全文获取类型
收费全文 | 26710篇 |
免费 | 1300篇 |
国内免费 | 9692篇 |
专业分类
化学 | 21709篇 |
晶体学 | 403篇 |
力学 | 176篇 |
综合类 | 379篇 |
数学 | 202篇 |
物理学 | 1664篇 |
综合类 | 13169篇 |
出版年
2024年 | 81篇 |
2023年 | 318篇 |
2022年 | 403篇 |
2021年 | 513篇 |
2020年 | 496篇 |
2019年 | 473篇 |
2018年 | 368篇 |
2017年 | 502篇 |
2016年 | 592篇 |
2015年 | 718篇 |
2014年 | 1578篇 |
2013年 | 1406篇 |
2012年 | 1394篇 |
2011年 | 1644篇 |
2010年 | 1639篇 |
2009年 | 1833篇 |
2008年 | 2060篇 |
2007年 | 1825篇 |
2006年 | 1900篇 |
2005年 | 1975篇 |
2004年 | 1912篇 |
2003年 | 1922篇 |
2002年 | 1805篇 |
2001年 | 1656篇 |
2000年 | 1346篇 |
1999年 | 1077篇 |
1998年 | 1036篇 |
1997年 | 774篇 |
1996年 | 725篇 |
1995年 | 729篇 |
1994年 | 592篇 |
1993年 | 404篇 |
1992年 | 455篇 |
1991年 | 472篇 |
1990年 | 431篇 |
1989年 | 341篇 |
1988年 | 134篇 |
1987年 | 66篇 |
1986年 | 39篇 |
1985年 | 27篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1959年 | 1篇 |
1957年 | 6篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
51.
JiangMinCHEN LuLingWU XianHUANG 《中国化学快报》2004,15(2):143-144
2,5-Disubstituted oxazoles were prepared conveniently by treatment of aromatic α-methyl ketones and nitriles with poly[styrene(iodosodiacetate)] in one-pot process. 相似文献
52.
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
53.
The First Intramolecular Charge Transfer Transition Based on 2-Ureido-4[1H]-pyrimidinone Binding Module 总被引:1,自引:0,他引:1
The first intramolecular charge transfer transition based on 2-ureido-4[1H]-pyrimidinone binding module was reported. 相似文献
54.
Solid Phase Synthesis of 2-Substituted 1,3-Oxazin-6-ones Using Resin-bound Cyclic Malonic Acid Ester
A facile solid phase synthesis of 2-substituted 1,3-oxazin-6-ones using polymer-supported Meldrum‘s acid has been reported. Reaction of the resin-bound cyclic malonic acid ester with triethyl orthoformate and subsequent double substitution with amide, afforded the corresponding polymer-supported acylaminomethylene cyclic malonic acid ester, which upon thermal treatment led to 1, 3-oxazin-6-ones in good yields and with high purity. 相似文献
55.
Zeolite A rods by self-assembly of zeolite A microcrystal were successfully synthesized by microwave-assisted hydrotherrnal synthesis. The average size of zeolite crystals consisting of self-assembling materials was about 300 nm and the length of zeolite rods was in the range of 15--30μm. 相似文献
56.
JingXiaWANG ChengYouKAN DeShanLIU 《中国化学快报》2004,15(10):1161-1163
Two novel polymerizable dyes with anthraquinone residue have been prepared, and their structures were characterized by FTIR, ^1HNMR and EA. 相似文献
57.
WeiMinSHI JianWU YiFengWU KaiXianQIAN 《中国化学快报》2004,15(12):1427-1429
A mono-funtionalised tetraphenylporphyrin (TPP) bearing valine moiety at the phenyl ring was synthesized for photocytotoxicity examination in four steps, starting from regiospecific mono-nitration of TPP at the phenyl ring. The in vitro photocytotoxicitic effect against SPC-Al adenocarcinona cell line was tested. 相似文献
58.
A positive Mg-Al-nitrate layered double hydroxides(LDHs) has been synthesized using a non-steady coprecipitation method.The shape.size,chemical composition,electrical property and anion exchange property of the positve nanoparticle were studied by SEM,XRD,FTIR,chemical analysis,spectroanalysis and meaxsuring of electrophoretic mobilities.Preliminary results show the positive nanoparticle is a promising precursor of polymer/LDHs nanocomposite. 相似文献
59.
60.