全文获取类型
收费全文 | 5943篇 |
免费 | 851篇 |
国内免费 | 521篇 |
专业分类
化学 | 1442篇 |
晶体学 | 61篇 |
力学 | 998篇 |
综合类 | 68篇 |
数学 | 2386篇 |
物理学 | 2360篇 |
出版年
2024年 | 10篇 |
2023年 | 62篇 |
2022年 | 115篇 |
2021年 | 132篇 |
2020年 | 145篇 |
2019年 | 124篇 |
2018年 | 151篇 |
2017年 | 183篇 |
2016年 | 269篇 |
2015年 | 212篇 |
2014年 | 261篇 |
2013年 | 488篇 |
2012年 | 331篇 |
2011年 | 362篇 |
2010年 | 301篇 |
2009年 | 398篇 |
2008年 | 356篇 |
2007年 | 394篇 |
2006年 | 355篇 |
2005年 | 285篇 |
2004年 | 298篇 |
2003年 | 249篇 |
2002年 | 220篇 |
2001年 | 181篇 |
2000年 | 211篇 |
1999年 | 193篇 |
1998年 | 151篇 |
1997年 | 128篇 |
1996年 | 93篇 |
1995年 | 100篇 |
1994年 | 73篇 |
1993年 | 82篇 |
1992年 | 76篇 |
1991年 | 56篇 |
1990年 | 41篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 29篇 |
1984年 | 23篇 |
1983年 | 8篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1957年 | 2篇 |
排序方式: 共有7315条查询结果,搜索用时 421 毫秒
31.
Giovanni Cupini Marcello Guidorzi Cristina Marcelli 《Journal of Differential Equations》2007,243(2):329-348
Classical one-dimensional, autonomous Lagrange problems are considered. In absence of any smoothness, convexity or coercivity condition on the energy density, we prove a DuBois-Reymond type necessary condition, expressed as a differential inclusion involving the subdifferential of convex analysis. As a consequence, a non-existence result is obtained. 相似文献
32.
本文给出了Banach空间广义分解定理的一个初等证明,并利用它来证明两个对称不等式.这是首次在Banach空间获得这样的不等式. 相似文献
33.
Myung-Soon Lee 《Applied Surface Science》2006,252(14):5019-5025
We prepared high quality Au(1 1 1) film on Si wafer through the spin coating and thermal decomposition of a gold ink, spin-coated-and-fired (SCAF) Au film. The X-ray measurements, XRD and pole-figure analysis, showed that the SCAF Au film has a (1 1 1) out-of-plane orientation with a random in-plane orientation. In order to confirm the chemical activity of the SCAF Au film, we demonstrate the formation of patterned structures with the film by using soft lithography technique. The chemical activities of this physically stable SCAF Au film to the alkanethiols were at least equivalent those of physically deposited the Au films. The possibility of the mass production of micro patterned structure with the SCAF Au film was also demonstrated over the wide region on Si wafer by the microcontact lithography. These suggest that the Au film will help the easy fabrication of various nanosized devices on Si wafer and other substrates. 相似文献
34.
A. Ulyanenkov 《Applied Surface Science》2006,253(1):106-111
Several novel methods for evaluation and interpretation of X-ray data from modern nanostructures are presented along with their applications. The background of methods and their relations to fundamental problems of X-ray analysis is shortly described. The key features of LEPTOS software, which is designed for the analysis of X-ray data measured with various geometries and setups and implements all discussed techniques, are discussed. 相似文献
35.
Adhesion of zein to solid substrates has been studied using surface energy profiles as indices and by adhesion mapping using
atomic force microscopy (AFM). Different plasticizers like glycerol and sorbitol have been used to form mixed films with zein
and properties of these films are studied using surface energy profiles. Comparison of the results from the different mixed
samples with those from the pure zein films showed that force mapping could identify areas rich in protein. The adhesion maps
produced were deconvoluted from sample topography and contrasted with the data obtained from contact angle measurements. A
comparison of the two methods shows that the extent of contact angle hysteresis is indicative of both hydrophobicity of the
surface as well as the force of adhesion. Mechanical properties and microstructure of zein films prepared by casting from
solutions and using Langmuir-Blodgett film technique have been investigated. Pure zein seemed brittle and exhibited an essentially
linear relationship between stress and strain. Films with plasticizer were tougher than these films. In general, mixed films
showed better mechanical properties than pure films and had higher ultimate tensile strength and increased per cent elongation.
Further, the mixed films of zein showed a higher force of adhesion compared to the pure films. 相似文献
36.
Bing-sheng He Zhen-hua Yang Xiao-ming Yuan 《Journal of Mathematical Analysis and Applications》2004,300(2):139-374
Proximal point algorithms (PPA) are attractive methods for monotone variational inequalities. The approximate versions of PPA are more applicable in practice. A modified approximate proximal point algorithm (APPA) presented by Solodov and Svaiter [Math. Programming, Ser. B 88 (2000) 371–389] relaxes the inexactness criterion significantly. This paper presents an extended version of Solodov–Svaiter's APPA. Building the direction from current iterate to the new iterate obtained by Solodov–Svaiter's APPA, the proposed method improves the profit at each iteration by choosing the optimal step length along this direction. In addition, the inexactness restriction is relaxed further. Numerical example indicates the improvement of the proposed method. 相似文献
37.
On Covariant Phase Space and the Variational Bicomplex 总被引:1,自引:0,他引:1
Enrique G. Reyes 《International Journal of Theoretical Physics》2004,43(5):1267-1286
The notion of a phase space in classical mechanics is well known. The extension of this concept to field theory however, is a challenging endeavor, and over the years numerous proposals for such a generalization have appeared in the literature. In this paper We review a Hamiltonian formulation of Lagrangian field theory based on an extension to infinite dimensions of J.-M. Souriau's symplectic approach to mechanics. Following G. Zuckerman, we state our results in terms of the modern geometric theory of differential equations and the variational bicomplex. As an elementary example, we construct a phase space for the Monge–Ampere equation. 相似文献
38.
39.
40.