全文获取类型
收费全文 | 81845篇 |
免费 | 7258篇 |
国内免费 | 10211篇 |
专业分类
化学 | 58641篇 |
晶体学 | 456篇 |
力学 | 2909篇 |
综合类 | 940篇 |
数学 | 14957篇 |
物理学 | 21411篇 |
出版年
2024年 | 163篇 |
2023年 | 822篇 |
2022年 | 1445篇 |
2021年 | 2796篇 |
2020年 | 2622篇 |
2019年 | 2506篇 |
2018年 | 2255篇 |
2017年 | 2307篇 |
2016年 | 2757篇 |
2015年 | 2663篇 |
2014年 | 3681篇 |
2013年 | 6431篇 |
2012年 | 3861篇 |
2011年 | 4625篇 |
2010年 | 3795篇 |
2009年 | 4676篇 |
2008年 | 4998篇 |
2007年 | 5346篇 |
2006年 | 4433篇 |
2005年 | 3598篇 |
2004年 | 3304篇 |
2003年 | 3042篇 |
2002年 | 4986篇 |
2001年 | 2400篇 |
2000年 | 2080篇 |
1999年 | 1740篇 |
1998年 | 1622篇 |
1997年 | 1302篇 |
1996年 | 1205篇 |
1995年 | 1098篇 |
1994年 | 1006篇 |
1993年 | 962篇 |
1992年 | 964篇 |
1991年 | 652篇 |
1990年 | 582篇 |
1989年 | 518篇 |
1988年 | 458篇 |
1987年 | 379篇 |
1986年 | 357篇 |
1985年 | 472篇 |
1984年 | 383篇 |
1983年 | 207篇 |
1982年 | 404篇 |
1981年 | 568篇 |
1980年 | 507篇 |
1979年 | 544篇 |
1978年 | 450篇 |
1977年 | 372篇 |
1976年 | 334篇 |
1973年 | 213篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
102.
103.
104.
A practical access to alkyl- and aryl-substituted (E)-2-(azidomethyl)alkenoates and related azido compounds from the corresponding allylic bromides in aqueous acetone is described. An alternative method to obtain the starting bromides based on heterogeneous catalysis under mild conditions was also investigated. 相似文献
105.
DING Bin-Gang ZHANG Da-Li LU Ding-Hui 《理论物理通讯》2006,46(1):113-118
We calculate the binding energies of Ni, Cu, Xe, Cs, Pt, Au, Np, Pu isotope chains using two interaction parameter sets NL-3 and NL-Z, and compared the relative errors of the even-even nuclei with those of odd-even nuclei and odd-odd nuclei. We find that the errors of binding energy of odd-even and odd-odd nuclei are not bigger than the one of even-even nuclei. The result shows that comparing with even-even nuclei, there is no systematic error and approximation in the calculations of the binding energy of odd-even and odd-odd nuclei with relativistic mean-field theory. In addition, the result is explained theoretically. 相似文献
106.
A. V. Bobylev 《Journal of statistical physics》2006,124(2-4):371-399
It is well-known that the classical Chapman-Enskog procedure does not work at the level of Burnett equations (the next step after the Navier-Stokes equations). Roughly speaking, the reason is that the solutions of higher equations of hydrodynamics (Burnett's, etc.) become unstable with respect to short-wave perturbations. This problem was recently attacked by several authors who proposed different ways to deal with it. We present in this paper one of possible alternatives. First we deduce a criterion for hyperbolicity of Burnett equations for the general molecular model and show that this criterion is not fulfilled in most typical cases. Then we discuss in more detail the problem of truncation of the Chapman-Enskog expansion and show that the way of truncation is not unique. The general idea of changes of coordinates (based on analogy with the theory of dynamical systems) leads finally to nonlinear Hyperbolic Burnett Equations (HBEs) without using any information beyond the classical Burnett equations. It is proved that HBEs satisfy the linearized H-theorem. The linear version of the problem is studied in more detail, the complete Chapman-Enskog expansion is given for the linear case. A simplified proof of the Slemrod identity for Burnett coefficients is also given. 相似文献
107.
Cai Xiaochun 《Annals of Differential Equations》2006,22(1):1-6
In this paper, we apply a critical point theorem and obtain the condition for the existence of three solutions to two-point boundary value problem of a second order nonlinear difference equation. 相似文献
108.
We propose a framework, based on classical mixture theory, to describe the isothermal flow of an incompressible fluid through a deformable inelastic porous solid. The modeling of the behavior of the inelastic solid takes into account changes in the elastic response due to evolution in the microstructure of the material. We apply the model to a compression layer problem. The mathematical problem generated by the model is a free boundary problem. 相似文献
109.
Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λKn into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P3,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008 相似文献
110.
具有模糊数的模糊多目标群体决策优选模型与方法 总被引:5,自引:0,他引:5
多目标群体决策问题是运筹学的一个重要研究领域,目前已经提出了一些有效的决策方法。但对目标值和权重均为模糊数的模糊多目标群体决策问题却研究不多,本对此类模糊多目标群体决策问题进行了探讨,利用相对正理想方案与相对负理想方案概念定义了相对差异距离,进而建立了模糊多目标群体决策优选模型与方法,并通过战役决心方案的评价说明了该方法是可行、有效的,可作为军事决策与决策支持系统的备选方法。 相似文献