全文获取类型
收费全文 | 304篇 |
免费 | 51篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 57篇 |
金属工艺 | 3篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
能源动力 | 2篇 |
轻工业 | 3篇 |
水利工程 | 2篇 |
无线电 | 34篇 |
一般工业技术 | 236篇 |
冶金工业 | 4篇 |
原子能技术 | 1篇 |
自动化技术 | 7篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 4篇 |
2020年 | 20篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 25篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 33篇 |
2011年 | 37篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1992年 | 1篇 |
排序方式: 共有356条查询结果,搜索用时 31 毫秒
1.
Silicon - The performance comparison and the temperature profile of AlGaN/GaN HEMT on different substrates are investigated. It results the maximum drain-source current (IDS) of 1.08 A/mm, 1.04... 相似文献
2.
Arivazhagan L. Nirmal D. Reddy P. Pavan Kumar Ajayan J. Godfrey D. Prajoon P. Ray Ashok 《SILICON》2021,13(9):3039-3046
Silicon - In this paper, AlGaN/GaN High Electron Mobility Transistor (HEMT) with stacked passivation (Diamond/SiN) is proposed and investigated. The implementation of stacked passivation in HEMT... 相似文献
3.
Phytoplankton as biomonitors: A study of Museum Lake in Government Botanical Garden and Museum,Thiruvananthapuram, Kerala India
下载免费PDF全文
![点击此处可从《Lakes & Reservoirs: Research and Management》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An assessment of the pollution status of Museum Lake in the Thiruvananthapuram Botanical Garden and Museum was conducted. Analysis of different community structures of the planktonic taxa in the lake revealed it is organically polluted, attributable to the organic litter from riparian vegetation. A total of 30 most pollution‐tolerant phytoplankton genera and 24 pollution‐tolerant species were identified. Pollution‐tolerant phytoplankton genera in the lake included Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae. Scenedesmus, Pinnularia, Euglena, Ankistrodesmus, Closterium, Crucigenia, Kirchneriella, Merismopedia and Oscillatoria were some of the phytoplankton pollution tolerant genera whereas, Nitzschia palea, Synedra acus, Scenedesmus quadricauda, Pandorina morum and Trachelomonas volvocina were some of the pollution tolerant species noted. Excessive nutrient loading from the surrounding area is definitely degrading the quality of this urban lake ecosystem. Detailed information regarding the pollution status of a waterbody is very important in this regard, noting it ultimately assists in undertaking proper management of a waterbody. The Palmer Algal Index score for Museum Lake was 37, indicating it is highly organic enriched. The results of different algal indices (e.g. Chlorophycean Index; Nygaard Index) indicated a eutrophic condition for Museum Lake, being attributed to its increased organic enrichment. Canonical correspondence analysis between environmental variables and the microalgal bioindicators also highlighted the influence of the physical and chemical parameters on phytoplankton abundance and distribution in Museum Lake. 相似文献
4.
We observed electron-beam-induced sintering of amorphous silica in oxidized submicrometer silicon particles and analyzed the nature of mass transport in linear and triangular particle assemblies. The movement of silica around the rigid crystalline cores occurs rapidly and fills the necks, but the relative core positions in the sintered product depends on the initial geometry of the confined oxide. However, a thin layer of silica remains stable against the flow. 相似文献
5.
Motoi Takahashi Toshiyuki Mori Fei Ye Ajayan Vinu Hidehiko Kobayashi John Drennan 《Journal of the American Ceramic Society》2007,90(4):1291-1294
A Pt on nano-sized CeO2 particles that in turn are supported on carbon black (CB) was synthesized using the co-impregnation method. This potential anode material for fuel cell applications was synthesized in a stepwise process. The pure CeO2 was synthesized using an ammonium carbonate precipitation method, and the Pt particles dispersed on the CeO2 in such a way that a uniform dispersion with the CB was obtained (Pt–CeO2 /CB). The electrochemical activity of the methanol (CH3 OH) oxidation reaction on the Pt–CeO2 /CB was investigated using cyclic voltammetry and chronoamperometry experimentation. The onset potential of CH3 OH oxidation reaction on the Pt–CeO2 /CB anode was shifted to a lower potential as compared with that on commercially available Pt–Ru/carbon (C) alloy anode. In addition, the activation energy of the Pt–CeO2 /CB anode was much lower than that of the Pt–Ru/C alloy anode. Moreover, the current density of the Pt–CeO2 /CB anode was much higher than that of the Pt–Ru/C alloy anode at temperatures between 28° and 60°C. These results suggest that the anode performance of the Pt–CeO2 /CB anode at the operating temperature of typical fuel cells (80°C) is superior to that of the more usual Pt–Ru/C alloy anode. Importantly, the rare metal, Ru, is not required in the present anode material and the amount of Pt required is also significantly reduced. As a consequence, we report a promising candidate Pt–CeO2 /CB composite anode for application in the development of direct methanol fuel cells. 相似文献
6.
A. Vinu T. Krithiga N. Gokulakrishnan P. Srinivasu S. Anandan K. Ariga V. Murugesan V.V. Balasubramanian T. Mori 《Microporous and mesoporous materials》2007,100(1-3):87-94
Three-dimensional cage type iron substituted mesoporous silica with different iron contents (FeSBA-1) was synthesized in a highly acidic media using cetyltriethylammonium bromide and tetraethylorthosilicate as a template and a silica source, respectively. Acylation of toluene with acetic anhydride (AA) was carried out over FeSBA-1 mesoporous catalysts with different nSi/nFe ratios in the temperature range 80–180 °C for a time-on-stream of 1–6 h under liquid phase conditions. The important factors affecting the conversion and the selectivity of the reaction, such as the reaction temperature, feed ratio, catalyst weight and time-on-stream were studied and the results are discussed in detail. The reaction conditions were optimized and the nAA/nToluene ratio of 2 and catalyst weight of 0.1 g (3.3 wt% of total reaction mixture) were maintained for all catalytic runs. It was found that the catalytic activity is strongly influenced by the amount of tetrahedral iron in the catalysts. Among the catalysts used in the present study, FeSBA-1(36) showed a high toluene conversion and selectivity to p-methylacetophenone (p-MAP) under the optimized reaction conditions. It was also found that the selectivity for p-MAP was always higher than m-MAP and o-MAP for all the catalysts and the activity of the catalysts changes in the following order: FeSBA-1(36) > FeSBA-1(90) > FeSBA-1(120). 相似文献
7.
8.
Gonglan Ye Yongji Gong Sidong Lei Yongmin He Bo Li Xiang Zhang Zehua Jin Liangliang Dong Jun Lou Robert Vajtai Wu Zhou Pulickel M. Ajayan 《Nano Research》2017,10(7):2386-2394
Two-dimensional layers of metal dichalcogenides have attracted much attention because of their ultrathin thickness and potential applications in electronics and optoelectronics.Monolayer SnS2,with a band gap of ~2.6 eV,has an octahedral lattice made of two atomic layers of sulfur and one atomic layer of tin.Till date,there have been limited reports on the growth of large-scale and high quality SnS2 atomic layers and the investigation of their properties as a semiconductor.Here,we report the chemical vapor deposition (CVD) growth of atomic-layer SnS2 with a large crystal size and uniformity.In addition,the number of layers can be changed from a monolayer to few layers and to bulk by changing the growth time.Scanning transmission electron microscopy was used to analyze the atomic structure and demonstrate the 2H stacking poly-type of different layers.The resultant SnS2 crystals is used as a photodetector with external quantum efficiency as high as 150%,suggesting promise for optoelectronic applications. 相似文献
9.
10.
Insight into In Situ Amphiphilic Functionalization of Few‐Layered Transition Metal Dichalcogenide Nanosheets
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)