全文获取类型
收费全文 | 151719篇 |
免费 | 1958篇 |
国内免费 | 683篇 |
专业分类
化学 | 86274篇 |
晶体学 | 2159篇 |
力学 | 5580篇 |
综合类 | 6篇 |
数学 | 17342篇 |
物理学 | 42999篇 |
出版年
2016年 | 1835篇 |
2015年 | 1564篇 |
2014年 | 1936篇 |
2013年 | 6125篇 |
2012年 | 4678篇 |
2011年 | 5958篇 |
2010年 | 3631篇 |
2009年 | 3287篇 |
2008年 | 5293篇 |
2007年 | 5334篇 |
2006年 | 5457篇 |
2005年 | 5259篇 |
2004年 | 4700篇 |
2003年 | 4168篇 |
2002年 | 4022篇 |
2001年 | 4013篇 |
2000年 | 3063篇 |
1999年 | 2565篇 |
1998年 | 2243篇 |
1997年 | 2283篇 |
1996年 | 2183篇 |
1995年 | 2108篇 |
1994年 | 1918篇 |
1993年 | 1868篇 |
1992年 | 2051篇 |
1991年 | 2051篇 |
1990年 | 1945篇 |
1989年 | 1953篇 |
1988年 | 1928篇 |
1987年 | 1883篇 |
1986年 | 1821篇 |
1985年 | 2474篇 |
1984年 | 2611篇 |
1983年 | 2196篇 |
1982年 | 2547篇 |
1981年 | 2320篇 |
1980年 | 2390篇 |
1979年 | 2322篇 |
1978年 | 2470篇 |
1977年 | 2360篇 |
1976年 | 2330篇 |
1975年 | 2239篇 |
1974年 | 2080篇 |
1973年 | 2262篇 |
1972年 | 1388篇 |
1971年 | 1064篇 |
1970年 | 1005篇 |
1969年 | 981篇 |
1968年 | 1097篇 |
1967年 | 1147篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Peter Naur 《BIT Numerical Mathematics》1986,26(2):175-187
The questions raised by A. M. Turing in his paper on thought and machines are discussed. Human thought is considered in turn as a concept of normal language usage, as a basic concept of psychology, and as the basis of intellectual activity. It is concluded that neither of these notions of thought identifies something specific that a human being can or cannot do. The imitation game proposed by Turing for deciding whether a machine can think is found to result from an arbitrary empoverishment of the channel of communication between the interrogator and the item under investigation. Turing's notions of thinking are shown to lead to logical difficulties. An alternative view of consciousness, that would place it beyond the reach of any finite test, is finally discussed. 相似文献
93.
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
94.
This paper shows that the dimension of internal structure of a component can be measured remotely to a resolution better than 5 μm by use of the combination of high resolution optical microscopy and image processing.A specialised high resolution, long working distance and diffraction limited lens was used to image within the component. A series of digital images were made to map spatially the interior of the component. An edge detector was then used to localise the specific location of features in order that an accurate internal measurement could be made. A visualisation of the internal surface finish was also achieved. 相似文献
95.
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
96.
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
97.
98.
99.
100.