全文获取类型
收费全文 | 45856篇 |
免费 | 259篇 |
国内免费 | 300篇 |
专业分类
化学 | 31754篇 |
晶体学 | 8篇 |
力学 | 324篇 |
综合类 | 8篇 |
数学 | 303篇 |
物理学 | 14018篇 |
出版年
2022年 | 23篇 |
2018年 | 29篇 |
2017年 | 19篇 |
2016年 | 40篇 |
2015年 | 20篇 |
2014年 | 63篇 |
2013年 | 55篇 |
2012年 | 3850篇 |
2011年 | 5496篇 |
2010年 | 927篇 |
2009年 | 185篇 |
2008年 | 4243篇 |
2007年 | 4353篇 |
2006年 | 4382篇 |
2005年 | 4178篇 |
2004年 | 3476篇 |
2003年 | 2522篇 |
2002年 | 2279篇 |
2001年 | 1523篇 |
2000年 | 1743篇 |
1999年 | 421篇 |
1998年 | 144篇 |
1997年 | 152篇 |
1996年 | 758篇 |
1995年 | 541篇 |
1994年 | 691篇 |
1993年 | 905篇 |
1992年 | 817篇 |
1991年 | 356篇 |
1990年 | 387篇 |
1989年 | 312篇 |
1988年 | 244篇 |
1987年 | 222篇 |
1986年 | 277篇 |
1985年 | 264篇 |
1984年 | 39篇 |
1983年 | 27篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1979年 | 24篇 |
1978年 | 16篇 |
1977年 | 25篇 |
1976年 | 27篇 |
1975年 | 35篇 |
1974年 | 22篇 |
1973年 | 22篇 |
1971年 | 21篇 |
1967年 | 17篇 |
1966年 | 16篇 |
1948年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 777 毫秒
1.
YBa2Cu3O7-x (YBCO) bulk is one of the most important high temperature superconducting materials for magnetic levitation applications, because it has a high magnetic irreversibility field Hirr at liquid nitrogen temperature, and can grow into large grains. The levitation force of YBCO bulk is proportional to the critical current density (Jc) and grain radius (r)[1], so higher Jc and r are appreciated for YBCO bulks to achieve higher levitation force. Now single-domain YBCO bulks up to s… 相似文献
2.
WANG Wen zhen * LIU Xin MENG Yi LIAO Dai zheng * JIANG Zong hui YAN Shi ping WANG Geng lin . Department of Chemistry Nankai University Tianjin P. R. China . State Key Laboratory of Coordination Chemistry Nanjing University Nanjijng P. R. China 《高等学校化学研究》2003,19(1)
IntroductionFive- coordinated complexes with d9- configuredcations have received much attention stereochemi-cally,spectrochemically and biologically,and havebeen comprehensively discussed[1] . Usually thereare two stable configurations for the copper( )complexes with five equal coordinating atoms:anapically elongated square pyramid( SP) and a com-pressed trigonal bipyramid( TBP) ,with an obviousenergetic preference for the latter coordination.When the ligands are rigid and provide angular d… 相似文献
3.
庞丹阳叶沿林 江栋兴郑涛王全进 李智焕李湘庆葛愉成 吴翠娥张高龙 胡青元王佳 A.Ozawa Y.Yamaguchi R.Kanungo D.Fang I.Tanihata 《中国物理快报》2004,21(11):2151-2154
The differential cross sections of quasielastic scattering of a 25 MeV/u ^6He from ^9Be target have been measured.The double-folding model approach is applied to generate the real part of the optical potential. The imaginary potential parameters as well as some of the real potential parameters are studied in comparison with the experimental data. The effect of the unstable nucleus is discussed. 相似文献
4.
本文介绍一种采用纯双相光栅进行激光束相干相加的方法。用一光栅能把单一光束高效率地分离成N个相等级次激光束,亦能以相同效率把N个相等级次的激光束转换成单一光束。实验证明,它能以75%的总转换效率将七束激光转换成一个单束激光。本文还描述一种实验装置,将两束氦-氖激光与三束氦-氖激光(波长为3.39μm)的功率合成,其效率可高达83%。 相似文献
5.
A.R.ELAMROUSS 《数学学报(英文版)》2005,21(1):129-142
This paper contains a generalization of the well-known Palais-Smale and Cerami compactness conditions. The compactness condition introduced is used to prove some general existence theorems for critical points. Some applications are given to differential equations. 相似文献
6.
CUI Xiao-bing ZHENG Shou-tian SUN Yan-qiong YANG Guo-yu ** . Coordination Hydrothermal Chemistry Group State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou P. R. China . State Key Laboratory of Coordination Chemistry Najing University Nanjing P. R. China 《高等学校化学研究》2004,(1)
IntroductionPolyoxometalatesarewidelystudiedfortheirin terestingapplicationsincatalysis ,electronicconduc tivity ,magnetism ,nonlinearopticsandmedicine[1— 4 ] .Whilethemechanismofthesynthesisofpolyoxometalatesremainselusiveandisoftende scribedasself assembly ,thereseemstobeanincreas inguseofthecombinationofthehydrothermalmethodandthestructure directingtemplate .There searchwiththismethodhasdemonstratedthatanum beroftransitionmetaloxides ,typicallyreducedmolybdenumoxides ,mixedvalancevanadiumo… 相似文献
7.
Quan Sen JIU Department of Mathematics Capital Normal University Beijing P.R.China Cheng HE Institute of Applied Mathematics Academy of Mathematics System Sciences Chinese Academy of Sciences Beijing P.R.China 《应用数学学报(英文版)》2004,(4)
In this paper we are interested in the sufficient conditions which guarantee the regularityof solutions of 3-D ideal magnetohydrodynamic equations in the arbitrary time interval [0,T].Fivesufficient conditions are given.Our results are motivated by two main ideas:one is to control theaccumulation of vorticity alone;the other is to generalize the corresponding geometric conditions of3-D Euler equations to 3-D ideal magnetohydrodynamic equations. 相似文献
8.
LI Zi-jian LIU Ning LIU Zhi-qiang LIU Shu-ying HAN Qi-de ZHANG You-yi . Institute of Vascular Medicine Peking University Third Hospital Key Laboratory of Molecular Cardiovascular Sciences Ministry of Education Beijing P. R. China . Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun P. R. China 《高等学校化学研究》2006,22(3):319-323
Introduction Adrenoceptors(ARs),membersofthesuperfami lyofG proteincoupledreceptors,arethemostimpor tantreceptorsinvolvedincardiacregulation[1].ARsin cardiacmuscleincludebothαARsandβARssub types,whileinmostmammalianheart,βARsarethe predominantsubtypes.… 相似文献
9.
<正> §5.数乘一个数λ与一个函数φ(x)的数乘运算λφ(x)有下列性质1°。如果φ_n(x)是基本列,则λφ_n(x)也是基本列。这个性质能使我们把这种运算推广到任意的广义函数f(x)=[φ_n(x)]上,只要假定 相似文献
10.
F.Oner R.A.Mamedoy 《理论物理通讯》2002,37(3):327-330
Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of the average Coulomb interaction between two particles.Coulomb energy difference according to shell model of light mirror nuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions.In this study,using the one-center expansion of exponential-type wavefunctions in terms of Slater-type orbitals with the same center,we derived formula for Coulomb energy difference of light mirror nuclei. 相似文献