全文获取类型
收费全文 | 20974篇 |
免费 | 3217篇 |
国内免费 | 2724篇 |
专业分类
化学 | 16147篇 |
晶体学 | 322篇 |
力学 | 1113篇 |
综合类 | 258篇 |
数学 | 2066篇 |
物理学 | 7009篇 |
出版年
2024年 | 48篇 |
2023年 | 328篇 |
2022年 | 657篇 |
2021年 | 670篇 |
2020年 | 750篇 |
2019年 | 784篇 |
2018年 | 616篇 |
2017年 | 637篇 |
2016年 | 985篇 |
2015年 | 960篇 |
2014年 | 1146篇 |
2013年 | 1506篇 |
2012年 | 1852篇 |
2011年 | 1913篇 |
2010年 | 1372篇 |
2009年 | 1206篇 |
2008年 | 1386篇 |
2007年 | 1185篇 |
2006年 | 1155篇 |
2005年 | 1088篇 |
2004年 | 884篇 |
2003年 | 758篇 |
2002年 | 844篇 |
2001年 | 596篇 |
2000年 | 513篇 |
1999年 | 450篇 |
1998年 | 322篇 |
1997年 | 295篇 |
1996年 | 293篇 |
1995年 | 278篇 |
1994年 | 217篇 |
1993年 | 191篇 |
1992年 | 173篇 |
1991年 | 155篇 |
1990年 | 136篇 |
1989年 | 116篇 |
1988年 | 94篇 |
1987年 | 65篇 |
1986年 | 68篇 |
1985年 | 70篇 |
1984年 | 33篇 |
1983年 | 35篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1975年 | 4篇 |
1971年 | 2篇 |
1957年 | 7篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
57.
Jing Zhang Dan Shan Shaolin Mu 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5573-5582
A copolymer, poly(aniline‐co‐o‐aminophenol), was prepared chemically by using ammonium peroxydisulfate as an oxidant. The monomer concentration ratio of o‐aminophenol to aniline strongly influences the copolymerization rate and properties of the copolymer. The optimum composition of a mixture for the chemical copolymerization consisted of 0.3 M aniline, 0.021 M o‐aminophenol, 0.42 M ammonium peroxydisulfate, and 2 M H2SO4. The result of cyclic voltammograms in a potential region of ?0.20 to 0.80 V (vs.SCE) indicates that the electrochemical activity of the copolymer prepared under the optimum condition is similar to that of polyaniline in more acid solutions. However, the copolymer still holds the good electrochemical activity until pH 11.0. Therefore, the pH dependence of the electrochemical property of the copolymer is improved, compared with poly(aniline‐co‐o‐aminophenol) prepared electrochemically, and is much better than that of polyaniline. The spectra of IR and 1H NMR confirm that o‐aminophenol units are included in the copolymer chain, which play a key role in extending the usable pH region of the copolymer. The visible spectra of the copolymers show that a high concentration ratio of o‐aminophenol to aniline in a mixture inhibits the chain growth. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5573–5582, 2007 相似文献
58.
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
59.
Jiamin Jin 《Acta Physica Hungarica A》2006,27(2-3):237-240
This poster presents the PHENIX results on high-p Tγ-hadron and π0-hadron correlations and shows the modification of away side jet shape by the medium. By comparing their jet shapes and yields, we see some evidence of the direct γ contribution to correlation functions. 相似文献
60.
Tao Jin Feng-Xian Jiang Xiao-Li Li Fang Wang Xiao-Hua Shen Rui-Qiang Zhang Hai-Shun Wu 《Applied Surface Science》2006,253(5):2708-2712
CoPt/Ag and [C/CoPt]n/Ag thin films have been prepared onto the glass substrates by magnetron sputtering. We investigated the evolution of texture and magnetic properties of CoPt/Ag and [C/CoPt]n/Ag films. The results show that C-doping plays an important role in improving (0 0 1) texture, improving the order parameter S, reducing the intergrain interactions, and making the magnetization reversal mechanism more close to Stoner-Wolfarth rotational mechanism. The growth mechanism of (0 0 1) texture also seems to be related strongly to the films thickness. Our results show that the highly (0 0 1)-oriented films with ordered fct phase have a significant potential for the perpendicular media of extremely high-density recording. 相似文献