全文获取类型
收费全文 | 1545566篇 |
免费 | 32221篇 |
国内免费 | 8204篇 |
专业分类
化学 | 680926篇 |
晶体学 | 20079篇 |
力学 | 74685篇 |
综合类 | 104篇 |
数学 | 242360篇 |
物理学 | 371539篇 |
无线电 | 196298篇 |
出版年
2021年 | 14746篇 |
2020年 | 17378篇 |
2019年 | 17529篇 |
2016年 | 29462篇 |
2015年 | 21785篇 |
2014年 | 32885篇 |
2013年 | 78877篇 |
2012年 | 41540篇 |
2011年 | 38403篇 |
2010年 | 39571篇 |
2009年 | 44247篇 |
2008年 | 41586篇 |
2007年 | 38527篇 |
2006年 | 46493篇 |
2005年 | 37475篇 |
2004年 | 39048篇 |
2003年 | 36602篇 |
2002年 | 37765篇 |
2001年 | 37199篇 |
2000年 | 32687篇 |
1999年 | 29513篇 |
1998年 | 27741篇 |
1997年 | 27536篇 |
1996年 | 27006篇 |
1995年 | 24766篇 |
1994年 | 24235篇 |
1993年 | 23608篇 |
1992年 | 23533篇 |
1991年 | 23678篇 |
1990年 | 22421篇 |
1989年 | 22015篇 |
1988年 | 21222篇 |
1987年 | 19867篇 |
1986年 | 18770篇 |
1985年 | 25271篇 |
1984年 | 26402篇 |
1983年 | 22337篇 |
1982年 | 23782篇 |
1981年 | 22933篇 |
1980年 | 22179篇 |
1979年 | 22113篇 |
1978年 | 23365篇 |
1977年 | 22928篇 |
1976年 | 22569篇 |
1975年 | 21271篇 |
1974年 | 20945篇 |
1973年 | 21456篇 |
1972年 | 15610篇 |
1968年 | 13295篇 |
1967年 | 13345篇 |
排序方式: 共有10000条查询结果,搜索用时 866 毫秒
101.
Physics of Atomic Nuclei - In this paper, the analysis of the relation between the multiplication factor of neutrons of the multiplying system measured in critical experiments and the system... 相似文献
102.
Siberian Mathematical Journal - Suppose that $ n $ is an integer, $ n\geq 3 $ . We prove that a periodic group saturated with a set of the finite simple groups $ O_{2n+1}(q) $ , where $ q $ is... 相似文献
103.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with... 相似文献
104.
M. Amar D. Andreucci R. Gianni C. Timofte 《Journal of Mathematical Analysis and Applications》2021,493(2):124533
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation. 相似文献
105.
Kobayashi M. Zhang Y. Ishikawa H. Sun J. Oddershede J. Juul Jensen D. Miura H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such... 相似文献
106.
Gladson S. Chrisben Prasad P. Siva Manickam Bhaskar 《Analog Integrated Circuits and Signal Processing》2021,109(3):571-583
Analog Integrated Circuits and Signal Processing - As the 5G era beckons in the world of communication and information technology, there is a surge in demand for battery-operated, mobile wireless... 相似文献
107.
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been... 相似文献
108.
Chenhui Ding Marion Breunig Jana Timm Roland Marschall Jürgen Senker Seema Agarwal 《Advanced functional materials》2021,31(49):2106507
Covalent organic frameworks (COFs) show advantageous characteristics, such as an ordered pore structure and a large surface area for gas storage and separation, energy storage, catalysis, and molecular separation. However, COFs usually exist as difficult-to-process powders, and preparing continuous, robust, flexible, foldable, and rollable COF membranes is still a challenge. Herein, such COF membranes with fiber morphology for the first time prepared via a newly introduced template-assisted framework process are reported. This method uses electrospun porous polymer membranes as a sacrificial large dimension template for making self-standing COF membranes. The porous COF fiber membranes, besides having high crystallinity, also show a large surface area (1153 m2 g−1), good mechanical stability, excellent thermal stability, and flexibility. This study opens up the possibility of preparation of large dimension COF membranes and their derivatives in a simple way and hence shows promise in technical applications in separation, catalysis, and energy in the future. 相似文献
109.
Alawainati F. A. Manaa H. Henari F. Z. Biyiklioglu Z. Arslan T. Jaafar A. 《Journal of Applied Spectroscopy》2021,88(5):951-957
Journal of Applied Spectroscopy - Detailed measurements of nonlinear optical properties and optical limiting for four phthalocyanine (Pc) derivatives (PcCo, PcCu, PcMn, and PcSi) are reported. The... 相似文献
110.