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991.
Piotr Maćkowiak 《Aequationes Mathematicae》2017,91(4):759-777
In the paper we present results on the continuity of nonlinear superposition operators acting in the space of functions of bounded variation in the sense of Jordan. It is shown that the continuity of an autonomous superposition operator is automatically guaranteed if the acting condition is met. We also give a simple proof of the fact that a nonautonomous superposition operator generated by a continuously differentiable function is uniformly continuous on bounded sets. Moreover, we present necessary and sufficient conditions for the continuity of a superposition operator (autonomous or nonautonomous) in a general setting. Thus, we give the answers to two basic open problems mentioned in the monograph (Appell et al. in Bounded variation and around, series in nonlinear analysis and application, De Gruyter, Berlin, 2014). 相似文献
992.
Anna Dowierciał Adam Jarmuła Piotr Wilk Wojciech Rypniewski Monika Kowalska Tomasz Frączyk Joanna Cieśla Wojciech Rode 《Structural chemistry》2017,28(3):667-674
Crystal structures of mouse thymidylate synthase (mTS) in complexes with (1) sulfate anion, (2) 2′-deoxyuridine 5′-monophosphate (dUMP) and (3) 5-fluoro-dUMP (FdUMP) and N 5,10-methylenetetrahydrofolate (meTHF) have been determined and deposited in Protein Data Bank under the accession codes 3IHI, 4E5O and 5FCT, respectively. The structures show a strong overall similarity to the corresponding structures of rat and human thymidylate synthases (rTS and hTS, respectively). Unlike with hTS, whose unliganded and liganded forms assume different conformations (“inactive” and “active,” respectively) in the loop 181–197, in each of the three mTS structures, the loop 175–191, homologous to hTS loop 181–197, populates the active conformer, with catalytic Cys 189 buried in the active site and directed toward C(6) of the pyrimidine ring of dUMP/FdUMP, pointing to protein’s inability to adopt the inactive conformation. The binary structures of either dUMP- or sulfate-bound mTS, showing the enzyme with open active site and extended C-terminus, differ from the structure of the mTS–5-FdUMP–meTHF ternary complex, with the active site closed and C-terminus folded inward, thus covering the active site cleft. Another difference pertains to the conformation of the Arg44 side chain in the active site-flanking loop 41–47, forming strong hydrogen bonds with the dUMP/FdUMP phosphate moiety in each of the two liganded mTS structures, but turning away from the active site entrance and loosing the possibility of H-bonding with sulfate in the sulfate-bound mTS structure. 相似文献
993.
Rafal Latala Piotr Mankiewicz Krzysztof Oleszkiewicz Nicole Tomczak-Jaegermann 《Discrete and Computational Geometry》2007,38(1):29-50
We consider polytopes in
that are generated by N vectors in
whose coordinates are independent subgaussian random variables. (A particular case of such polytopes are symmetric random
polytopes generated by N independent vertices of the unit cube.) We show that for a random pair of such polytopes the Banach-Mazur
distance between them is essentially of a maximal order n. This result is an analogue of the well-known Gluskin's result
for spherical vectors. We also study the norms of projections on such polytopes and prove an analogue of Gluskin's and Szarek's
results on basis constants. The proofs are based on a version of "small ball" estimates for linear images of random subgaussian
vectors. 相似文献
994.
Piotr Niemiec 《Topology and its Applications》2007,154(3):655-664
The aim of this paper is to answer the following question: let (X,?) and (Y,d) be metric spaces, let A,B⊂Y be continuous images of the space X and let be a fixed continuous surjection. When is the inequality
995.
The signal-to-noise ratio (SNR) performance and practicality issues of a four-element phased-array coil and an implantable coil system were compared for rat spinal cord magnetic resonance imaging (MRI) at 7 T. MRI scans of the rat spinal cord at T10 were acquired from eight rats over a 3 week period using both coil systems, with and without laminectomy. The results demonstrate that both the phased array and the implantable coil systems are feasible options for rat spinal cord imaging at 7 T, with both systems providing adequate SNR for 100-mum spatial resolution at reasonable imaging times. The implantable coils provided significantly higher SNR, as compared to the phased array (average SNR gain of 5.3x between the laminectomy groups and 2.5x between the nonlaminectomy groups). The implantable coil system should be used if maximal SNR is critical, whereas the phased array is a good choice for its ease of use and lesser invasiveness. 相似文献
996.
Szymański J Pobozy E Trojanowicz M Wilk A Garstecki P Hołyst R 《The journal of physical chemistry. B》2007,111(19):5503-5510
We report on the electrophoretic mobility and on the thermal diffusion of lysozyme proteins dissolved in aqueous solutions of a nonionic surfactant (C12E6) at a wide range of concentrations of the surfactant (0-20% by weight). We want to estimate the influence of a dense network of elongated micelles of C12E6 on the effective charge of the proteins as observed in the capillary electrophoresis experiments. The possible mechanism leading to the change in the effective charge of protein could involve the deformation of the cloud of counterions around the protein when it squeezes through the narrow (of the order of a protein diameter) aqueous channels formed in the solution of elongated micelles. The combination of independent measurements of the electrophoretic mobility of a family of modified proteins (lysozyme charge ladder [Colton et al. J. Am. Chem. Soc. 1997, 119, 12701]), of the microviscosity of the solutions of surfactant (obtained via fluorescence correlation spectroscopy), and of the hydrodynamic radius of the proteins (photon correlation spectroscopy) allow us to conclude that the effective charge of the proteins is not affected by the presence of surfactant, even at high concentrations. 相似文献
997.
Wojciechowski PM Michalska D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(3):948-955
The theoretical IR and Raman spectra of para-halogenoanilines, 4-XC(6)H(4)NH(2) (X=F, Cl and Br) were calculated by using the density functional B3LYP method with the 6-311++G(df,pd) basis set. The theoretical spectra show very good agreement with experiment. The rigorous normal coordinate analyses have been performed, and the detailed vibrational assignment has been made on the basis of the calculated potential energy distributions (PEDs). Several ambiguities and contradictions in the previously reported vibrational assignments have been clarified. The "marker bands" and the effects of the halogen substituent on the characteristic aniline bands in the IR and Raman spectra are discussed. 相似文献
998.
999.
Naïm M Bhat S Rankin KN Dennis S Chowdhury SF Siddiqi I Drabik P Sulea T Bayly CI Jakalian A Purisima EO 《Journal of chemical information and modeling》2007,47(1):122-133
We present a binding free energy function that consists of force field terms supplemented by solvation terms. We used this function to calibrate the solvation model along with the binding interaction terms in a self-consistent manner. The motivation for this approach was that the solute dielectric-constant dependence of calculated hydration gas-to-water transfer free energies is markedly different from that of binding free energies (J. Comput. Chem. 2003, 24, 954). Hence, we sought to calibrate directly the solvation terms in the context of a binding calculation. The five parameters of the model were systematically scanned to best reproduce the absolute binding free energies for a set of 99 protein-ligand complexes. We obtained a mean unsigned error of 1.29 kcal/mol for the predicted absolute binding affinity in a parameter space that was fairly shallow near the optimum. The lowest errors were obtained with solute dielectric values of Din = 20 or higher and scaling of the intermolecular van der Waals interaction energy by factors ranging from 0.03 to 0.15. The high apparent Din and strong van der Waals scaling may reflect the anticorrelation of the change in solvated potential energy and configurational entropy, that is, enthalpy-entropy compensation in ligand binding (Biophys. J. 2004, 87, 3035-3049). Five variations of preparing the protein-ligand data set were explored in order to examine the effect of energy refinement and the presence of bound water on the calculated results. We find that retaining water in the final protein structure used for calculating the binding free energy is not necessary to obtain good results; that is the continuum solvation model is sufficient. Virtual screening enrichment studies on estrogen receptor and thymidine kinase showed a good ability of the binding free energy function to recover true hits in a collection of decoys. 相似文献
1000.
We present the first model-independent comparison of recent measurements of the entropy and of the critical temperature of a unitary Fermi gas, performed by Luo et al., with the most complete results currently available from finite temperature Monte Carlo calculations. The measurement of the critical temperature in a cold fermionic atomic cloud is consistent with a value T(c) = 0.23(2)epsilon(F) in the bulk, as predicted by the present authors in their Monte Carlo calculations. 相似文献