全文获取类型
收费全文 | 502681篇 |
免费 | 5471篇 |
国内免费 | 2196篇 |
专业分类
化学 | 261953篇 |
晶体学 | 7677篇 |
力学 | 22930篇 |
综合类 | 68篇 |
数学 | 60985篇 |
物理学 | 156735篇 |
出版年
2021年 | 4212篇 |
2020年 | 4670篇 |
2019年 | 5138篇 |
2018年 | 6937篇 |
2017年 | 7118篇 |
2016年 | 10002篇 |
2015年 | 6047篇 |
2014年 | 9603篇 |
2013年 | 22781篇 |
2012年 | 18259篇 |
2011年 | 21919篇 |
2010年 | 16076篇 |
2009年 | 15788篇 |
2008年 | 20008篇 |
2007年 | 20000篇 |
2006年 | 18595篇 |
2005年 | 16481篇 |
2004年 | 15102篇 |
2003年 | 13373篇 |
2002年 | 13244篇 |
2001年 | 15203篇 |
2000年 | 11430篇 |
1999年 | 8766篇 |
1998年 | 7354篇 |
1997年 | 7145篇 |
1996年 | 6887篇 |
1995年 | 6019篇 |
1994年 | 6041篇 |
1993年 | 5775篇 |
1992年 | 6391篇 |
1991年 | 6578篇 |
1990年 | 6221篇 |
1989年 | 6103篇 |
1988年 | 5831篇 |
1987年 | 5859篇 |
1986年 | 5677篇 |
1985年 | 7308篇 |
1984年 | 7406篇 |
1983年 | 6189篇 |
1982年 | 6449篇 |
1981年 | 6011篇 |
1980年 | 5814篇 |
1979年 | 6214篇 |
1978年 | 6354篇 |
1977年 | 6371篇 |
1976年 | 6360篇 |
1975年 | 5941篇 |
1974年 | 5991篇 |
1973年 | 6107篇 |
1972年 | 4526篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
A multigrid acceleration technique developed for solving the three-dimensional Navier–Stokes equations for subsonic/transonic flows has been extended to supersonic/hypersonic flows. An explicit multistage Runge–Kutta type of time-stepping scheme is used as the basic algorithm in conjunction with the multigrid scheme. Solutions have been obtained for a blunt conical frustum at Mach 6 to demonstrate the applicability of the multigrid scheme to high-speed flows. Computations have also been performed for a generic High-Speed Civil Transport configuration designed to cruise at Mach 3. These solutions demonstrate both the efficiency and accuracy of the present scheme for computing high-speed viscous flows over configurations of practical interest. 相似文献
993.
994.
S. É. Lapin 《Mathematical Notes》1993,54(1):701-704
Translated from Matematicheskie Zametki, Vol. 54, No. 1, pp. 52–56, July, 1993. 相似文献
995.
A deflecting system formed by two parallel-plate capacitors on opposite sides of an optoelectronic element that alters the
energy of a beam of charged particles, is calculated numerically. The conditions for correcting the chromatic beam spreading
in the plane of the target are found. Good agreement with the results of an approximate analytical calculation is demonstrated.
Zh. Tekh. Fiz. 67, 86–88 (December 1997) 相似文献
996.
X. S. Wu Xuehai Wu Yunping Li Zhangde Lu Liangen Gong Ping Zhou Qing Zhang 《Fiber and Integrated Optics》1993,12(1):97-103
Miniature, etching ridge InGaAsP/InP Phase Modulator with highly efficient phase shifting efficiency of 60°/V.mm and 43°/V.mm for TE and TM modes, respectively, and 3 dB bandwidth of 650 MHz at 1.52 μm are reported. It is well suited for integrated opto-electronics. Some functions depending on bandwidth of the devices are discussed. 相似文献
997.
Summary We present the preliminary results of a time-dependent simulation, with the Smoothed-Particle Hydrodynamics tecnique, of the
accretion of gas onto Schwartzschild black holes. The flow should exibit a stable shock for the parameters chosen. In the
case of 1D axisymmetric simulations, we find that the predicted inner shock position is unstable. For 2D axisymmetric simulations,
in the light of the first runs, we argue that in this case shocks may be a more common result. 相似文献
998.
L. Ward 《Optics & Laser Technology》1993,25(6):393-395
The well-known equations for the optical functions of reflectance, transmittance and phase changes on reflection and transmission for a solid material have been rearranged into the form of simple geometric figures in the u, v (n, k) plane. The curves for Fp show a singularity on the n-axis. 相似文献
999.
S. Ya. Khavinson 《Journal of Mathematical Sciences》1993,63(2):275-290
The paper is devoted to the theory of factorization of univalent analytic functions on a compact Riemann surface with boundary. The main component of the theory is a new method for the removal of the periods of certain functions (the natural analogues of the Schwarz integral and Blaschke products) along the boundary curves and bundle sections.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 170, pp. 285–313, 1989. 相似文献
1000.