全文获取类型
收费全文 | 95625篇 |
免费 | 8793篇 |
国内免费 | 8390篇 |
专业分类
化学 | 30612篇 |
晶体学 | 394篇 |
力学 | 11211篇 |
综合类 | 1704篇 |
数学 | 36637篇 |
物理学 | 32250篇 |
出版年
2024年 | 130篇 |
2023年 | 799篇 |
2022年 | 1619篇 |
2021年 | 1908篇 |
2020年 | 2150篇 |
2019年 | 2307篇 |
2018年 | 2007篇 |
2017年 | 2491篇 |
2016年 | 2874篇 |
2015年 | 2433篇 |
2014年 | 3708篇 |
2013年 | 6496篇 |
2012年 | 4148篇 |
2011年 | 4804篇 |
2010年 | 4155篇 |
2009年 | 5550篇 |
2008年 | 5862篇 |
2007年 | 6039篇 |
2006年 | 5537篇 |
2005年 | 4744篇 |
2004年 | 4362篇 |
2003年 | 4270篇 |
2002年 | 3940篇 |
2001年 | 3309篇 |
2000年 | 3178篇 |
1999年 | 2864篇 |
1998年 | 2623篇 |
1997年 | 2158篇 |
1996年 | 1885篇 |
1995年 | 1754篇 |
1994年 | 1616篇 |
1993年 | 1371篇 |
1992年 | 1307篇 |
1991年 | 1028篇 |
1990年 | 855篇 |
1989年 | 712篇 |
1988年 | 664篇 |
1987年 | 563篇 |
1986年 | 469篇 |
1985年 | 556篇 |
1984年 | 558篇 |
1983年 | 279篇 |
1982年 | 437篇 |
1981年 | 463篇 |
1980年 | 339篇 |
1979年 | 339篇 |
1978年 | 251篇 |
1977年 | 233篇 |
1976年 | 173篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing
it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate
εF
2(x,Q)2/ε In Q
2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data. 相似文献
102.
溴酸钾-亚甲蓝催化光度法测定硝酸盐和亚硝酸盐 总被引:16,自引:1,他引:15
用镉柱将NO-3 还原为NO-2 ,利用在磷酸介质中NO-2 对溴酸钾氧化亚甲蓝这一褪色反应具有强烈的催化作用而建立了同时测定痕量硝酸盐和亚硝酸盐的新方法。本方法简便、快速、灵敏 ,对亚硝酸盐和硝酸盐测定的线性范围分别为 0~ 2 0 0 μg·L-1和 0 0 0 3~ 310 μg·L-1,用于测定各种水样中痕量NO-2 和NO-3 的含量均获得满意结果 相似文献
103.
104.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献
105.
106.
107.
A. Mielke 《Journal of statistical physics》1991,62(3-4):509-528
The magnetic properties of the one-dimensional Hubbard model with a hardcore interaction on a ring (periodic boundary conditions) are investigated. At finite temperatures it is shown to behave up to exponentially small corrections as a pure paramagnet. An explicit expression for the ground-state degeneracies is derived. The eigenstates of this model are used to perform a perlurbational treatment for large but finite interactions. In first order inU
1 an effective Hamiltonian for the one-dimensional Hubbard model is derived. It is the Hamiltonian of the one-dimensional Hcisenberg model with antiferromagnetic couplings between nearest neighbor spins. An asymptotic expansion for the ground-state energy is given. The results are valid for arbitrary densities of electrons. 相似文献
108.
109.
ZHAO Ren ZHANG Li-Chun HU Shuang-Qi 《理论物理通讯》2006,46(10)
We generalize the method that is used to study corrections to Cardy-Verlinde formula due to generalized uncertainty principle and discuss corrections to Cardy-Verlinde formula due to generalized uncertainty principle in (anti)-de Sitter space. Because in de Sitter black hole spacetime the radiation temperature of the black hole horizon is different from the one of the cosmological horizon, this spacetime is a thermodynamical non-equilibrium spacetime. 相似文献
110.
Lubomír Kubáček 《Applications of Mathematics》2006,51(6):565-582
Some remarks to problems of point and interval estimation, testing and problems of outliers are presented in the case of multivariate
regression model.
This work was supported by the Council of Czech Government J14/98:153100011. 相似文献