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   316976篇
  免费   4347篇
  国内免费   1113篇
化学   172618篇
晶体学   4482篇
力学   13222篇
综合类   7篇
数学   36858篇
物理学   95249篇
  2020年   2010篇
  2019年   1975篇
  2018年   1998篇
  2017年   1897篇
  2016年   3922篇
  2015年   3280篇
  2014年   4476篇
  2013年   14175篇
  2012年   10828篇
  2011年   13513篇
  2010年   8363篇
  2009年   8347篇
  2008年   12464篇
  2007年   12702篇
  2006年   12351篇
  2005年   11304篇
  2004年   10194篇
  2003年   8998篇
  2002年   8854篇
  2001年   10176篇
  2000年   7787篇
  1999年   6160篇
  1998年   4932篇
  1997年   4774篇
  1996年   4840篇
  1995年   4411篇
  1994年   4161篇
  1993年   3984篇
  1992年   4470篇
  1991年   4328篇
  1990年   4054篇
  1989年   3873篇
  1988年   4162篇
  1987年   3817篇
  1986年   3709篇
  1985年   5376篇
  1984年   5463篇
  1983年   4428篇
  1982年   4812篇
  1981年   4846篇
  1980年   4607篇
  1979年   4717篇
  1978年   4711篇
  1977年   4690篇
  1976年   4634篇
  1975年   4548篇
  1974年   4402篇
  1973年   4559篇
  1972年   2602篇
  1971年   1894篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
61.
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE.  相似文献   
62.
Active anodes, especially those consisting of metal mixed oxides (MMOs) containing Ru and/or Ir oxides, have been applied in the treatment of wastewater, especially when chloride ions are present. Their characteristics continuously drive the study of applications of these materials, be they in the degradation of different organic molecules, the preparation of new electrode materials and in the association of various processes to increase pollutant removal. Thus, this brief review aims to present some of the recent advances in the application of active anode materials in environmental electrochemistry. Focussing on the 2018–2020 period, it is possible to note many applied studies, using commercially available materials, covering a wide range of target pollutants. Still other studies aim to modify the catalyst surfaces to increase the mineralization capacity, and the use of these anodes in the production of free chlorine species to mediate indirect organic reduction is observed.  相似文献   
63.
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct...  相似文献   
64.
Methodology and Computing in Applied Probability - The problem of optimally controlling one-dimensional diffusion processes until they enter a given stopping set is extended to include Markov...  相似文献   
65.
66.
Ding  Q.  Yao  M.  Wu  Sh.  Zeng  M.  Xue  N.  Wu  D.  Xu  J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the...  相似文献   
67.
Xu  H. J.  Zhang  Q. G.  Debenest  G. 《Transport in Porous Media》2021,140(3):625-627
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the...  相似文献   
68.
69.
70.
Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min.  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