全文获取类型
收费全文 | 9857篇 |
免费 | 370篇 |
国内免费 | 156篇 |
专业分类
化学 | 4996篇 |
晶体学 | 158篇 |
力学 | 264篇 |
综合类 | 24篇 |
数学 | 1872篇 |
物理学 | 3069篇 |
出版年
2023年 | 186篇 |
2022年 | 259篇 |
2021年 | 334篇 |
2020年 | 371篇 |
2019年 | 223篇 |
2018年 | 304篇 |
2017年 | 304篇 |
2016年 | 322篇 |
2015年 | 288篇 |
2014年 | 498篇 |
2013年 | 790篇 |
2012年 | 531篇 |
2011年 | 593篇 |
2010年 | 544篇 |
2009年 | 538篇 |
2008年 | 406篇 |
2007年 | 430篇 |
2006年 | 445篇 |
2005年 | 303篇 |
2004年 | 245篇 |
2003年 | 202篇 |
2002年 | 146篇 |
2001年 | 214篇 |
2000年 | 103篇 |
1999年 | 147篇 |
1998年 | 91篇 |
1997年 | 85篇 |
1996年 | 49篇 |
1995年 | 53篇 |
1994年 | 50篇 |
1993年 | 39篇 |
1992年 | 48篇 |
1991年 | 37篇 |
1990年 | 49篇 |
1989年 | 41篇 |
1988年 | 180篇 |
1987年 | 253篇 |
1986年 | 288篇 |
1985年 | 41篇 |
1984年 | 58篇 |
1983年 | 19篇 |
1982年 | 30篇 |
1981年 | 54篇 |
1980年 | 32篇 |
1979年 | 23篇 |
1978年 | 34篇 |
1977年 | 27篇 |
1976年 | 9篇 |
1973年 | 15篇 |
1971年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
271.
272.
Yunus Bekdemir Halil Kutuk Sibel Celik John G. Tillett 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):973-980
The acid catalysed hydrolysis of some cyclic sulfamates, X-3-(p-tolylsulfonyl)-1,2,3-benzoxathiazole 2,2-dioxides ( 1a , X = Me; 1b , X = H; 1c , X = Cl; 1d , X = NO 2 ) have been studied in concentrated aqueous sulfuric and perchloric acid solutions. Analysis of the data by the Excess Acidity Method, activation parameters, substituent, solvent deuterium isotope effect and order of the catalytic effects of the acids are all in agreement with an A-1 mechanism in the studied range. 相似文献
273.
274.
275.
Teodor M. Atanackovic Marko Janev Stevan Pilipovic Dusan Zorica 《Central European Journal of Physics》2013,11(10):1350-1360
In this work we extend our previous results and derive an expansion formula for fractional derivatives of variable order. The formula is used to determine fractional derivatives of variable order of two elementary functions. Also we propose a constitutive equation describing a solidifying material and determine the corresponding stress relaxation function. 相似文献
276.
It has been observed on the oxidized V2 O5/γ-Al2 O3 that C3H6 form alkoxides which were converted to acetone during the desorption of adsorbate phase at 373 K. C3 H8 may form π-complexes on the reduced form of the same catalyst. However, the intensities of the bands in the adadsorption of C3 H8 were very weak as compared with the case of C3 H6 adsorption. Therefore, it was not reasonable to assign these bands clearly as any of the surface type species. 相似文献
277.
278.
279.
《Photonics and Nanostructures》2014,12(1):2-8
In this work we describe an ultraviolet subwavelength focusing in plasmonic nanostructures. A system which provides a 20–25 times local field enhancement at a wavelength of 350 nm is proposed. This system represents a metalized V-shaped groove in a surface of a dielectric medium. Subwavelength focusing is achieved by a plasmon wave propagation along the surface of metal film and by the transfer of electromagnetic field through the dielectric medium. The influence of system parameters on a local field enhancement is investigated. A simplified model that allows for determining the geometric parameters of an optimized resonator is proposed. 相似文献
280.
M. V. Savina 《Physics of Atomic Nuclei》2011,74(3):496-504
A brief survey of the present-day status of the problem of multidimensional-black-hole production at accelerators according
to models featuring large extra dimensions is given. The respective production cross section and the Hawking temperature and
decay rate are estimated versus model parameters. Possible flaws and assumptions whose accurate inclusion can reduce significantly
the probability of blackhole production at accelerators in relation to earlier optimistic estimates are also discussed. 相似文献