全文获取类型
收费全文 | 162274篇 |
免费 | 7710篇 |
国内免费 | 4785篇 |
专业分类
化学 | 94176篇 |
晶体学 | 2519篇 |
力学 | 7360篇 |
综合类 | 290篇 |
数学 | 16490篇 |
物理学 | 53934篇 |
出版年
2022年 | 1688篇 |
2021年 | 1851篇 |
2020年 | 2125篇 |
2019年 | 2007篇 |
2018年 | 1867篇 |
2017年 | 1723篇 |
2016年 | 3031篇 |
2015年 | 2728篇 |
2014年 | 3438篇 |
2013年 | 7431篇 |
2012年 | 6567篇 |
2011年 | 7683篇 |
2010年 | 4993篇 |
2009年 | 4749篇 |
2008年 | 6354篇 |
2007年 | 6155篇 |
2006年 | 6101篇 |
2005年 | 5569篇 |
2004年 | 4740篇 |
2003年 | 4235篇 |
2002年 | 4056篇 |
2001年 | 4344篇 |
2000年 | 3502篇 |
1999年 | 2992篇 |
1998年 | 2593篇 |
1997年 | 2532篇 |
1996年 | 2478篇 |
1995年 | 2379篇 |
1994年 | 2076篇 |
1993年 | 1958篇 |
1992年 | 2169篇 |
1991年 | 2064篇 |
1990年 | 1974篇 |
1989年 | 1915篇 |
1988年 | 1887篇 |
1987年 | 1841篇 |
1986年 | 1735篇 |
1985年 | 2283篇 |
1984年 | 2362篇 |
1983年 | 1958篇 |
1982年 | 2269篇 |
1981年 | 2063篇 |
1980年 | 2089篇 |
1979年 | 2068篇 |
1978年 | 2186篇 |
1977年 | 2092篇 |
1976年 | 2115篇 |
1975年 | 2053篇 |
1974年 | 1895篇 |
1973年 | 2102篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A classic 1970 paper of B. Muckenhoupt established necessary and sufficient conditions for weightedL
p
convergence of Hermite series, that is, orthogonal expansions corresponding to the Hermite weight. We generalize these to orthogonal expansions for a class of Freud weightsW
2:=e
–2Q
, by first proving a bound for the difference of the orthonormal polynomials of degreen+1 andn–1 of the weightW
2. Our identical necessary and sufficient conditions close a slight gap in Muckenhoupt's conditions for the Hermite weight at least forp>1. Moreover, our necessary conditions apply whenQ(x)=|x|, >1 while our sufficient conditions apply at least for =2,4,6,....Communicated by Vilmos Totik. 相似文献
992.
It is shown how to represent algebraically all functions that have a zero sum on all -dimensional subspaces ofPG(n,q) or ofAG(n,q). In this way one can calculate the dimensions of related codes, or one can represent interesting sets of points by functions. 相似文献
993.
994.
995.
Pochodzalla J Möhlenkamp T Rubehn T Schüttauf A Wörner A Zude E Begemann-Blaich M Blaich T Emling H Ferrero A Gross C Immé G Iori I Kunde GJ Kunze WD Lindenstruth V Lynen U Moroni A Müller WF Ocker B Raciti G Sann H Schwarz C Seidel W Serfling V Stroth J Trautmann W Trzcinski A Tucholski A Verde G Zwieglinski B 《Physical review letters》1995,75(6):1040-1043
996.
Artuso M Gao M Goldberg M He D Horwitz N Moneti GC Mountain R Muheim F Mukhin Y Playfer S Rozen Y Stone S Xing X Zhu G Bartelt J Csorna SE Egyed Z Jain V Gibaut D Kinoshita K Pomianowski P Barish B Chadha M Chan S Cowen DF Eigen G Miller JS O'Grady C Urheim J Weinstein AJ Würthwein F Asner DM Athanas M Bliss DW Brower WS Masek G Paar HP Gronberg J Korte CM Kutschke R Menary S Morrison RJ Nakanishi S Nelson HN Nelson TK Qiao C Richman JD Roberts D Ryd A Tajima H Witherell MS Balest R Cho K 《Physical review letters》1995,75(5):785-789
997.
Martin Anderle Herwig Schweng Karl E. Kürten Karl W. Kratky 《Journal of statistical physics》1995,81(3-4):843-849
We present evidence that the performance of the traditional fully connected Hopfield model can be dramatically improved by carefully selecting an information-specific connectivity structure, while the synaptic weights of the selected connections are the same as in the Hopfield model. Starting from a completely disconnected network we let genuine Hebbian synaptic connections grow, one by one, until a desired degree of stability is achieved. Neural pathways are thus fixed notbefore, butduring the learning phase. 相似文献
998.
C. E. I. Carneiro M. J. de Oliveira W. F. Wreszinski 《Journal of statistical physics》1995,79(1-2):347-376
We show rigorously that the ground state of a quantum chain with competing ferromagnetic nearest and antiferromagnetic next nearest interactions undergoes a transition from ferromagnetic to helical type, in the isotropic case, for a certain value of the relevant ratio of coupling constants. Boundaries of the phase diagram are also determined in the anisotropic case. The stability of a special quantum state (corresponding to a classical modulated phase of =/3) is analyzed by an extension of Holstein-Primakoff arguments, along a line of constant ratio of couplings, showing in particular a sequence of (instability) gaps. Finally, a natural adaptation of a variational wave function due to Huse and Elser is used to study several portions of the phase diagram, with very good agreement with previous theoretical results. 相似文献
999.
1000.
W. U. Boeglin 《Czechoslovak Journal of Physics》1995,45(4-5):295-335
Coincidence experiments with electrons provide new information on the structure of nucleons and nuclei. Using new CW accelerators, kinematic regions can be explored with high precision which have not been accessible previously. The equipment and the necessary steps in the analysis of (e,ep) experiments will be discussed and illustrated with new data taken at the MAMI facility.Lectures given at the Indian-Summer School on Electron Scattering of Nucleons and Nuclei, Prague (Czech Republic), September 1994. 相似文献