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   723篇
  免费   14篇
化学   379篇
晶体学   3篇
力学   9篇
数学   134篇
物理学   212篇
  2023年   6篇
  2021年   9篇
  2020年   8篇
  2019年   10篇
  2018年   10篇
  2017年   9篇
  2016年   18篇
  2015年   19篇
  2014年   47篇
  2013年   83篇
  2012年   35篇
  2011年   17篇
  2010年   21篇
  2009年   12篇
  2008年   25篇
  2007年   17篇
  2006年   14篇
  2005年   9篇
  2003年   12篇
  2002年   17篇
  2001年   12篇
  2000年   8篇
  1999年   8篇
  1998年   14篇
  1997年   7篇
  1996年   7篇
  1995年   8篇
  1993年   9篇
  1992年   8篇
  1991年   7篇
  1990年   12篇
  1989年   16篇
  1988年   9篇
  1987年   11篇
  1986年   11篇
  1985年   6篇
  1984年   11篇
  1983年   10篇
  1982年   11篇
  1981年   11篇
  1980年   11篇
  1979年   12篇
  1978年   14篇
  1977年   8篇
  1976年   7篇
  1975年   8篇
  1974年   7篇
  1973年   8篇
  1972年   8篇
  1970年   6篇
排序方式: 共有737条查询结果,搜索用时 15 毫秒
31.
Hypernuclear structure models are briefly reviewed. Phenomena related to hypernuclear polarization are displayed. A discussion is given of nuclear and hypernuclear neutron orbitals extraction. Preliminary results on angular distributions for the reaction6Li(K , ) 6 Li are presented.Presented at the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.The collaboration of Dr. M. Sotona and Dr. L. Majling in the speedy preparation of the AD results and discussions with them and with Prof. B. Povh are greatly acknowledged.  相似文献   
32.
Interaction of quantum system S a described by the generalised × eigenvalue equation A| s =E s S a | s (s=1,...,) with quantum system S b described by the generalised n×n eigenvalue equation B| i = i S b | i (i=1,...,n) is considered. With the system S a is associated -dimensional space X a and with the system S b is associated an n-dimensional space X n b that is orthogonal to X a . Combined system S is described by the generalised (+n)×(+n) eigenvalue equation [A+B+V]| k = k [S a +S b +P]| k (k=1,...,n+) where operators V and P represent interaction between those two systems. All operators are Hermitian, while operators S a ,S b and S=S a +S b +P are, in addition, positive definite. It is shown that each eigenvalue k i of the combined system is the eigenvalue of the × eigenvalue equation . Operator in this equation is expressed in terms of the eigenvalues i of the system S b and in terms of matrix elements s |V| i and s |P| i where vectors | s form a base in X a . Eigenstate | k a of this equation is the projection of the eigenstate | k of the combined system on the space X a . Projection | k b of | k on the space X n b is given by | k b =( k S b B)–1(V k P})| k a where ( k S b B)–1 is inverse of ( k S b B) in X n b . Hence, if the solution to the system S b is known, one can obtain all eigenvalues k i } and all the corresponding eigenstates | k of the combined system as a solution of the above × eigenvalue equation that refers to the system S a alone. Slightly more complicated expressions are obtained for the eigenvalues k i } and the corresponding eigenstates, provided such eigenvalues and eigenstates exist.  相似文献   
33.
We modify the definition of Dirac cohomology in such a way that the standard properties of the usual Dirac cohomology, valid for modules with infinitesimal character, become valid also for modules with only generalized infinitesimal character.  相似文献   
34.
J. Bezić  S. Žumer 《Liquid crystals》2013,40(6):1695-1713
Abstract

A part of homotopy theory is applied to classify planar structures in chiral nematic liquid crystals confined to cylindrical cavities. The resulting classification is exact in the approximation of undeformed chiral nematic surfaces. Within this approach the relative stability of possible planar structures with surface and bulk disclination lines is discussed. The number and the shape of these disclinations, which in some cases form spiral structures, are predicted. Further approximate analytical expressions for non-singular director fields close to disclination lines with integral strength are introduced. Our predictions, which are also in agreement with some previously suggested pictures of such director fields, are used to improve stability considerations of the confined planar chiral nematic structures in tubes and droplets.  相似文献   
35.
The results of thermal study and mechanism of the oxidation process of synthetic Ag2S in air are presented in this article based on the comparative analysis of DTA and XRD results, as well as by constructed phase stability diagrams (PSD) for the Ag–S–O system.  相似文献   
36.
37.
The negatively charged, water‐soluble, hydrophobically modified poly(sodium glutamate)s containing different amounts of alkyl grafts were synthesized. First, poly(γ‐benzyl‐L‐glutamate) was prepared by ring‐opening polymerization of the corresponding N‐carboxyanhydride, which was in the next step aminolysed with octylamine. After removal of the remaining benzyl protective groups, the alkyl‐modified poly(sodium glutamate)s [P(Glu‐oa)] were obtained and, together with the oppositely charged N,N,N‐trimethyl chitosan (TMC), used for the preparation of nanoparticles (NPs) of a recombinant granulocyte colony‐stimulating factor (GCSF) protein by polyelectrolyte complexation method. It is observed that, beside electrostatic interaction, the hydrophobic grafts on poly(sodium glutamate)s significantly contribute to association efficiency (AE) with GCSF protein. The addition of TMC solution to the dispersion of GCSF/P(Glu‐oa) complexes results in formation of much more defined NPs with high AE and final protein loading. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2976–2985  相似文献   
38.
We consider one-dimensional Schrödinger-type operators in a bounded interval with non-self-adjoint Robin-type boundary conditions. It is well known that such operators are generically conjugate to normal operators via a similarity transformation. Motivated by recent interests in quasi-Hermitian Hamiltonians in quantum mechanics, we study properties of the transformations and similar operators in detail. In the case of parity and time reversal boundary conditions, we establish closed integral-type formulae for the similarity transformations, derive a non-local self-adjoint operator similar to the Schrödinger operator and also find the associated “charge conjugation” operator, which plays the role of fundamental symmetry in a Krein-space reformulation of the problem.  相似文献   
39.
40.
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