全文获取类型
收费全文 | 171388篇 |
免费 | 2325篇 |
国内免费 | 718篇 |
专业分类
化学 | 92413篇 |
晶体学 | 2467篇 |
力学 | 7610篇 |
综合类 | 7篇 |
数学 | 17756篇 |
物理学 | 54178篇 |
出版年
2021年 | 1001篇 |
2020年 | 1131篇 |
2019年 | 1150篇 |
2018年 | 1161篇 |
2017年 | 1172篇 |
2016年 | 2337篇 |
2015年 | 1920篇 |
2014年 | 2493篇 |
2013年 | 7713篇 |
2012年 | 6292篇 |
2011年 | 7963篇 |
2010年 | 4892篇 |
2009年 | 5041篇 |
2008年 | 7331篇 |
2007年 | 7304篇 |
2006年 | 7049篇 |
2005年 | 6561篇 |
2004年 | 5884篇 |
2003年 | 5072篇 |
2002年 | 4974篇 |
2001年 | 6035篇 |
2000年 | 4571篇 |
1999年 | 3481篇 |
1998年 | 2629篇 |
1997年 | 2628篇 |
1996年 | 2572篇 |
1995年 | 2282篇 |
1994年 | 2169篇 |
1993年 | 2036篇 |
1992年 | 2355篇 |
1991年 | 2312篇 |
1990年 | 2027篇 |
1989年 | 2014篇 |
1988年 | 2033篇 |
1987年 | 1965篇 |
1986年 | 1879篇 |
1985年 | 2785篇 |
1984年 | 2764篇 |
1983年 | 2212篇 |
1982年 | 2403篇 |
1981年 | 2282篇 |
1980年 | 2235篇 |
1979年 | 2183篇 |
1978年 | 2253篇 |
1977年 | 2210篇 |
1976年 | 2137篇 |
1975年 | 2126篇 |
1974年 | 2030篇 |
1973年 | 2114篇 |
1972年 | 1203篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
By using two sections of erbium doped fiber and a fiber optical reflector, a novel, highly efficient L bandamplifier is demonstrated with significantly power-conversion-efficiency enhancement and the gain increasing of as much as 13 dB. 相似文献
142.
C.-G. Duan L.-H. Song L.-J. Huo G.-L. Li 《The European Physical Journal C - Particles and Fields》2003,29(4):557-561
The energy loss effect in nuclear matter, which is a nuclear effect apart from the nuclear effect on the parton distribution as in deep-inelastic scattering process, can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the nuclear parton distribution studied only with lepton deep-inelastic scattering experimental data, the measured Drell-Yan production cross sections for 800 GeV proton incident on a variety of nuclear targets are analyzed within the Glauber framework which takes into account the energy loss of the beam proton. It is shown that the theoretical results with considering the energy loss effect are in good agreement with the FNAL E866 data.Arrival of the final proofs: 24 June 2003 相似文献
143.
144.
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
145.
J.-C. Thomas L. Achouri J. Äystö R. Béraud B. Blank G. Canchel S. Czajkowski P. Dendooven A. Ensallem J. Giovinazzo N. Guillet J. Honkanen A. Jokinen A. Laird M. Lewitowicz C. Longour F. de Oliveira Santos K. Peräjärvi M. Stanoiu 《The European Physical Journal A - Hadrons and Nuclei》2004,21(3):419-435
146.
147.
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
148.
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
149.
Jeannette H. C. Woerner 《商业与工业应用随机模型》2005,21(1):27-44
In the framework of stochastic volatility models we examine estimators for the integrated volatility based on the pth power variation (i.e. the sum of pth absolute powers of the log‐returns). We derive consistency and distributional results for the estimators given high‐frequency data, especially taking into account what kind of process we may add to our model without affecting the estimate of the integrated volatility. This may on the one hand be interpreted as a possible flexibility in modelling, for example adding jumps or even leaving the framework of semimartingales by adding a fractional Brownian motion, or on the other hand as robustness against model misspecification. We will discuss possible choices of p under different model assumptions and irregularly spaced data. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
150.