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261.
262.
基于 HL-2M 真空室烘烤保温要求,通过有限元分析和原型件实验确定采用陶瓷纤维与纳米级微孔材
料组合作为 HL-2M 真空室保温材料。在 30℃时,保温层的导热系数小于 0.027W⋅m−1·℃−1;300℃时,导热系数
小于 0.038W⋅m−1·℃−1。在保温层厚度 25mm、热面温度 300℃且达到稳态时,冷面可控制在 85℃以下,线圈侧的
温度低于 60℃,整体热损失小于 12kW,满足 HL-2M 真空室烘烤需求。 相似文献
263.
Mesoporous chitosan‐immobilized iron tetrakis(4‐carboxyphenyl)porphyrin as a model of cytochrome P‐450 enzyme for oxidation of ethylbenzene
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Mesoporous chitosan‐grafted iron tetra (4‐carboxyphenyl) porphyrin catalyst (Fe TCPP/mesp‐CTS) was prepared and investigated as a practical model for the nano‐cavity and coordinate regulation‐catalysis(CRC) function in cytochrome P‐450 enzyme. Fe TCPP/mesp‐CTS was characterized by X‐ray Diffraction (XRD), Thermogravimetry (TG), Ultraviolet–visible spectroscopy(UV‐Vis), Ultraviolet–visible– Diffuse reflectance spectroscopy (UV‐DRS), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray photoelectron spectroscopy (XPS) techniques. The catalytic activity of Fe TCPP/mesp‐CTS for ethylbenzene oxidation was investigated and it was proved to be a better catalyst than Fe TCPP/macp‐CTS based on the ethylbenzene conversion, turnover numbers(TON), and the reusability. These results are attributed to the mesocavity and CRC of amino group in Fe TCPP/mesp‐CTS. The highest ethylbenzene conversion and yields of ketone and alcohol were 24.4% and 18.2%, respectively. 相似文献
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Weihua Zhou Zoukangning Yu Ming Zhang Lifu Zhang Jingping Yin Qingyun Ai Liqiang Huang Feng Liu Jianrong Zeng Yiwang Chen 《Journal of Polymer Science.Polymer Physics》2019,57(14):941-951
In order to explore the role of fluorine atoms on photostability as well as morphology control of active layer in the presence of 1,4‐butanedithiol (BT), the four polymers with or without fluorine atoms in the backbones including polythieno[3,4‐b]thiophene/benzodithiophene, poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo(1,2‐b:4,5‐b9)dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene‐)‐2‐6‐diyl)], poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)], and poly[4,8‐bis‐(2‐ethyl‐hexyl‐thiophene‐5‐yl)‐benzo[1,2‐b:4,5‐b0]dithiophene‐2,6‐diyl]‐alt‐[2‐(20‐ethyl‐hexanoyl)‐thieno [3,4‐b]thiophen‐4,6‐diyl] were selected for comparison. It is found that the specimens containing fluorine atoms in polymer backbones showed of higher stability after illumination for 1 h in the presence of BT additive, contributing to the higher domain purity. The specific interaction between fluorine atoms and thiol groups was demonstrated by the appearance of novel absorption peak at 2663.1 cm?1, in addition to the broadening of peak at 2556.2 cm?1 ascribing to S? H stretching vibration as confirmed by Fourier transform infrared (FTIR) spectroscopy. The finding may guide the accurate use of thiols as effective solvent additive in morphology and stability optimization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 941–951 相似文献
266.
Zhipeng Lin Hao Zhang Guofeng Liang Yanqi Jin Hongbin Zeng Jiawang Li Jian Chen Weihong Zhang Fangyan Xie Yanshuo Jin Hui Meng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3112-3118
A composite of FeOOH nanocubes anchored on carbon ribbons has been synthesized and used as a cathode material for Li/O2 batteries. Fe2+ ion-exchanged resin serves as a precursor for both FeOOH nanocubes and carbon ribbons, which are formed simultaneously. The as-prepared FeOOH cubes are proposed to have a core–shell structure, with FeOOH as the shell and Prussian blue as the core, based on information from XPS, TEM, and EDS mapping. As a cathode material for Li/O2 batteries, FeOOH delivers a specific capacity of 14816 mA h g−1cathode with a cycling stability of 67 cycles over 400 h. The high performance is related to the low overpotential of the oxygen reduction/evolution reaction on FeOOH. The cube structure, the supporting carbon ribbons, and the -OOH moieties all contribute to the low overpotential. The discharge product Li2O2 can be efficiently decomposed in the FeOOH cathode after a charging process, leading to higher cycling stability. Its high activity and stability make FeOOH a good candidate for use in non-aqueous Li/O2 batteries. 相似文献
267.
268.
Xiao Hu An Zeng Ming-Sheng Shang 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(2):46
Recommender system is an effective tool to find the most relevant information for onlineusers. By analyzing the historical selection records of users, recommender system predictsthe most likely future links in the user-item network and accordingly constructs apersonalized recommendation list for each user. So far, the recommendation process ismostly investigated in static user-item networks. In this paper, we propose a model whichallows us to examine the performance of the state-of-the-art recommendation algorithms inevolving networks. We find that the recommendation accuracy in general decreases with timeif the evolution of the online network fully depends on the recommendation. Interestingly,some randomness in users’ choice can significantly improve the long-term accuracy of therecommendation algorithm. When a hybrid recommendation algorithm is applied, we find thatthe optimal parameter gradually shifts towards the diversity-favoring recommendationalgorithm, indicating that recommendation diversity is essential to keep a high long-termrecommendation accuracy. Finally, we confirm our conclusions by studying therecommendation on networks with the real evolution data. 相似文献
269.
Synthesis and characterization of intrinsic high‐barrier polyimide derived from a novel diamine monomer containing rigid planar moiety
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Yi‐Wu Liu Jie Huang Jing‐Hua Tan Yi Zeng Qian Ding Xian‐Wei Xiang Yue‐Jun Liu Hai‐liang Zhang 《Journal of polymer science. Part A, Polymer chemistry》2017,55(14):2373-2382
A new diamine monomer containing rigid planar fluorenone moiety, 2,7‐bis(4‐aminophenyl)‐9H‐fluoren‐9‐one, was synthesized through Suzuki coupling reaction. Then it was reacted with pyromellitic dianhydride to obtain a polyimide (FOPPI) via a conventional two‐step polymerization process. The prepared FOPPI exhibits excellent barrier properties, with the oxygen transmission rate and water vapor transmission rate low to 3.2 cm3·m?2·day?1 and 2.9 g·m?2·day?1, respectively. The results of wide angle X‐ray diffractograms, positron annihilation lifetime spectroscopy, and molecular dynamics simulations reveal that the excellent barrier properties of FOPPI are mainly ascribed to the crystallinity, high chain rigidity, and low free volume, which are resulted from the rigid planar moiety. FOPPI also shows outstanding thermal stability and mechanical properties with a glass transition temperature up to 420 °C, 5% loss temperature of 607 °C, coefficient of thermal expansion of 1.28 ppm K?1, and tensile strength of 150.8 MPa. The polyimide has an attractive potential application prospect in the flexible electronics encapsulation area. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2373–2382 相似文献
270.
High Energy Chemistry - Intramolecular crosslinking of polyvinylidene fluoride (PVDF) was observed to have occurred when the PVDF homogeneous solution was subject to γ-ray irradiation, which... 相似文献