全文获取类型
收费全文 | 118篇 |
免费 | 10篇 |
国内免费 | 8篇 |
专业分类
综合类 | 2篇 |
化学工业 | 10篇 |
机械仪表 | 41篇 |
轻工业 | 3篇 |
石油天然气 | 5篇 |
无线电 | 42篇 |
一般工业技术 | 23篇 |
冶金工业 | 6篇 |
自动化技术 | 4篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 10篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 13篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 31 毫秒
1.
采用溶胶凝胶方法成功地制备了掺杂稀土铽离子的 Zn O和 Mg0 .1 5Zn0 .85薄膜。通过对 X射线衍射结果的分析表明 ,稀土离子替代了 Zn2 +的格位 ,进入了半导体基质的晶格中。从阴极射线发光结果可以发现 ,在Mg0 .1 5Zn0 .85O基质中 ,可以观察到来源于稀土铽离子各能级的发射 ,而 Zn O:Tb的薄膜只能观察到较强的铽离子 5D4 — 7F5能级的跃迁。这可能是由于 Mg0 .1 5Zn0 .85O基质的能隙 (3 .65 e V)比 Zn O更宽 (3 .3 e V) ,其对铽离子的能量传递更有效的缘故。 相似文献
2.
3.
Berg Alexander Caroff Philippe Shahid Naeem Lockrey Mark N. Yuan Xiaoming Borgström Magnus T. Tan Hark Hoe Jagadish Chennupati 《Nano Research》2017,10(2):672-682
Ternary Ⅲ-Ⅴ nanowires (NWs) cover a wide range of wavelengths in the solar spectrum and would greatly benefit from being synthesized as position-controlled arrays for improved vertical yield,reprodudbility,and tunable optical absorption.Here,we report on successful selective-area epitaxy of metal-particle-free vertical InxGa1-xP NW arrays using metal-organic vapor phase epitaxy and detail their optical properties.A systematic growth study establishes the range of suitable growth parameters to obtain uniform NW growth over a large array.The optical properties of the NWs were characterized by room-temperature cathodoluminescence spectroscopy.Tunability of the emission wavelength from 870 nm to approximately 800 nm was achieved.Transmission electron microscopy and energy dispersive X-ray measurements performed on crosssection samples revealed a pure wurtzite crystal structure with very few stacking faults and a slight composition gradient along the NW growth axis. 相似文献
4.
Using recent papers on scanning electron microscopy (SEM) of chemical vapor deposition (CVD) diamond films, two analytical applications of the SEM are discussed: the morphologic investigations (secondary electron emission mode) and the recognition of impurities and defects [cathodoluminescence (CL) mode]. Studies of CVD diamond films by SEM demonstrate that the morphologies of these films are affected by synthesis conditions, especially by substrate temperature, methane concentration, and total pressure in the reactor. CL spectra and images are useful tools for clarifying the relationship between emission centers and different types of defects generated during the process of diamond crystal growth. The paper shows that the investigations of the morphology, crystallinity, local CL emission, as well as the surface distribution of CL spectra on CVD diamond films by SEM led to the correlative information for quality estimation of films in comparison with natural diamond. 相似文献
5.
Cathodoluminescence study of semiconductor oxide micro- and nanostructures grown by vapor deposition
Nano- and microstructures of SnO(2), In(2)O(3) and ZnO have been grown during thermal treatment of compacted powders under argon flow. Indium-doped SnO(2) tube-shaped structures with rectangular cross-section are obtained by adding a fraction of In(2)O(3) to the starting SnO(2) powder. In-rich nanoislands were found to grow on some edges of the tubes. ZnO nanostructures doped with Sn or Eu were grown by adding SnO(2) and Eu(2)O(3) powder, respectively, to the ZnO precursor powder. All the samples have been characterized by the emissive and cathodoluminescence (CL) modes of scanning electron microscopy. CL images from SnO(2):In and In(2)O(3):Sn tubes and islands show a higher emission from the Sn-rich structures related to oxygen deficiency. CL of doped ZnO enables to detect the presence of dopant in specific regions or structures. CL appears to be a useful technique to study optical and electronic properties of semiconductor oxide nanostructures. 相似文献
6.
AbstractSpatially and spectrally resolved low-energy cathodoluminescence (CL) microscopy was applied to the characterization of nanostructures. CL has the advantage of revealing not only the presence of luminescence centers but also their spatial distribution. The use of electrons as an excitation source allows a direct comparison with other electron-beam techniques. Thus, CL is a powerful method to correlate luminescence with the sample structure and to clarify the origin of the luminescence. However, caution is needed in the quantitative analysis of CL measurements. In this review, the advantages of cathodoluminescence for qualitative analysis and disadvantages for quantitative analysis are presented on the example of nanostructures. 相似文献
7.
Georg Koschek 《Journal of microscopy》1992,168(1):79-84
The suitability of cathodoluminescence (CL) measurements for differentiating between different paint pigments is demonstrated with an example of a combined energy-dispersive X-ray (EDX) and CL analysis of different zinc oxide (ZnO) pigments in a paint fragment where the EDX spectra are virtually identical, but where the CL spectra show significant differences. Consequently, it is possible to distinguish different pigments on the basis of CL spectra and monochromatic CL micrographs. 相似文献
8.
Zinc oxide (ZnO) stacked films were prepared by repeating a procedure involving KrF excimer laser irradiation at various energy fluences (Ef) of sol-gel-derived precursors. All the stacked films are wurtzite-type and highly c-axis oriented on glass substrates. The green cathodoluminescence (CL) efficiency of the films is strongly influenced by the preparation conditions. Especially, laser Ef and stacking number are important control factors. The stacked film prepared under optimized preparation conditions consists of large grains and indicate low electric resistivity. The green CL efficiency of the stacked film is 0.0139 lm/W, which is higher than those of ZnO thin films prepared by a single stacking. 相似文献
9.
10.
This paper investigates the effectiveness of multiple indium atomic planes in reducing the dislocation density in GaAs epitaxial
layers grown by metalorganic molecular beam epitaxy on GaAs-coated Si substrates prepared by metalorganic chemical vapor deposition.In situ reflection high-energy electron diffraction patterns show that, during the growth of multiple indium atomic-plane structures,
two-dimensional growth takes place. Cross-sectional transmission electron microscope observation shows that InAs sublayers
are commensurate; hence the critical thickness of the InAs layer in this structure is more than one-monolayer. Cathodoluminescence
examination indicates that the defect density decreases as the number (<60) of indium atomic planes increases. This new structure
is more effective in dislocation reduction than conventional In0.1Ga0.9As/GaAs strained-layer superlattices. 相似文献