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991.
992.
Rösch O Gunnarsson O Zhou XJ Yoshida T Sasagawa T Fujimori A Hussain Z Shen ZX Uchida S 《Physical review letters》2005,95(22):227002
We present angle-resolved photoemission spectroscopy (ARPES) data on undoped La2CuO4, indicating polaronic coupling between bosons and charge carriers. Using a shell model, we calculate the electron-phonon coupling and find that it is strong enough to give self-trapped polarons. We develop an efficient method for calculating ARPES spectra in undoped systems. Using the calculated couplings, we find the width of the phonon sideband in good agreement with experiment. We analyze reasons for the observed dependence of the width on the binding energy. 相似文献
993.
Adaptive optics is used to compensate for modal dispersion in digital transmission through multimode fiber (MMF). At the transmitter, a spatial light modulator (SLM) controls the launched field pattern. An estimate of intersymbol interference (ISI) caused by modal dispersion is formed at the receiver and fed back to the transmitter, where the SLM is adjusted to minimize ISI. Error-free transmission of 10 Gbit/s non-return-to-zero signals through standard 50 microm graded-index MMFs up to 11.1 km long is demonstrated. It is shown that a single SLM can compensate for modal dispersion across a 600 GHz bandwidth. 相似文献
994.
Brouet V Yang WL Zhou XJ Choi HJ Louie SG Cohen ML Goldoni A Parmigiani F Hussain Z Shen ZX 《Physical review letters》2004,93(19):197601
We observe, with angle-resolved photoemission, a dramatic change in the electronic structure of two C60 monolayers, deposited, respectively, on Ag (111) and (100) substrates, and similarly doped with potassium to half filling of the C60 lowest unoccupied molecular orbital. The Fermi surface symmetry, the bandwidth, and the curvature of the dispersion at Gamma point are different. Orientations of the C60 molecules on the two substrates are known to be the main structural difference between the two monolayers, and we present new band-structure calculations for some of these orientations. We conclude that orientations play a key role in the electronic structure of fullerides. 相似文献
995.
Fifty different carbon–hydrogen distances have been predicted from ab initio MP2/6-311+G(d,p) calculations, which range from a short value of 1.0611 Å for HCNO to a long value of 1.1044 Å for H2CO. The values include those predicted for a series of methyl (CH3) moieties where the two different C–H distances vary by as much as 0.005 Å. These predicted values are compared to r
0(C–H) distances obtained from the isolated carbon–hydrogen stretching frequencies, as well as to r
0 or r
s
parameters obtained from microwave data. Except for the very short C–H bonds, the ab initio values from the MP2/6–311+G(d,p) calculations can be used for the carbon–hydrogen distances with error limits of ± 0.003 Å. By utilizing the spectral data from CD3CClO, it is shown that combination bands in the C–H stretching region could cause problems in the identification of the isolated C–H stretching frequency from the CD2HCClO isotopomer. The value of the ab initio predicted C–H distances for checking unusually long or short r
s
(C–H) or r
0 values is demonstrated. 相似文献
996.
Using FT-Raman spectroscopy, column wicking technique and the equations of Washburn as well as van Oss et al., the surface properties of xylan, the main component in hemicelluloses, has been characterized and estimated. Raman spectrum showed that xylan has been structured by acetyl group and methyl-bonded glucurono group. Obtained results show that the surface free energy of xylan is higher in comparison with literature reported values for cellulose because the former has a larger Lifshitz–van der Waals component than the latter. However, xylan has been found to have very smaller polarity and orientation data than that of cellulose. 相似文献
997.
Fabrication of alternating polycation and albumin multilayer coating onto stainless steel by electrostatic layer-by-layer adsorption 总被引:1,自引:0,他引:1
Ji J Tan Q Fan DZ Sun FY Barbosa MA Shen J 《Colloids and surfaces. B, Biointerfaces》2004,34(3):185-190
Multilayer films consisting of polyethylenimine (PEI) and albumin were successfully prepared on biomedical 316L stainless steel surface via electrostatic self-assembly of the PEI and albumin. The process of electrostatic self-assembly of PEI/albumin was monitored by125I radiolabeling, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The EIS data revealed that the multilayer coating was stable in Tris-HCl (pH 7.35) buffer solution for 21 days. 125I radiolabeling experiments indicated that less than 10% albumin was eluted by PBS in 45 days. Static platelet adhesion experiments indicated that the PEI/albumin deposited on stainless steel could resist platelet adhesion effectively. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices. 相似文献
998.
Since two solvent polarity parameters, e.g., the Et(30) defined by Reichardt and the pi* defined by Kamlet and Taft, respectively, plotted with the K coefficient of the Mark-Houwink-Sakurada equation, presented good linear fits, this paper suggests applying the extrapolating method in the same way as the Zisman plot to obtain similar polarity parameters for polymers. In order to verify those obtained polarity parameter values for various polymers, literature-reported polarity values determined using other techniques are referenced and indicate that this paper introduced a simplified approach that can be applied to evaluate the polarity parameters for polymers. In this paper, since we observe that various polymers are of interest to present absolutely different slope tendencies, e.g., positive and negative, it is also suggested that polarity properties of polymers may be reinterpreted. 相似文献
999.
Shen M Li G Lu BZ Hossain A Roschangar F Farina V Senanayake CH 《Organic letters》2004,6(22):4129-4132
[reaction: see text] The first practical and economical process for synthesis of 2,3-disubstituted indole compounds has been developed with high regioselectivity by palladium-catalyzed indolization of 2-bromo- or chloroanilines and their derivatives with internal alkynes. 相似文献
1000.
The paper is concerned with a non-cooperative differential game for two players. We first consider Nash equilibrium solutions in feedback form. In this case, we show that the Cauchy problem for the value functions is generically ill-posed. Looking at vanishing viscosity approximations, one can construct special solutions in the form of chattering controls, but these also appear to be unstable. In the second part of the paper we propose an alternative semi-cooperative pair of strategies for the two players, seeking a Pareto optimum instead of a Nash equilibrium. In this case, we prove that the corresponding Hamiltonian system for the value functions is always weakly hyperbolic.Revised: May 2004 相似文献