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   2150篇
  免费   55篇
  国内免费   26篇
化学   1155篇
晶体学   8篇
力学   43篇
数学   480篇
物理学   545篇
  2023年   6篇
  2022年   22篇
  2021年   63篇
  2020年   37篇
  2019年   46篇
  2018年   57篇
  2017年   47篇
  2016年   68篇
  2015年   57篇
  2014年   71篇
  2013年   99篇
  2012年   149篇
  2011年   142篇
  2010年   103篇
  2009年   99篇
  2008年   154篇
  2007年   145篇
  2006年   125篇
  2005年   127篇
  2004年   126篇
  2003年   69篇
  2002年   72篇
  2001年   45篇
  2000年   26篇
  1999年   31篇
  1998年   39篇
  1997年   27篇
  1996年   19篇
  1995年   24篇
  1994年   21篇
  1993年   11篇
  1992年   9篇
  1991年   7篇
  1990年   10篇
  1989年   7篇
  1988年   3篇
  1986年   5篇
  1985年   7篇
  1984年   4篇
  1982年   4篇
  1981年   7篇
  1980年   6篇
  1977年   4篇
  1976年   2篇
  1975年   4篇
  1974年   2篇
  1972年   2篇
  1970年   3篇
  1969年   5篇
  1968年   3篇
排序方式: 共有2231条查询结果,搜索用时 15 毫秒
991.
Numerical Algorithms - An algorithm is proposed for finding numerical solutions of a kinetic equation that describes an infinite system of point particles placed in $\mathbb {R}^{d} (d \geq 1)$ ....  相似文献   
992.
This paper presents subjective evaluation results for images reproducing metallic luster. The images were produced by a six-band high-dynamic-range imaging technique, which provides high color fidelity and the capability of various tone mapping operations. The preferences for images produced by four kinds of tone mapping operations were evaluated by means of a paired comparison method under the conditions that observers could or could not refer to real scenes. The evaluation results indicated that preferences for images depend on tone mapping operations, especially for objects that have the luster changing over a large area with moderately high intensity. In addition, when referring to a real scene, the spatially varying tone compression, which reproduces the color and complex characteristics of metallic luster, was significantly preferable to the tone mappings by other approaches. Without a real scene, the preference was also strong for images produced by simply saturating pixel values at highlights.  相似文献   
993.
A series of Co(III) anionic complexes of Schiff bases obtained from substituted salicylaldehydes and optically active amino acids has been synthesized. The ion pairing of these anions to a lithium cation can be used to induce asymmetry into lithium-catalyzed trimethylsilylcyanation of aldehydes and Michael reactions. The influence of the temperature, solvent polarity and structural modification of the chiral anion on the enantioselectivity of the catalysis has been investigated.  相似文献   
994.
We generalize some classical results in the theory of extreme problems for nonoverlapping domains.  相似文献   
995.
We overview our recent theoretical results on spatio-spectral control, diffraction management, and broadband all-optical switching of polychromatic light in periodically curved one and two dimensional arrays of coupled optical waveguides. In particular, we show that polychromatic light beams and patterns produced by white-light and supercontinuum sources can experience wavelength-independent normal, anomalous, or zero diffraction in specially designed structures. We also demonstrate that in the nonlinear regime, it is possible to achieve broadband all-optical switching of polychromatic light in a directional waveguide coupler with special bending of the waveguide axes. Our results suggest novel opportunities for creation of all-optical logical gates and switches which can operate in a very broad frequency region, e.g., covering the entire visible spectrum. Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Świnoujście, Poland  相似文献   
996.
We report here about effective FRET process (73–99%) in mono-Mg2+ complexes of symmetrical crown ether bis(styryl) dyes. The FRET process has not been observed in the free state and in binuclear complexes. The formation of mononuclear complex provides two styrylic fragments with appropriate positions of absorption and emission bands for FRET. The other important parameter for FRET is the proper geometric orientation of both chromophores, which attain sandwich conformation with close positioning of complexed and free styryl fragments induced by ion-modulated geometry reorganization of the bis-dye.  相似文献   
997.
998.
999.
In geometric function theory there is a well-known field related to estimates for functionals that depend on the inner radii of nonoverlapping domains. Many authors has contributed to the development of this field. Today, great attention is being paid to the study of extremal problems for nonoverlapping domains with free poles. In this paper, one result of this kind is generalized and strengthened.  相似文献   
1000.
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