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   1069篇
  免费   94篇
  国内免费   5篇
化学   845篇
晶体学   3篇
力学   19篇
数学   129篇
物理学   172篇
  2023年   29篇
  2022年   20篇
  2021年   44篇
  2020年   63篇
  2019年   54篇
  2018年   22篇
  2017年   30篇
  2016年   52篇
  2015年   61篇
  2014年   45篇
  2013年   56篇
  2012年   66篇
  2011年   80篇
  2010年   38篇
  2009年   43篇
  2008年   45篇
  2007年   41篇
  2006年   48篇
  2005年   26篇
  2004年   17篇
  2003年   19篇
  2002年   19篇
  2001年   13篇
  2000年   12篇
  1999年   11篇
  1998年   13篇
  1996年   4篇
  1995年   7篇
  1994年   4篇
  1993年   8篇
  1992年   5篇
  1991年   7篇
  1990年   6篇
  1989年   13篇
  1988年   10篇
  1987年   7篇
  1986年   6篇
  1985年   8篇
  1984年   4篇
  1983年   5篇
  1982年   10篇
  1981年   7篇
  1980年   8篇
  1979年   4篇
  1977年   15篇
  1976年   8篇
  1975年   11篇
  1974年   6篇
  1973年   9篇
  1937年   5篇
排序方式: 共有1168条查询结果,搜索用时 125 毫秒
961.
962.
To enable the investigation of low-affinity biomolecular complexes with confocal single-molecule spectroscopy, we have developed a microfluidic device that allows a concentrated sample to be diluted by up to five orders of magnitude within milliseconds, at the physical limit dictated by diffusion. We demonstrate the capabilities of the device by studying the dissociation kinetics and structural properties of low-affinity protein complexes using single-molecule two-color and three-color Förster resonance energy transfer (FRET). We show that the versatility of the device makes it suitable for studying complexes with dissociation constants from low nanomolar up to 10 μm , thus covering a wide range of biomolecular interactions. The design and precise fabrication of the devices ensure simple yet reliable operation and high reproducibility of the results.  相似文献   
963.
964.
965.
966.
A key feature of dynamic problems which offer degrees of freedom to the decision maker is the necessity for a goal-oriented decision making routine which is employed every time the logic of the system requires a decision. In this paper, we look at optimization procedures which appear as subroutines in dynamic problems and show how discrete event simulation can be used to assess the quality of algorithms: after establishing a general link between online optimization and discrete event systems, we address performance measurement in dynamic settings and derive a corresponding tool kit. We then analyze several control strategies using the methodologies discussed previously in two real world examples of discrete event simulation models: a manual order picking system and a pickup and delivery service.  相似文献   
967.
A rapid and efficient protocol assisted by microwave irradiation for the synthesis of esters using methanesulfonic acid (CH3SO3H) supported on Al2O3 (AMA) as catalyst and free of solvent is described. The products were obtained in good yields and purity, with reduced reaction time, and the process is simple and environmentally benign.  相似文献   
968.
In recent years, interest in nanostructured electrode materials for use in supercapacitors has been on the rise. Nickel oxide has been reported as a good candidate for supercapacitor applications due to its high theoretical capacitance and low cost. However, its poor electrical conductivity has resulted in actual poor specific capacitance and cycling ability. Over the years, researchers have studied various techniques to modify the structure and composition of NiO with the aim of improving its electrochemical performance. In this review, we opine that NiO-based electrodes can be fabricated using different approaches and different composite forms in order to obtain cells of high efficiency and specific capacitances. We discuss the recent advances in NiO-based electrodes fabricated using different approaches.  相似文献   
969.
970.
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