全文获取类型
收费全文 | 15703篇 |
免费 | 1611篇 |
国内免费 | 828篇 |
专业分类
化学 | 6243篇 |
晶体学 | 546篇 |
力学 | 1103篇 |
综合类 | 171篇 |
数学 | 4683篇 |
物理学 | 5396篇 |
出版年
2024年 | 11篇 |
2023年 | 106篇 |
2022年 | 169篇 |
2021年 | 203篇 |
2020年 | 326篇 |
2019年 | 307篇 |
2018年 | 313篇 |
2017年 | 359篇 |
2016年 | 500篇 |
2015年 | 455篇 |
2014年 | 680篇 |
2013年 | 1267篇 |
2012年 | 709篇 |
2011年 | 1100篇 |
2010年 | 891篇 |
2009年 | 1020篇 |
2008年 | 1057篇 |
2007年 | 1146篇 |
2006年 | 1058篇 |
2005年 | 837篇 |
2004年 | 810篇 |
2003年 | 751篇 |
2002年 | 619篇 |
2001年 | 485篇 |
2000年 | 439篇 |
1999年 | 392篇 |
1998年 | 386篇 |
1997年 | 296篇 |
1996年 | 229篇 |
1995年 | 214篇 |
1994年 | 203篇 |
1993年 | 125篇 |
1992年 | 109篇 |
1991年 | 71篇 |
1990年 | 75篇 |
1989年 | 51篇 |
1988年 | 57篇 |
1987年 | 40篇 |
1986年 | 38篇 |
1985年 | 28篇 |
1984年 | 39篇 |
1983年 | 17篇 |
1982年 | 38篇 |
1981年 | 26篇 |
1980年 | 17篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
K. Kubilius 《Acta Appl Math》2003,78(1-3):233-242
We consider the integral equation driven by a standard Brownian motion and by a fractional Brownian motion. Sufficient conditions under which the equation has a weak solution are obtained. 相似文献
62.
J. T. Hoeft M. Polcik D. I. Sayago M. Kittel R. Terborg R. L. Toomes J. Robinson D. P. Woodruff M. Pascal G. Nisbet C. L. A. Lamont 《Surface science》2003,540(2-3):441-456
The local adsorption geometry of CO adsorbed in different states on Ni(1 0 0) and on Ni(1 0 0) precovered with atomic hydrogen has been determined by C 1s (and O 1s) scanned-energy mode photoelectron diffraction, using the photoelectron binding energy changes to characterise the different states. The results confirm previous spectroscopic assignments of local atop and bridge sites both with and without coadsorbed hydrogen. The measured Ni–C bondlengths for the Ni(1 0 0)/CO states show an increase of 0.16 ± 0.04 Å in going from atop to bridge sites, while comparison with similar results for Ni(1 1 1)/CO for threefold coordinated adsorption sites show a further lengthening of the bond by 0.05 ± 0.04 Å. These changes in the Ni–CO chemisorption bondlength with bond order (for approximately constant adsorption energy) are consistent with the standard Pauling rules. However, comparison of CO adsorbed in the atop geometry with and without coadsorbed hydrogen shows that the coadsorption increases the Ni–C bondlength by only 0.06 ± 0.04 Å, despite the decrease in adsorption energy of a factor of 2 or more. This result is also reproduced by density functional theory slab calculations. The results of both the experiments and the density functional theory calculations show that CO adsorption onto the Ni(1 0 0)/H surface is accompanied by significant structural modification; the low desorption energy may then be attributed to the energy cost of this restructuring rather than weak local bonding. 相似文献
63.
QiangWU DaChunYANG 《数学学报(英文版)》2005,21(1):81-94
In this paper, two classes of closely related multilinear singular and fractional integrals,which include the commutators as special cases, are studied and their boundedness on Herz type spaces is discussed. In fact, it is proved that these operators are actually not bounded in certain extreme cases. 相似文献
64.
Gabriele Bonanno 《Journal of Global Optimization》1998,12(1):101-104
In this note we introduce a suitable class of functionals, including the class of integral functionals, and prove that any (strict) local minimum of a functional of this class, defined on a decomposable space, is a (strict) global minimum. So, the recent result obtained by Giner in [1] is specified and extended. 相似文献
65.
66.
共振原子蒸气中激光脉冲的时空特性 总被引:4,自引:2,他引:2
在柱对称条件下,利用耦合的布洛赫-麦克斯韦方程,研究了激光脉冲在原子蒸气介质中的共振传播。考察了脉中在时空中的演化。数值计算结果表明激光脉冲在传播中,由于自感应透明与光波的衍射效应,表现出复杂的相干现象。 相似文献
67.
S. Albeverio S. N. Lakaev J. I. Abdullaev 《Functional Analysis and Its Applications》2002,36(3):212-216
A Hamiltonian describing four bosons that move on a lattice and interact by means of pair zero-range attractive potentials is considered. A stronger version of the Hunziker–Van Vinter–Zhislin theorem on the essential spectrum is established. It is proved that the set of eigenvalues lying to the left of the essential spectrum is finite for any interaction energy of two bosons and is empty if this energy is sufficiently small. 相似文献
68.
69.
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
70.