》2013,324(2):589-600
For a disordered two-dimensional model of a topological insulator (such as a Kane-Mele model with disordered potential) with small coupling of spin invariance and time-reversal symmetry breaking terms (such as a Rashba spin-orbit coupling and a Zeeman term), it is proved that the spin edge currents persist provided there is a spectral gap and the spin Chern numbers are well-defined and non-trivial. These are sufficient conditions for being in the quantum spin Hall phase. The result materializes the general philosophy that topological insulators are topologically non-trivial bulk systems with persistent edge or surface currents. 相似文献
995.
Motivated by a recent experimental observation of a nodal liquid on both single crystals and thin films of Bi2Sr2CaCu2O8 + δ by Chatterjee et al. [Nature Phys. 6 (2010) 99], we perform a field-theoretical renormalization group (RG) analysis of a two-dimensional model such that only eight points located near the “hot spots” on the Fermi surface are retained, which are directly connected by spin density wave ordering wavevector. We derive RG equations up to two-loop order describing the flow of renormalized couplings, quasiparticle weight, several order-parameter response functions, and uniform spin and charge susceptibilities of the model. We find that while the order-parameter susceptibilities investigated here become non-divergent at two loops, the quasiparticle weight vanishes in the low-energy limit, indicating a breakdown of Fermi liquid behavior at this RG level. Moreover, both uniform spin and charge susceptibilities become suppressed in the scaling limit which indicate gap openings in both spin and charge excitation spectra of the model. 相似文献
996.
Angelamaria Cardone Ida Del Prete Hermann Brunner 《Journal of Difference Equations and Applications》2013,19(9):1531-1543
Sufficient conditions for the asymptotic periodicity of solutions of nonlinear discrete Volterra equations of Hammerstein type are obtained. Such results are applied to analyze the property of a class of numerical methods to preserve the asymptotic periodicity of the analytical solution of Volterra integral equations. 相似文献
997.
This article presents a model which describes the chemical decomposition of organic binders, the combined Maxwell-Stefan and Knudsen diffusion and the seepage flow of multiple gaseous reaction products through a porous body and the implementation of the model into a finite element framework. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
Sanjay Dutta Sergey M. Dibrov Bao T. Ho Cody J. Higginson Thomas Hermann 《Journal of chemical crystallography》2012,42(2):119-129
Abstract
The compound 5, containing the novel heterocycle 2-oxa-4,7-diazabicyclo[3.3.1]non-3-ene, has been obtained in a synthetic approach toward oxazoles and 1,3-diazepanes of natural product-like complexity from cyclization and rearrangement of δ-lactam cyanamides. When this procedure was applied to a silyl-protected N-((3S,4S,5S)-4,5-dihydroxy-2-oxopiperidin-3-yl)cyanamide (2b) formation of the novel heterobicyclic scaffold 5 was observed along with the expected oxazole (3b) and diazepane (4b) products. The crystal structures of 5 and diazepane 4b are described. Compound 5 crystallized from methanol in the monoclinic system, P21 space group with unit cell parameters a = 15.3402(9), b = 7.2717(4), c = 22.5803(13), β = 106.8620(10) and a cell volume of 2410.5(2) A3. 相似文献999.
We consider the relation between higher spin gauge fields and real Kac–Moody Lie algebras. These algebras are obtained by double and triple extensions of real forms \mathfrakg0{\mathfrak{g}_0} of the finite-dimensional simple algebras \mathfrakg{\mathfrak{g}} arising in dimensional reductions of gravity and supergravity theories. Besides providing an exhaustive list of all such algebras, together with their associated involutions and restricted root diagrams, we are able to prove general properties of their spectrum of generators with respect to a decomposition of the triple extension of \mathfrakg0{\mathfrak{g}_0} under its gravity subalgebra \mathfrakgl(D,\mathbb R){\mathfrak{gl}(D,\mathbb {R})} . These results are then combined with known consistent models of higher spin gauge theory to prove that all but finitely many generators correspond to non-propagating fields and there are no higher spin fields contained in the Kac–Moody algebra. 相似文献
1000.
Nicolas Plumeré Bernd Speiser Prof. Dr. Hermann A. Mayer Prof. Dr. Dominik Joosten Dr. Lars Wesemann Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(4):936-946
A general method for the functionalization of silica surfaces with silicon hydride (Si–H) groups is described for four different preparations of silica. The silica surface is reduced in a two‐step chlorination–reduction procedure within a simple gas‐flow system at high temperatures. After initial dehydroxylation of the silica surface, silicon chloride groups are formed by the reaction with thionyl chloride. The chlorination activates otherwise inaccessible surface siloxane moieties. A high silicon–hydride surface concentration results from the subsequent reduction of the chlorinated surface with hydrogen. The physical properties of the resulting silica are analyzed using scanning electron microscopy, as well as dynamic light scattering and Brunauer–Emmet–Teller measurements. The chlorination–reduction sequence has no significant impact on the structure, surface area and mesopore size of the silica materials used. The surface of the materials is characterized by diffuse reflectance infrared Fourier transform (DRIFT) and 29Si CP/MAS NMR spectroscopy. The silicon–hydride groups are mostly of the ‐type. The use of high temperatures (>800 °C) results in the condensation of internal and surface silanol groups. Therefore, materials with both a fully condensed silica matrix as well as a surface free of silanol groups are obtained. The materials are ideal precursors for further molecular silica surface modification, as demonstrated with a ferrocene derivative. 相似文献