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921.
In view of important role of inducing and manipulating the magnetism in 2D materials for the development of low-dimensional spintronic devices, the magnetism of GaN monolayer with Ga vacancy and nonmagnetic chemical doping are investigated using first-principles calculations. It is found that pure GaN monolayer has graphene-like structure and is nonmagnetic. While, a neutral Ga vacancy can induce 3 μB intrinsic magnetic moment, localized mainly on the neighboring N atoms. Interestingly, after one Mg or Si atom doping in g-GaN with Ga vacancy, the magnetic moment can be modified to 4 μB or 2 μB respectively due to the change in hole number. Meantime, Mg-doped g-GaN with Ga vacancy shows half-metal character. With the increasing of doping concentrations, the magnetic moment can be further tuned. The results are interesting from a theoretical point of view and may open opportunities for these 2D GaN based materials in magnetic devices. 相似文献
922.
3-cube-based Förster resonance energy transfer (FRET) microscopy, a sensitized acceptor FRET quantification method, has been widely used to visualize dynamic protein–protein interaction in living cells. Determining the FRET sensitized-quenching transition factor (G factor) of a particular donor-acceptor pair and optical system is crucial for 3-cube FRET quantification. We here improved the acceptor photobleaching-based G factor determination method (termed as mPb-G) and the two-plasmid-based G factor determination method (termed as mTP-G) for rapid and reliable measurement of the G factor. mTP-G method determines G factor by simultaneously detecting three images of cells exclusively expressing each of two tandem constructs with multiple donors and multiple acceptors. This method circumvents switchover of the cells exclusively expressing each of the two constructs. mPb-G method images G factor by detecting three images of cells expressing a donor-acceptor tandem FRET construct before and after partially photobleaching acceptor. We performed the two methods on our dual-channel wide-field FRET microscope to obtain reliable G factor, and also measured the FRET efficiency and acceptor-to-donor concentration ratio of tandem constructs with different acceptor-donor stoichiometries in living HepG2 cells. mTP-G and mPb-G methods provide two simple and reliable tools for determining the G factor, in turn, quantitatively measuring FRET signal and monitoring dynamic biochemical processes in living cells. 相似文献
923.
Novel classes of dynamical systems are introduced, including many-body problems characterized by nonlinear equations of motion of Newtonian type (“acceleration equals forces”) which determine the motion of points in the complex plane. These models are solvable, namely their con?guration at any time can be obtained from the initial data by algebraic operations, amounting to the determination of the zeros of a known time-dependent polynomial in the independent variable z. Some of these models are multiply periodic, isochronous or asymptotically isochronous; others display scattering phenomena. 相似文献
924.
The subgrid-scale dynamics of stratified flows is studied in a horizontally introduced turbulent jet with coexistence of stable and unstable stratification of a low Richardson number case and a high Richardson number case. The positive production of subgrid-scale kinetic energy and the production of scalar variance suggest the forward energy cascade. The subgrid-scale buoyant destruction plays a role as a sink of subgrid-scale kinetic energy in the stable stratification while holds a role of turbulent generation in the unstable stratification. The role-switch of buoyant destruction in the stable stratification of high-Ri case implies the occurrence of a destabilising process triggered by the coupled instability mechanisms. The energy balance assumption related to the production of and the dissipation of subgrid-scale kinetic energy as well as the subgrid-scale buoyant destruction may fail. The a-priori test suggests the scale-invariant dynamic and standard Smagorinsky models not to work properly here, while the scale-dependent dynamic model gives a decent performance but with restrictions of the ratio between two testing filter scales. 相似文献
925.
Jürgen Dippon 《随机分析与应用》2013,31(5):765-798
Parallelization of stochastic approximation procedures can reduce computation and total observation time of a system. Concerning the number of all observations used by the pure sequential and the suggested parallel method a weak invariance principle implies the asymptotic equivalence of both methods. A loglog invariance principle and a rate of a.s. convergence result describe the pathwise properties. Due to the parallel design asymptotic confidence regions can readily be constructed either by computing the bootstrap distribution or the Gaussian limit distribution determined by the empirical covariance 相似文献
926.
927.
Victoria Otero-Espinar 《Journal of Difference Equations and Applications》2013,19(12):1225-1241
This paper is devoted to the study of the existence of extremal solutions to a first-order initial value problem on an interval of an arbitrary time scale. We prove the existence of extremal solutions for problems satisfying Carathéodory's conditions. Moreover, they are approximated uniformly by a sequence of lower and upper solutions to this problem, respectively. We also can warrant the existence and approximation of extremal solutions for the problem by relaxing their continuity properties. 相似文献
928.
直接以麦克斯韦方程组的解表征拉盖尔-高斯光束。基于麦克斯韦方程组解的矢量角谱表述和电磁光束的矢量结构理论,利用一些数学技巧导出了拉盖尔-高斯光束的TE项和TM项在近场的解析表达式。利用所导出的公式,在近场描绘了拉盖尔-高斯光束的TE项、TM项及整个光束的光强分布。并对角度依赖分别为余弦和正弦关系的拉盖尔-高斯光束的矢量结构进行了比较,结果显示两者整个光束的光斑完全相似,唯一的区别是子瓣的空间方位不同且两者的内部矢量结构完全不相同。 相似文献
929.
930.
High-resolution Kβ spectra of Cr oxide were measured using a non-conventional spectrometer. Theoretical spectra were obtained using the DV-Xα method in order to interpret the Kβ spectrum structures. Kβ spectrum structures were analyzed and spectral parameters show a great sensitivity to the oxidation state and to the Cr-O distance. High-purity samples of CrO2 were obtained by means of thermal treatment at 513 °C under oxygen pressure of 200 bar. X-ray diffraction patterns show a typical rutile structure, without spurious phases. The CrO2 data allowed to confirm the linear dependency of the Kβ1,3 and Kβ2,5 energy positions with the oxidation state. The energy of the Kβ2,5 line relative to the Kβ1,3 line seems to be a suitable parameter for characterization of the oxidation state. The relative Kβ″ transition probability per Cr-O falls exponentially with Cr-O increasing distance. This behaviour was not found in the literature for Cr oxides. 相似文献