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   963篇
  免费   28篇
  国内免费   3篇
化学   584篇
晶体学   6篇
力学   22篇
数学   91篇
物理学   291篇
  2023年   3篇
  2022年   20篇
  2021年   21篇
  2020年   21篇
  2019年   18篇
  2018年   17篇
  2017年   19篇
  2016年   34篇
  2015年   24篇
  2014年   24篇
  2013年   47篇
  2012年   52篇
  2011年   66篇
  2010年   40篇
  2009年   37篇
  2008年   48篇
  2007年   54篇
  2006年   36篇
  2005年   34篇
  2004年   40篇
  2003年   31篇
  2002年   36篇
  2001年   14篇
  2000年   27篇
  1999年   6篇
  1998年   6篇
  1997年   12篇
  1996年   12篇
  1995年   8篇
  1994年   12篇
  1993年   14篇
  1992年   15篇
  1991年   14篇
  1990年   20篇
  1989年   11篇
  1988年   16篇
  1987年   10篇
  1986年   11篇
  1985年   7篇
  1984年   3篇
  1983年   6篇
  1982年   11篇
  1981年   6篇
  1980年   3篇
  1979年   5篇
  1978年   3篇
  1977年   4篇
  1976年   4篇
  1973年   2篇
  1972年   2篇
排序方式: 共有994条查询结果,搜索用时 15 毫秒
171.
172.
173.
174.
A novel microfluidic thread/paper‐based analytical device (μTPAD) to detect glucose through a colorimetric assay is described. The μTPAD was fabricated from nylon thread trifurcated into three channels terminating at analysis sites comprised of circular zones of chromatography paper, which have previously been spotted with glucose of different concentrations. A solution of glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) is transported via capillary action to the analysis sites where a yellow‐brown color is observed indicating oxidation of iodide to iodine. The device was then dried, scanned, and analyzed yielding a correlation between yellow intensity and glucose concentrations. Both a flat platform constructed mainly of tape, and a cone platform constructed from tape and polyvinyl chloride, are described. Studies to quantitate glucose in artificial urine showed good correlation using the μTPAD.  相似文献   
175.
Novel amine- or ammonium-terminated carbosilane dendrimers of type nG-[Si{OCH2(C6H3)-3,5-(OCH2CH2NMe2)2}]x, nG-[Si{O(CH2)2N(Me)(CH2)2NMe2}]x and nG-[Si{(CH2)3NH2}]x or nG-[Si{OCH2(C6H3)-3,5-(OCH2CH2NMe3 +I-)2}]x, nG-[Si{O(CH2)2N(Me)(CH2)2NMe3 +I-}]x, and nG-[Si{(CH2)3NH3 +Cl-}]x have been synthesized and characterized up to the third generation by two strategies: 1) alcoholysis of Si--Cl bonds with amino alcohols and subsequent quaternization with MeI, and 2) hydrosilylation of allylamine with Si--H bonds of the dendritic systems and subsequent quaternization with HCl. Quaternized carbosilane dendrimers are soluble in water, although degradation is apparent due to hydrolysis of Si--O bonds. However, dendrimers containing Si--C bonds are water-stable. The biocompatibility of the second-generation dendrimers in primary cell cultures of peripheral blood mononuclear cells (PBMCs) and erythrocytes have been analyzed, and they show good toxicity profiles over extended periods. In addition, we describe a study on the interactions between the different carbosilane dendrimers and DNA oligodeoxynucleotides (ODNs) and plasmids along with a comparative analysis of their toxicity. They can form complexes with DNA ODNs and plasmids at biocompatible doses via electrostatic interaction. Also a preliminary transfection assay has been accomplished. These results demonstrate that the new ammonium-terminated carbosilane dendrimers are good base molecules to be considered for biomedical applications.  相似文献   
176.
States in20Ne were populated by the10B(16O,6Li) reaction, and levels were observed up to 11 MeV in excitation energy. Cross sections were measured at 7° (lab) for bombarding energies from 44.4 to 46 MeV in 400 keV intervals. The reaction appears to be predominantly due to compound nucleus formation, and good agreement was found between the measured cross sections and Hauser-Feshbach calculations, assuming the known spin values of20Ne.  相似文献   
177.
Transport in Porous Media - Consolidated drained triaxial tests arise as one of the most exhaustive methods to quantify the strength, volumetric behavior and failure process of rocks. Understanding...  相似文献   
178.
179.
We perform dynamical calculations on two robust N2–N2 potential energy surfaces in order to intercompare pressure broadening coefficients derived from close coupling and coupled states quantum dynamical methods, the semi-classical model of Robert and Bonamy and a full classical method. The coupled states and full classical results compare well with the experimental results or with close coupling values when available. This study confirms that the classical method is a good alternative at room and high temperatures to quantum dynamical methods. The results obtained using the semi-classical method however deviate from the other sets of data at all temperatures considered here (77–2400 K).  相似文献   
180.
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