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排序方式: 共有162条查询结果,搜索用时 31 毫秒
71.
采用MNDO(UHF)方法计算了金刚石(100)-(1×1):2H双氢化表面和(100)-(2×1):H单氢化表面的脱氢势垒,论证了决定金刚石附氢表面脱氢势垒大小的主要因素是气相-表面吸附氢原子间的相互排斥大小,得出(100)面两种表面结构脱氢势垒的理论预言值分别为71和59kJ·mol-1,均大于(111)面脱氢势垒的理论预言值42kJ·mol-1.揭示了在同等生长条件下金刚石(111)面可供成核和生长的反应基多于(100)面,与实验上得到的同等生长条件下(111)面的相对生长率大于(100)面的结论是一致的。 相似文献
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Yaduo Song Yanxin Jiang Prof. Longjiang Deng Prof. Guang Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(72):e202202717
Developing high-performance functional polymer-based electrolytes is important for realizing next generation safe lithium metal batteries. In this study, a new type of quasi-solid polymer network electrolyte (SIPH-x-y%) was prepared by combining synthesized polymer network (SIPH) containing urethane bond linked ionic liquids (ILs), polyethylene glycol (PEG), and disulfide bond moieties, lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), and glyme type additive. It was found that SIPH-20-40% was mechanically flexible, self-healable, and showed high ionic conductivity of 2.67×10−4 S cm−1. Also, SIPH-20-40% possesses a high lithium ion transference number of 0.43 and good electrochemical stability. These properties enabled the SIPH-20-40% electrolyte membrane to support Li/Li symmetrical cell to cycle stably during long term Li plating and stripping. The Li/SIPH-20-40%/LFP showed high delivered specific capacity and good stability (166.1 mAh g−1 after 106 cycles at 0.2 C). Such glyme doped polymer network electrolyte provides new experimental findings for developing polymer-based electrolyte with excellent mechanical integrity and battery related properties. 相似文献
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Compound 1 containing two nitronyl nitroxide units bridged by tetra(ethyleneoxy) was designed and synthesized for sensing metal ions, by taking the features of nitronyl nitroxides: a chromophore showing absorption in visible range, reversible oxidation/reduction and coordination to metal ions. The absorption spectrum of 1 was altered markedly upon mixing with a few rare earth metal ions and some transition metal ions. Moreover, the oxidation potential of 1 was shifted to more positive range in the presence of metal ions including Pb2+, Ba2+, and Ca2+. Thus, compound 1 can sense metal ions both spectroscopically and electrochemically. 相似文献
78.
This paper is devoted to the study of the structure of the double Ringel-Hall algebra D(Λ) for an infinite dimensional hereditary algebra A, which is given by a valued quiverΓover a finite field, and also to the study of the relations of D(Λ)-modules with representations of valued quiverΓ. 相似文献
79.
Yanxin Wei Chen Lu Shengsheng Jiang Yanyan Zhang Qiuchun Li Wen‐Ju Bai Xiqing Wang 《Angewandte Chemie (International ed. in English)》2020,59(8):3043-3047
Herein, we report an engineered enzyme that can monooxygenate unprotected tryptophan into the corresponding 3a‐hydroxyhexahydropyrrolo[2,3‐b]indole‐2‐carboxylic acid (HPIC) in a single, scalable step with excellent turnover number and diastereoselectivity. Taking advantage of directed evolution, we analyzed the stepwise oxygen‐insertion mechanism of tryptophan 2,3‐dioxygenases, and transformed tryptophan 2,3‐dioxygenase from Xanthomonas campestris into a monooxygenase for oxidative cyclization of tryptophans. It was revealed that residue F51 is vital in determining the product ratio of HPIC to N′‐formylkynurenine. Our reactions and purification procedures use no organic solvents, resulting in an eco‐friendly method to prepare HPICs for further applications. 相似文献
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Pan Mingxiang Li Shunpu Zhao Deqian Wang Weihua Wen Ping Yu Yude Nie Yuxin Zhao Shengxue Zhuang Yanxin Chen Xichen 《中国科学G辑(英文版)》2003,46(2):158-163
This paper reports the investigation results on directional growth of Al−Mg2Si eutectic alloy in the SZ2 unmanned spaceship. The analysis shows that microgravity has influence on the directional growth
of Al−Mg2Si eutectic alloy. The eutectic colony in space-grown sample is larger than that in ground-grown sample, and the directional
effect is not so good as that of terrestrial sample. But there is no obvious difference in the lamellar thickness between
these samples, and lamellar interspacing in space sample is smaller than that grown on the ground. A simple discussion is
done on the gravity effect on the directional growth of Al−Mg2Si eutectic alloy. 相似文献