全文获取类型
收费全文 | 130987篇 |
免费 | 1776篇 |
国内免费 | 490篇 |
专业分类
化学 | 72782篇 |
晶体学 | 2148篇 |
力学 | 5061篇 |
综合类 | 6篇 |
数学 | 12889篇 |
物理学 | 40367篇 |
出版年
2016年 | 1450篇 |
2015年 | 1165篇 |
2014年 | 1503篇 |
2013年 | 5033篇 |
2012年 | 3729篇 |
2011年 | 4791篇 |
2010年 | 2959篇 |
2009年 | 2748篇 |
2008年 | 4280篇 |
2007年 | 4352篇 |
2006年 | 4393篇 |
2005年 | 4281篇 |
2004年 | 3732篇 |
2003年 | 3340篇 |
2002年 | 3260篇 |
2001年 | 3676篇 |
2000年 | 2768篇 |
1999年 | 2265篇 |
1998年 | 1970篇 |
1997年 | 1941篇 |
1996年 | 1898篇 |
1995年 | 1863篇 |
1994年 | 1600篇 |
1993年 | 1594篇 |
1992年 | 1810篇 |
1991年 | 1794篇 |
1990年 | 1732篇 |
1989年 | 1727篇 |
1988年 | 1727篇 |
1987年 | 1718篇 |
1986年 | 1625篇 |
1985年 | 2186篇 |
1984年 | 2303篇 |
1983年 | 1922篇 |
1982年 | 2246篇 |
1981年 | 2073篇 |
1980年 | 2115篇 |
1979年 | 2081篇 |
1978年 | 2214篇 |
1977年 | 2127篇 |
1976年 | 2141篇 |
1975年 | 2075篇 |
1974年 | 1915篇 |
1973年 | 2140篇 |
1972年 | 1300篇 |
1971年 | 995篇 |
1970年 | 917篇 |
1969年 | 932篇 |
1968年 | 1062篇 |
1967年 | 1105篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
142.
We study photoproduction of jets and heavy flavors in a polarized collider mode of HERA and in polarized ep collisions at √S ≈ GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton’s polarized gluon distribution and to the completely unknown parton distributions of longitudinally polarized photons. 相似文献
143.
We provide a detailed investigation of limits of N–soliton solutions of the Toda lattice as N tends to infinity. Our principal results yield new classes of Toda solutions including, in particular, new kinds of soliton–like
(i.e., reflectionless) solutions. As a byproduct we solve an inverse spectral problem for one–dimensional Jacobi operators
and explicitly construct tri–diagonal matrices that yield a purely absolutely continuous spectrum in (-1,1) and give rise
to an eigenvalue spectrum that includes any prescribed countable and bounded subset of .
Received: 16 October 1995/Accepted: 23 July 1996 相似文献
144.
Merck W.F.H. Zatelepin V.N. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(5):947-953
The aim of this paper is to extend our knowledge about the gas-dynamic processes in arcs during immobility time. For this purpose, the conservation equations in a magnetohydrodynamic approximation were coupled with the thermochemical and Maxwell equations. Special features arc the introduction of dissociation and ionization of nitrogen and oxygen, and the simultaneous calculation of the distributions of current density and magnetic induction in the arc. Numerical calculations were performed with a reduced two-dimensional (2-D) time-dependent model. Results of the calculations were compared with measurements. The development in time of the measured and calculated are voltage and arc chamber pressure show very good agreement. The pumping effect of the double vortex in the arc region was confirmed by optical measurements. It is concluded that the three-layer model is a good representation for the main physical features during the immobility time, and that the presence of highly conducting gas in the downstream region of the arc is essential for its downstream movement 相似文献
145.
A. Hoffknecht O. Uwira A. Frank S. Schennach W. Spies M. Wagner S. Schippers A. Müller R. Becker M. Kleinod N. Angert P.H. Mokler 《Hyperfine Interactions》1998,114(1-4):257-261
The origin of the widely observed enhancement of rates for electron-ion recombination at very low energies is still unknown.
We investigated the recombination of Au25+ with free electrons in a merged-beams experiment at the UNILAC accelerator of the GSI in Darmstadt. At E
rel= 0 eV we found an enormous enhancement factor of 365 compared to the theory of radiative recombination. An increase of the
electron density by a factor of 10 had not much influence on the measured rate coefficient.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
146.
147.
148.
Studies that focus on the decision making process can be classified in (at least) two ways: by psychological content and by contextual content. The first describes the degree to which the analysis focuses on the mental processes associated with decision making and the second deals with the degree to which the analysis is dependent upon the study's context. Several studies are examined in terms of where they fall in this two-dimensional taxonomy. Two analyses of maritime command and control conducted by the authors are examined more fully within this taxonomy. Both are context full, but are at opposite ends of the psychological content spectrum. These categorizations are useful in focusing future research aimed at developing models of decision making. 相似文献
149.
150.