全文获取类型
收费全文 | 154897篇 |
免费 | 27058篇 |
国内免费 | 27909篇 |
专业分类
化学 | 109328篇 |
晶体学 | 3092篇 |
力学 | 9778篇 |
综合类 | 2407篇 |
数学 | 20780篇 |
物理学 | 64479篇 |
出版年
2024年 | 489篇 |
2023年 | 2604篇 |
2022年 | 5450篇 |
2021年 | 5609篇 |
2020年 | 5928篇 |
2019年 | 5870篇 |
2018年 | 5414篇 |
2017年 | 5651篇 |
2016年 | 6929篇 |
2015年 | 7596篇 |
2014年 | 9204篇 |
2013年 | 11947篇 |
2012年 | 13627篇 |
2011年 | 14092篇 |
2010年 | 11055篇 |
2009年 | 10821篇 |
2008年 | 11690篇 |
2007年 | 10364篇 |
2006年 | 9965篇 |
2005年 | 8394篇 |
2004年 | 6621篇 |
2003年 | 5015篇 |
2002年 | 4851篇 |
2001年 | 4319篇 |
2000年 | 4205篇 |
1999年 | 3338篇 |
1998年 | 2447篇 |
1997年 | 2088篇 |
1996年 | 2052篇 |
1995年 | 1807篇 |
1994年 | 1672篇 |
1993年 | 1420篇 |
1992年 | 1225篇 |
1991年 | 1070篇 |
1990年 | 893篇 |
1989年 | 729篇 |
1988年 | 599篇 |
1987年 | 519篇 |
1986年 | 472篇 |
1985年 | 370篇 |
1984年 | 300篇 |
1983年 | 252篇 |
1982年 | 192篇 |
1981年 | 143篇 |
1980年 | 116篇 |
1979年 | 83篇 |
1978年 | 47篇 |
1977年 | 34篇 |
1975年 | 33篇 |
1957年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
本文是文[1-7]的继续,研究变权综合问题,从确定变权的经验公式入手引出了变权原理,给出了变权的公理化定义,讨论了与之有关的均衡函数及其梯度向量。 相似文献
102.
The Al2O3−CdSe interface of a thin-film transistor is investigated in the frequency range 30 Hz-30 kHz under weak depletion and accumulation.
The surface states are, most likely, located in the insulator Al2O3 with a concentration varying from 4·1018 to 1019 cm−3 eV−1. The surface states have a negligible influence on the thin-film transistor operation. 相似文献
103.
104.
We employ a first-principles plane wave method with the
relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter
(HGH) scheme in the frame of DFT to calculate
the equilibrium lattice parameters and the thermodynamic properties of
AlB2 compound with hcp structure. The obtained lattice parameters are in
good agreement with the available experimental data and those calculated by
others. Through the quasi-harmonic Debye model, obtained successfully are
the dependences of the
normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized
primitive cell volume V/V0 on pressure P, the variation of the thermal
expansion α with pressure P and temperature T, as well as the Debye
temperature \ThetaD and the heat capacity CV on pressure P and
temperature T. 相似文献
105.
106.
Li Boyu 《数学学报(英文版)》1991,7(3):247-251
H. Crapo raised in 1982 the following problem: IfP is a complete lattice, is Retr (P) a complete lattice? here Retr (P) denotes the set of all retraction operators onP with the pointwise order, that is,f≤g in Retr (P) ifff(x)≤g(x) for everyx inP. An affirmative answer will be given in the present paper. 相似文献
107.
Zi-Cai Li 《Numerical Methods for Partial Differential Equations》1989,5(4):279-295
The nonconforming combination of Ritz-Galerkin and finite difference methods is presented for solving elliptic boundary value problems with singularities. The Ritz-Galerkin method is used in the subdomains including singularities, the finite difference method is used in the rest of the solution domain. Moreover, on the common boundary of two regions where two different methods are used, the continuity conditions are constrained only on the nodes of difference grids. Theoretical analysis and numerical experiments have shown that average errors of numerical solutions and their generalized derivatives can reach the convergence rate O(h2-δ), where h is the mesh spacing of uniform difference grids, and δ is an arbitrarily small, positive number. This convergence rate is better than O(h), obtained by the nonconforming combination of the Ritz-Galerkin and finite element methods. 相似文献
108.
This paper reports that the growth of RuOx(110) thin layer growth on Ru(0001)
has been investigated by means of scanning tunnelling microscope (STM). The STM
images showed a domain structure with three rotational domains of RuOx(110)
rotated by an angle of 120℃.
The as-grown RuOx(110) thin layer is expanded from the bulk-truncated
RuOx(110) due to the large mismatch between RuOx(110) and the
Ru(0001) substrate. The results also indicate that growth of RuOx(110)
thin layer on the Ru(0001) substrate by oxidation tends first to formation
of the Ru-O (oxygen) chains in the [001] direction of RuOx(110). 相似文献
109.
110.