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   1809篇
  免费   30篇
  国内免费   9篇
化学   1013篇
晶体学   17篇
力学   58篇
数学   269篇
物理学   491篇
  2023年   9篇
  2022年   28篇
  2021年   37篇
  2020年   31篇
  2019年   21篇
  2018年   17篇
  2017年   13篇
  2016年   43篇
  2015年   46篇
  2014年   38篇
  2013年   92篇
  2012年   89篇
  2011年   97篇
  2010年   69篇
  2009年   77篇
  2008年   94篇
  2007年   88篇
  2006年   90篇
  2005年   96篇
  2004年   72篇
  2003年   56篇
  2002年   48篇
  2001年   45篇
  2000年   41篇
  1999年   26篇
  1998年   29篇
  1997年   25篇
  1996年   24篇
  1995年   21篇
  1994年   21篇
  1993年   21篇
  1992年   14篇
  1991年   8篇
  1990年   15篇
  1988年   8篇
  1986年   12篇
  1985年   25篇
  1984年   31篇
  1983年   13篇
  1982年   16篇
  1981年   14篇
  1980年   19篇
  1979年   16篇
  1978年   11篇
  1977年   16篇
  1976年   15篇
  1974年   8篇
  1973年   12篇
  1972年   8篇
  1969年   6篇
排序方式: 共有1848条查询结果,搜索用时 15 毫秒
1.
2.
We study a class of nonlinear regression models for scalar or vectorial response when the explanatory variable is a function. We introduce a consistent estimator of the parameters of models in this class when functions are evaluated at randomly chosen observation points. To cite this article: F. Rossi, B. Conan-Guez, C. R. Acad. Sci. Paris, Ser. I 340 (2005).  相似文献   
3.
The diastereoselective synthesis of naphthyl amino alcohols via nucleophilic addition to racemic 1-dimethylamino-2-methylpentan-3-one was studied. The use of the appropriate experimental conditions allowed the synthesis of both diastereoisomers. The relative configurations were established via NOESY experiments.  相似文献   
4.
For ϕ a δ-subharmonic function, sharp results are obtained that connectA(r, ϕ), B(r, ϕ) andT(r, ϕ), whereA(r, ϕ)=inf|z|=r ϕ(z),B(r, ϕ)=sup|z|=r ϕ(z), andT(r, ϕ) is the Nevanlinna characteristics.  相似文献   
5.
Bulk carbon impurities segregate at the Fe(1 0 0) surface and, upon thermal annealing, can form metastable surface phases with local and long range order and peculiar electronic properties. We present a surface science study of C-segregated Fe(1 0 0) with scanning tunneling microscopy, angle resolved photoemission, and ab initio calculations of the surface structure and electron states. In particular the c(3√2 × √2) structure, observed for 0.67 atomic layers of C segregated at the iron surface, is found to be due to self-organized carbon stripes made of zig-zag chains. The strong hybridization between C and Fe was observed in ARPES spectra.  相似文献   
6.
Abstract. In this paper we study the notion of perimeter associated with doubling metric measures or strongly weights. We prove that the metric perimeter in the sense of L. Ambrosio and M. Miranda jr. coincides with the metric Minkowski content and can be obtained also as a -limit of Modica-Mortola type degenerate integral functionals. Received: 27 August 2001 / Accepted: 29 November 2001 / Published online: 10 June 2002 Investigation supported by University of Bologna, funds for selected research topics and by GNAMPA of INdAM, Italy. The authors are very grateful to Luigi Ambrosio and Francesco Serra Cassano for making their preprints available to them, for listening with patience and for many unvaluable suggestions.  相似文献   
7.
Particle filters are presently among the most powerful tools for filtering discrete time non linear systems. However the presence of unknown parameters in the system equations makes their use more complex and can even impair their convergence properties. This Note shows how an on-line consistent estimation of these parameters can be obtained simultaneously to that of the state variables to be filtered. This approach relies upon a kernel-based non parametric estimation of conditional probability densities from successive Monte Carlo generations of system particles. To cite this article: V. Rossi, J.-P. Vila, C. R. Acad. Sci. Paris, Ser. I 340 (2005).  相似文献   
8.
Intramolecular cyclization of 2-acyl-1-propargyl-1H-indoles in the presence of ammonia provides an easy entry to pyrazino[1,2-a]indole nucleus.  相似文献   
9.
High-spin states in196Pb have been populated using the reaction170Er(30Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin.  相似文献   
10.
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