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   109篇
  免费   3篇
  国内免费   2篇
电工技术   3篇
化学工业   21篇
金属工艺   9篇
机械仪表   4篇
建筑科学   3篇
能源动力   5篇
轻工业   9篇
水利工程   3篇
无线电   17篇
一般工业技术   15篇
冶金工业   14篇
自动化技术   11篇
  2023年   2篇
  2022年   1篇
  2021年   8篇
  2020年   3篇
  2019年   6篇
  2018年   5篇
  2017年   4篇
  2016年   9篇
  2015年   3篇
  2014年   7篇
  2013年   4篇
  2012年   8篇
  2011年   3篇
  2010年   2篇
  2008年   1篇
  2007年   3篇
  2006年   2篇
  2004年   4篇
  2003年   3篇
  2002年   1篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1996年   2篇
  1994年   2篇
  1993年   4篇
  1992年   2篇
  1988年   3篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1974年   3篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1964年   1篇
排序方式: 共有114条查询结果,搜索用时 0 毫秒
31.
Weak amylopectin gels have been formed directly following dissolution of waxy maize granules. Rheological characterisation of these gels has been carried out as a function of stress and frequency. The gels are visually clear and homogeneous, and environmental scanning electron microscopy shows no trace of the original granules remaining. It is postulated that the origin of the gel network lies in pairwise aggregation of outer chains of the amylopectin molecules, presumably via double helix formation. However, these pairs of chain segments do not aggregate to develop crystallinity.  相似文献   
32.
根据主要从事半导体及电子市行业市场调研的机构Databeans调查.电气和电子元件占一般汽车总成本约20%。该公司估计一辆2004年生产的低价位汽车上有150到180个电子元件.而现在生产的高价位汽车上则最少包含400个电子元件。  相似文献   
33.
In this paper, we describe a self-aligned process to produce short-channel vertical power DMOSFETs in 4H-SiC. By reducing the channel length to /spl les/0.5 /spl mu/m, the specific on-resistance of the MOSFET channel is proportionally reduced, significantly enhancing performance.  相似文献   
34.
In this work, Cu2ZnSnS4 (CZTS) thin films were prepared by the sulfurization of metal precursors deposited sequentially via radio frequency magnetron sputtering on Mo-coated soda-lime glass. The stack order of the precursors was Mo/Zn/Sn/Cu. Sputtered precursors were annealed in sulfur atmosphere with nine different conditions to study the impact of sulfurization time and substrate temperature on the structural, morphological, and optical properties of the final CZTS films. X-ray fluorescence was used to determine the elemental composition ratio of the metal precursors. Final CZTS films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). XRD and EDS were combined to investigate the films’ structure and to identify the presence of secondary phases. XRD analysis indicated an improvement in film crystallinity with an increase of the substrate temperature and annealing times. Also indicated was the minimization and/or elimination of secondary phases when the films experienced longer annealing time. EDS revealed slight Sn loss in films sulfurized at 550°C; however, an increase of the sulfurization temperature to 600°C did not confirm these results. SEM study showed that films treated with higher temperatures exhibited dense morphology, indicating the completion of the sulfurization process. The estimated absorption coefficient was on the order of 104 cm?1 for all CZTS films, and the values obtained for the optical bandgap energy of the films were between 1.33 eV and 1.52 eV.  相似文献   
35.
36.
A major drawback for CuO as an efficient photocathode in photoelectrochemical (PEC) water splitting is its instability in aqueous solution. In this paper, we report that Ti alloying can enhance the stability of CuO in PEC water splitting but at the cost of reduced crystallinity and optical absorption, and therefore reduced photocurrent. We further report that a balance between the stability and photocurrent can be realized by a bilayer configuration—a thin Ti-alloyed CuO layer on a pure CuO thin film. Our results indicate that the thickness of the top Ti-alloyed CuO layer should be optimized to realize the best stability and photocurrent.  相似文献   
37.
The main focus of the research was to correlate the microstructure with dielectric and magnetic properties of Bi1-xBaxFeO3 samples. Bi1-xBaxFeO3 samples(x = 0.1, 0.2 and 0.3) were synthesized by the conventional solid-state reaction method using nano-powders of Bi2O3, Fe2O3, and BaCO3. Thereafter, field emission scanning electron microscope and X-ray diffraction(XRD) techniques were used to examine the structure and phase of the samples. Phase analysis by XRD indicated that the single-phase perovskite structure was formed with possible increment in lattice parameter with increasing Ba doping. Complex permeability(u'iand u'i) measured using impedance analyzer confirmed the increase in magnetic property with increasing Ba doping. Finally, dielectric constant(k) was analyzed as a function of temperature at different frequencies. Dielectric constant as high as 2900 was attained in this research for Bi0.8Ba0.2FeO3 sample due to reduction in leakage current at this composition.  相似文献   
38.
39.
40.
Information-processing time was compared for serial and spatially distributed visual presentations with performance measures that permit the separation of total time into its during-display and post-display components. For all subjects, there was a significant saccadic overhead, that is, less time was required with the serial format, which allowed data access without eye movements. However, the magnitude of the overhead decreased as task complexity increased. All subjects were able to exercise some control over the distribution of total processing time, trading off short during-display times with longer post-display times and vice versa.  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