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41.
Electrons on infinite coupled chains with nearest neighbour couplings under uniform electric and magnetic fields can be expressed as conditionally solvable systems, which concerns both discrete coordinate and wavenumber representations. We then have to account for multiparameter extra-conditions relying on the single chain phase of the system, which amounts to perform a suitable selection of parameters. The implicit plots provided by such conditions exhibit both regular and irregular patterns. This results in the onset of a finite number of Wannier–Stark resonances, now by performing rescalings needed. However, this time the resonance width is sensitive to the quantum number characterizing the Stark-ladder. Bound-state limits, rescalings and approximations proceeding irrespective of the wavenumber have also been presented. 相似文献
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A.L. SampaioD.C. Lobão L.C.S. NunesP.A.M. dos Santos L. Silva J.A.O. Huguenin 《Optics and Lasers in Engineering》2011,49(1):32-35
In this paper, we present a study of metallic surface roughness using the Hurst exponent calculated from speckle pattern. A set of samples was prepared using polishing techniques and the roughness was directly measured by means of an optical profilometer. To study the H exponent, an experiment was performed by illuminating the samples using an expanded laser beam and the surface image was captured by a CCD camera. We applied techniques of the Hurst exponent calculation, traditionally calculated from surface profile, in the digitalized speckle patterns generated by the rough surfaces. We showed a clear dependence of the H exponent on roughness of the samples. We demonstrated that this tool is very sensitive to defects in the surfaces and can be used for roughness control. 相似文献
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A generalization of the original Jensen-Shannon divergence (JSD) is presented in this work, which gives rise to a non-extensive one-parameter divergence providing a powerful dissimilarity measure between electronic distributions. The analysis performed in this study employs the JTD measure to compare one-particle densities of neutral and ionized atomic systems, that generalizes and improves some previous results based on other measures of divergence. Such an improvement mainly arises from the capability of JTD to modify, by means of its order parameter, the relative contribution of specific relevant regions of the atomic densities under comparison, in both position and momentum spaces. Relevant information of the ionization processes attending to structural pattern and periodicity is found, as well as the strong correlation between extremal values of the neutral-cation JTD and those of the atomic ionization potential. Similar conclusions are obtained from processes involving an anion. The analysis includes a study of the dependence of JTD on its order for fixed atomic couples. 相似文献
47.
Steffen Härting Anna Marciniak‐Czochra 《Mathematical Methods in the Applied Sciences》2014,37(9):1377-1391
We explore a mechanism of pattern formation arising in processes described by a system of a single reaction–diffusion equation coupled with ordinary differential equations. Such systems of equations arise from the modeling of interactions between cellular processes and diffusing growth factors. We focus on the model of early carcinogenesis proposed by Marciniak‐Czochra and Kimmel, which is an example of a wider class of pattern formation models with an autocatalytic non‐diffusing component. We present a numerical study showing emergence of periodic and irregular spike patterns because of diffusion‐driven instability. To control the accuracy of simulations, we develop a numerical code on the basis of the finite‐element method and adaptive mesh grid. Simulations, supplemented by numerical analysis, indicate a novel pattern formation phenomenon on the basis of the emergence of nonstationary structures tending asymptotically to a sum of Dirac deltas. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Shengqiang Tang Jianxian Zheng Wentao Huang 《Applied mathematics and computation》2009,215(7):2768-2774
In this work, the K∗(l,p) equation is investigated. The sine-cosine method, the tanh method and the extended tanh method are efficiently used for analytic study of this equation. New solitary patterns solutions and compactons solutions are formally derived. The proposed schemes are reliable and manageable. 相似文献
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We generalize the concept of a break by considering pairs of arbitrary rounds. We show that a set of home-away patterns minimizing the number of generalized breaks cannot be found in polynomial time, unless P=NP. When all teams have the same break set, the decision version becomes easy; optimizing remains NP-hard. 相似文献