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   4681篇
  免费   448篇
  国内免费   318篇
化学   2870篇
晶体学   31篇
力学   215篇
综合类   20篇
数学   796篇
物理学   1515篇
  2023年   56篇
  2022年   137篇
  2021年   131篇
  2020年   161篇
  2019年   118篇
  2018年   124篇
  2017年   111篇
  2016年   157篇
  2015年   163篇
  2014年   200篇
  2013年   288篇
  2012年   373篇
  2011年   324篇
  2010年   241篇
  2009年   211篇
  2008年   285篇
  2007年   235篇
  2006年   215篇
  2005年   188篇
  2004年   149篇
  2003年   128篇
  2002年   119篇
  2001年   96篇
  2000年   118篇
  1999年   77篇
  1998年   70篇
  1997年   65篇
  1996年   89篇
  1995年   64篇
  1994年   69篇
  1993年   56篇
  1992年   60篇
  1991年   43篇
  1990年   33篇
  1989年   46篇
  1988年   42篇
  1987年   34篇
  1986年   44篇
  1985年   41篇
  1984年   39篇
  1983年   28篇
  1982年   21篇
  1981年   19篇
  1980年   24篇
  1979年   19篇
  1978年   17篇
  1977年   22篇
  1976年   23篇
  1975年   19篇
  1973年   12篇
排序方式: 共有5447条查询结果,搜索用时 0 毫秒
51.
Journal of Radioanalytical and Nuclear Chemistry - In this work, a series of radiolabeled 2-nitroimidazole-based iodotriazoles containing positively charged, negatively charged, or neutral...  相似文献   
52.
Chu KK  Lim D  Mertz J 《Optics letters》2007,32(19):2846-2848
We describe a technique to enhance both the weak-signal relative sensitivity and the dynamic range of a laser scanning optical microscope. The technique is based on maintaining a fixed detection power by fast feedback control of the illumination power, thereby transferring high measurement resolution to weak signals while virtually eliminating the possibility of image saturation. We analyze and demonstrate the benefits of adaptive illumination in two-photon fluorescence microscopy.  相似文献   
53.
54.
55.
56.
Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992,optical parametric chirped pulse amplification(OPCPA)became the most promising method for the amplification of broadband optical pulses.In the meantime,we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers.The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level.Meanwhile,the output pulse duration based on optical parametric amplification has entered the range of fewoptical-cycle field.In this paper,we overview the basic principles,trends in development,and current state of the ultrashort and laser systems based on OPCPA,respectively.  相似文献   
57.
4‐Benzamido‐TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO3 under room temperature conditions has been developed. The credible, operationally convenient and economical, and condition mild oxidation protocol is particularly of interest in laboratory and in fine chemicals manufacture.  相似文献   
58.
Protein 4′-phosphopantetheinylation is an essential post-translational modification (PTM) in prokaryotes and eukaryotes. So far, only five protein substrates of this specific PTM have been discovered in mammalian cells. These proteins are known to perform important functions, including fatty acid biosynthesis and folate metabolism, as well as β-alanine activation. To explore existing and new substrates of 4′-phosphopantetheinylation in mammalian proteomes, we designed and synthesized a series of new pantetheine analogue probes, enabling effective metabolic labelling of 4′-phosphopantetheinylated proteins in HepG2 cells. In combination with a quantitative chemical proteomic platform, we enriched and identified all the currently known 4′-phosphopantetheinylated proteins with high confidence, and unambiguously determined their exact sites of modification. More encouragingly, we discovered, using targeted chemical proteomics, a potential 4′-phosphopantetheinylation site in the protein of mitochondrial dehydrogenase/reductase SDR family member 2 (DHRS2).  相似文献   
59.
Liang  Xingyue  Xia  Jianwei  Li  Yongmin  Lu  Junwei  Chu  Yuming 《Nonlinear dynamics》2022,108(2):1409-1423
Nonlinear Dynamics - This article investigates the issue of hybrid-triggered control for fuzzy Markov jump system under input saturation. First, a hybrid-triggered control scheme is presented,...  相似文献   
60.
This work reported the discovery of N-triflimide (NTf)-based zwitter-ionic liquids (ZILs) that exhibit UCST-type phase transitions in water, and their further structural optimization in fine-tuning polarity to ultimately afford newfangled thermosensitive materials carrying attractive and biocompatible Tc values that clearly demonstrated the true value of the tunability of ZIL structure. This research established that with non-aromatic, acyclic ZILs as small-molecule thermoresponsive materials, their mixing and de-mixing with water triggered by temperatures are entirely reversible.  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