全文获取类型
收费全文 | 1755篇 |
免费 | 209篇 |
国内免费 | 156篇 |
专业分类
化学 | 1259篇 |
晶体学 | 37篇 |
力学 | 77篇 |
综合类 | 28篇 |
数学 | 173篇 |
物理学 | 546篇 |
出版年
2023年 | 22篇 |
2022年 | 25篇 |
2021年 | 46篇 |
2020年 | 46篇 |
2019年 | 54篇 |
2018年 | 49篇 |
2017年 | 43篇 |
2016年 | 60篇 |
2015年 | 82篇 |
2014年 | 96篇 |
2013年 | 128篇 |
2012年 | 144篇 |
2011年 | 148篇 |
2010年 | 91篇 |
2009年 | 82篇 |
2008年 | 133篇 |
2007年 | 112篇 |
2006年 | 92篇 |
2005年 | 91篇 |
2004年 | 85篇 |
2003年 | 51篇 |
2002年 | 50篇 |
2001年 | 45篇 |
2000年 | 50篇 |
1999年 | 35篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有2120条查询结果,搜索用时 15 毫秒
51.
52.
HongMing Weng 《中国科学:物理学 力学 天文学(英文版)》2018,61(3):038231
正Recently Guo et al.[1]have performed a systematic simulation on the high-pressure phases of the first experimentally available Weyl semimetals TaAs family.Through such a cheap but powerful technique,they theoretically found a new 相似文献
53.
[Cp∗IrCl2]2 catalyses the cyclization of 2-alkynylanilines into indoles. A wide variety of substrates is tolerated. A reaction pathway involving intramolecular hydroamination is proposed. 相似文献
54.
Wei Jiang Zheng-Long Yang Ding Weng Jun-Wei Wangb Yun-Feng Lu Min-Juan Zhang Zhen-Zhong Yang 《中国化学快报》2014,25(6):849-853
PbTe/SnTe hybrid nanocrystals with designed shape, chemical composition and narrow size distribution were synthesized by an efficient solvothermal approach. This approach enables mass and economical synthesis of PbTe-based nanocrystals. The organic ligands were completely removed by pretreatment with a super-hydride solution, making it possible to fabricate fully dense and robust thermoelectric devices with increased electrical conductivity. 相似文献
55.
Chen Chen Weng Xinliang Xu Xiao Xia Xiong Xiu Lian Lu Yi Feng Zhou 《Russian Journal of General Chemistry》2013,83(12):2447-2452
We have demonstrated that the fragments of Telaprevir can act as organocatalysts for asymmetric aldol reactions between aromatic aldehydes and acetone under mild conditions. The reaction conditions have been optimized in terms of the catalyst nature, choice of temperature, solvent, additive, and the catalyst loading. Under proper conditions, fairly good yield and enantioselectivity have been achieved. 相似文献
56.
Visible light-induced hydroxyalkylation of 2H-benzothiazoles with alcohols via selectfluor oxidation
A visible-light induced metal-free approach was described for the hydroxyalkylation of 2H-benzothiazoles with alcohols by using selectfluor as the oxidant. A variety of 2H-benzothiazoles and alcohols could be tolerated, providing a mild and simple method for the synthesis of C2-hydroxyalkylated 2H-benzothiazoles in moderate to good yields. Besides, ethers were also compatible in this reaction, leading to corresponding C2 ether-substituted 2H-benzothiazoles with high regioselectivity. 相似文献
57.
Xiaoting Li Tao Hu Biao Wang Wenjian Weng Gaorong Han Chenglu Song Ning Ma Piyi Du 《Journal of Physics and Chemistry of Solids》2013
(100) Oriented (PbxSr1−x)TiO3 (PST) thin films were prepared on indium tin oxide coated glass substrates by sol–gel technique with rapid thermal processing. The dielectric permittivity and tunability of the thin films with different dispersion degrees of orientation were investigated in detail by characterizing the full width at half maximum of their (100) peak based on rocking curves at different annealing temperatures. Influence of orientation dispersion on dielectric properties was exhibited in the tunable dielectric thin films. It shows that the dielectric constant and hence the tunability of the sol–gel derived PST thin films are improved with the decrease in the dispersion degree of orientation of the perovskite phase other than the increase in the content of crystalline phase in the thin films. The dielectric constant (capacitance) and figure of merit of the oriented thin films are 3–6 times and 1 times higher than that of randomly oriented thin film respectively. 相似文献
58.
Reported herein is the FeCl3-promoted intermolecular sulfoesterification of o-(1-alkynyl)benzoates with disulfides, which provides a convenient and efficient method for synthesis of 4-sulfenylisocoumarins. Various functional groups such as methoxy, halides, ester, cyano and silicon groups in the substrates are tolerated, and heterocycle-fused chalcogenylpyrones are also successfully achieved directly from the corresponding heterocyclic precursors under the same reaction conditions. In addition, starting from diynylbenzoate, this reaction sequence can be combined with a bicyclization step leading to the tetracyclic (E)-3-(2-phenyl-3-phenylchalcogenylinden-1-ylidene)isobenzofuranone frameworks with high regiospecificity and exclusive trans stereoselectivity. 相似文献
59.