全文获取类型
收费全文 | 1793篇 |
免费 | 108篇 |
国内免费 | 138篇 |
专业分类
化学 | 87篇 |
力学 | 27篇 |
综合类 | 15篇 |
数学 | 1751篇 |
物理学 | 159篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 29篇 |
2021年 | 18篇 |
2020年 | 46篇 |
2019年 | 45篇 |
2018年 | 37篇 |
2017年 | 44篇 |
2016年 | 40篇 |
2015年 | 31篇 |
2014年 | 66篇 |
2013年 | 150篇 |
2012年 | 51篇 |
2011年 | 66篇 |
2010年 | 71篇 |
2009年 | 87篇 |
2008年 | 129篇 |
2007年 | 108篇 |
2006年 | 104篇 |
2005年 | 79篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 71篇 |
2001年 | 72篇 |
2000年 | 54篇 |
1999年 | 46篇 |
1998年 | 48篇 |
1997年 | 48篇 |
1996年 | 20篇 |
1995年 | 16篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 11篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 23篇 |
1975年 | 4篇 |
1974年 | 7篇 |
排序方式: 共有2039条查询结果,搜索用时 203 毫秒
111.
L. V. Perova 《Computational Mathematics and Mathematical Physics》2008,48(6):1001-1023
Propagation of small perturbations in a two-layer inviscid stratified fluid is studied. It is assumed that the higher density fluid occupies the lower unbounded half-space, while the lower density fluid occupies the upper unbounded half-space. The source of the excitation is a plane wave traveling along the interface of the fluids. An explicit analytical solution to the problem is constructed, and its existence and uniqueness are proved. The long-time wave pattern developing in the fluids is analyzed. 相似文献
112.
Timo J. Tolmunen Antti V. Räisänen 《International Journal of Infrared and Millimeter Waves》1989,10(4):505-518
The multiplication efficiency of a millimeter-wave Schottky-varactor quintupler with fixed idler terminations was studied. The highest efficiency measured was 4.2% at 168 GHz with 10 mW input power and 3.3% with 40 mW input power. Over the range from 165 GHz to 170 GHz the output power was 0.7–1.3 mW withp
in
=40 mW. 相似文献
113.
Biological specimens have to be prepared for imaging in the electron microscope in a way that preserves their native structure. Two-dimensional (2D) protein crystals to be analyzed by electron crystallography are best preserved by sugar embedding. One of the sugars often used to embed 2D crystals is trehalose, a disaccharide used by many organisms for protection against stress conditions. Sugars such as trehalose can also be added to negative staining solutions used to prepare proteins and macromolecular complexes for structural studies by single-particle electron microscopy (EM). In this review, we describe trehalose and its characteristics that make it so well suited for preparation of EM specimens and we review specimen preparation methods with a focus on the use of trehalose. 相似文献
114.
115.
Orientable Hamilton Cycle Embeddings of Complete Tripartite Graphs II: Voltage Graph Constructions and Applications
下载免费PDF全文
![点击此处可从《Journal of Graph Theory》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In an earlier article the authors constructed a hamilton cycle embedding of in a nonorientable surface for all and then used these embeddings to determine the genus of some large families of graphs. In this two‐part series, we extend those results to orientable surfaces for all . In part II, a voltage graph construction is presented for building embeddings of the complete tripartite graph on an orientable surface such that the boundary of every face is a hamilton cycle. This construction works for all such that p is prime, completing the proof started by part I (which covers the case ) that there exists an orientable hamilton cycle embedding of for all , . These embeddings are then used to determine the genus of several families of graphs, notably for and, in some cases, for . 相似文献
116.
Balazard, Saias, and Yor proved that the Riemann Hypothesis is equivalent to a certain weighted integral of the logarithm of the Riemann zeta-function along the critical line equaling zero. Assuming the Riemann Hypothesis, we investigate the rate at which a truncated version of this integral tends to zero, answering a question of Borwein, Bradley, and Crandall and disproving a conjecture of the same authors. A simple modification of our techniques gives a new proof of a classical Omega theorem for the function S(t) in the theory of the Riemann zeta-function. 相似文献
117.
118.
We prove the existence of multiple solutions for some systems of second order ODEs with Dirichlet boundary conditions. Such systems are obtained by coupling scalar ODEs with different growth conditions. The proof relies on a global continuation technique. 相似文献
119.
Repeated convolution of a probability measure on leads to the central limit theorem and other limit theorems. This paper investigates what kinds of results remain without positivity. It reviews theorems due to Schoenberg, Greville, and Thomée which are motivated by applications to data smoothing (Schoenberg and Greville) and finite difference schemes (Thomée). Using Fourier transform arguments, we prove detailed decay bounds for convolution powers of finitely supported complex functions on . If M is an hermitian contraction, an estimate for the off‐diagonal entries of the powers of is obtained. This generalizes the Carne–Varopoulos Markov chain estimate. 相似文献
120.
Yoshihiro Sawano 《Mathematische Nachrichten》2014,287(2-3):352-358
The Brézis‐Gallouët‐Wainger inequality describes a subtle embedding property into . The relation between the Brézis‐Gallouët‐Wainger inequality and the real interpolation functor together with the sharpness of the results is discussed in the present paper. As our first main results shows, it turns out that there are two intermediate terms between and the logarithmic boundedness, which is supposed to be the right‐hand side of the Brézis‐Gallouët‐Wainger inequality. As the second result, the first result is extended to inequalities which reflect the meaning of the second index of Besov spaces and the interpolation theorem. 相似文献