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   1881篇
  免费   119篇
  国内免费   97篇
电工技术   29篇
综合类   111篇
化学工业   597篇
金属工艺   29篇
机械仪表   33篇
建筑科学   33篇
矿业工程   17篇
能源动力   21篇
轻工业   436篇
水利工程   6篇
石油天然气   21篇
武器工业   14篇
无线电   133篇
一般工业技术   507篇
冶金工业   33篇
原子能技术   1篇
自动化技术   76篇
  2024年   18篇
  2023年   45篇
  2022年   69篇
  2021年   73篇
  2020年   61篇
  2019年   55篇
  2018年   50篇
  2017年   65篇
  2016年   54篇
  2015年   59篇
  2014年   106篇
  2013年   109篇
  2012年   154篇
  2011年   152篇
  2010年   123篇
  2009年   144篇
  2008年   109篇
  2007年   122篇
  2006年   120篇
  2005年   107篇
  2004年   73篇
  2003年   51篇
  2002年   50篇
  2001年   20篇
  2000年   33篇
  1999年   16篇
  1998年   15篇
  1997年   17篇
  1996年   10篇
  1995年   6篇
  1994年   3篇
  1993年   3篇
  1992年   2篇
  1991年   2篇
  1989年   1篇
排序方式: 共有2097条查询结果,搜索用时 39 毫秒
51.
针对喷码机油墨压力控制存在时滞性的特点和现有的油墨压力控制系统控制参数不易调节、调节时间过长、抗干扰能力不强等问题,结合模糊控制器和PI控制器两者的优点,设计并实现了一个模糊PI双模控制器对油墨压力进行调节。实际测试结果表明:与现有的油墨压力控制系统相比,设计的模糊PI控制器能够有效地对油墨压力进行控制,超调量较小,调节时间较短、控制精度及抗干扰均取得了较好的效果。  相似文献   
52.
针对印刷数字化流程中的油墨预置技术,提出一种基于图像分析的油墨预置技术。选择RIP(Raster Image Processor)后的1bit TIFF图像为基础数据,提取各墨区对应的网点面积率;建立了网点面积率和墨键开度的数学模型,并采用最小二乘法求解模型参数,从而实现油墨预置。实验结果表明,所求取的油墨预置量可以较好地拟合原来的数据,采用该技术可以提高印刷工作效率,减少印刷浪费。  相似文献   
53.
阐述了玻璃幕墙的传热系数K值与遮阳系数Sc的取值不同对空调冷负荷的影响;指出了不能单纯以K值来评估玻璃幕墙的热工性能的优劣,Sc值对热工性能影响更大,只有综合考虑K值和Sc值及环境因素,才能选择一个节能、环保的合适玻璃幕墙.  相似文献   
54.
采用乳液共聚法制备聚氨酯-聚丙烯酸酯复合乳液,并以酞菁蓝为颜料配制了塑料凹版水性油墨,讨论了封端剂丙烯酸-β-羟乙基酯含量和颜料含量对水性油墨性能的影响.结果表明,随着HEA用量的增加,PUA复合乳液和水性油墨的粘度增加,但油墨的稳定性先得到改善而后下降;随着颜料含量的增加,水性油墨的稳定性变差,13%的颜料含量为宜;该水性油墨不仅对PET薄膜具有优异的附着牢度,对OPP薄膜同样具有良好的附着牢度并具有良好的耐水性能.  相似文献   
55.
采用气浮—缩聚—SBR工艺处理油墨生产废水,通过加药气浮去除油墨废水中的悬浮油、乳化油后再进行碱性缩聚,使废水中的醛类变成生化的碳源,再进入SBR生化反应器进行降解,出水指标CODCr可降至150mg/L以下。  相似文献   
56.
化工可持续发展的思考   总被引:6,自引:0,他引:6  
介绍了社会可持续发展的概念和重要性,及实施生态化工的一些具体途径:化学过程及工艺的绿色化,可再生资源的开发及废弃资源的综合利用,发展纳米科技及微化工技术,强化过程及化工集成,建设生态工业园区,并推进化工信息化。  相似文献   
57.
《Advanced Powder Technology》2021,32(10):3845-3859
Catalyst layers (CL), as an active component of the catalyst coated membrane (CCM), form the heart of the polymer electrolyte membrane fuel cell (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as CL precursors need to be modulated, which are then applied onto a membrane to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods, which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of the inks. Herein, we introduce new concepts, S score, and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.  相似文献   
58.
我国绿色环保油墨标准现状及思考   总被引:1,自引:0,他引:1  
本文介绍了国内外绿色环保油墨标准的现状,分析了我国绿色环保油墨标准存在的问题,提出了建议。  相似文献   
59.
Unused base inks that are not going to be used for printing production are considered to be hazardous materials. Their disposal is expensive, and strict environmental regulations should be followed for their disposal. As an alternative, this article describes how spectral data of unused base inks can be gathered and mixed to generate new colors to incorporate them back to print production for small‐volume jobs. In this study, 30 different Pantone colors were selected as target colors. The CIE L*a*b* spectral data of Pantone colors and unused base inks were gathered via a spectrophotometer. A commercial formulation software, based on multiflux theory and CIE L*a*b* color space, was used to formulate ink recipes that contained the base inks. To quantify the performance of ink recipes, they were mixed and printed using an offset printability tester. The CIELAB ΔE*ab metric, developed by CIE, was used to detect the visual differences between the target Pantone Color and printed colors.  相似文献   
60.
Patterned photonic crystals with structural colors on textile substrates have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study utilized an ink-jet printing technology to prepare high-quality photonic crystal patterns with structural colors on polyester substrates. The self-assembly temperature of poly(styrene-N-methylol acrylamide) (P(St-NMA)) microspheres set to construct photonic crystals were deeply optimized. Moreover, the structural colors of prepared photonic crystal patterns were characterized and evaluated. When the mass fraction of P(St-NMA) microspheres was 1.0 wt.%, the pH value ranged from 5 to 7, and the surface tension was in the range of 63.79 to 71.20 mN/m, inks could present the best print performance. At 60 °C, prepared P(St-NMA) microsphere inks were good for printing to obtain patterned photonic crystals with regular arrangement and beautiful structural colors. Specifically, photonic crystals with different colors could be constructed by regulating the diameter of microspheres in inks, and prepared structural colors exhibited distinct iridescent phenomenon. The present results could provide a theoretical basis for the industrial realization of patterned photonic crystals by ink-jet printing technology.  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