全文获取类型
收费全文 | 282525篇 |
免费 | 3452篇 |
国内免费 | 1183篇 |
专业分类
化学 | 155276篇 |
晶体学 | 4227篇 |
力学 | 11887篇 |
综合类 | 12篇 |
数学 | 30240篇 |
物理学 | 85518篇 |
出版年
2020年 | 1850篇 |
2019年 | 1802篇 |
2018年 | 1775篇 |
2016年 | 3650篇 |
2015年 | 2909篇 |
2014年 | 3817篇 |
2013年 | 12205篇 |
2012年 | 9397篇 |
2011年 | 11888篇 |
2010年 | 7379篇 |
2009年 | 7334篇 |
2008年 | 10857篇 |
2007年 | 10846篇 |
2006年 | 10572篇 |
2005年 | 9994篇 |
2004年 | 8913篇 |
2003年 | 7735篇 |
2002年 | 7674篇 |
2001年 | 8779篇 |
2000年 | 6811篇 |
1999年 | 5354篇 |
1998年 | 4251篇 |
1997年 | 4256篇 |
1996年 | 4139篇 |
1995年 | 3863篇 |
1994年 | 3573篇 |
1993年 | 3434篇 |
1992年 | 3883篇 |
1991年 | 3831篇 |
1990年 | 3464篇 |
1989年 | 3472篇 |
1988年 | 3474篇 |
1987年 | 3432篇 |
1986年 | 3242篇 |
1985年 | 4679篇 |
1984年 | 4725篇 |
1983年 | 3854篇 |
1982年 | 4315篇 |
1981年 | 4099篇 |
1980年 | 4052篇 |
1979年 | 4026篇 |
1978年 | 4202篇 |
1977年 | 4062篇 |
1976年 | 4021篇 |
1975年 | 3938篇 |
1974年 | 3688篇 |
1973年 | 3978篇 |
1972年 | 2361篇 |
1971年 | 1732篇 |
1967年 | 1739篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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
72.
JETP Letters - The problem of storing ultracold neutrons over a plane magnetic mirror in the presence of gravity is considered. For neutrons with a definite polarization, the sum of the magnetic... 相似文献
73.
74.
W. Hampe 《Fresenius' Journal of Analytical Chemistry》1885,24(1):588-590
Ohne Zusammenfassung 相似文献
75.
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
76.
77.
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
78.
The disturbance of sleep by traffic noise is a major problem area in noise pollution. Extensive laboratory tests using multichannel electroencephalograms (EEG) have been carried out by many workers to determine the general response of people when exposed to noise during sleep. An experimental technique for obtaining results in people's homes has been developed using a simplified one-channel EEG. The responses of six people in the age range 19-24 were measured. A significant correlation was found between sleep disturbance and traffic noise when the noise is expressed in EPNdB. In the home experiments the subjects appeared to be approximately 10 dB less sensitive to noises than laboratory subjects for similar noise exposure. There also appeared to be some adaptation to the noise exposure; however, only one subject was tested for a period of 20 days and was insufficient to give definite results on adaptation. 相似文献
79.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
80.
H E Cline W E Lorensen R J Herfkens G A Johnson G H Glover 《Magnetic resonance imaging》1989,7(1):45-54
A three-dimensional examination of blood vessels is provided using MR data from seven cases. The vascular surfaces are constructed with an algorithm that automatically follows the selected artery or vein and generates a projected three-dimensional gradient shaded image. Fast 3DFT pulse sequences were optimized to enhance the time-of-flight contrast of the intravascular region. By increasing the surface threshold value in a three-dimensional head study, the flesh of a patient's face was peeled away to demonstrate the superfacial temporal artery. Gated cardiac images show the great vessels and cardiac chambers. A three-dimensional view of the aorta shows an irregular surface in the vicinity of an adrenal tumor. 3D MR exams provide a non-invasive technique for assessing vascular morphology in a clinical setting. 相似文献