全文获取类型
收费全文 | 11006篇 |
免费 | 836篇 |
国内免费 | 733篇 |
专业分类
化学 | 1418篇 |
晶体学 | 75篇 |
力学 | 924篇 |
综合类 | 122篇 |
数学 | 6910篇 |
物理学 | 3126篇 |
出版年
2024年 | 12篇 |
2023年 | 98篇 |
2022年 | 168篇 |
2021年 | 168篇 |
2020年 | 203篇 |
2019年 | 227篇 |
2018年 | 202篇 |
2017年 | 227篇 |
2016年 | 239篇 |
2015年 | 210篇 |
2014年 | 330篇 |
2013年 | 882篇 |
2012年 | 365篇 |
2011年 | 503篇 |
2010年 | 499篇 |
2009年 | 1017篇 |
2008年 | 1055篇 |
2007年 | 885篇 |
2006年 | 838篇 |
2005年 | 581篇 |
2004年 | 413篇 |
2003年 | 466篇 |
2002年 | 459篇 |
2001年 | 347篇 |
2000年 | 305篇 |
1999年 | 296篇 |
1998年 | 309篇 |
1997年 | 214篇 |
1996年 | 146篇 |
1995年 | 120篇 |
1994年 | 117篇 |
1993年 | 64篇 |
1992年 | 65篇 |
1991年 | 71篇 |
1990年 | 50篇 |
1989年 | 42篇 |
1988年 | 42篇 |
1987年 | 36篇 |
1986年 | 32篇 |
1985年 | 35篇 |
1984年 | 39篇 |
1983年 | 22篇 |
1982年 | 42篇 |
1981年 | 22篇 |
1980年 | 22篇 |
1979年 | 16篇 |
1978年 | 21篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
J. E. Fischer E. Werwa P. A. Heiney 《Applied Physics A: Materials Science & Processing》1993,56(3):193-196
We have used both reflection-geometry and grazing-incidence-geometry X-ray scattering to study thin films of C60 evaporated onto mica substrates via a hot-wall technique. The growth mode yields close-packed C60 planes, which are parallel to the substrate surface and which exhibit out-of-plane correlation lengths of 850 Å. In the film plane the C60 is at best pseudo-epitaxial, with a 0.9° distribution of crystallite orientations, a 450 Å in-plane correlation length, and a 3.7% lattice mismatch, better than obtained by other thin film techniques but far from the accepted definition of single crystal thin film epitaxy. 相似文献
12.
在摄像机进行航拍的图像处理系统中,由摄像机运动所引起的视频运动,背景变化是主要特点。在进行图像采集时,每个像素都在变化,采用传统的图像编码方式进行图像压缩,压缩效果比较差。提出了基于块分割的精确运动估计算法,它是一种很好的图像压缩方法。 相似文献
13.
P. Nithiananthi 《Solid State Communications》2006,137(8):427-430
The binding energies of a hydrogenic donor both in the parabolic and non-parabolic conduction band model within the effective mass approximation have been computed for the low-dimensional semiconducting systems (LDSS) like quantum well, quantum well wire and quantum dot taking GaAs/AlxGa1−xAs systems as an example. It is observed that the effect of non-parabolicity is not effective when the system goes to lower dimensionality. The diamagnetic susceptibility of a hydrogenic donor impurity has also been computed in these LDSS in the infinite barrier model. Since no theoretical or experimental works on the diamagnetic susceptibility of LDSS are available in the literature, as a realistic case the diamagnetic susceptibility has been computed in the finite barrier model (x=0.3) for a quantum well and the results are discussed in the light of semiconductor-metal transition. 相似文献
14.
15.
Necessary conditions for the Gâteaux differentiability of the distance function to a set are considered. A series of characterizing results is obtained. 相似文献
16.
Mathematical Notes - 相似文献
17.
We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch. 相似文献
18.
本文采用求解Schroedinger方程和数值计算方法,研究了Ⅴ-型三能级原子与双模奇偶纠缠相干光场相互作用系统的光子统计性质,结果表明:此性质与双模奇偶纠缠相干光场的纠缠程度、失谐量、原子的初态以及双模光的平均光子数相关联. 相似文献
19.
R. S. Martynov Yu. M. Nechepurenko 《Computational Mathematics and Mathematical Physics》2006,46(7):1155-1167
For a discrete linear stochastic dynamical system, computation of the response matrix to the external action from a subspace using given observational data is examined. An algorithm is proposed and substantiated that makes it possible to improve the numerical accuracy and to reduce the amount of observational data compared to the general case where an arbitrary external action is allowed. As an illustration, a discrete system arising in the analysis of a linear stochastic dynamical continuous-time system is considered more thoroughly. Some numerical results are presented. 相似文献
20.
E. A. Bailov N. Temirgaliev 《Computational Mathematics and Mathematical Physics》2006,46(9):1515-1525
Sharp estimates (in the power scale) are obtained for the discretization error in the solutions to Poisson’s equation whose right-hand side belongs to a Korobov class. Compared to the well-known Korobov estimate, the order is almost doubled and has an ultimate value in the power scale. 相似文献