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排序方式: 共有294条查询结果,搜索用时 31 毫秒
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采用双光路双靶材脉冲激光沉积(PLD)系统在p-Si衬底上外延生长InGaN薄膜,研究了InGaN薄膜的显微组织结构和n-InGaN/p-Si异质结的电学性能。研究表明,InGaN薄膜为单晶结构,沿[0001]方向择优生长,薄膜表面光滑致密,In的原子含量为35%。霍尔(Hall)效应测试表明In0.35Ga0.65N薄膜呈n型半导体特性,具有高的载流子浓度和迁移率及低的电阻率。I-V曲线分析表明In0.35Ga0.65N/p-Si异质结具有良好的整流特性,在±4 V时的整流比为25,开路电压为1.32 V。In0.35Ga0.65N/p-Si异质结中存在热辅助载流子隧穿和复合隧穿两种电流传输机制。经拟合,得到异质结的反向饱和电流为1.05×10-8 A,势垒高度为0.86 eV,理想因子为6.87。 相似文献
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Yue Liu Mingxin Lv Lu Li Hailong Yu Qiong Wu Jinhui Pang Yuxiang Liu Congxia Xie Shitao Yu Shiwei Liu 《应用有机金属化学》2019,33(4)
An amino‐functionalized silica‐coated Fe3O4 nanocomposite (Fe3O4@SiO2/APTS) was synthesized. The Fe3O4@SiO2 microspheres possessed a well‐defined core–shell structure, uniform sizes and high magnetization. An immobilized ruthenium nanoparticle catalyst (Fe3O4@SiO2/APTS/Ru) was obtained after coordination and reduction of Ru3+ on the Fe3O4@SiO2/APTS nanocomposite. The Ru nanoparticles were not only ultra‐small with nearly monodisperse sizes but also had strong affinity with the surface of Fe3O4@SiO2/APTS. The obtained catalyst exhibited excellent catalytic performance for the hydrogenation of a variety of aromatic nitro compounds, even at room temperature. Moreover, Fe3O4@SiO2/APTS/Ru was easily recovered using a magnetic field and directly reused for at least five cycles without significant loss of its activity. 相似文献
4.
High-power fiber-to-fiber coupling is extensively used in fiber laser applications,and its performance is determined by coupling efficiency.We demonstrate a novel method for alignment and monitoring efficiency by detecting backscattering power at the fiber end cap.The relationship between alignment error and backscattering power is determined by simulations and experiments.Through this method,a state-of-the-art kW-level fiberto-fiber optic switch is developed(transmission efficiency>97%).It performs well for longer than 60 min.To the best of our knowledge,it is the first time to establish the mathematical model based on this method.Our results can provide guidance in high-power fiber-to-fiber coupling. 相似文献
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Shiwei Pan Fan Chen Yanyan Zhang Liang Shao Prof. Dr. Lingling Chu 《Angewandte Chemie (International ed. in English)》2023,62(31):e202305426
A Markovnikov-selective hydrodifluoromethylation of alkynes with BrCF2H via nickel catalysis is described. This protocol proceeds via a migratory insertion of nickel hydride to alkyne followed by a CF2H-coupling, enabling straightforward access to diverse branched CF2H-alkenes with high efficiency and exclusive regioselectivity. The mild condition applies to a wide array of aliphatic and aryl alkynes with good functional group compatibility. Mechanistic studies are presented to support the proposed pathway. 相似文献
6.
Lu Luo Shuai Tang Jiangyue Wu Shiwei Jin Hua Zhang 《Chemical record (New York, N.Y.)》2023,23(4):e202300023
Aromatic organoboron compounds are highly valuable building blocks in organic chemistry. They were mainly synthesized through aromatic C−H and C−Het borylation, in which transition metal-catalysis dominate. In the past decade, with increasing attention to sustainable chemistry, numerous transition metal-free C−H and C−Het borylation transformations have been developed and emerged as efficient methods towards the synthesis of aromatic organoboron compounds. This account mainly focuses on recent advances in transition metal-free aromatic C−H, C−N, C−S, and C−O borylation transformations and provides insights to where further developments are required. 相似文献
7.
Jilong Li Yanhui Wang Rushuo Li Bowen Lu Yungang Yuan Hongwei Gao Shiwei Song Shuyu Zhou Jianbing Zang 《Electroanalysis》2021,33(10):2252-2259
A self-modified film electrode consisting of homogeneous snowflake-shaped nanoparticles on the amorphous carbon substrate (HNAC) was prepared by low temperature carbonization of phenolic resin. Such a unique structure was beneficial to enhance the electroanalysis signal responds. Simultaneous detection of DA and UA was performed on the HNAC using differential pulse voltammetry (DPV) at pH 8 phosphate buffer. The well-defined oxidation peak potential separation reached 260 mV between DA and UA. Meanwhile, the detection limit of HNAC were 0.401 μM (DA) and 2.800 μM (UA). 相似文献
8.
Generally applicable and efficient esterification of aldehydes with alcohols catalyzed by cyclopalladated ferrocenylimine 下载免费PDF全文
The palladacycle‐catalyzed esterification of a variety of aldehydes with alcohols was developed. This reaction allows formation of esters in moderate to excellent yields not only for various aldehydes but also alcohols. In addition, the esterification could proceed well under mild conditions with a low catalyst loading of 0.0625 mol%. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Lu Li Shiwei Liu Yanjing Shi Shitao Yu Congxia Xie Chunjie Qi 《Research on Chemical Intermediates》2013,39(5):2095-2105
Terpinyl acetate, an important natural flavor, can be synthesized by esterification of α-pinene with acetic acid under acidic conditions. In this work, seven acidic ionic liquids were first synthesized, using octadecylamine ethoxylates (AC 1810, AC 1815, AC 1820, and AC 1830) as the cations, and characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy. The ionic liquids were then used as catalysts in the synthesis of terpinyl acetate. The effect of preparation conditions on catalyst performance was examined. It was found that the acidic ionic liquid 1-(3-sulfonic acid)propyl-3-poly(ethylene glycol) octadecylamine polyoxyethylene ether tetrafluoroborate ([PAC1815]+[BF4]?) was an excellent catalyst for synthesis of terpinyl acetate. The effects of the conditions used for preparation of terpinyl acetate were examined in detail, and the optimum preparation conditions were obtained. Under the optimum conditions, the yield of terpinyl acetate reached 35.70 %. When the catalyst was reused for the 5th time, the yield of terpinyl acetate was still 32.00 %. The results showed that effective separation and recycling of catalyst could contribute to developing a new strategy for synthesis of terpinyl acetate. 相似文献