全文获取类型
收费全文 | 306786篇 |
免费 | 4273篇 |
国内免费 | 1426篇 |
专业分类
化学 | 171819篇 |
晶体学 | 4442篇 |
力学 | 12453篇 |
综合类 | 23篇 |
数学 | 34842篇 |
物理学 | 88906篇 |
出版年
2021年 | 1838篇 |
2020年 | 2240篇 |
2019年 | 2240篇 |
2018年 | 2102篇 |
2017年 | 2050篇 |
2016年 | 4330篇 |
2015年 | 3558篇 |
2014年 | 4593篇 |
2013年 | 13463篇 |
2012年 | 10998篇 |
2011年 | 13676篇 |
2010年 | 8339篇 |
2009年 | 8203篇 |
2008年 | 12505篇 |
2007年 | 12366篇 |
2006年 | 12064篇 |
2005年 | 11359篇 |
2004年 | 10101篇 |
2003年 | 8752篇 |
2002年 | 8544篇 |
2001年 | 9096篇 |
2000年 | 7140篇 |
1999年 | 5622篇 |
1998年 | 4486篇 |
1997年 | 4523篇 |
1996年 | 4414篇 |
1995年 | 4063篇 |
1994年 | 3808篇 |
1993年 | 3640篇 |
1992年 | 4069篇 |
1991年 | 3992篇 |
1990年 | 3623篇 |
1989年 | 3609篇 |
1988年 | 3620篇 |
1987年 | 3584篇 |
1986年 | 3366篇 |
1985年 | 4932篇 |
1984年 | 4958篇 |
1983年 | 4059篇 |
1982年 | 4536篇 |
1981年 | 4270篇 |
1980年 | 4236篇 |
1979年 | 4165篇 |
1978年 | 4337篇 |
1977年 | 4204篇 |
1976年 | 4122篇 |
1975年 | 4047篇 |
1974年 | 3785篇 |
1973年 | 4040篇 |
1972年 | 2403篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
101.
Jeroen J. L. M. Cornelissen W. Sander Graswinckel Alan E. Rowan Nico A. J. M. Sommerdijk Roeland J. M. Nolte 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1725-1736
The conformational properties of polymers derived from isocyanodipeptides have been investigated with a combination of model calculations, X‐ray diffraction, and circular dichroism spectroscopy. Depending on the configuration of the side chains, defined arrays of hydrogen bonds along the polymeric backbone are formed. This leads to a well‐defined conformation as, for example, expressed in the formation of lyotropic liquid‐crystalline phases and increased helical stability. Upon the disruption of the hydrogen bonds by a strong acid, a less well‐defined macromolecular conformation is observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1725–1736, 2003 相似文献
102.
M Lepère R Gobeille V.Malathy Devi M.A.H Smith B Aoaeh A.W Mantz 《Journal of Molecular Spectroscopy》2004,224(1):7-12
We have analyzed the methyl fluoride RQ(J,0)Q branch lines located near 1475 cm−1 using a simultaneous multi-spectrum fitting technique. In this analysis we have used previously recorded diode-laser data in which we collected many data points covering only one or two Q branch lines in a particular run. The analysis consists of simultaneously fitting 57 spectra collected with numerous pressure and path length conditions for all absorption lines. The data are concatenated to create one continuous spectrum of the Q branch. We have determined the intensity and self-broadened widths at 296 K for 23 RQ(J,0) lines. 相似文献
103.
104.
W. Hampe 《Fresenius' Journal of Analytical Chemistry》1885,24(1):588-590
Ohne Zusammenfassung 相似文献
105.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
106.
Jong Chan Lee Jin Young Park So Young Yoon Yong Hun Bae Seung Jun Lee 《Tetrahedron letters》2004,45(1):191-193
A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described. 相似文献
107.
108.
109.
X Y Liu C J Li 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(10):1215-1223
To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP. 相似文献
110.