首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1505篇
  免费   36篇
  国内免费   3篇
化学   1161篇
晶体学   21篇
力学   39篇
数学   47篇
物理学   276篇
  2022年   14篇
  2020年   18篇
  2019年   28篇
  2018年   15篇
  2017年   14篇
  2016年   17篇
  2015年   35篇
  2014年   28篇
  2013年   67篇
  2012年   62篇
  2011年   63篇
  2010年   35篇
  2009年   41篇
  2008年   88篇
  2007年   67篇
  2006年   84篇
  2005年   73篇
  2004年   71篇
  2003年   48篇
  2002年   68篇
  2001年   45篇
  2000年   37篇
  1999年   22篇
  1998年   15篇
  1997年   19篇
  1996年   23篇
  1995年   10篇
  1994年   29篇
  1993年   17篇
  1992年   25篇
  1991年   15篇
  1990年   16篇
  1989年   13篇
  1988年   16篇
  1987年   16篇
  1986年   18篇
  1985年   16篇
  1984年   26篇
  1983年   15篇
  1982年   21篇
  1980年   20篇
  1979年   13篇
  1978年   13篇
  1977年   24篇
  1976年   8篇
  1975年   17篇
  1974年   18篇
  1973年   13篇
  1971年   14篇
  1968年   10篇
排序方式: 共有1544条查询结果,搜索用时 15 毫秒
91.
A series of 2-aminoethanol derivatives was synthesized and their inhibitory activities against protein kinase C were investigated. Among these compounds, 2-endo-hexadecylamino-5-norbornene-2- exo-methanol (4h) and 2-endo-hexadecylamino-5-norbornene-2,3-exo-dimethanol (4i) inhibited protein kinase C at the IC50 values of 2 x 10(-5) and 1 x 10(-5) M, respectively, but not protein kinase A at a concentration of 1 x 10(-3) M. The structure-activity relationships are discussed.  相似文献   
92.
1,8-[1,8-Naphthalenediylbis(4',4-biphenyldiyl)]naphthalene, a very stable strained cyclophane, has been synthesized in moderate yield using the copper-catalyzed coupling of 1, 8-bis(4-(tributylstannyl)phenyl)naphthalene. The X-ray analysis of the titled compound discloses bent p,p'-biphenylylene chains with splayed naphthalene rings, and the p,p'-biphenylylene chains located face-to-face indicate a fairly strong pi-pi interaction.  相似文献   
93.
The concept, the present status, key issues and future prospects of a novel hexagonal binary decision diagram (BDD) quantum circuit approach for III–V quantum large-scale integrated circuits (QLSIs) are presented and discussed. In this approach, the BDD logic circuits are implemented on III–V semiconductor-based hexagonal nanowire networks controlled by nanoscale Schottky gates. The hexagonal BDD QLSIs can operate at delay-power products near the quantum limit in the quantum regime as well as in the many-electron classical regime. To demonstrate the feasibility of the present approach, GaAs Schottky wrap gate (WPG)-based single-electron BDD node devices and their integrated circuits were fabricated and their proper operations were confirmed. Selectively grown InGaAs sub-10 nm quantum wires and their hexagonal networks have been investigated to form high-density hexagonal BDD QLSIs operating in the quantum regime at room temperature.  相似文献   
94.
An angle-resolved X-ray photoelectron spectroscopic study has been performed on structures of self-assembling systems, viz ferrocenylthiols on a gold (111) crystal. The angular dependence of the intensities of photoemission reveals that ferrocenyl groups are on the outermost layer, separated from the gold substrate by hydrocarbon chains of the thiol groups.  相似文献   
95.
Nuclear polarization was measured by means of beam foil spectroscopy for a3He+ ion produced by an electron capture process of a3He2+ from a polarized sodium atom in an incident energy range from 20 to 28 keV. Assuming that a polarized electron of a sodium atom is predominantly captured to the 3d orbital of a3He+ ion andcascades down to the 1s ground state via the 2p orbital, an alignment factorA 0 col (L=2) for the 3d orbital of a3He+ ion was extracted by comparing the observed initial sodium polarization andfinal nuclear polarization. The observedA 0 col (L=2) showed a less pronounced energy dependence andwere qualitatively reproduced by the theoretical calculation.  相似文献   
96.
97.
Critical behaviour of the temperature derivative of the electrical resistivity at the Néel temperature is treated. For a small Fermi wave vector, the divergence is the same as that of the specific heat both above and below the Néel temperature. For a large Fermi wave vector, in paramagnetic region, the contributions from the critical and the other regions of q-space are of the same divergence as the specific heat but of different signs from each other. Below Néel temperature, the gap effect is the main origin of divergence.  相似文献   
98.
99.
Anomalous magnetoresistance in heavily antimony doped germanium is studied down to 5 mK. The experimental results is reasonably interpreted within a framework of s-d interaction with a negative exchange constant. Electrons localized in a sense of Anderson are suggested to play a role of d electrons when Coulomb correlation is introduced.  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号