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   1115篇
  免费   45篇
  国内免费   2篇
化学   776篇
晶体学   24篇
力学   21篇
数学   131篇
物理学   210篇
  2023年   19篇
  2022年   25篇
  2021年   22篇
  2020年   46篇
  2019年   34篇
  2018年   34篇
  2017年   22篇
  2016年   37篇
  2015年   23篇
  2014年   37篇
  2013年   66篇
  2012年   69篇
  2011年   87篇
  2010年   40篇
  2009年   32篇
  2008年   63篇
  2007年   71篇
  2006年   44篇
  2005年   52篇
  2004年   28篇
  2003年   26篇
  2002年   25篇
  2001年   13篇
  2000年   13篇
  1999年   6篇
  1998年   10篇
  1997年   7篇
  1996年   6篇
  1995年   8篇
  1994年   14篇
  1993年   10篇
  1991年   7篇
  1987年   5篇
  1986年   6篇
  1981年   7篇
  1980年   7篇
  1978年   8篇
  1977年   7篇
  1976年   5篇
  1975年   5篇
  1971年   6篇
  1970年   6篇
  1969年   8篇
  1968年   8篇
  1964年   4篇
  1963年   6篇
  1962年   8篇
  1961年   11篇
  1958年   7篇
  1955年   5篇
排序方式: 共有1162条查询结果,搜索用时 15 毫秒
1.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions. The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both experimentally and theoretically.  相似文献   
2.
3.
A four-noded rectangular element with seven degrees of freedom at each node is developed for buckling analysis of laminated plate structures having any number of layers with a constant thickness of individual layers. The displacement model is so chosen that it can explain adequately the parabolic distribution of transverse shear stresses and the non-linearity of in-plane displacements across the thickness. A geometrical stiffness matrix is developed using in-plane stresses. A wide range of plates from thick to thin are examined under uniaxial loading conditions. The results are compared with the existing analytical and numerical solutions. The present formulations confirm its applicability for buckling analysis of a wide range of plates.  相似文献   
4.
Within the framework of the covariant simultaneous approach of quantum field theory, a complex system of two identical scalar particles with third- and fourth-order self-action is examined. Explicit forms of the retarded component of the Green's two-time function and of the energy-dependent interaction operator of the system are obtained in the lowest orders of perturbation theory. Three-dimensional quasi-potential equations for the relativistic wave function of a bound state are derived. Based on the results obtained, a complex system of two Higgs bosons is examined.  相似文献   
5.
J N Das  A Dey  K Chakrabarti 《Pramana》1995,45(1):41-46
Schwinger variational principle has been used to calculate triple differential cross-sections for ionization of hydrogen atoms by positrons at intermediate and high energies for Ehrhardt type asymmetric geometry. The results agree in general with the calculations of Brauneret al [8] and with the second Born calculation.  相似文献   
6.
The analogue of the 0+ ground state in 118Sn has been observed in the compound nucleus 118Sb through 117Sn(p,n γ) 117Sb reaction. The neutron decays of this analogue resonance have been studied from the deexciting γ-rays of the residual nucleus 117Sb. From off resonance excitation functions, spin assignments have been made to states in 117Sb, on the basis of Hauser-Feshbach formalism. The resonance parameters of the isobaric analogue resonance have been determined, including the total, proton and neutron decay widths.  相似文献   
7.
8.
Summary Eriochromecyanine RC has been used as chromogenic reagent for the photometric determination of rhodium(III) on a micro scale. A coloured Rh(III)-ECRC chelate with max 530 nm at pH 4.0 (25°C) is formed. A detailed study has been made concerning to characteristics, composition and stability of the chelate. Standard deviation was ±1.17%.
Über die photometrische Bestimmung von dreiwertigem Rhodium mit Eriochromcyanin RC
Zusammenfassung Ergebnisse einer Untersuchung über die Zusammensetzung und Stabilität des Komplexes werden mitgeteilt. Das Absorptionsmaximum liegt bei 530 nm (pH 4,0; 25°C). Bestimmungen konnten mit einer Standardabweichung von ±1,17% durchgeführt werden.
  相似文献   
9.
The compositional dependence of the glass transition temperature (T g), and the temperature of the maximum rate of crystallization (T p) of As-Se glasses containing Sb has been measured using non-isothermal DSC. The variation of these characteristic temperatures is found useful in interpreting the structural changes in As-Sb-Se glasses. The role of Sb in these glasses and its effect on the crystallization characteristics is analyzed.  相似文献   
10.
The problem of calculating the thermodynamic properties of two-dimensional semiclassical hard-body fluids is studied. Explicit expressions are given for the first-order quantum corrections to the free energy, equation of state, and virial coefficients. The numerical results are calculated for the planar hard dumbbell fluid. Significant features are the increase in quantum corrections with increasing eta and increasing L*=L/sigma(0).  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