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   144篇
  免费   7篇
电工技术   5篇
化学工业   43篇
金属工艺   3篇
机械仪表   3篇
建筑科学   12篇
能源动力   3篇
轻工业   5篇
水利工程   1篇
无线电   11篇
一般工业技术   24篇
冶金工业   16篇
自动化技术   25篇
  2024年   2篇
  2023年   3篇
  2022年   11篇
  2021年   1篇
  2020年   6篇
  2019年   1篇
  2018年   5篇
  2017年   7篇
  2015年   3篇
  2014年   6篇
  2013年   14篇
  2012年   2篇
  2011年   7篇
  2010年   9篇
  2009年   9篇
  2008年   5篇
  2007年   4篇
  2006年   4篇
  2005年   3篇
  2004年   9篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   4篇
  1997年   1篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   2篇
  1989年   1篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   3篇
  1979年   2篇
  1973年   1篇
  1971年   2篇
  1968年   1篇
排序方式: 共有151条查询结果,搜索用时 31 毫秒
61.
62.
The λ-scheme     
A scheme for integrating the Euler equations of compressible flow in any hyperbolic case is presented. The scheme relies on the concept of characteristics but is strictly a finite difference scheme. Improvements is accuracy and physical consistence due to the scheme are discussed and results of its application to complex flows are shown.  相似文献   
63.
64.
    
In this study, we investigate the effects of electric field-assisted ion exchange (EF-IE) on potassium for sodium ion exchanges of soda borosilicate and soda lime silicate glasses. The results show that applying an electric field (E-field) with the intensity of 1000 V cm−1 for few minutes produces an exchanged layer with a thickness comparable to the conventional chemical strengthening for 4 hours. There is a critical E-field that increases the mobility and, therefore, the diffusion coefficient of the potassium ions in the glasses. The increase is, perhaps, related to the evolution of the glass structure due to the penetration of potassium ions under an E-field. Vickers indentations showed that strong compression is generated in the glass by EF-IE; however, the bending strength improvement is limited because of the presence of large surface defects and the stress distribution inhomogeneity.  相似文献   
65.
    
Chloride contents at the steel–mortar interface that initiate steel corrosion were determined for carbon steel in alkali-activated fly ash mortar for three different exposure conditions: exposure to 1 M NaCl solution; leaching in deionized water and then exposure to 1 M NaCl solution; and leaching in deionized water, aging in air at 20°C and natural CO2 concentration, and then exposure to 1 M NaCl solution. For comparison, a Portland cement mortar, exposed to 1 M NaCl solution, was studied. The median values of the corrosion-initiating chloride contents (average over the full length of the rebar) in the alkali-activated fly ash mortar varied between 0.35 and 1.05 wt% Cl with respect to binder, consistently lower than what was obtained for the Portland cement mortar, but with no clear trend regarding the exposure conditions. For most of the alkali-activated fly ash mortar specimens, preferential corrosion at the connection between the working electrode and the external measurement setup was observed, while preferential corrosion did not occur for the Portland cement mortar. Scanning electron microscopy and auxiliary experiments in synthetic solutions indicated that this behavior was caused by inhomogeneities at the steel–mortar interface in the alkali-activated mortar, likely due to its peculiar rheological properties in the fresh state.  相似文献   
66.
Journal of Porous Materials - Carbon monoxide releasing molecule-2 (CORM-2) exhibited protection against cardiac hypoxia reoxygenation injury (H/R). However, its poor water solubility and short...  相似文献   
67.
The hydrophobic or hydrophilic properties of solid catalysts often have a crucial influence on their properties in liquid-phase catalytic reactions. Several methods to measure liquid-phase adsorption on catalytic solids are compared, and special attention is given to the liquid chromatographic method. The experimental setup and the determination of adsorption constants are discussed. Finally, adsorption data measured via the chromatographic method are used to gain insight into liquid-phase catalytic reactions, particularly oxidations with Ti zeolites.  相似文献   
68.
In this work the room temperature electrical conductivity of Si(B)OC glasses made via polymer pyrolysis at 1200°C and 1400°C (maximum temperature) and having different amount of boron was measured. When B content is increased from zero (pure SiOC glass) up to B/Si=0.5 the electrical conductivity increases in 2 orders of magnitude from 4.09±0.64×10?5 up to 2.93±1.91×10?3 with a corresponding decrease in the activation energy from about 1.08 to 0.51 eV. This results shows for the first time that the electrical conductivity of Si‐based polymer‐derived ceramics can be controlled by the amount of the doping element. The structure of the Si(B)OC glasses has been studied with different techniques including FT‐IR, XRD and Raman spectroscopy. The Raman study indicates that B partially substitutes C into the sp2 C planes of the free carbon phase forming trigonal BC3 units. Accordingly, the evolution of the electrical properties with the B content has been correlated with the corresponding structural evolution and a hypothesis is presented to rationalize the role of boron on the electrical conductivity of SiOBC glasses.  相似文献   
69.
The biocompatibility and the antioxidant activity of barium titanate (BaTiO3) and lithium niobate (LiNbO3) were investigated on a neuronal cell line, the PC12, to explore the possibility of using piezoelectric nanoparticles in the treatment of inner ear diseases, avoiding damage to neurons, the most delicate and sensitive human cells. The cytocompatibility of the compounds was verified by analysing cell viability, cell morphology, apoptotic markers, oxidative stress and neurite outgrowth. The results showed that BaTiO3 and LiNbO3 nanoparticles do not affect the viability, morphological features, cytochrome c distribution and production of reactive oxygen species (ROS) by PC12 cells, and stimulate neurite branching. These data suggest the biocompatibility of BaTiO3 and LiNbO3 nanoparticles, and that they could be suitable candidates to improve the efficiency of new implantable hearing devices without damaging the neuronal cells.  相似文献   
70.
In automated production processes grasping devices and methods play a crucial role in the handling of many parts, components and products. This keynote paper starts with a classification of grasping phases, describes how different principles are adopted at different scales in different applications and continues explaining different releasing strategies and principles. Then the paper classifies the numerous sensors used to monitor the effectiveness of grasping (part presence, exchanged force, stick-slip transitions, etc.). Later the grasping and releasing problems in different fields (from mechanical assembly to disassembly, from aerospace to food industry, from textile to logistics) are discussed. Finally, the most recent research is reviewed in order to introduce the new trends in grasping. They provide an outlook on the future of both grippers and robotic hands in automated production processes.  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