全文获取类型
收费全文 | 6687篇 |
免费 | 445篇 |
国内免费 | 15篇 |
专业分类
化学 | 5164篇 |
晶体学 | 44篇 |
力学 | 76篇 |
数学 | 778篇 |
物理学 | 1085篇 |
出版年
2023年 | 57篇 |
2022年 | 67篇 |
2021年 | 111篇 |
2020年 | 203篇 |
2019年 | 196篇 |
2018年 | 82篇 |
2017年 | 103篇 |
2016年 | 273篇 |
2015年 | 254篇 |
2014年 | 312篇 |
2013年 | 357篇 |
2012年 | 490篇 |
2011年 | 519篇 |
2010年 | 305篇 |
2009年 | 255篇 |
2008年 | 400篇 |
2007年 | 377篇 |
2006年 | 343篇 |
2005年 | 286篇 |
2004年 | 267篇 |
2003年 | 216篇 |
2002年 | 203篇 |
2001年 | 122篇 |
2000年 | 104篇 |
1999年 | 81篇 |
1998年 | 80篇 |
1997年 | 94篇 |
1996年 | 78篇 |
1995年 | 94篇 |
1994年 | 102篇 |
1993年 | 80篇 |
1992年 | 69篇 |
1991年 | 52篇 |
1990年 | 38篇 |
1989年 | 60篇 |
1988年 | 33篇 |
1987年 | 30篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 26篇 |
1983年 | 15篇 |
1982年 | 19篇 |
1981年 | 23篇 |
1980年 | 25篇 |
1979年 | 26篇 |
1978年 | 27篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 16篇 |
1973年 | 13篇 |
排序方式: 共有7147条查询结果,搜索用时 281 毫秒
11.
12.
13.
T. Engel M. Würtz S. Borneis St. Becker I. Klaft A. Kohl T. Kühl F. Laeri D. Marx K. Meier R. Neumann F. Schmitt P. Seelig L. Völker 《Hyperfine Interactions》1997,108(1-3):251-258
Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening
is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser
systems specialized on the specific needs of laser spectroscopy at storage rings is reported.
Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different
Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast
qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator.
It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a
frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz.
This laser can be advantageous for laser cooling of ion beams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
The contributions to the coefficient functions of the quark and the mixed quark-gluon condensate to mesonic correlators are calculated for the first time to all orders in the quark masses, and to lowest order in the strong coupling constant. Existing results on the coefficient functions of the unit operator and the gluon condensate are reviewed. The proper factorization of short- and long-distance contributions in the operator product expansion is discussed in detail. It is found that to accomplish this task rigorously the operator product expansion has to be performed in terms ofnon-normal-ordered condensates. The resulting coefficient functions are improved with the help of the renormalization group. The scale invariant combination of dimension 5 operators, including mixing with the mass operator, which is needed for the renormalization group improvement, is calculated in the leading order.Supported by the German Bundesministerium für Forschung und Technologie, under the contract 06 TM 761 相似文献
15.
We derive a moderate deviation principle for the lower tail probabilities of the length of a longest increasing subsequence in a random permutation. It refers to the regime between the lower tail large deviation regime and the central limit regime. The present article together with the upper tail moderate deviation principle in Ref. 12 yields a complete picture for the whole moderate deviation regime. Other than in Ref. 12, we can directly apply estimates by Baik, Deift, and Johansson, who obtained a (non-standard) Central Limit Theorem for the same quantity. 相似文献
16.
Matthias Kriesell 《Graphs and Combinatorics》2002,18(1):133-146
Let k≤n be positive integers. A finite, simple, undirected graph is called k-critically n-connected, or, briefly, an (n,k)-graph, if it is noncomplete and n-connected and the removal of any set X of at most k vertices results in a graph which is not (n−|X|+1)-connected. We present some new results on the number of vertices of an (n,k)-graph, depending on new estimations of the transversal number of a uniform hypergraph with a large independent edge set.
Received: April 14, 2000 Final version received: May 8, 2001 相似文献
17.
A magic labelling of a set system is a labelling of its points by distinct positive integers so that every set of the system has the same sum,
the magic sum. Examples are magic squares (the sets are the rows, columns, and diagonals) and semimagic squares (the same, but without
the diagonals). A magilatin labelling is like a magic labelling but the values need be distinct only within each set. We show that the number of n × n magic or magilatin labellings is a quasipolynomial function of the magic sum, and also of an upper bound on the entries in
the square. Our results differ from previous ones because we require that the entries in the square all be different from
each other, and because we derive our results not by ad hoc reasoning but from a general theory of counting lattice points in rational inside-out polytopes. We also generalize from
set systems to rational linear forms.
Dedicated to the memory of Claudia Zaslavsky, 1917–2006
Received August 10, 2005 相似文献
18.
19.
The parallel version of precondition techniques is developed for matrices arising from the Galerkin boundary element method for two-dimensional domains with Dirichlet boundary conditions. Results were obtained for implementations on a transputer network as well as on an nCUBE-2 parallel computer showing that iterative solution methods are very well suited for a MIMD computer. A comparison of numerical results for iterative and direct solution methods is presented and underlines the superiority of iterative methods for large systems. 相似文献