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951.
超导磁体等效材料参数的有限元预测 总被引:2,自引:0,他引:2
HT—7U超导托卡马克装置中纵场超导磁体是由多种材料组成的且具有周期性分布的大型复杂的重要结构,对其宏观等效材料参数的准确掌握在其结构设计阶段是十分重要的。本文着重介绍了利用小参数展开的渐近均匀化方法对其进行等效处理的过程,并采用有限元方法预测出其等效弹性模量与热膨胀系数等,这些都为纵场磁体结构的力学计算与传热分析提供了必要的参数。 相似文献
952.
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954.
This paper reports on a theoretical analysis of spin‐Hamiltonian parameters and local lattice structure for Pd(I) center in γ‐irradiated Pd(II)(acac)2. Through the crystal‐ and ligand‐field theory, the microscopic spin‐Hamiltonian parameters and local molecular structure for Pd(I) center in the γ‐irradiated Pd(II)(acac)2 system have been studied by using the high‐order perturbation formulas and Newman's superposition model. Based on these calculations, it was found that the distance of the metal‐ligand bonds in the square planar complex for Pd(I) center in the γ‐irradiated Pd(II)(acac)2 system increases by 0.1Å. To understand the detailed physical and chemical properties of the [Pd(I)(acac)2]2– complex, the contributions of the spin‐orbit coupling of ligand to spin‐Hamiltonian parameters for Pd(I) ion are considered. The theoretical results are in reasonable agreement with the experimental values. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
955.
Experimental EPR spectra in several modified vanadate glass systems reveal hyperfine structure (hfs) lines whose widths vary with the molar ratio of modifier to vanadium pentoxide, R. In the RNa2O.V2O5 system, for example, hfs lines show no resolution at low R values (near 0.1); by contrast, these lines exhibit dramatic narrowing as R approaches 0.5. In the model proposed here, this narrowing is due to an increase in hopping time for small polarons associated with V4+ ions in these systems. Increases in polaron hopping times are accompanied by increases in electron spin-spin relaxation times T2's, and, an associated narrowing of EPR linewidths. Experiments confirm that spectral widths are limited by electron T2's due to the fact that EPR linewidths do not vary with temperature down to 4.2 K. Resolved spectra in RNa2O.V2O5 at R = 0.5 reveal a hyperfine coupling parameter of 0.0177 ± 0.0008 T, corresponding to an upper-limit polaron hopping frequency of 487 ± 20 MHz. By similar analyses, the systems of RCaO.V2O5, RBaO.V2O5, and RLi2O.V2O5 exhibit comparable polaron hopping frequencies limits of 480 ± 20 MHz, 469 ± 20 MHz, and 468 ± 20 MHz, respectively, when R is near 1.0. In addition to the relaxation effects discussed here, results of modeling of resolved spectra to obtain hyperfine coupling constants A|| and A┴, and g┴ values g|| and g┴ are presented and discussed. 相似文献
957.
给出了铯原子光泵磁共振测量磁场的原理.利用MEMS封装与制造技术,设计了一种芯片级的激光铯磁场传感系统,可实现对微弱磁场的检测. 相似文献
958.
In this paper,we propose a three point approximating subdivision scheme,with three shape parameters,that unifies three different existing three point approximating schemes.Some sufficient conditions for subdivision curve C0 to C3 continuity and convergence of the scheme for generating tensor product surfaces for certain ranges of parameters by using Laurent polynomial method are discussed.The systems of curve and surface design based on our scheme have been developed successfully in garment CAD especially for clothes modelling. 相似文献
959.
This paper considers variable selection for moment restriction models.We propose a penalized empirical likelihood(PEL) approach that has desirable asymptotic properties comparable to the penalized likelihood approach,which relies on a correct parametric likelihood specification.In addition to being consistent and having the oracle property,PEL admits inference on parameter without having to estimate its estimator's covariance.An approximate algorithm,along with a consistent BIC-type criterion for selecting ... 相似文献
960.
M.G. Brik 《Journal of luminescence》2011,131(12):2642-2645
In the present paper, we report on consistent crystal field calculations of the Cr3+ ions energy levels in KAl(MoO4)2 using actual D3d site symmetry of the Cr3+ position and employing the exchange charge model (ECM) of the crystal field. In addition to the energy level calculations, the Huang-Rhys factor S=5.7 and effective phonon energy ?ω=268 cm-1 were evaluated in the single configurational coordinate model. Detailed treatment of the microscopic crystal field effects in the ECM framework allowed to obtain analytical dependence of the crystal field strength 10Dq on the Cr-O interionic distance and extracting from it the values of some parameters of the electron-vibrational interaction (EVI) in the KAl(MoO4)2:Cr3+ system. All obtained results are compared with experimental data and discussed; agreement between the calculated and experimental parameters is good. 相似文献