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   622801篇
  免费   6364篇
  国内免费   1739篇
化学   331992篇
晶体学   9293篇
力学   28100篇
综合类   20篇
数学   74833篇
物理学   186666篇
  2021年   4854篇
  2020年   5534篇
  2019年   6006篇
  2018年   7875篇
  2017年   7735篇
  2016年   11827篇
  2015年   7400篇
  2014年   11380篇
  2013年   27724篇
  2012年   21063篇
  2011年   25773篇
  2010年   18238篇
  2009年   17896篇
  2008年   23843篇
  2007年   23861篇
  2006年   22130篇
  2005年   19919篇
  2004年   18414篇
  2003年   16416篇
  2002年   16242篇
  2001年   17947篇
  2000年   13815篇
  1999年   10850篇
  1998年   9167篇
  1997年   8947篇
  1996年   8598篇
  1995年   7812篇
  1994年   7810篇
  1993年   7442篇
  1992年   8443篇
  1991年   8460篇
  1990年   8156篇
  1989年   7826篇
  1988年   8004篇
  1987年   7780篇
  1986年   7388篇
  1985年   9621篇
  1984年   9941篇
  1983年   8137篇
  1982年   8276篇
  1981年   8187篇
  1980年   7828篇
  1979年   8169篇
  1978年   8551篇
  1977年   8380篇
  1976年   8407篇
  1975年   7704篇
  1974年   7821篇
  1973年   7961篇
  1972年   5626篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
Chemisorption is a well-known phenomenon for many interfaces between organic semiconductors and metals. It is shown that many published data indicate that the occurrence of chemisorption can be rationalized upon the consideration of the metal work function versus the electron affinity of the organic semiconductor.  相似文献   
232.
The ultraviolet band systemsA 1Π-X 1Σ+ of P14N and P15N were excited in an electrodeless tube containing traces of phosphorus specpure nitrogen and neon using a microwave discharge (2450 MHz). Bands of the isotopic species, P15N, were obtained using15N2 enriched to 95.5%. Rotational analyses of eleven bands of P14N and sixteen bands of P15N were carried out. Three perturbing statese 3Σ,d 3Δ andb 3Π, arising from the lower valence configurations were identified from the observed perturbations in thev′=0–4 levels of theA 1Π state. Deperturbation studies led to the determination of molecular constants of the perturbing states. Vibrational assignments of the perturbing states were made from isotope shift studies.  相似文献   
233.
It is observed experimentally that a periodic array of resistively coupled LC-oscillators with ans-shaped nonlinearity exhibits stable non-uniform voltage and current distributions. The dependence of the resulting structure on the coupling resistance and the boundary conditions is investigated. The structure is rather insensitive to variations of the boundary values. The experiments are well described by a two-variable reaction-diffusion equation.  相似文献   
234.
The {1/2, 0, 1/2} nuclear superstructure in an La0.93Sr0.07MnO3 manganite orthorhombic crystal is revealed using thermal-neutron diffraction. It is demonstrated that this superlattice belongs to the class of distortion-type structures and is directly associated with a 1/16-type ordering of Mn4+ and Mn3+ ions in a collinear ferromagnetic phase of the La0.93Sr0.07MnO3 manganite.  相似文献   
235.
236.
237.
238.
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time.  相似文献   
239.
A self-consistent, completely quantum calculation of the structure of the inner crust of neutron stars is carried out in the Wigner-Seitz approximation with a realistic phenomenological nuclear energy functional, where pair correlations of neutrons and protons are included in the explicit form. It has been shown that the superfluidity of neutrons and protons affects the structure of the ground state of the crust.  相似文献   
240.
We examine several interesting relationships and expressions involving Fourier-Feynman transform, convolution product and first variation for functionals in the Fresnel class F(B) of an abstract Wiener space B. We also prove a translation theorem and Parseval's identity for the analytic Feynman integral. This revised version was published online in June 2006 with corrections to the Cover Date.  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