全文获取类型
收费全文 | 15621篇 |
免费 | 2855篇 |
国内免费 | 2872篇 |
专业分类
化学 | 12199篇 |
晶体学 | 276篇 |
力学 | 824篇 |
综合类 | 229篇 |
数学 | 1698篇 |
物理学 | 6122篇 |
出版年
2024年 | 61篇 |
2023年 | 330篇 |
2022年 | 626篇 |
2021年 | 722篇 |
2020年 | 730篇 |
2019年 | 746篇 |
2018年 | 626篇 |
2017年 | 662篇 |
2016年 | 843篇 |
2015年 | 900篇 |
2014年 | 1055篇 |
2013年 | 1293篇 |
2012年 | 1460篇 |
2011年 | 1454篇 |
2010年 | 1152篇 |
2009年 | 1119篇 |
2008年 | 1210篇 |
2007年 | 1022篇 |
2006年 | 964篇 |
2005年 | 787篇 |
2004年 | 574篇 |
2003年 | 440篇 |
2002年 | 434篇 |
2001年 | 355篇 |
2000年 | 278篇 |
1999年 | 250篇 |
1998年 | 204篇 |
1997年 | 170篇 |
1996年 | 163篇 |
1995年 | 148篇 |
1994年 | 117篇 |
1993年 | 96篇 |
1992年 | 67篇 |
1991年 | 71篇 |
1990年 | 56篇 |
1989年 | 47篇 |
1988年 | 29篇 |
1987年 | 14篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1975年 | 2篇 |
1965年 | 3篇 |
1959年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Bai-suo JIN~ 《中国科学A辑(英文版)》2007,50(9):1303-1315
In the factor analysis model with large cross-section and time-series dimensions,we pro- pose a new method to estimate the number of factors.Specially if the idiosyncratic terms satisfy a linear time series model,the estimators of the parameters can be obtained in the time series model. The theoretical properties of the estimators are also explored.A simulation study and an empirical analysis are conducted. 相似文献
22.
23.
The fission barrier for ^240pu is investigated beyond the second saddle point in the potentiM energy surface by the constrained relativistic mean field method with the newly proposed parameter set PK1. The microscopic correction for the centre-of-mass motion is essentiM to provide the correct potential energy surface. The shell effects that stabilize the nuclei against the fission is also investigated by the Strutinsky method. The shapes for the ground state, fission isomer and saddle-points, etc, are studied in detail. 相似文献
24.
In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
25.
Wei Gang SU Huai Jie ZHONG 《数学学报(英文版)》2006,22(2):515-522
This paper introduces the concept of the generalized Riesz operators and the concept of the generalized West decomposition of a general operator which generalizes the definition of the West decomposition of Riesz operators, and proves that the following three statements are equivalent on a general Banach space:
(a) Every generalized Riesz operator has the generalized West decomposition;
(b) Every operator makes strong Stampfli theorem true; Every operator has Apostol's compact correction. 相似文献
26.
文章针对焊件检测过程中需大量采集和分析实时图像的要求 ,利用小波分析的特点 ,相关跟踪识别视频图像运动状态 ,实现自动采集、分析处理和储存一并完成 ,解决了视频图像连续捕获不能得到高像质的问题。 相似文献
27.
In this paper, we give an application ofUV-decomposition method of convex programming to multiobjective programming, and offer a new algorithm for solving semi-infinite multiobjective programming. Finally, the superlinear convergence of the algorithm is proved. 相似文献
28.
29.
Let φ be a normal function on [0,1) and A'(φ)(1
相似文献
30.
In this article, the linear and nonlinear shear rheological behaviors of polylactide (PLA)/clay (organophilic‐montmorillonite) nanocomposites (PLACNs) were investigated by an Advanced Rheology Expanded System rheometer. The nanocomposites were prepared by master batch method using a twin‐screw extruder with poly(ε‐caprolactone) (PCL) as a compatibilizer. The presence of org‐MMT leads to obvious pseudo‐solid‐like behaviors of nanocomposite melts. The behaviors caused by the formation of a “percolating network” derived from the reciprocity among the strong related sheet particles. Therefore, the storage moduli, loss moduli, and dynamic viscosities of PLACNs show a monotonic increase with MMT content. Nonterminal behaviors exists in PLACNs nanocomposites. Besides the PLACNs melts show a greater shear thinning tendency than pure PLA melt because of the preferential orientation of the MMT layers. Therefore, PLACNs have higher moduli but better processibility compared with pure PLA. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3189–3196, 2007 相似文献