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   348篇
  免费   22篇
  国内免费   2篇
化学   259篇
晶体学   1篇
力学   22篇
数学   25篇
物理学   65篇
  2024年   1篇
  2023年   4篇
  2022年   12篇
  2021年   8篇
  2020年   13篇
  2019年   10篇
  2018年   11篇
  2017年   13篇
  2016年   28篇
  2015年   25篇
  2014年   25篇
  2013年   54篇
  2012年   26篇
  2011年   33篇
  2010年   20篇
  2009年   19篇
  2008年   16篇
  2007年   16篇
  2006年   11篇
  2005年   12篇
  2004年   7篇
  2002年   1篇
  1997年   2篇
  1995年   1篇
  1983年   3篇
  1982年   1篇
排序方式: 共有372条查询结果,搜索用时 15 毫秒
81.
A simple, efficient, and ecofriendly procedure has been developed for the synthesis of quinoline and its derivatives in a one-pot reaction of aniline with crotonaldehyde or methyl vinyl ketone using phosphomolybdic acid as solid acid catalyst in miceller media. The catalyst was easily recycled and reused.  相似文献   
82.
The diversity of applications, versatality of property modifications, motivations for development and commercial significance of polymer alloys are reviewed with reference to commercially available materials. The key steps and scientific considerations central to the development of thermoplastic blend systems are discussed. The scientific considerations in developing the technology, such as thermodynamics of polymer-polymer miscibility, thermal and mechanical compatibility, phase diagram/morphology, interphase adhesion, and kinetics of solidification are highlighted with the help of specific examples from practice. Specific areas for research and development in polymer alloys in India are indicated emphasizing the need for an applied research bias. Presented at the Symposium on ‘Polymer Science and Engineering’ during Annual Meeting of the Academy, Nainital October 1982.  相似文献   
83.
84.
85.
Naturally occurring antimicrobial peptides (AMPs) are powerful defence tools to tackle pathogenic microbes. However, limited natural production and high synthetic costs in addition to poor selectivity limit large‐scale use of AMPs in clinical settings. Here, we present a series of synthetic AMPs (SAMPs) that exhibit highly selective and potent killing of Mycobacterium (minimum inhibitory concentration <20 μg mL?1) over E. coli or mammalian cells. These SAMPs are active against rapidly multiplying as well as growth saturated Mycobacterium cultures. These SAMPs are not membrane‐lytic in nature, and are readily internalized by Mycobacterium and mammalian cells; whereas in E. coli, the lipopolysaccharide layer inhibits their cellular uptake, and hence, their antibacterial action. Upon internalization, these SAMPs interact with the unprotected genomic DNA of mycobacteria, and impede DNA‐dependent processes, leading to bacterial cell death.  相似文献   
86.
87.
Management of rotavirus diarrhoea cases and prevention of nosocomial infection require rapid diagnostic method at the patient care level. Diagnostic tests currently available are not routinely used due to economic or sensitivity/specificity constraints. Agarose-based sieving media and running conditions were modulated by using central composite design and response surface methodology for screening and electropherotyping of rotaviruses. The electrophoretic resolution of rotavirus genome was calculated from input parameters characterising the gel matrix structure and running conditions. Resolution of rotavirus genome was calculated by densitometric analysis of the gel. The parameters at critical values were able to resolve 11 segmented rotavirus genome. Better resolution and electropherotypic variation in 11 segmented double-stranded RNA genome of rotavirus was detected at 1.96% (w/v) agarose concentration, 0.073 mol l−1 ionic strength of Tris base–boric acid–ethylenediamine tetraacetic acid buffer (1.4×) and 4.31 h of electrophoresis at 4.6 V cm−1 electric field strength. Modified agarose gel electrophoresis can replace other methods as a simplified alternative for routine detection of rotavirus where it is not in practice.  相似文献   
88.
JPC – Journal of Planar Chromatography – Modern TLC - A simple, precise, and accurate high-performance thin-layer chro-matographic method has been established for determination of...  相似文献   
89.
A novel strategy, involving anchoring and un-anchoring of coumarin based fluorophore, has been established for the selective detection of Au3+ species. Selective sensing of Gold (Au3+) was triggered due to alkynophilicity of gold ions to create lateral fluorescence of a latent fluorophore. The 4-methyl-2-oxo-2H-chromen-7-yl 2-(2-phenylethynyl) benzoate (CEB) probe was synthesized by reacting 7-hydroxy-4-methylcoumarin with iodo-benzoic acid. CEB probe has an absorption at 300 nm and 335 nm which decreases gradually and new absorption appeared at 406 nm due to Au3+ promoted ester hydrolysis selectively over other metal ions with great sensitivity, which accompanies a turn on fluorescence change produced by 7-hydroxy coumarin. The principle behind this sensing strategy is activation of triple bond induced uniquely by Au+3 ions leading to cascade and delivers active fluorophore. The sensing mechanism was proposed and supported by 1H NMR, MS and TD-DFT experiments. The density functional theory (DFT) and time dependent density functional theory (TD-DFT) theoretical results of the CEB-probe and Au3+ reaction is in good agreement with the experimental results. Additionally, probe could be well incorporated onto the test strips for effective detection of Au3+.  相似文献   
90.
Oxidation of nitrogen-containing heteroaryl-2-methanols to esters with Ag2O and isopropyl iodide is reported. This methodology is very mild and can tolerate many functional groups.  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