检索结果-南通市图书馆

Synergistic silver-mediated and palladium-catalyzed nondirected olefination of aryl C–h bond: quick access to multi-substituted aryl olefins

引用

Science China Chemistry 2024年第3期67卷 882-889页

作者： Jian Yao lili Shao Xiaohong huo Xiaoming Wang Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Frontiers Science Center for Transformative MoleculesSchool of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 20032China School of Chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China

Transition metal-catalyzed olefination of aryl C-h bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-h olefination of arenes, also known as Fujiwara-Moritani reaction, has been established as one of the most efficient methods, the substrates are largely limited to terminal olefins with electron-withdrawing group(s). herein, we report a synergistic silver-mediated and palladium-catalyzed non-directed C-h olefination of arenes with vinyl(pseudo)halides, which offers a complementary strategy to the typical Fujiwara-Moritani reaction. The reactions proceeded well for a variety of halogenated arenes, heteroarenes, and olefin substrates, providing an efficient access to various multi-substituted aryl olefins, including trisubstituted/tetrasubstituted olefins and several complex olefins derived from medicines or natural products. Mechanistic studies indicated a bimetallic Pd/Ag cooperation is operative in the catalysis, i.e., the reaction is initiated by aryl C-h bond cleavage via ligation with phosphine/Ag species, followed by transferring of the aryl moiety to a vinyl palladium intermediate,which is in turn formed by oxidative addition of vinyl(pseudo)halide to a Pd complex. This method enables the synthesis of a wide range of challenging multi-substituted vinyl products from simple arenes(directing-group free) in a streamlined and controllable fashion.

关键词： direct C–h olefination multi-substituted aryl alkenes bimetallic Pd/Ag cooperation C–h functionalization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synergistic asymmetric diarylation of tethered alkenes via C–h functionalization of simple(hetero)arenes

引用

Science China Chemistry 2024年第8期67卷 2710-2718页

作者： Jian Yao Can Zhao lili Shao Xiaohong huo Xiaoming Wang Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Frontiers Science Center for Transformative MoleculesSchool of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Organometallic Chemistry and Shanghai hongkong Joint Laboratory in Chemical Synthesis Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China School of Chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China

By virtue of the atom-and step-economy, utilization of simple arenes as a supplant of pre-prepared aryl metal species or aryl halides for the synthesis of arylated chiral molecules has attracted great attention from the synthetic community. While transition-metal-catalyzed enantioselective diarylation of tethered alkenes has been employed to prepare important chiral cyclic compounds, the direct use of simple arenes as aryl precursors is still underdeveloped, probably due to the difficulties in the effective control of the reactivity, site-selectivity and/or enantioselectivity. herein we report an asymmetric Pd/Ag dual metal catalytic system for the non-directed, site-and enantioselective domino heck/intermolecular C–h functionalization of *** studies showed that Pd and Ag act in cooperation in the catalysis and the chiral bisphosphine ligand plays a bifunctional role, i.e., assisting the silver species in the cleavage of the aryl C–h bond, while inducing the enantioselectivity on direct complexation with palladium. This method provides an efficient approach to the corresponding chiral oxindoles with good enantiomeric excesses from a broad scope of arenes, including fluoroarenes, heteroarenes and several complex products derived from medicines or natural products.

关键词： asymmetric Pd/Ag dual metal catalytic system simple arenes C–h functionalization bifunctional role chiral oxindoles

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Naturally occurring PA^(E206K)point mutation in 2009 h1N1 pandemic influenza viruses impairs viral replication at high temperatures

引用

Virologica Sinica 2024年第1期39卷 71-80页

作者： Mengmeng Cao Qiannan Jia Jinghua Li lili Zhao Li zhu Yufan Zhang Shan Li Tao Deng National Institute of Pathogen Biology Chinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing100730China CAS Key Laboratory of Pathogen Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing100101China

The emergence of influenza virus A pandemic h1N1 in April 2009 marked the first pandemic of the 21st *** this study,we observed significant differences in the polymerase activities of two clinical 2009 h1N1 influenza A virus isolates from Chinese and Japanese *** comparison of the three main protein subunits(PB2,PB1,and PA)of the viral RNA-dependent RNA polymerase complex and subsequent mutational analysis revealed that a single amino acid substitution(E206K)was responsible for the observed impaired replication *** in vitro experiments showed that presence of PAE206K decreased the replication of influenza A/WSN/33 virus in mammalian cells and a reduction in the virus’s pathogenicity in *** studies revealed that PAE206K is a temperature-sensitive mutant associated with the inability to transport PB1–PA complex to the nucleus at high temperature(39.5℃).hence,this naturally occurring variant in the PA protein represents an ideal candidate mutation for the development of live attenuated influenza vaccines.

关键词： h1N1 Influenza A virus Polymerase acidic protein Point mutation Viral replication

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Elucidating the structure-activity relationship of Cu-Ag bimetallic catalysts for electrochemical CO_(2) reduction

引用

Journal of Energy Chemistry 2024年第6期93卷 345-351,I0009页

作者： Qining huang lili Wan Qingxuan Ren Jingshan Luo Institute of Photoelectronic Thin Film Devices and Technology State Key Laboratory of Photovoltaic Materials and CellsKey Laboratory of Photoelectronic Thin Film Devices and Technology of TianjinMinistry of Education Engineering Research Center of Thin Film Photoelectronic TechnologyNankai UniversityTianjin 300350China Frontiers Science Center for New Organic Matter Nankai UniversityTianjin 300071China haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Developing bimetallic catalysts is an effective strategy for enhancing the activity and selectivity of electrochemical CO_(2) reduction reactions,where understanding the structure-activity relationship is essential for catalyst ***,we prepared two Cu-Ag bimetallic catalysts with Ag nanoparticles attached to the top or the bottom of Cu *** tested in a flow cell,the Cu-Ag catalyst with Ag nanoparticles on the bottom achieved a faradaic efficiency of 54%for ethylene production,much higher than the catalyst with Ag nanoparticles on the *** catalysts were further studied in the h-cell and zero-gap MEA *** was found that placing the two metals in the intensified reaction zone is crucial to triggering the tandem reaction of bimetallic *** work elucidates the structure-activity relationship of bimetallic catalysts for CO_(2) reduction and demonstrates the importance of considering both catalyst structures and cell characteristics to achieve high activity and selectivity.

关键词： Electrochemical CO_(2)reduction Bimetallic catalyst Cu-Ag Structure-activity relationship

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The importance of data assimilation components for initial conditions and subsequent error growth

引用

Science China Earth Sciences 2024年第1期67卷 105-116页

作者： Zhongrui WANG haohao SUN lili LEI Zhe-Min TAN Yi ZhANG Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210023China Frontiers Science Center for Critical Earth Material Cycling Nanjing UniversityNanjing 210023China

Despite a specific data assimilation method,data assimilation(DA)in general can be decomposed into components of the prior information,observation forward operator that is given by the observation type,observation error covariances,and background error *** a classic Lorenz model,the influences of the DA components on the initial conditions(ICs)and subsequent forecasts are systematically investigated,which could provide a theoretical basis for the design of DA for different scales of *** forecast errors undergo three typical stages:a slow growth stage from 0 h to 5 d,a fast growth stage from 5 d to around 15 d with significantly different error growth rates for ensemble and deterministic forecasts,and a saturation stage after 15 *** strategies that provide more accurate ICs can improve the *** assimilation is superior to offline assimilation,and a flow-dependent background error covariance matrix(Pf)provides better analyses than a static background error covariance matrix(B)for instantaneous observations and frequent time-averaged observations;but the opposite is true for infrequent time-averaged observations,since cycling simulation cannot construct informative priors when the model lacks predictive skills and the flow-dependent Pf cannot effectively extract information from low-informative observations as the static *** observations contain more information than time-averaged observations,thus the former is preferred,especially for infrequent observing ***,ensemble forecasts have advantages over deterministic forecasts,and the advantages are enlarged with less informative observations and lower predictive-skill model priors.

关键词： Data assimilation Atmospheric predictability Background error covariances Ensemble forecasts

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Biased Bi-Population Evolutionary Algorithm for Energy-Efficient Fuzzy Flexible Job Shop Scheduling with Deteriorating Jobs

引用

Complex System Modeling and Simulation 2024年第1期4卷 15-32页

作者： Libao Deng Yingjian Zhu Yuanzhu Di lili Zhang School of Information Science and Engineering Harbin Institute of TechnologyWeihai 264209China. Department of Computer Science Maynooth UniversityMaynoothW23 F2H6 the School of Computing Dublin City UniversityDublinD09 V209Ireland.

There are many studies about flexible job shop scheduling problem with fuzzy processing time and deteriorating scheduling,but most scholars neglect the connection between them,which means the purpose of both models is to simulate a more realistic factory *** this perspective,the solutions can be more precise and practical if both issues are considered ***,the deterioration effect is treated as a part of the fuzzy job shop scheduling problem in this paper,which means the linear increase of a certain processing time is transformed into an internal linear shift of a triangle fuzzy processing *** from that,many other contributions can be stated as follows.A new algorithm called reinforcement learning based biased bi-population evolutionary algorithm(RB2EA)is proposed,which utilizes Q-learning algorithm to adjust the size of the two populations and the interaction frequency according to the quality of population.A local enhancement method which combimes multiple local search stratgies is *** interaction mechanism is designed to promote the convergence of the *** experiments are designed to evaluate the efficacy of RB2EA,and the conclusion can be drew that RB2EA is able to solve energy-efficient fuzzy flexible job shop scheduling problem with deteriorating jobs(EFFJSPD)efficiently.

关键词： bi-population evolutionary algorithm Q-learning algorithm fuzzy deteriorating effect energy flexible job shop scheduling

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Preparation of α-high Strength Gypsum from Flue Gas Desulfurization Gypsum Pretreated by hydrothermal-aging Method

引用

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 75-81页

作者：苏一鑫 GAO lili 陈学青 LI Zhishui 李雲 CAO Jilin Engineering Research Center of Seawater Utilization Technology of Ministry of Education School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China heze Center for Disease Control and Prevention Heze 274010China Tianjin Bohua Yongli Chemical Industry Co. Ltd.Tianjin 300452China

The synthesis of α-calcium sulfate hemihydrate (α-CSh) from flue gas desulfurization (FGD)gypsum is a good way to realize the comprehensive utilization of FGD gypsum. To obtainα-CSh with the satisfactory performances, a facile hydrothermal-aging pretreatment process for FGD gypsum raw materials was proposed, where FGD gypsum was firstly hydrothermally converted to α-CSh whiskers, and α-CSh whiskers were further hydrated to synthesize CaSO4·2h2O (CSD) by aging under the regulation of N,N'-methylenebisacrylamide (MBA). The effects of aging time, MBA addition, aging temperature, and ph on the morphology of the synthesized CSD were investigated. The synthesized CSD crystals exhibit highly uniform prismatic morphology with the length of ca 100μm and the whiteness of 91.56%. The regulation mechanism of MBA was also illustrated. The synthesized CSD crystals with prismatic morphology were further used as raw materials to synthesize the short columnar α-CSh. The absolute dry compressive strength of paste prepared from the short columnar α-CSh is 40.85 MPa, which reaches α40 strength grade.

关键词： flue gas desulphurization gypsum α-calcium sulfate hemihydrate hydrothermal-aging method N,N'-methylenebisacrylamide prismatic CSD

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A high-entropy-designed cathode with V^(5+)-V^(2+) multi-redox for high energy density sodium-ion batteries

引用

Journal of Energy Chemistry 2024年第10期97卷 429-437,I0008页

作者： Xiang Ding Xiaofen Yang Yibing Yang Liangwei Liu Yi Xiao lili han College of Chemistry and Materials Science Fujian Normal University.Fuzhou 350007FujianChina State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002FujianChina

Na_(3)V_(2)(PO_(4))_(3)(NVP)is gifted with fast Na^(+)conductive NASICON *** it still suffers from low electronic conductivity and inadequate energy ***,a high-entropy modification strategy is realized by doping V^(3+)site with Ga^(3+)/Cr^(3+)/Al^(3+)/Fe^(3+)/In^(3+)simultaneously(***_(3)V_(2-x)(GaCrAlFeIn)_x(PO_(4))_(3);x=0,0.04,0.06,and 0.08)to stimulate the V^(5+)■V^(2+)reversible multi-electron *** configuration high-entropy can effectively suppress the structural collapse,enhance the redox reversibility in high working voltage(4.0 V),and optimize the electronic induced *** in-situ X-ray powder diffraction and in-situ electrochemical impedance spectroscopy tests efficaciously confirm the robust structu ral recovery and far lower polarization throughout an entire charge-discharge cycle during 1.6-4.3 V,***,the density functional theory calculations clarify the stronger metallicity of high-entropy electrode than the bare that is derived from the more mobile free electrons surrounding the vicinity of Fermi *** grace of high-entropy design and multi-electron transfer reactions,the optimal Na_(3)V_(1.7)(GaCrAlFeIn)_(0.06)(PO_(4))_(3)can exhibit perfect cycling/rate performances(90.97%@5000 cycles@30 C;112 mA h g^(-1)@10 C and 109 mA h g^(-1)@30 C,2.0-4.3 V).Furthermore,it can supply ultra-high185 mA h g^(-1)capacity with fa ntastic energy density(522 W h kg^(-1))in half-cells(1.4-4.3 V),and competitive capacity(121 mA h g^(-1))as well as energy density(402 W h kg^(-1))in full-cells(1.6-4.1 V),demonstrating enormous application potential for sodium-ion batteries.

关键词： Na_(3)V_(2)(PO_(4))_(3) high-entropy V^(5+)■V^(2+)multi-redox high energy density Sodium-ion batteries

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Green carbonization of waste coffee grounds into porous C/Fe hybrids for broadband and high-efficiency microwave absorption

引用

Journal of Materials Science & Technology 2024年第3期170卷 1-10页

作者： Xin Wen Cui Li hui Liu Guohua Fan Yanan Tang Chuncheng hao lili Ma Pingan Song Institute of Advanced Electrical Materials College of Materials Science and EngineeringQingdao University of Science and TechnologyQingdao 266042China Center for Future Materials University of Southern QueenslandSpringfieldQLD 4300Australia School of Agriculture and Environmental Science University of Southern QueenslandSpringfieldQLD 4300Australia

Recently great effort s have been focused on designing high-performance microwave absorbers using sustainable biomass resources,but there remains a lack of green and efficient fabrication ***,inspired by natural porous character of biomass waste,we demonstrated a green one-step route to convert waste coffee grounds into porous C/Fe hybrids,and further explored their potential applications for broadband and high-efficiency microwave *** this design,the WCG-20-750(incorporated 20 wt%Fe(C_(5)h_(7)O_(2))_(3)catalyst and carbonized at 750℃)exhibited porous microstructure with the highest char yield of 55.45 wt%.Furthermore,the as-prepared C/Fe hybrids from WCG-20-750 displayed excellent microwave absorption ***,the minimum reflection loss(RL_(min))reached to-52.86 dB and the widest effective absorption bandwidth(EAB)was 6.40 Ghz at the thickness of 3.0 *** work provides an economically viable and environmentally friendly strategy to convert biomass wastes into value-added microwave absorbers,ultimately making contributions to the upcycling of renewable biomass resources and the fostering of sustainable environment.

关键词： Waste recycling Microwave absorption Green carbonization Porous carbon Biomass

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Confinement of ionomer for electrocatalytic CO2 reduction reaction via efficient mass transfer pathways

引用

National Science Review 2024年第2期11卷 168-176页

作者： Xiaowei Du Peng Zhang Gong Zhang hui Gao lili Zhang Mengmeng Zhang Tuo Wang Jinlong Gong School of Chemical Engineering and Technology Key Laboratory for Green Chemical Technology of the Ministry of Education Tianjin University Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) National Industry-Education Platform of Energy Storage Tianjin University Joint School of the National University of Singapore and Tianjin University International Campus of Tianjin University haihe Laboratory of Sustainable Chemical Transformations

Gas diffusion electrodes（GDEs） mediate the transport of reactants, products and electrons for the electrocatalytic CO2reduction reaction（CO2RR） in membrane electrode assemblies. The random distribution of ionomer, added by the traditional physical mixing method, in the catalyst layer of GDEs affects the transport of ions and CO2. Such a phenomenon results in elevated cell voltage and decaying selectivity at high current densities. This paper describes a pre-confinement method to construct GDEs with homogeneously distributed ionomer, which enhances mass transfer locally at the active centers. The optimized GDE exhibited comparatively low cell voltages and high CO Faradaic efficiencies（FE > 90%） at a wide range of current densities. It can also operate stably for over 220 h with the cell voltage staying almost unchanged. This good performance can be preserved even with diluted CO2feeds, which is essential for pursuing a high single-pass conversion rate. This study provides a new approach to building efficient mass transfer pathways for ions and reactants in GDEs to promote the electrocatalytic CO2RR for practical applications.

关键词： CO2 electroreduction gas diffusion electrode mass transfer ionomer Ag catalyst

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：