全文获取类型
收费全文 | 22716篇 |
免费 | 2066篇 |
国内免费 | 1646篇 |
专业分类
化学 | 3386篇 |
晶体学 | 106篇 |
力学 | 1680篇 |
综合类 | 571篇 |
数学 | 15193篇 |
物理学 | 5492篇 |
出版年
2024年 | 24篇 |
2023年 | 186篇 |
2022年 | 411篇 |
2021年 | 410篇 |
2020年 | 443篇 |
2019年 | 441篇 |
2018年 | 439篇 |
2017年 | 603篇 |
2016年 | 690篇 |
2015年 | 461篇 |
2014年 | 878篇 |
2013年 | 1452篇 |
2012年 | 987篇 |
2011年 | 1248篇 |
2010年 | 1180篇 |
2009年 | 1557篇 |
2008年 | 1589篇 |
2007年 | 1550篇 |
2006年 | 1436篇 |
2005年 | 1151篇 |
2004年 | 1026篇 |
2003年 | 990篇 |
2002年 | 904篇 |
2001年 | 807篇 |
2000年 | 730篇 |
1999年 | 649篇 |
1998年 | 577篇 |
1997年 | 485篇 |
1996年 | 429篇 |
1995年 | 362篇 |
1994年 | 275篇 |
1993年 | 223篇 |
1992年 | 223篇 |
1991年 | 179篇 |
1990年 | 151篇 |
1989年 | 129篇 |
1988年 | 119篇 |
1987年 | 106篇 |
1986年 | 66篇 |
1985年 | 102篇 |
1984年 | 97篇 |
1983年 | 66篇 |
1982年 | 105篇 |
1981年 | 75篇 |
1980年 | 90篇 |
1979年 | 92篇 |
1978年 | 62篇 |
1977年 | 56篇 |
1976年 | 41篇 |
1974年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
A. Shaporenko A. Terfort M. Grunze M. Zharnikov 《Journal of Electron Spectroscopy and Related Phenomena》2006
Analysis of photoemission spectra of complex thioaromatic self-assembled monolayers (SAMs) requires the knowledge and understanding of such spectra for the basic systems. Keeping this goal in mind, synchrotron-based high-resolution X-ray photoelectron spectroscopy was used to characterize SAMs formed from the simplest thioaromatic compounds, namely thiophenol, 1,1′-biphenyl-4-thiol and 1,1′;4′,1″-terphenyl-4-thiol on evaporated Au(1 1 1) and Ag(1 1 1) substrates. The acquired S 2p and C 1s spectra were analyzed in terms of fine structure and initial and final state effects in the photoemission process. The assignment of the individual spectral features was considered in detail. Conclusions on quality and chemical and structural homogeneity of the investigated SAMs were derived. 相似文献
142.
Here we present a theoretical analysis of the effect of inelastic electron scattering on spin-dependent transport characteristics (conductance, current–voltage dependence, magnetoresistance, shot noise spectrum, Fano factor) for magnetic nanojunction. Such device is composed of molecular quantum dot (with discrete energy levels) connected to ferromagnetic electrodes (treated within the wide-band approximation), where molecular vibrations are modeled as dispersionless phonons. Non-perturbative computational scheme, used in this work, is based on the Green's function theory within the framework of mapping technique (GFT–MT), which transforms the many-body electron–phonon interaction problem into a single-electron multi-channel scattering problem. The consequence of the localized electron–phonon coupling is polaron formation. It is shown that polaron shift and additional peaks in the transmission function completely change the shape of considered transport characteristics. 相似文献
143.
144.
条件愈苦,意志愈坚 --记王淦昌早年的科研活动 总被引:1,自引:0,他引:1
文章介绍了中国物理学家王淦昌早期的科研工作,特别是在抗日战争时期的科研成绩.王淦昌早期的科研贡献并不是在先进的实验仪器上,在条件优裕的实验室内完成的,而是在实验设备缺乏,科学文献不足等极端困难的环境中完成的.从王淦昌身上,可以看到那个时代中国优秀科学家脚踏实地、执志若金的奋斗精神. 相似文献
145.
Jian‐guo Tang 《Mathematical Methods in the Applied Sciences》2006,29(11):1327-1338
An implicit iterative method is applied to solving linear ill‐posed problems with perturbed operators. It is proved that the optimal convergence rate can be obtained after choosing suitable number of iterations. A generalized Morozov's discrepancy principle is proposed for the problems, and then the optimal convergence rate can also be obtained by an a posteriori strategy. The convergence results show that the algorithm is a robust regularization method. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
146.
High even order generalizations of the traditional upwind method are introduced to solve second order ODE-BVPs without recasting
the problem as a first order system. Both theoretical analysis and numerical comparison with central difference schemes of
the same order show that these new methods may avoid typical oscillations and achieve high accuracy. Singular perturbation
problems are taken into account to emphasize the main features of the proposed methods.
AMS subject classification (2000) 65L10, 65L12, 65L50 相似文献
147.
对Hajek-Renyi不等式进行了推广,利用推广的不等式给出了随机变量序列绝对平均意义下的强大数定律的一个条件. 相似文献
148.
This article studies the inshore-offshore fishery model with impulsive diffusion. The existence and global asymptotic stability of both the trivial periodic solution and the positive periodic solution are obtained. The complexity of this system is also analyzed. Moreover, the optimal harvesting policy are given for the inshore subpopulation, which includes the maximum sustainable yield and the corresponding harvesting effort. 相似文献
149.
A. A. Maleev 《Computational Mathematics and Mathematical Physics》2006,46(12):2031-2039
Stationary and nonstationary Jacobi-like iterative processes for solving systems of linear algebraic equations are examined. For a system whose coefficient matrix A is an H-matrix, it is shown that the convergence rate of any Jacobi-like process is at least as high as that of the point Jacobi method as applied to a system with 〈A〉 as the coefficient matrix, where 〈A〉 is a comparison matrix of A. 相似文献
150.
基于SPA的双枝模糊决策分析 总被引:3,自引:0,他引:3
将集对理论(SPA)与双枝模糊决策理论相结合,用集对分析的方法研究进行双枝模糊决策的方法,分别对双枝模糊决策因素域和双枝模糊决策的上枝、下枝和双枝进行了集对分析,给出了用SPA进行双枝模糊决策的性质,同时讨论了双枝模糊决策的动态分析方法,以及双枝模糊决策度强弱态势预测的方法,从而为双枝模糊决策理论的研究提供了新的视角和方法,为双枝模糊决策的应用提供了更方便的工具和更强的理论支持。 相似文献