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   331863篇
  免费   4728篇
  国内免费   1171篇
化学   180635篇
晶体学   4489篇
力学   13612篇
综合类   16篇
数学   39450篇
物理学   99560篇
  2021年   2027篇
  2020年   2273篇
  2019年   2236篇
  2018年   2310篇
  2017年   2202篇
  2016年   4403篇
  2015年   3666篇
  2014年   4940篇
  2013年   14784篇
  2012年   11699篇
  2011年   14450篇
  2010年   8892篇
  2009年   8852篇
  2008年   13253篇
  2007年   13428篇
  2006年   12999篇
  2005年   12294篇
  2004年   11230篇
  2003年   9646篇
  2002年   9213篇
  2001年   10473篇
  2000年   8082篇
  1999年   6324篇
  1998年   5071篇
  1997年   4927篇
  1996年   5045篇
  1995年   4604篇
  1994年   4352篇
  1993年   4200篇
  1992年   4683篇
  1991年   4470篇
  1990年   4172篇
  1989年   3971篇
  1988年   4235篇
  1987年   3901篇
  1986年   3793篇
  1985年   5457篇
  1984年   5519篇
  1983年   4495篇
  1982年   4879篇
  1981年   4903篇
  1980年   4654篇
  1979年   4750篇
  1978年   4774篇
  1977年   4737篇
  1976年   4684篇
  1975年   4569篇
  1974年   4440篇
  1973年   4568篇
  1972年   2561篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
71.
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   
72.
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   
73.
74.
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an...  相似文献   
75.
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   
76.
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   
77.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually.  相似文献   
78.
79.
80.
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