全文获取类型
收费全文 | 145475篇 |
免费 | 23946篇 |
国内免费 | 16621篇 |
专业分类
化学 | 99772篇 |
晶体学 | 1804篇 |
力学 | 9540篇 |
综合类 | 1000篇 |
数学 | 16702篇 |
物理学 | 57224篇 |
出版年
2024年 | 460篇 |
2023年 | 2710篇 |
2022年 | 4847篇 |
2021年 | 5353篇 |
2020年 | 5627篇 |
2019年 | 5596篇 |
2018年 | 4892篇 |
2017年 | 4674篇 |
2016年 | 6952篇 |
2015年 | 6861篇 |
2014年 | 8416篇 |
2013年 | 10962篇 |
2012年 | 13023篇 |
2011年 | 13395篇 |
2010年 | 9170篇 |
2009年 | 9027篇 |
2008年 | 9568篇 |
2007年 | 8633篇 |
2006年 | 7940篇 |
2005年 | 6663篇 |
2004年 | 5032篇 |
2003年 | 4044篇 |
2002年 | 3893篇 |
2001年 | 3117篇 |
2000年 | 2676篇 |
1999年 | 2843篇 |
1998年 | 2406篇 |
1997年 | 2225篇 |
1996年 | 2334篇 |
1995年 | 1892篇 |
1994年 | 1831篇 |
1993年 | 1458篇 |
1992年 | 1315篇 |
1991年 | 1177篇 |
1990年 | 960篇 |
1989年 | 684篇 |
1988年 | 569篇 |
1987年 | 466篇 |
1986年 | 469篇 |
1985年 | 387篇 |
1984年 | 282篇 |
1983年 | 196篇 |
1982年 | 167篇 |
1981年 | 133篇 |
1980年 | 92篇 |
1979年 | 65篇 |
1978年 | 42篇 |
1976年 | 45篇 |
1975年 | 45篇 |
1974年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
103.
104.
谐振子薛定谔方程的简单解法 总被引:2,自引:0,他引:2
物质的许多物理与化学性质都可以用线性谐振子模型解释,本文用简单的数学运算求解线性谐振子的薛定谔方程,避免了特殊函数等复杂的数学运算,得出了量子力学教材完全相同的结果。 相似文献
105.
High-level ab initio calculations are carried out to study the relative stability of the two hydrogen bonded structures of water-hydrogen sulfide complex, one with water as the proton donor (A) and the other with hydrogen sulfide as the proton donor (B). The results show that structure A is considerably more stable than B at the correlated level, which is in contrast with previous results obtained from Hartree-Fock calculations. 相似文献
106.
Based on the effective-field theory with self-spin correlations and the differential operator technique,physical properties of the spin-2 system with biaxial crystal field on the simple cubic, body-centered cubic, as well as faced-centered lattice have been studied. The influences of the external longitudinal magnetic field on the magnetization,internal energy, specific heat, and susceptibility have been discussed in detail. The phenomenon that the magnetization in the ground state shows quantum effects produced by the biaxial transverse crystal field has been found. 相似文献
107.
108.
Sang Kyu Lee Min Ju Cho Jung‐Il Jin Dong Hoon Choi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):531-542
New photocrosslinkable maleimide copolymers have been synthesized by the attachment of a tricyanopyrrolidene‐based chromophore. The 2‐(3‐cyano‐4‐(2‐{4‐[hexyl‐(6‐hydroxy‐hexyl)‐amino]‐phenyl}‐vinyl)‐5‐oxo‐1‐{4‐[4‐(3‐oxo‐3‐phenyl‐propenyl)‐ phenoxy]‐butyl}‐1,5‐dihydro‐pyrrol‐2‐ylidene)‐malononitrile chromophore exhibits nonlinear optical activity and contains a chalcone moiety that is sensitive to UV light (λ = 330–360 nm) for crosslink formation. The maleimide monomers have also been functionalized with chalcone moieties. The resultant copolymers exhibit great processability, and one of them shows a maximum electrooptic coefficient of 90 pm/V at 1300 nm. We could control the thermal stability of the electrooptic coefficient with the newly synthesized photoreactive copolymers successfully. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 531–542, 2007 相似文献
109.
Jiguo Yu Qiuju Bian Guizhen Liu Na Wang 《Journal of Applied Mathematics and Computing》2007,25(1-2):283-291
A simple graphG is said to be fractionaln-factor-critical if after deleting anyn vertices the remaining subgraph still has a fractional perfect matching. For fractionaln-factor-criticality, in this paper, one necessary and sufficient condition, and three sufficient conditions related to maximum matching, complete closure are given. 相似文献
110.
Recently, the theory of sortability of partition property has been shown to be an effective tool to prove the existence of an optimal partition with that property. In this paper, we extend the theory to multi-partition where the partition is on t types of components. We apply our results to settle an optimal assignment problem whose proof was incomplete as given in the literature. 相似文献