全文获取类型
收费全文 | 19297篇 |
免费 | 2443篇 |
国内免费 | 16456篇 |
专业分类
化学 | 28828篇 |
晶体学 | 409篇 |
力学 | 888篇 |
综合类 | 704篇 |
数学 | 2080篇 |
物理学 | 5287篇 |
出版年
2024年 | 147篇 |
2023年 | 628篇 |
2022年 | 724篇 |
2021年 | 770篇 |
2020年 | 608篇 |
2019年 | 633篇 |
2018年 | 508篇 |
2017年 | 641篇 |
2016年 | 745篇 |
2015年 | 816篇 |
2014年 | 1469篇 |
2013年 | 1389篇 |
2012年 | 1232篇 |
2011年 | 1258篇 |
2010年 | 1322篇 |
2009年 | 1382篇 |
2008年 | 1525篇 |
2007年 | 1434篇 |
2006年 | 1494篇 |
2005年 | 1492篇 |
2004年 | 1487篇 |
2003年 | 1515篇 |
2002年 | 1375篇 |
2001年 | 1486篇 |
2000年 | 1155篇 |
1999年 | 1043篇 |
1998年 | 985篇 |
1997年 | 977篇 |
1996年 | 949篇 |
1995年 | 914篇 |
1994年 | 1066篇 |
1993年 | 883篇 |
1992年 | 842篇 |
1991年 | 787篇 |
1990年 | 696篇 |
1989年 | 771篇 |
1988年 | 254篇 |
1987年 | 219篇 |
1986年 | 194篇 |
1985年 | 155篇 |
1984年 | 95篇 |
1983年 | 97篇 |
1982年 | 19篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
61.
2H-1,2,3-Diazaphospholes 3a-3h were prepared from various ketone acylhydrazones and phosphorus trichloride in the presence of triethylamine. Compounds 3 underwent feasible hetero-Diels-Alder reactions with cyclopentadiene to afford the respective anellated [1,2,3]diazaphospholes 4a--4d as well as 4a‘--4d‘ in moderate yields. The endo rule in the reaction was observed under kinetic control conditions. 相似文献
62.
The polyacrylic acid functionalized polystyrene nanospheres were synthesized and self-assembled into irregular, densely packed monolayers in non-aqueous media. The polymer nanoparticles were chemically adhered to substrates. The morphologies of the resulting films were investigated. The impact of the volume fraction of alcohol in the mixed solvents on the particle adsorption and fabrication of nanosphere assembled films was examined. 相似文献
63.
NianYuanTAN XiaoMingXIAO ZeLinLI TakekoMATSUMURA-INOUE 《中国化学快报》2004,15(6):687-690
A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol-2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis,electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra. 相似文献
64.
FengSHI HongYangLI XiaoJunPENG RongZHANG XiaoQiangCHEN JiangLiFAN LiChengSUN 《中国化学快报》2004,15(12):1407-1410
As photosensitizer for solar cell, a new ruthenium (Ⅱ) complex with four ester groups had been synthesized, in which a phenol substituted by {[(2-hydroxy-5-tert-butylbenzyl)(pyridyl-2-methyl)amino]methyl} is covalently linked to ruthenium (Ⅱ) tris-bipyridine. The structures of the new compounds were confirmed by NMR and ESI-MS spectra. The electrochemical and photochemical properties were also studied. 相似文献
65.
DongXiangLI WanGuoHOU ShuPingLI MingTuHAO GaoYongZHANG 《中国化学快报》2004,15(2):224-227
The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc,which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations. 相似文献
66.
LinBAI JinXianWANG 《中国化学快报》2004,15(3):286-287
A simple, rapid and environmental friendly method for the synthesis of biaryl compounds under microwave irradiation is reported. 相似文献
67.
PinHuaLI LeiWANG MinWANG JinCanYAN 《中国化学快报》2004,15(11):1295-1298
A Glaser coupling reaction of terminal alkynes in the presence of nickel chloride withoutany organics and bases in hot water has been developed, which produces the correspondinghomo-coupling products in good yields. 相似文献
68.
XiangBaoMENG HuiLI QingLI ZhongJunLI 《中国化学快报》2004,15(7):777-778
An unusual reductive ring-opening reaction of phthalimide with sodium hydride in anhydrous DMF was observed for the first time. The presumed mechanism was described in detail. 相似文献
69.
70.
在硝酸介质中,痕量铬(Ⅵ)能灵敏的催化氧化DBC褪色。研究了反应的最佳条件,建立了测定痕量铬(Ⅵ)的新方法。检出限可达10^-9g/ml,测定范围为0.12--0.7μgCrC(Ⅵ)/10ml,方法简便、灵敏、快速、准确。用于测定水中的痕量铬(Ⅵ),获得了满意的结果。 相似文献