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   228篇
  免费   15篇
  国内免费   1篇
电工技术   1篇
化学工业   105篇
金属工艺   1篇
机械仪表   3篇
建筑科学   5篇
矿业工程   2篇
能源动力   22篇
轻工业   12篇
水利工程   1篇
石油天然气   1篇
无线电   22篇
一般工业技术   32篇
冶金工业   12篇
原子能技术   3篇
自动化技术   22篇
  2024年   1篇
  2022年   4篇
  2021年   7篇
  2020年   3篇
  2019年   4篇
  2018年   10篇
  2017年   10篇
  2016年   15篇
  2015年   8篇
  2014年   9篇
  2013年   26篇
  2012年   13篇
  2011年   15篇
  2010年   16篇
  2009年   20篇
  2008年   20篇
  2007年   13篇
  2006年   14篇
  2005年   4篇
  2004年   1篇
  2003年   5篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   4篇
  1996年   2篇
  1994年   2篇
  1992年   2篇
  1990年   2篇
  1989年   2篇
  1983年   1篇
  1982年   1篇
  1962年   1篇
排序方式: 共有244条查询结果,搜索用时 687 毫秒
231.
232.
A novel donor–acceptor type conducting polymer based on BODIPY dye as acceptor and EDOT units as donor parts is synthesized electrochemically. The unique combination of BODIPY and EDOT units provides an ambipolar (n- and p-doping processes) low band gap material (4). This is the first example of p–n junction in an organic π-conjugated material where BODIPY unit is incorporated directly in the main chain. Furthermore, the polymer film exhibits electrochromic behavior upon p-doping: a color change from light violet (neutral) to indigo (oxidized).  相似文献   
233.
A novel conducting polymer was successfully synthesized via electropolymerization of 1-(1H-pyrrol-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole. The electrochemical and electro-optical properties of the corresponding polymer, which was the first example of polymer containing 1,1′-bipyrrole units, were elaborated using electroanalytical and spectroscopic techniques. Cyclic voltammograms and electro-optical studies showed that the polymer has a stable and well-defined reversible redox process as well as electrochromic behavior. The processable polymer film also possessed a yellowish orange light emitter property.  相似文献   
234.
The main purpose of this study was to examine if disgust toward unpalatable foods would be reduced among food-deprived subjects and if this attenuation would occur automatically even under moderate levels of food deprivation. Subjects were either satiated or food deprived for 15 hours and electromyographic activity was recorded at the levator muscle region while they were watching pictures of palatable versus unpalatable foods, and pictures of positive versus disgust-related control pictures. For control purposes, subjects' activity of the zygomaticus and corrugator muscles was also recorded. As compared with satiated subjects, food-deprived subjects exhibited stronger activity in the zygomaticus muscle region when watching pictures of palatable foods (but not when watching positive control pictures). More important, hungry subjects exhibited weaker activity in the levator muscle region when watching pictures of unpalatable foods (but not when watching disgusting control pictures). Thus, this is the first study ever to show that specific emotions (disgust) are moderated by homeostatic dysregulation automatically. Results indicate that the modulation of facial expressions might play an important role in lowering the threshold for food intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
235.
New compounds consisting of aniline units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis and cyclic voltammetry in an aqueous solution containing 3.0 mol L?1 H2SO4. Chemical polymerization was carried out using (NH4)2S2O8 as oxidizing agent. It was found that both methods gave the same polymer product without any cleavage of the polyether bridge between aniline rings. The polymers were characterized using the Fourier transform infrared spectroscopic technique and the thermal behavior of electrochemically prepared polymers was investigated using thermogravimetric analysis. Spectroelectrochemical properties of the films were investigated using the in situ UV‐visible spectroscopic technique. Copyright © 2007 Society of Chemical Industry  相似文献   
236.
Video games in psychotherapy.   总被引:1,自引:0,他引:1  
Video games have found their way into the clinical care of youth in most medical fields, and academic interest in their use is increasing steadily. The popularity of video games among youth may qualify them as a useful tool in psychotherapy for children and adolescents. Limited literature on use of video games in mental health care suggests that they can help young patients become more cooperative and enthusiastic about psychotherapy. Recent experience suggests that video games may facilitate therapeutic relationships, complement the psychological assessment of youth by evaluating cognitive skills, and elaborate and clarify conflicts during the therapy process. Concerns about video game content, perceived effects on youth, and lack of familiarity with this medium may form a barrier in their use in therapy offices. Further research on the benefits of video game use in psychotherapy, including patient characteristics that may moderate outcomes, is needed. Finally, future collaborations between clinicians and video game developers may produce specific games to be used in psychotherapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
237.
Behaviour of masonry structures under earthquake loading. The objective of the seismic design of structures is to provide sufficient resistance considering the ductility of the structure. With experiments on storey‐high walls at the University of Dortmund the performance of masonry shear walls under simulated earthquake loading was identified up to failure. The nonlinear behaviour of the walls was evaluated with regard to resistance and potential for ductility. Depending on the type of the limit state the walls exhibited different quantities of ductility. Analyses showed that within certain limits mechanisms with higher ductility can be attained by appropriate tuning of the structural parameters. Considering configurations of walls typical for terraced houses and apartment buildings the structural ductility and the corresponding behaviour factors for seismic design (see EC 8 and DIN 4149) were assessed.  相似文献   
238.
It has been shown that in the context of a linear theory for a floating body with six degrees of freedom each of the 6× 6 added-mass and damping matrices contains three distinct Cartesian second-order tensors in regard to translational, rotational and interaction between translational and rotational oscillations. As a result of this, a new technique based on the transformation law of second-order tensors is introduced for motion analysis of offshore platforms which can be used as an alternative to the common methods in offshore engineering.  相似文献   
239.
The management of resources has been claimed to be as important as scheduling methods. Inefficiency in managing resources may bring about severe delays and cost overruns caused by resource shortages in some cases and/or idle resources in others. Therefore, resources should be utilized efficiently to prevent project failures. Resource leveling is one of the approaches that are used for the management of resources. It aims to minimize fluctuations, peaks, and valleys in resource utilization without changing the completion time of a project and the number of resources required. Although the main principle behind traditional resource leveling is achieving an even flow of resources while the original project duration remains unchanged, the literature supports the need to develop an efficient model that discriminates among the activities that are selected for participation in resource leveling. For this purpose, this study has developed a model that considers the float consumption rates of activities in resource leveling. The float consumption rate is the percentage that is set to determine the maximum amount of float which will be consumed to shift the start time of the activity. The proposed model allows a scheduler to assign float consumption rates to each activity that can be used during the resource leveling procedure. When the required information is inputted, the proposed model automatically changes the required daily resources as it shifts the noncritical activities along their available total float times. The proposed model is expected to minimize the likelihood of severe delays and cost overruns. The model is demonstrated by constructing a network and its resource utilization histograms.  相似文献   
240.
Abstract

Pyrolysis kinetics of the Yeni Çeltek lignite/sugar beet pulp blends prepared at different ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100) were investigated by thermogravimetric analysis in the present study. All the experiments were carried out in nitrogen atmosphere under non-isothermal conditions with a heating rate range of 30 K/min in the pyrolysis temperature interval of 298–1,173 K. The Arrhenius model is applied to determine the kinetic parameters from TG/DTG curves. Apparent activation energies of the lignite and sugar beet pulp were calculated as 51.55 kJ/mol and 97.27 kJ/mol, respectively. Activation energies of the blends were also calculated and were found to vary between 54.87 and 74.83 kJ/mol. Effects of blending ratio of lignite to sugar beet pulp on kinetic parameters were investigated and the results were discussed.  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