全文获取类型
收费全文 | 12456篇 |
免费 | 1268篇 |
国内免费 | 908篇 |
专业分类
化学 | 1034篇 |
晶体学 | 38篇 |
力学 | 608篇 |
综合类 | 99篇 |
数学 | 3395篇 |
物理学 | 3341篇 |
综合类 | 6117篇 |
出版年
2024年 | 46篇 |
2023年 | 117篇 |
2022年 | 524篇 |
2021年 | 553篇 |
2020年 | 339篇 |
2019年 | 284篇 |
2018年 | 291篇 |
2017年 | 330篇 |
2016年 | 332篇 |
2015年 | 355篇 |
2014年 | 653篇 |
2013年 | 757篇 |
2012年 | 636篇 |
2011年 | 742篇 |
2010年 | 611篇 |
2009年 | 715篇 |
2008年 | 702篇 |
2007年 | 897篇 |
2006年 | 734篇 |
2005年 | 692篇 |
2004年 | 549篇 |
2003年 | 505篇 |
2002年 | 474篇 |
2001年 | 377篇 |
2000年 | 326篇 |
1999年 | 292篇 |
1998年 | 251篇 |
1997年 | 248篇 |
1996年 | 185篇 |
1995年 | 153篇 |
1994年 | 157篇 |
1993年 | 121篇 |
1992年 | 117篇 |
1991年 | 99篇 |
1990年 | 80篇 |
1989年 | 83篇 |
1988年 | 76篇 |
1987年 | 39篇 |
1986年 | 26篇 |
1985年 | 27篇 |
1984年 | 21篇 |
1983年 | 7篇 |
1982年 | 22篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1973年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We discuss whether an appropriately defined dimensionless scalar function might be an acceptable candidate for the gravitational entropy, by explicitly considering Szekeres and Bianchi type VI
h
models that admit an isotropic singularity. We also briefly discuss other possible gravitational entropy functions, including an appropriate measure of the velocity dependent Bel-Robinson tensor.
PACS: 04.20.-q 95.30.Sf 98.80.Jk 相似文献
82.
David Loffreda 《Surface science》2006,600(10):2103-2112
Adsorption thermodynamics based on density functional theory (DFT) calculations are exposed for the interaction of several multifunctional molecules with Pt and Au(1 1 0)-(1 × 2) surfaces. The Gibbs free adsorption energy explicitly depends on the adsorption internal energy, which is derived from DFT adsorption energy, and the vibrational entropy change during the chemisorption process. Zero-point energy (ZPE) corrections have been systematically applied to the adsorption energy. Moreover the vibrational entropy change has been computed on the basis of DFT harmonic frequencies (gas and adsorbed phases, clean surfaces), which have been extended to all the adsorbate vibrations and the metallic surface phonons. The phase diagrams plotted in realistic conditions of temperature (from 100 to 400 K) and pressure (0.15 atm) show that the ZPE corrected adsorption energy is the main contribution. When strong chemisorption is considered on the Pt surface, the multifunctional molecules are adsorbed on the surface in the considered temperature range. In contrast for weak chemisorption on the Au surface, the thermodynamic results should be held cautiously. The systematic errors of the model (choice of the functional, configurational entropy and vibrational entropy) make difficult the prediction of the adsorption-desorption phase boundaries. 相似文献
83.
We find the existence of a quantum thermal effect, “Hawking absorption.” near the inner horizon of the Kerr–Newman black hole. Redefining the entropy, temperature, angular velocity, and electric potential of the black hole, we give a new formulation of the Bekenstein–Smarr formula. The redefined entropy vanishes for absolute zero temperature of the black hole and hence it is interpreted as the Planck absolute entropy of the KN black hole. 相似文献
84.
85.
86.
In this paper, it is shown that some of the results of torus actions on Poincaré duality spaces, Borel’s dimension formula
and topological splitting principle to local weights, hold if ‘torus’ is replaced by ‘pro-torus’. 相似文献
87.
Jinyan Fan 《Computational Optimization and Applications》2006,34(2):215-227
In this paper, we present the new trust region method for nonlinear equations with the trust region converging to zero. The
new method preserves the global convergence of the traditional trust region methods in which the trust region radius will
be larger than a positive constant. We study the convergence rate of the new method under the local error bound condition
which is weaker than the nonsingularity. An example given by Y.X. Yuan shows that the convergence rate can not be quadratic.
Finally, some numerical results are given.
This work is supported by Chinese NSFC grants 10401023 and 10371076, Research Grants for Young Teachers of Shanghai Jiao Tong
University, and E-Institute of Computational Sciences of Shanghai Universities.
An erratum to this article is available at . 相似文献
88.
Howel Tong 《应用数学学报(英文版)》2002,18(2):177-184
Abstract I reflect upon the development of nonlinear time series analysis since 1990 by focusing on five majorareas of development. These areas include the interface between nonlinear time series analysis and chaos,thenonparametric/semiparametric approach,nonlinear state space modelling,financial time series and nonlinearmodelling of panels of time series. 相似文献
89.
吸附树脂对对甲苯胺的静态吸附行为及其热力学性质的研究 总被引:2,自引:0,他引:2
对比 Amberlite XAD-4与两种新型吸附树脂 NK和新 H对对甲苯胺的静态吸附行为 ,根据吸附等温线研究并讨论吸附热力学性质 .两种新型吸附树脂对对甲苯胺的吸附能力明显强于 Amberlite XAD-4 ,微孔作用机制及表面部分极性起决定作用 .吸附焓变 ΔH<0表明吸附为放热过程 ,降低温度有利于吸附 .对吸附焓变和自由能变的讨论同时表明树脂对对甲苯胺的吸附为多层物理吸附过程 .吸附熵变 ΔS表明吸附树脂表面的不均匀性和吸附质分子在树脂表面的分布及其局域运动与吸附有密切关系 . 相似文献
90.
We investigate function spaces of generalised smoothness of Besov and Triebel–Lizorkin type. Equivalent quasi-norms in terms
of maximal functions and local means are given. An atomic decomposition theorem for this type of spaces is proved.
Mathematics Subject Classification (2000) 46E35 相似文献