全文获取类型
收费全文 | 127396篇 |
免费 | 1631篇 |
国内免费 | 461篇 |
专业分类
化学 | 70792篇 |
晶体学 | 2041篇 |
力学 | 4972篇 |
综合类 | 5篇 |
数学 | 12316篇 |
物理学 | 39362篇 |
出版年
2016年 | 1337篇 |
2015年 | 1072篇 |
2014年 | 1401篇 |
2013年 | 4938篇 |
2012年 | 3575篇 |
2011年 | 4590篇 |
2010年 | 2838篇 |
2009年 | 2644篇 |
2008年 | 4089篇 |
2007年 | 4154篇 |
2006年 | 4234篇 |
2005年 | 4158篇 |
2004年 | 3592篇 |
2003年 | 3272篇 |
2002年 | 3169篇 |
2001年 | 3594篇 |
2000年 | 2697篇 |
1999年 | 2210篇 |
1998年 | 1903篇 |
1997年 | 1901篇 |
1996年 | 1824篇 |
1995年 | 1791篇 |
1994年 | 1556篇 |
1993年 | 1545篇 |
1992年 | 1769篇 |
1991年 | 1759篇 |
1990年 | 1691篇 |
1989年 | 1692篇 |
1988年 | 1687篇 |
1987年 | 1686篇 |
1986年 | 1598篇 |
1985年 | 2148篇 |
1984年 | 2274篇 |
1983年 | 1892篇 |
1982年 | 2222篇 |
1981年 | 2029篇 |
1980年 | 2079篇 |
1979年 | 2064篇 |
1978年 | 2189篇 |
1977年 | 2092篇 |
1976年 | 2118篇 |
1975年 | 2054篇 |
1974年 | 1897篇 |
1973年 | 2102篇 |
1972年 | 1282篇 |
1971年 | 975篇 |
1970年 | 912篇 |
1969年 | 923篇 |
1968年 | 1050篇 |
1967年 | 1101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
193.
In the nineteenth century, field theory brilliantly resolveda number of questions that had taxed mathematicians for centuries;for example, The circle cannot be squared by straightedge and compass, and solving polynomial equations by radicalsis not always possible. These successes have continued to beheld up as superb examples of the power of mathematical thought,and are demonstrated at an undergraduate level. The purposeof this article is to provide another such natural example whichleads to a concrete realisation of the free group on 2 generators. 相似文献
194.
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
195.
196.
We present an update of Garland's work on the cohomology of certain groups, construct a class of groups many of which satisfy
Kazhdan's Property (T) and show that properly discontinuous and cocompact groups of automorphisms of (4,4) or (6,3)-complexes
do not satisfy Property (T).
Submitted: September 1996, final version: March 1997 相似文献
197.
Magnetic Properties of the Cobaltates Na6CoS4, Na6CoSe4, and K6CoS4 The alkali metal cobalt chalcogenides Na6CoS4, Na6CoSe4, and K6CoS4 crystallize in the space group P63mc with Z = 4. The structure is characterized by isolated [CoX4]-tetrahedra. The magnetic susceptibilities show Curie-Weiss behaviour. The deviations at low temperatures are caused by antiferromagnetic interactions. The magnetic moments are discussed with regard to ligand-field parameters. 相似文献
198.
The results of Monte Carlo simulations of the beta dose rate to enamel are presented. The dose rates are the most comprehensive to date, incorporating the beta spectrum from 21 different radionuclides, all internal conversion and Auger electrons, the majority of the bremsstrahlung radiation, effects due to radon loss in the uranium series, and variations in the moisture content of the sediment. Applications to a new dating technique in archaeology using electron spin resonance and beta-gradient isochrons are discussed. 相似文献
199.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
200.
M. W. Brenner K. A. Gridnev S. E. Belov W. Ershov E. Indola 《Physics of Atomic Nuclei》2002,65(4):612-615
The interaction of α particles above 5 MeV with a 2s-1d target is dominated by resonances. It cannot be described only in terms of a mean-field one-body potential. An analysis of the elastic α-particle scattering by 28Si encourages the comprehension of the resonance states to be mainly fragments of a mixed-parity band. In the present article, the angular distributions of particles scattered by 32S are analyzed in terms of such bands. The analysis of new data from an experiment made at Florida State University reveals the existence of states that do not belong to the above bands. This follows from a coupled-channel analysis of the elastic and inelastic (2+) cross sections. An α-particle structure at the nuclear surface is suggested. 相似文献