检索结果-南通市图书馆

Precise gradient separation of nanoparticles using reduced graphene oxide-polyoxomolybdate membranes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第01期 209-216页

作者： Yixin Yang Wanlei Zhao Ruoxuan Zheng Hongqiang Li wei Chen Yu-Fei Song State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Quzhou Institute for Innovation in Resource Chemical Engineering

The purification and size sieving of nanoparticles （NPs） represents a significant scientific ***,the r GO-polyoxometalates (POMs=PMo12,Mo132and Mo368) membranes were fabricated successfully via a simple and scalable POMsassisted in-situ photoreduction *** the mass ratio of r GO to PMo12was 1:30,the resultant r GO-PMo12membranes with highly ordered and uniform nanochannels of 1.0 nm can be obtained,which showed an accurate carbon quantum dots（CQDs） separation with a cut-off size approximately 1.0 *** increase of the size of the interlayered POMs from PMo12（1.0 nm）,{Mo132}（2.9 nm） to{Mo368}（3.8 nm）,the resultant r GO-PMo12,r GO-Mo132and r GO-Mo368exhibited precise gradient separation of CQDs and Au nanoparticles by size exclusion *** results pave a promising way to construct new twodimensional （2D） membranes for highly efficient size-selective separation.

关键词：

同方期刊数据库

考虑社会学习的产品定价和质量决策——参照效应与消费者异质性的影响

在线全文

学校读者我要写书评

暂无评论

管理工程学报 2025年第1期39卷 196-213页

作者：李锋魏莹华南理工大学工商管理学院暨南大学管理学院广州品牌创新发展研究基地

消费者通过观察电商平台的产品评论信息更新对产品质量的感知,这种社会学习行为直接影响消费者的购买决策以及企业的产品质量和价格策略。本文考虑消费者购买过程中的两种参照效应:学习参照和体验参照。前者指购买前消费者关于产品质量... 详细信息

消费者通过观察电商平台的产品评论信息更新对产品质量的感知,这种社会学习行为直接影响消费者的购买决策以及企业的产品质量和价格策略。本文考虑消费者购买过程中的两种参照效应:学习参照和体验参照。前者指购买前消费者关于产品质量的预判对社会学习的效果产生参照效应;后者指学习更新后的质量感知对于消费者购买后的质量体验形成参照。本文构建多智能体模型,以产品评论信息为载体,研究消费者社会学习中的参照效应以及消费者异质性对企业产品质量和价格决策的影响,之后进一步讨论了平台信息策略和企业区别定价策略的效果。研究发现:首先,社会学习中的学习参照效应导致企业降低价格、提高质量且从中受损;而体验参照效应提高用户评价信息均值和集中度,从而使企业提高定价且从中受益。总体而言,社会学习行为有利于企业但参照效应对企业不利。其次,消费者对于产品质量感知的差异程度影响社会学习和参照效应的效果。当质量感知差异程度较低时,考虑参照效应的社会学习行为对企业的价格和质量决策的影响不明显;当感知差异增大到一定程度时,会显著降低企业的价格并影响质量决策。再次,企业从消费者质量先验感知差异程度中受益,但受损于质量后验体验的差异程度。和统一价格策略相比,区别定价能够提高企业收益,但对质量决策影响甚微。最后,平台与卖方共享消费者信息可以减少企业的机会损失,而与买方共享分类统计信息对企业决策影响不大。研究结果同时提供了丰富的管理启示。

关键词：社会学习参照效应质量区别定价智能体建模与仿真

维普期刊数据库

同方期刊数据库

Deciphering the role of ultra-low-loaded rhodium in NiFe-MIL-53 for superior oxygen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第1期100卷 77-86页

作者： Jinzhi Jia Jinhua Zhang Kailu Guo Lanyue Zhang Gening Du Hao You Junfeng Huang Mudong Tu Hua Li Yong Peng wei Dou Cailing Xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical Engineering School of Materials and Energy Lanzhou University College of Chemistry and Chemical Engineering Luoyang Normal University

Designing highly active and stable electrocatalysts of oxygen evolution reaction （OER） is one of the crucial *** this study,a novel OER electrocatalyst,NiFe-MIL-53 modified with ultra-low rhodium（Rh@NiFe-MIL-53）,is successfully prepared via the hydrothermal ***-situ Raman spectroscopy and electrochemical impedance spectroscopy reveal that the doped Rh accelerates the phase transformation of NiFe-MIL-53 and the in-situ formed Rh@NiFeOOH is the actual active *** importantly,the enhanced reversibility of electrochemical reconstruction between NiFeOOH and NiFe（OH）2after doping Rh is beneficial for improving the electrochemical stability of the catalyst.X-ray photoelectron spectroscopy spectra show the strong electronic interaction between single-atom Rh and Ni/Fe in Rh@***,theoretical calculations confirm that the integration of single-atom Rh into the NiFeOOH successfully reduces the band gap,regulates the d-band center （εd）,accelerates the charge transfer,and optimizes the adsorption behavior of oxygen-containing intermediates,thereby lowering the energy barrier of rate-determining ***,the optimized Rh@NiFe-MIL-53 exhibits excellent OER activity （240 mV） with a small Tafel slope of 48.2 mV dec-1and long-term durability (over1270 h at 10 m A cm-2and 110 h at 200 mA cm-2).This work presents a new perspective on designing highly efficient OER electrocatalysts.

关键词： X ray photoelectron spectroscopy

学科类培训机构缩减对学生在校时长的影响:基于“双减”政策的评估研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

华东师范大学学报（教育科学版） 2025年第1期43卷 37-48页

作者：陆伟魏易杭州师范大学经亨颐教育学院杭州311121 北京大学中国教育财政科学研究所北京100871

对校外培训机构的治理整顿是“双减”改革的重要内容之一。本文使用大众点评网学科类培训机构的商铺信息,结合高德地图地理编码和搜索POI应用接口,以及全国中小学教育信息化使用情况调查等数据,实证检验了学科类校外培训机构缩减对学生... 详细信息

对校外培训机构的治理整顿是“双减”改革的重要内容之一。本文使用大众点评网学科类培训机构的商铺信息,结合高德地图地理编码和搜索POI应用接口,以及全国中小学教育信息化使用情况调查等数据,实证检验了学科类校外培训机构缩减对学生在校时长的影响。研究发现:(1)“双减”期间,全国层面学科类培训机构的缩减比例约为88%。(2)学校周边学科类培训机构的缩减程度越高,学生每天待在学校内的时间也越多,也即校内教育与校外教育出现一定程度的替代,且这种替代效应在弱势阶层群体中更为明显;在北上广深四个一线城市不明显,但在其他众多二三线城市可以观察到。(3)学校周边学科类培训机构的缩减程度越高,学生在学校内完成课后作业的概率也越高,而在校外辅导班完成课后作业的概率则越低;但培训机构缩减对学生完成课后作业的总时长没有影响。

关键词： “双减” 学科类培训机构校外培训在校时长

High-performance transparent graphene-based antennas

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Science China Technological Sciences 2025年

作者： Chaoye HONG Lusong wei weijia WANG Youmei TANG Qinghai ZHU Jiangtao HUANGFU Mingsheng XU College of Integrated Circuits State Key Laboratory of Silicon and Advanced Semiconductor Materials Zhejiang University College of Information Science and Electronic Engineering Zhejiang University

With the continuous development of wireless communication technology, applications in the military, aerospace,and vehicle wireless communication sectors have demanded miniaturized and aesthetically pleasing antennas. Transparent antennas, which combine the advantages of optical and radio-frequency(RF) technologies, have become a popular research topic. However, existing transparent antennas often suffer from complex preparation processes, fragile materials, poor conductivity, and low optical transmittance. Here, we develop hybrid conductive thin films using graphene and silver nanowires,achieving a transmittance of 86% and a sheet resistance of 7.8 Ω/sq with high environmental stability. We demonstrate the suitability of this nanocomposite in two applications: a transparent ultrahigh-frequency RF-identification tag folded dipole antenna and a transparent X-band microwave half-wave dipole antenna. These antennas offer high gain, high radiation efficiency, and small size, indicating that transparent graphene-based antennas have remarkable potential for intelligent information sensor systems.

关键词：

Ca2+ cation-mediated microenvironment for electrochemical hydrodimerization of furfural

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年

作者： wei Du Shuangshuang Cha Can Lei Mengxin Qu Zhongqiang Deng Ming Gong Xinhe Bao Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University State Key Laboratory of Catalysis National Laboratory for Clean Energy Collaborative Innovation Center of Chemistry for Energy Materials Dalian Institute of Chemical Physics Chinese Academy of Sciences

Furfural is one of the most important biomass-based platform molecules as sustainable precursors for chemicals and fuels. The electrochemical hydrodimerization of furfural can generate hydrofuroin, which is a promising precursor for gasoline or jet ***, steering the selectivity toward hydrodimerization under near-neutral conditions that suppress polymerization and disproportionation of furfural remains challenging. Herein, we discovered that tuning the electrolyte cations could be an effective and alternative strategy for modulating furfural reduction to the traditional electrocatalyst design. Under the optimal Ca2+cations,hydrofuroin yield could be much improved from other cations with hydrofuroin selectivity of 95.5%. The systematic characterization of the ion-centered double layer reflected the suitable sizes and charges of hydrated Ca2+for suppressing the hydrogen evolution reaction from activation of surrounding water molecules as well as encouraging furfural accumulation via non-covalent interaction for directing the electron transfer to furfurals. Ions with smaller or larger sizes can either activate local water molecules or form a crowded ionic interface that casts an adverse effect on furfural enrichment. This work not only presents an effective strategy for facilitating biomass valorization via hydrodimerization but also emphasizes the essential role of the ion-centered microenvironment for steering the electrocatalytic pathways.

关键词：

Facile synthesis of metal-polyphenol-formaldehyde coordination polymer colloidal nanoparticles with sub-50 nm for T_(1)-weighted magnetic resonance imaging

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第2期32卷 842-848页

作者： Jing Qin guohai Liang Bingxi Feng Gen Wang Na Wu Yonghui Deng Ahmed AElzatahry Abdulaziz Alghamdi Yongxi Zhao Jing wei The Key Laboratory of Biomedical Information Engineering of Ministry of Education School of Life Science and TechnologyXi'an Jiaotong UniversityXi'an 710049China College of Biophotonics South China Normal UniversityGuangzhou 510631China Department of Chemistry Fudan UniversityShanghai 200433China Materials Science and Technology Program College of Arts and SciencesQatar UniversityPO Box 2713DohaQatar Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

Plant polyphenol-based coordination polymers(CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applicatio ns,but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. He rein,a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species(e.g., Gd,Cu,Ni,Zn,Fe)and ultra-small diameter(8.6-37.8 nm) using nontoxic plant polyphenol(e.g..tannic acid,gallic acid) as a polymerizable *** molecules react with formaldehyde firstly,which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal *** ultrafine nanoparticles with stably chelated metal io ns are highly water dispersible and thus advantageous for *** an example,ultra-small Gd contained CPs exhibit higher longitudinal relaxivity(r_(1)=25.5 L mmol^(-1) s^(-1)) value with low r2/r1(1.19) than clinically used Magnevist(Gd-DTPA,r1=3.7 L mmol^(-1) s^(-1)) .Due to the enhanced permeability and retention effect,they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.

关键词： Coordination polymer Nanoparticle Self-assembly Plant polyphenol Contrast agent

维普期刊数据库

Efficient photocatalytic reduction of CO2 to formate by a molecular noble metal-free system

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期 152-156页

作者： Lihua Zhang Lingjing Chen Huatian Shi Yue wei Gui Chen Tai-Chu Lau School of Environment and Civil Engineering Research Center for Eco-environmental Engineering Dongguan University of Technology Department of Chemistry and Institute of Molecular Functional Materials City University of Hong Kong

Reducing CO2to carbon-neutral solar fuels can not only alleviate the energy demand but also mitigate the greenhouse *** present,developing an efficient non-noble metal photo/electrocatalytic system for converting CO2to a specific product beyond CO is still a big ***,we report a new cobalt complex bearing 2,2′-bi-1,10-phenanthroline ligand that can photocatalytically reduce CO2to formate （HCOO-）.Turnover number （TON） for HCOO-up to 677 with 99%selectivity can be achieved using organic dyes purpurin as photosensitizer and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole （BIH） as sacrificial reductant in a CO2-saturated NMP/TEA （v/v,3:1） solution under visible light *** potential electrolysis at-1.41 V （***/Ag Cl） in the presence of 12 m M Et3NHBF4also produced HCOO-with Faradaic efficiency of 39%.Spectroscopic and electrochemical studies suggest that a[CoI-H]species is the key intermediate for CO2reduction.

关键词：

同方期刊数据库

Moment Redistribution Effect of the Continuous Glass Fiber Reinforced Polymer-Concrete Composite Slabs Based on Static Loading Experiment

在线全文

学校读者我要写书评

暂无评论

Structural Durability & Health Monitoring 2025年第1期19卷 105-123页

作者： Zhao-Jun Zhang Wen-wei Wang Jing-Shui Zhen Bo-Cheng Li De-Cheng Cai Yang-Yang Du Hui Huang Offshore Oil Engineering Co.Ltd. Tianjin300461China Department of Bridge Engineering School of TransportationSoutheast UniversityNanjing211189China

This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment *** experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs,and a calculation method based on the conjugate beam method was *** composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab *** methods,epoxy resin bonding,and stud connection,were used to connect the composite slabs with the steel *** experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process:concrete cracking and steel bar yielding at the internal *** contrast,the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading *** the concrete at the internal support cracked,the bending moment decreased in the internal support section and increased in the midspan *** the steel bars yielded,the bending moment further decreased in the internal support section and increased in the mid-span *** GFRP profiles do not experience cracking,there was no significant decrease in the bending moment of the mid-span *** test specimens experienced compressive failure of concrete at the mid-span *** results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support *** proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs.

关键词： Moment redistribution GFRP-concrete composite slabs bending moment experimental study analysis model