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   828篇
  免费   21篇
  国内免费   7篇
化学   633篇
晶体学   12篇
力学   4篇
数学   37篇
物理学   170篇
  2023年   6篇
  2022年   9篇
  2020年   6篇
  2019年   9篇
  2018年   9篇
  2016年   11篇
  2015年   8篇
  2014年   15篇
  2013年   43篇
  2012年   39篇
  2011年   33篇
  2010年   25篇
  2009年   28篇
  2008年   36篇
  2007年   46篇
  2006年   61篇
  2005年   39篇
  2004年   47篇
  2003年   45篇
  2002年   33篇
  2001年   14篇
  2000年   16篇
  1999年   16篇
  1998年   14篇
  1997年   8篇
  1996年   13篇
  1995年   5篇
  1994年   10篇
  1993年   13篇
  1992年   11篇
  1991年   6篇
  1988年   11篇
  1987年   9篇
  1985年   8篇
  1984年   6篇
  1983年   7篇
  1982年   11篇
  1981年   8篇
  1979年   15篇
  1978年   9篇
  1977年   6篇
  1976年   7篇
  1975年   5篇
  1974年   13篇
  1972年   4篇
  1970年   4篇
  1969年   8篇
  1968年   6篇
  1967年   11篇
  1966年   5篇
排序方式: 共有856条查询结果,搜索用时 46 毫秒
1.
Journal of Thermal Analysis and Calorimetry - Nitrocellulose (NC) is prone to spontaneous decomposition with exothermic heat release and thus is generally evaluated for stability during the storage...  相似文献   
2.
3.
We have numerically shown the existence of coupled wedge plasmons (CWPs) which propagates along a nano gap of a twin metal wedge. The CWPs are formed by wedge plasmons which can interact with each other. The dispersion relations of the wavenumber, propagation distance, and beam area of CWPs, are described and show that the characteristics of CWPs are similar to those of wedge plasmons and of gap plasmons. We also propose a new plasmon waveguide composed of twin metal wedges with a nano gap.  相似文献   
4.
We investigate low-temperature behaviors of a system with chirality-pair interaction on a one-dimensional lattice. In the course of the investigation, we evaluate asymptotic forms of the characteristic values of the integral equation satisfied by the Mathieu functions. It turns out that the low-temperature behavior of correlation length of the chirality-pair correlation function is different from the one for the Ising model of spin ±1 but akin to the one for the Ising model of infinite spin.  相似文献   
5.
EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr3+ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr3+ ion with the ligands.  相似文献   
6.
The height distribution of the dayside cusp aurora and the relation between optical emissions and net downward electron energy flux are discussed. These two important characteristics of day-side cusp aurora are still unknown. It is instructive to compare particle flux and optical luminosity because these two quantities should be proportional if the cusp aurora is caused by electron impact, as has been found for nighttime aurora in the oval. Furthermore, there should then be a direct relation between auroral altitudes and particle energy. Based on coordinated auroral observations at Svalbard and Greenland, together with simultaneous, overhead F-9 satellite measurements, these quantities have been evaluated  相似文献   
7.
8.
We describe a finite complex B as I-trivial if there does not exist a Z2-map from Si−1 to S(α) for any vector bundle α over B and any integer i with i>dimα. We prove that the m-fold suspension of projective plane FP2 is I-trivial if and only if m≠0,2,4 for F=C, m≠0,4 for F=H. In the case where F is the Cayley algebra, the m-fold suspension is shown to be I-trivial for every m>0.  相似文献   
9.
An intrinsic principle of least action is presented for the intrinsic dynamism of chemical reactions. Then, as the stationary trajectory, a meta-IRC (intrinsic reaction coordinate) draws a geodesic curve in a rigged Riemannian space. This establishes a geodesic law for the intrinsic dynamism. Moreover, a diagrammatic perturbation theory is formulated for the intrinsic dynamism, and a dynamical interaction between a chemically reacting system and a background system is investigated. Then, the structural stability of the system is discussed using a new concept of the dynamical potential field. An example is given in order to elucidate the present theory.Dedicated to Prof. Hermann Hartmann on the occasion of his 65th birthday.  相似文献   
10.
The nature of the 1,3 hydrogen rearrangement of formamidine (H2N-CH=NH) and the solvent effects on that reaction are studied with ab initio molecular orbital calculations on the basis of the supermolecule model. The reaction path and the motion of the migrating hydrogen atom are traced by using the concept of the intrinsic reaction coordinate (IRC). Four types of orientation of one water molecule to formamidine at the transition state of reaction are examined and the results are discussed from the standpoint of the orbital interactions.  相似文献   
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