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Study of the effect of chemical composition on the surface wettability of three-dimensional graphene foams 被引量:2
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作者 Guihua Huang Xinhong Song +6 位作者 Yiying Chen Fangyuan lin Yipeng Huang feiming li Zhiyong Guo Qiuhong Yao Xi Chen 《Chinese Chemical Letters》 SCIE CAS CSCD 2020年第7期1839-1842,共4页
The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping cha... The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping changes the chemical composition and wettability of the 3D graphene material.To realize the controllable surface wettability of graphene materials,aminobenzene sulfonic acid(ABSA)was selected as a typical doping agent for the preparation of nitrogen and sulfur co-doped 3D graphene foam(SNGF)using a hydrothermal method.Different from using o-ABSA or p-ABSA as the dopant,SNGF with tunable surface wettability is obtained only when m-ABSA is used.This result indicates that the substituent position of-SO3H group in the benzene ring of ABSA is rather important for the tunable wettability.This work provides some theo retical foundations for dopant selection and some new insights in manipulating the properties of 3D graphene foams by adjusting the configuration of dopants. 展开更多
关键词 3D graphene foam Surface wettability Dopant configuration Chemical composition Aminobenzene sulfonic acid
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Catalytic Difunctionalization of Alkenes under Visible Light Irradiation:Synthesis of Iminofuranones
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作者 Boyu liu Guangxian Chen +6 位作者 Lele Zhang Feiwei Yan feiming li Zhixiong Cai Mingqiang Huang lina Cai Shunyou Cai 《Chinese Journal of Chemistry》 2025年第7期798-804,共7页
Here,we show a cost-effective and environmentally friendly method for synthesizing iminofuranones using visible light and the photocatalyst 2-bromoanthraquinone.Our approach uses only oxygen as the oxidant,avoiding th... Here,we show a cost-effective and environmentally friendly method for synthesizing iminofuranones using visible light and the photocatalyst 2-bromoanthraquinone.Our approach uses only oxygen as the oxidant,avoiding the need for additional transition metals and strong oxidizing agents.By employing a mixed solvent system of DMF and CHCl_(3) under ambient conditions,we have achieved highly diastereoselective conversions of various 2-vinyl benzamides and alkenyl amides into functionalized iminoisobenzofuranones and iminofuranones.This versatile process is broadly applicable and enables late-stage structural modifications of complex substrates with bioactive moieties. 展开更多
关键词 PHOTOCATALYSIS AMIDES CYCLIZATION OXYGENATION Radical reactions Singlet oxygen DIASTEREOSELECTIVITY Oxygen heterocycles
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Embedding lead halide perovskite quantum dots in carboxybenzene microcrystals improves stability 被引量:6
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作者 Wei Xu Zhixiong Cai +4 位作者 feiming li Jing Dong Yiru Wang Yaqi Jiang Xi Chen 《Nano Research》 SCIE EI CAS CSCD 2017年第8期2692-2698,共7页
The stability of lead halide perovskite quantum dots (PQDs) was improved by embedding them in carboxybenzene microcrystals. The resulting needle-shaped mixed microcrystals preserved the strong photoluminescence of t... The stability of lead halide perovskite quantum dots (PQDs) was improved by embedding them in carboxybenzene microcrystals. The resulting needle-shaped mixed microcrystals preserved the strong photoluminescence of the PQDs. Compared with previously reported polystyrene-encapsulated PQDs, the carboxybenzene crystals were robust and protected the dots from moisture and photodegradation. The enhanced stability was attributed to the tight matrix of carboxybenzene microcrystals, which protected the PQDs from moisture. This versatile strategy protected various QDs, including all-inorganic PQDs and chalcogenide QDs (e.g., CdSe/ZnS QDs and CuInS/ZnS QDs). It provides a facile and versatile method of protecting PQDs and may enable applications in solid-state systems with high color quality requirements such as displays, lasers, and light emitting diodes. 展开更多
关键词 perovskite nanocrystals perovskite quantum dots down-conversion white LEDs carboxybenzene crystals
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知识追踪模型融入遗忘和数据量因素对预测精度的影响 被引量:10
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作者 叶艳伟 李菲茗 +1 位作者 刘倩倩 林丽娟 《中国远程教育》 CSSCI 北大核心 2019年第8期20-26,共7页
近年来,在线学习的人越来越多,在在线教学过程中教育者需要同时面对更多学习者,不可能了解每一个学习者的知识弱点与问题领域,并据此为学习者提供个性化的学习指导。本研究的目的是及时、准确推断学习者的问题领域,让学习者清楚自身的... 近年来,在线学习的人越来越多,在在线教学过程中教育者需要同时面对更多学习者,不可能了解每一个学习者的知识弱点与问题领域,并据此为学习者提供个性化的学习指导。本研究的目的是及时、准确推断学习者的问题领域,让学习者清楚自身的知识弱点,让教育者更加了解每一个学习者的知识水平,让在线学习系统自动向学习者推荐高效的学习路径和恰当的学习资源。在实验中,分析对比了知识追踪模型及其扩展模型的预测精度,分析了扩展模型使用学习者的所有数据与每个学习者的部分数据的预测准确性差异。结果显示:知识追踪模型可以较好估计学习者知识掌握情况;知识追踪扩展模型的预测精度更好;模型使用学习者部分数据可以获得比使用全部数据更好的预测精度;在学习者学习过程中遗忘时时存在,扩展模型使用部分数据在加快运行进度的同时更有利于精确估计学习者知识水平进而推荐更有效的个性化学习资源与学习路径。 展开更多
关键词 在线学习 知识弱点 问题领域 学习路径 学习资源 知识追踪及其扩展模型 预测精度 预测准确性差异
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计算机交互式评价的开发研究——以科学探究为例 被引量:5
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作者 李菲茗 张浩 +1 位作者 林丽娟 黄怡 《中国远程教育》 CSSCI 北大核心 2020年第5期29-37,77,共10页
计算机交互式评价以计算机模拟的形式呈现学科知识及其系统结构,并支持新颖的交互形式。评价学生的科学探究能力不仅需要创设丰富的任务情境,同时也要收集和分析学生的行为和作答数据。鉴于交互式评价与科学探究评价的契合性,文章基于... 计算机交互式评价以计算机模拟的形式呈现学科知识及其系统结构,并支持新颖的交互形式。评价学生的科学探究能力不仅需要创设丰富的任务情境,同时也要收集和分析学生的行为和作答数据。鉴于交互式评价与科学探究评价的契合性,文章基于以证据为中心(Evidence-Centered Design,ECD)的评价设计理念,解析了交互式科学探究评价的设计流程。首先,介绍了评价设计的理论基础--ECD框架。其次,结合科学探究评价的典型研究项目,以评价设计流程的任务分析、任务创设和数据分析为主线,总结了任务分析的领域信息来源、任务情境标准、任务创设的界面形式、学生作品和系统响应,以及数据分析中使用的多种数学模型。最后,讨论了交互式评价在评价的标准、实用性、非认知因素以及协同开发等方面应关注的问题和未来的发展方向,旨在丰富我国有关交互式评价开发的理论和实践研究。 展开更多
关键词 ECD 计算机交互式评价 过程性数据 科学探究 任务分析 任务创设 数据分析
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Colloidal CsPbBr3 perovskite nanocrystal films as electrochemiluminescence emitters in aqueous solutions 被引量:4
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作者 Zhixiong Cai feiming li +4 位作者 Wei Xu Shujun Xia Jingbin Zeng Shaogui He Xi Chen 《Nano Research》 SCIE EI CAS CSCD 2018年第3期1447-1455,共9页
Perovskite nanocrystals (NCs), which have emerged as a new class of phosphors with superb luminescence properties and bandgaps that can be easily tuned using chemical methods, have generated tremendous interest for ... Perovskite nanocrystals (NCs), which have emerged as a new class of phosphors with superb luminescence properties and bandgaps that can be easily tuned using chemical methods, have generated tremendous interest for a wide variety of applications where colloidal quantum dots have been very successful as carrier sources. In this study, self-assembled films of CsPbBr3 NCs were produced via drop casting of colloidal NCs onto glassy carbon electrodes (GCEs) to form an NC film-modified electrode. The possible fabrication process of the CsPbBr3 NCs films was discussed. We further studied the anodic electrochemiluminescence (ECL) behavior of the perovskite CsPbBr3 NCs film using cyclic voltammetry with tripropylamine (TPA) as a coreactant, and a possible ECL mechanism was proposed. Briefly, TPA was oxidized to produce strongly reducing radical spedes, which can react with electrochemically oxidized CsPbBr3 NCs to generate excited CsPbBr3 NCs* capable of light emission. The relative stability of the ECL emission of the CsPbBr3 NC films under aqueous conditions was also investigated, and it was found that they showed operational stability over the first three hours, indicating suitable reliability for application as sensing materials. The results suggested that semiconducting perovskite NCs have great potential for application in the ECL field. 展开更多
关键词 perovskite CsPbBr3 colloidal nanocrystals film aqueous solution
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