检索结果-南通市图书馆

结构化学 2024年第4期43卷 24-30页

作者： Runze Liu yankai bian Weili Dai School of Materials Science and Engineering & National Institute for Advanced Materials Nankai UniversityTianjin300350PR China

Zeolite is one of the most important heterogeneous catalysts in acid catalytic *** that the catalytic behaviors of zeolites are mostly related to their acidic characteristics,extensive attention has been attracted to the measurements of acid type,strength and concentration in *** techniques including Fourier-transform infrared(FTIR)spectroscopy,probe-assisted 1H,13C and 31P magic angle spinning nuclear magnetic resonance spectroscopy(MAS NMR)as well as temperature programmed desorption of ammonia(NH3-TPD)have been developed for determining the acid ***,a single approach is defective to characterize the acid sites ***,combining the probe-assisted(e.g.,NH3 and CD3CN)1H MAS NMR and NH3-TPD,the acid sites in different zeolites including the acid type,density and strength were *** commonly utilized NH3-TPD to determine the acid strength of zeolite samples with different topologies should be rigorously considered owing to zeolite confinement *** the desorption temperature of NH3 probe molecules,the acid type(Le.,Brønsted acid sites(BAS)and Lewis acid sites(LAS))and the corresponding density could be determined by NH3 probe-assisted 1H MAS NMR spectroscopy,while the acid strength could be investigated via CD3CN probe-assisted 1H MAS NMR spectroscopy.

关键词： ^(1)H MAS NMR NH_(3)-TPD BAS LAS Zeolites

General radical difluoromethylation using difluoroacetic anhydride via photoredox catalysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第8期67卷 2637-2646页

作者： Meng He yankai Yang Heng Zhang Zhipeng Guan Zhi-Bing Dong Hong Yi Aiwen Lei School of Chemistry and Environmental Engineering Wuhan Institute of TechnologyWuhan 430205China College of Chemistry and Molecular Sciences and Institute for Advanced Studies(IAS) Wuhan UniversityWuhan 430072China

CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their reactivity and preparation. Herein, we develop a simple and general visible-light-catalyzed radical difluoromethylation reaction of alkenes, dienes, and heteroaromatics using commercially available, easy-to-handle, and low-cost difluoroacetic anhydride as the CF_(2)H reagent. This scalable protocol enables the convenient synthesis of a range of CF_(2)H-containing compounds under mild conditions, exhibiting a broad substrate scope and functional group tolerance. Potential applications are further demonstrated by gram-scale synthesis, sunlight experiments, derivatization experiments as well as the synthesis of bioactive molecules.

关键词： radical difluoromethylation alkenes/dienes/heteroaromatics difluoroacetic anhydride photoredox

Synergistically enhanced dielectric, insulating and thermally conductive performances of sandwich PMMA based dielectric films

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2024年第3期34卷 591-597页

作者： Dongmei Zhang Yufan Li Yuchao Li Zhonggui Sun Hanxue Zhu Lujia Yang Yanhu Zhan yankai Li Shi Wang Jun-Wei Zha School of Mathematical Sciences Liaocheng University School of Materials Science and Engineering Liaocheng University State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM) Nanjing University of Posts & Telecommunications School of Chemistry and Biological Engineering University of Science and Technology Beijing

A tri-layered(B-G-B) dielectric films were simply prepared by alternatively spin-coating boron nitride/polymethylmethacrylate(BN/PMMA, B) and graphene nanosheets(GNS/PMMA, G) compound solutions. The structure, morphology, thermal conductivity, and particularly the dielectric and relaxation behaviors were systematically studied. Results showed that a good exfoliation and dispersion of BN and GNS can be simply achieved through intensive mechanical compounding with PMMA in the internal mixer. The dielectric constant and breakdown strength of the obtained 1-3-1(B-G-B) sandwich composite film reached 4.3(@1 kHz) and 458.6kV/mm, being 119 % and 113 % higher than that of pure PMMA, respectively. Furthermore, the overall thermal conductivity of sandwich 1-3-1 composite increased by 112 % due to the addition of thermally conductive BN and GNS. The sandwich design strategy provided an effective way of achieving good permittivity, high insulation, and improved thermal conductivity simultaneously, showing potential applications in the miniaturization and integration of electronic devices.

关键词： Breakdown strength Composites Dielectric constant Sandwich structure Thermal conductivity

Crosstalk between glioblastoma and tumor microenvironment drives proneural–mesenchymal transition through ligand-receptor interactions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Genes & Diseases 2024年第2期11卷 874-889页

作者： Yancheng Lai Xiaole Lu yankai Liao Pei Ouyang Hai Wang Xian Zhang Guanglong Huang Songtao Qi Yaomin Li Department of Neurosurgery Institute of Brain DiseaseNanfang HospitalSouthern Medical UniversityGuangzhouGuangdong 510515China Laboratory for Precision Neurosurgery Nanfang HospitalSouthern Medical UniversityGuangzhouGuangdong 510515China

Glioblastoma(GBM)is the most common intrinsic and aggressive primary brain tumor in adults,with a median survival of approximately 15 *** heterogeneity is considered responsible for the treatment resistance and unfavorable ***-mesenchymal transition(PMT)represents GBM malignant progression and recurrence,which might be a breakthrough to understand GBM heterogeneity and overcome treatment *** is a complicated process influenced by crosstalk between GBM and tumor microenvironment,depending on intricate ligand-receptor *** this review,we summarize the autocrine and paracrine pathways in the GBM microenvironment and related ligand-receptor interactions inducing *** also discuss the current therapies targeting the PMT-related autocrine and paracrine ***,this review offers a comprehensive understanding of the failure of GBM-targeted therapy and ideas for future tendencies of GBM treatment.

关键词： Autocrine Glioblastoma Ligand-receptor interaction Microenvironment Paracrine Proneural-mesenchymal transition

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

区域GPS网共模误差的提取与成因分析

测绘科学技术学报 2020年第2期37卷 138-143页

作者：谢琰李震岳建平边延凯华北水利水电大学河南郑州450046 河海大学地球科学与工程学院江苏南京211100

以位于美国南加州区域的41个GPS站点为例,利用主成分分析法对该区域共模误差进行了有效提取,结果表明共模误差在该区域空间响应具有较好的一致性。滤波后,均方根值(RMS)在E方向上平均降低了42.9%,在N方向上平均降低了39.1%,在U方向上平... 详细信息

以位于美国南加州区域的41个GPS站点为例,利用主成分分析法对该区域共模误差进行了有效提取,结果表明共模误差在该区域空间响应具有较好的一致性。滤波后,均方根值(RMS)在E方向上平均降低了42.9%,在N方向上平均降低了39.1%,在U方向上平均降低了28.8%,表明空间滤波能够有效提高GPS坐标精度。此外,滤波后各站点相对于LOWS站点的相关系数在E方向上平均下降了89.3%,在N方向上平均下降了92.3%,在U方向上平均下降了86.5%,结果证实了共模误差是区域GPS网中各站点之间空间相关的主要来源。最后,皮尔逊相关性分析和小波相干分析证实了质量负载并不能有效地解释共模误差,共模误差最有可能来源于空间传播延迟误差。

关键词：共模误差主成分分析皮尔逊相关性小波相干质量负载

在线全文

学校读者我要写书评

暂无评论

GPS RTK在异形建筑物放样中的应用

测绘科学 2018年第6期43卷 156-160页

作者：边延凯高伟段茜茜张治刚天津城建大学地质与测绘学院天津300384

针对异形建筑物传统施工放样过程操作复杂、效率低下的问题,该文提出了采用GPS RTK进行异性建筑物施工中的放样工作。以天津市文化中心商业项目为例,利用GPS RTK技术分别对建筑物的主轴线和异形次轴线进行了放样工作,并与全站仪在放样... 详细信息

针对异形建筑物传统施工放样过程操作复杂、效率低下的问题,该文提出了采用GPS RTK进行异性建筑物施工中的放样工作。以天津市文化中心商业项目为例,利用GPS RTK技术分别对建筑物的主轴线和异形次轴线进行了放样工作,并与全站仪在放样过程和数据精度两个方面进行了对比分析,实现了异型建筑物快速、高效的施工放样。实验结果表明,GPS RTK技术不仅在放样过程中操作简单,节约资金,而且放样精度满足工程要求,相对全站仪来说具有很大优势,有助于提高复杂异形建筑物的施工放样效率。

关键词： GPS RTK 异形建筑主轴线次轴线施工放样

Heteroatom Structural Engineering Enables Ethenylene-Bridged Bisisoindigo-Based Copolymers to Exhibit Unique n-Type Transistor Performance

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2024年第2期6卷 473-486页

作者： Yuchai Pan Weifeng Zhang yankai Zhou Xuyang Wei Hao Luo Jinbei Wei Liping Wang Gui Yu Beijing National Laboratory for Molecular Sciences CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190 School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049 School of Material Science and Engineering University of Science and Technology BeijingBeijing 100083

Herein,we report three novel electron-deficient aromatics,ethenylene-bridged bisisoindigos 3,3′-((3E,3′E)-((E)-ethene-1,2-diyl)bis(1-(4-decyltetradecyl)-2-oxoind-oline-6-yl-3-ylidene))bis(1-(4-decyltetradecyl)-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one)(NCCN),3,3′-((3E,3′E)-((E)-ethene-1,2-diyl)bis(1-(4-decyltetradecyl)-7-fluoro-2-oxoindoline-6-yl-3-ylidene))bis(1-(4-decyltetradecyl)-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one)(NFFN),and(3E,3″E)-6,6″-((E)-ethene-1,2-diyl)bis(1,1′-bis(4-decyltetradecyl)-[3,3′-bipyrrolo[2,3-b]pyridinylidene]-2,2′(1H,1′H)-dione)(NNNN),and their derived donor–acceptor(D–A)copolymers,namely poly[3,3′-((3E,3′E)-((E)-ethene-1,2-diyl)bis(1-(4-decyltetradecyl)-2-oxoindoline-6-yl-3-ylidene))bis(1-(4-decyltetradecyl)-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one-6-yl)]-alt-[5,6-difluoro-4,7-di[(thiophen-2-yl)-5-yl)]benzo[c][1,2,5]thiadiazole](PNCCN-FBT),poly[3,3′-((3E,3′E)-((E)-ethene-1,2-diyl)bis(1-(4-decyltetradecyl)-7-fluoro-2-oxoindoline-6-yl-3-ylidene))bis(1-(4-decyltetradecyl)-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one-6-yl)]-alt-[5,6-difluoro-4,7-di[(thiophen-2-yl)-5-yl)]benzo[c][1,2,5]thiadiazole](PNFFNFBT),and poly[(3E,3″E)-6′,6‴-((E)-ethene-1,2-diyl)bis(1,1′-bis(4-decyltetradecyl)-[3,3′-bipyrrolo[2,3-b]pyridinylidene]-2,2′(1H,1′H)-dione-6-yl)]-alt-[5,6-difluoro-4,7-di[(thiophen-2-yl)-5-yl)]benzo[c][1,2,5]thiadiazole](PNNNN-FBT),in which 5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole(FBT)acts as the electron-donating *** ethenylene-bridging unit reduces the steric hindrance of the three *** of heteroatoms,such as fluorine and sp2-nitrogen atoms,endows them with multiple CH···F,CH···N,and N···S intramolecular hydrogen bonds/nonbinding interactions,resulting in increasing backbone planarity from NCCN,NFFN,to NNNN,and thus from PNCCN-FBT,PNFFN-FBT,to *** found that all copolymers formed an improved molecular packing in the 1-chloronaphthalene(CN)-processed thin film compared with the 1,2-d

关键词： D-A copolymers bisisoindigos heteroatom structural engineering n-type field-effect transistors electron mobilities

Residential energy transition and chronic respiratory diseases

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Innovation 2024年第3期5卷 33-43页

作者： Hongcheng Wei Qiurun Yu Danrong Chen Mingzhi Zhang Quanquan Guan Bo Hang Antoine M.Snijders Adrian Covaci yankai Xia State Key Laboratory of Reproductive Medicine and Offspring Health Center for Global HealthSchool of Public HealthNanjing Medical UniversityNanjing 211166China Key Laboratory of Modern Toxicology of Ministry of Education School of Public HealthNanjing Medical UniversityNanjing 211166China The Affiliated Wuxi People’s Hospital of Nanjing Medical University Wuxi People’s HospitalWuxi Medical CenterNanjing Medical UniversityWuxi 214023China Biological Systems and Engineering Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Toxicological Centre University of Antwerp2610 WilrijkBelgium

Obtaining clean energy is of prime importance for planetary health and sustainable *** aimed to assess the association between residential energy transition and the risk of chronic respiratory *** data from the Global Health Observatory and Global Burden of Diseases,Injuries,and Risk Factors Study,we delineated the spatial distribution and temporal trends of the population using clean fuels for cooking at a global *** the China Health and Retirement Longitudinal Study,we performed rigorous and well-structured multistage analyses incorporating both cross-sectional and prospective data analyses to examine the associations between solid fuel use,residential energy transition,duration of solid fuel use,and the risk of chronic respiratory *** great progress,huge disparities in access to clean energy persist *** energy transition was associated with a lower risk of chronic respiratory *** the period of 2011–2013,compared with persistent solid fuel users,both participants who switched from solid to clean fuels(adjusted risk ratio[RR]0.78,95%confidence interval[CI]0.62–0.98)and persistent clean fuel users(adjusted RR 0.71,95%CI 0.57–0.89)had significantly lower risk of chronic respiratory diseases(p<0.001 for trend).Consistent associations were observed in the period of 2011–2015 and 2011–*** energy transition from solid to clean fuels could reduce the risk of chronic respiratory *** is a valuable lesson for policy-makers and the general public to accelerate energy switching to alleviate the burden of chronic respiratory diseases and achieve health benefits,particularly in low-and middle-income countries.

关键词： cooking income globally

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

“去方程化”的分数应用题教学探究

教学与管理 2024年第5期 32-36页

作者：牛延凯山东省淄博市高新区教育和体育事业中心

分数应用题是小学数学的难点,现有教材中大量借助方程处理分数中的复杂数量关系。《义务教育数学课程标准(2022年版)》将方程内容从小学移出后,亟需形成“去方程化”的分数应用题教学变革。分析现有教材的变迁、对比国外教材,可以发现... 详细信息

分数应用题是小学数学的难点,现有教材中大量借助方程处理分数中的复杂数量关系。《义务教育数学课程标准(2022年版)》将方程内容从小学移出后,亟需形成“去方程化”的分数应用题教学变革。分析现有教材的变迁、对比国外教材,可以发现方程并不是分数应用题教学的必要条件。在不借助方程时,首先通过“量”和“率”的分类讨论,把握分数应用题和整数应用题的迁移联系;进一步通过构建数量关系结构,明晰分数问题中加减乘除列式的算术意义;最后通过比、分数、除法之间的大单元联系,实现分数应用题的整体教学。

关键词：小学数学分数应用题方程 “去方程化”

BIM在国内建筑项目全生命周期中的应用研究与进展

在线全文

学校读者我要写书评

暂无评论

天津城建大学学报 2017年第5期23卷 356-362页

作者：边延凯高伟林沂段茜茜张治刚天津城建大学地质与测绘学院天津300384 北京大学遥感与GIS研究所北京100871

BIM技术具有三维可视化、协调性、模拟性和优化性等特点,能够对建设过程的相关信息进行实时更新和直观展示,以便各部门间的交流与沟通,并通过模拟分析来减少设计变更和施工返工,有效节约了建设成本和工期.本文全面综述了BIM技术近年来... 详细信息

BIM技术具有三维可视化、协调性、模拟性和优化性等特点,能够对建设过程的相关信息进行实时更新和直观展示,以便各部门间的交流与沟通,并通过模拟分析来减少设计变更和施工返工,有效节约了建设成本和工期.本文全面综述了BIM技术近年来在国内建筑项目全生命周期的应用与进展,归纳、概述了BIM技术在建筑项目中规划阶段、设计阶段、施工阶段和运维阶段的17个主要应用点,并提出了BIM技术在结合层次分析法和集成测绘地理信息新技术等方面应用的新思路,可以为BIM技术在国内建筑行业的全面推广提供借鉴;分析了BIM技术在现有应用中存在的问题,并给出了全面采用BIM技术的相应建议.

关键词：建筑项目 BIM 全生命周期