检索结果-南通市图书馆

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

Neural Network-Based State Estimation for Nonlinear Systems With Denial-of-Service Attack Under Try-Once-Discard Protocol

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第10期11卷 2182-2184页

作者： Xueli wang Shangwei Zhao Ming Yang Xin wang xiaoming Wu the Key Laboratory of Computing Power Network and Information Security Ministry of EducationShandong Computer Science CenterQilu University of Technology(Shandong Academy of Sciences)Jinan 250014 Shandong Provincial Key Laboratory of Computer Networks Shandong Fundamental Research Center for Computer ScienceJinan 250014China Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China

Dear Editor,This letter deals with state estimation issues of discrete-time nonlinear systems subject to denial-of-service(DoS)attacks under the try-once-discard(TOD)*** specifically,to reduce the communication burden,a TOD protocol with novel update rules on protocol weights is designed for scheduling measurement *** addition,unknown nonlinear functions vulnerable to DoS attacks are considered due to the openness and vulnerability of the network.

关键词： Service DoS service

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

在线全文

学校读者我要写书评

暂无评论

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

Two-Dimensional Perovskite Single Crystals for High-Performance X-ray Imaging and Exploring MeV X-ray Detection

在线全文

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2024年第1期7卷 139-146页

作者： Xieming Xu Yiheng Wu Yi Zhang Xiaohui Li Fang wang xiaoming Jiang Shaofan Wu Shuaihua wang Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of chinese academy of sciences Beijing 100049China Division of Nuclear Technology and Applications Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Scintillation semiconductors play increasingly important medical diagnosis and industrial inspection ***,two-dimensional(2D)perovskites have been shown to be promising materials for medical X-ray imaging,but they are mostly used in low-energy(≤130 keV)*** detection of MeV X-rays,which ensure thorough penetration of the thick shell walls of containers,trucks,and aircraft,is also highly desired in practical industrial ***,scintillation semiconductors for high-energy X-ray detection are currently ***,This paper reports a 2D(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single crystal with outstanding sensitivity and stability toward X-ray radiation that provides an ultra-wide detectable X-ray range of between 8.20 nGy_(air)s^(-1)(50 keV)and 15.24 mGy_(air)s^(-1)(9 MeV).The(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single-crystal detector with a vertical structure is used for high-performance X-ray imaging,delivering a good spatial resolution of 4.3 Ip mm^(-1)in a plane-scan imaging *** ionic migration in the 2D perovskite enables the vertical device to be operated with hundreds of keV to MeV X-ray radiation at high bias voltages,leading to a sensitivity of 46.90μC Gy_(air)-1 cm^(-2)(-1.16 Vμm^(-1))with 9 MeV X-ray radiation,demonstrating that 2D perovskites have enormous potential for high-energy industrial applications.

关键词： MeV X-ray detection single-crystal X-ray detectors two-dimensional perovskites X-ray imaging

Failure mechanism and safety control technology of a composite strata roadway in deep and soft rock masses:a case study

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第7期21卷 2427-2444页

作者： ZHAO Chengwei ZHOU Hui SUN xiaoming ZHANG Yong MIAO Chengyu wang Jian State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of chinese academy of sciences Beijing 100049China State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China

The construction of coal mines often encounters deep composite soft rock roadways,which is characterized by significant deformation and poor *** deeply study the failure mechanism and large deformation challenges of a composite strata roadway in deep and soft rock masses,a numerical model of 3DEC tetrahedral blocks was established based on the method of rock quality designation(RQD).The results showed that original support cannot prevent asymmetric failure and large deformation due to the adverse geological environment and unsuitable support *** to the failure characteristics,a coupling support of“NPR bolt/cable+mesh+shotcrete+steel pipe”was proposed to control the stability of the surrounding *** excellent mechanical properties of large deformation(approximately 400 mm)and high constant resistance force(bolt with 180 k N;cable with 350 k N)were evaluated by the tensile *** numerical results showed that the maximum deformation was minimized to 243 mm,and the bearing capacity of the surrounding rock of the roadway was *** field test results showed that the maximum deformation of the surrounding rock was 210 mm,and the forces of the NPR bolt and cable were stable at approximately 180 k N and 350 k N,*** demonstrated the effectiveness of the coupling support with the NPR bolt and cable,which could be a guiding significance for the safety control of large deformation and failure in deep composite soft rock roadways.

关键词： 3DEC Composite strata roadway Soft rock NPR bolt and cable Asymmetric large deformation

Macro-superlubricity in sputtered MoS_(2)-based films by decreasing edge pinning effect

在线全文

学校读者我要写书评

暂无评论

Friction 2024年第1期12卷 52-63页

作者： Chunmeng DONG Dong JIANG Yanlong FU Desheng wang Qinqin wang Lijun WENG Ming HU xiaoming GAO Jiayi SUN State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

To date,MoS_(2) can only be achieved at *** pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to ***,we plan to pin edge planes of MoS_(2) with nanospheres,and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce *** sputtered MoS_(2) film was prepared by the physical vapor deposition(PVD)in *** enough Cu_(2)O nanospheres(~40 nm)were generated in situ at the edge plane of MoS_(2) layers by liquid phase *** incommensurate structure(mismatch angle(θ)=8°)caused by MoS_(2) layers was formed before *** friction coefficient of the films(5 N,1,000 r/min)was~6.0×10^(−3) at the *** friction,MoS_(2) layers pinned on numerous of Cu_(2)O nanoparticles reduced its edge pinning effect and decreased ***,much more incommensurate was formed,developing macro-superlubricity.

关键词： sputtered MoS_(2)film Cu_(2)O nanospheres edge pinning effect macro-superlubricity

Modeling and analysis of pointing error for non-landing vehicle-mounted photoelectric theodolite

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

Optoelectronics Letters 2024年第5期20卷 294-298页

作者： GAO Qingjia wang Chong LIU Yanjun wang xiaoming WU Tongbang ZHANG Haoyuan Changchun institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Troop 95859 the Chinese People's Liberation ArmyJiuquan 735018China

In order to achieve high accuracy measurement for non-landing vehicle-mounted photoelectric theodolite(NVPT) with continuous zoom optical system, a theoretical model of pointing error is presented. Starting with the working mode, the error source of the whole closed loop which affects the pointing error is analyzed. The measurement equation is derived using a coordinate transformation. The pointing error model is then obtained with the help of Monte Carlo method. The error of an NVPT prototype is measured, showing that the pointing error can be predicted accurately. A high precision NVPT with continuous zoom optical system is successfully designed and analyzed, with an accuracy of 11.9″ at azimuth and 10.9″ at elevation, when the optical focal length is set between 1 000 mm and 4 000 mm.

关键词： error mounted system

Structural effects of sulfonamides on the proliferation dynamics of sulfonamide resistance genes in the sequencing batch reactors and the mechanism

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2024年第1期135卷 161-173页

作者： Ligui Wu Mingyu wang Lingling Rong Wenbiao wang Linwei Chen Qiaofeng Wu Haoyu Sun Xiangfeng Huang xiaoming Zou College of Environmental Science and Engineering Tongji UniversityShanghai 200092China School of Life Science Jinggangshan UniversityJi’an 343009China Key Laboratory of Organic Compound Pollution Control Engineering(MOE) School of Environmental and Chemical EngineeringShanghai UniversityShanghai 200444China Fuzhou Urban and Rural Construction Group Co.Ltd. Fuzhou 350007China

Antibiotic resistance genes(ARGs)can be easily promoted by antibiotics,however,the structural effects of antibiotics on the proliferation of ARGs dynamic and the associated mechanisms remain obscure in,especially,activated sludge sequencing batch *** the present study,the effects of 9 sulfonamides(SAs)with different structures on the proliferation dynamic of sulfonamide resistance genes(Suls)in the activated sludge sequencing batch reactors and the corresponding mechanisms were determined(30 days),and the results showed that the largest proliferation value(ΔA^(R))of Suls dynamic for SAs(sulfachloropyridazine)was approximately 2.9 times than that of the smallest one(sulfadiazine).The proliferation of Suls was significantly related to the structural features(minHBint6,SssNH,SHBd and SpMax2_Bhm)that represent the biological activity of *** interpret the phenomenon,a mechanistic model was developed and the results indicated that the biodegradation of SAs(T_(1/2))rather than conjugative transfer frequency or mutation frequency tends to be the key process for affecting Suls proliferation.T_(1/2)was proved to be dependent on the interactions between SAs and receptors(E_(binding)),the cleavage mode(bond dissociation energy),and the site of nucleophilic ***,the metagenomic analysis showed that SAs posed significant effect on antibiotic resistome and Tnp31 played a vital role in the proliferation of ***,our findings provide important insight into a theoretical basis for understanding the structural effects of SAs on the proliferation of ARGs in SBR systems.

关键词： Activated sludge Sulfonamides Suls Proliferation Mechanism

Novel alleles among soybean Bowman-Birk proteinase inhibitor gene families

在线全文

学校读者我要写书评

暂无评论

Science China(Life sciences) 2008年第8期51卷 687-692页

作者： wang YuePing1,2, CHEN XiongTing2 & QIU LiJuan1 1 National Key Facility for crop Gene Resources and Genetic Improvement, Key Laboratory of crop Germplasm & Biotechnology(MOA)/institute of crop Science, chinese academy of agricultural sciences, Beijing 10008, China 2 institute of Tropical Biotechnology, chinese academy of Tropical agricultural sciences, Haikou 571101, China 1. National Key Facility for crop Gene Resources and Genetic Improvement Key Laboratory of Crop Germplasm & Biotechnology (MOA)/Institute of Crop Science Chinese Academy of Agricultural Sciences Beijing 10008 China 2. institute of Tropical Biotechnology Chinese Academy of Tropical Agricultural Sciences Haikou 571101 China

Trypsin inhibitors have been found in various animals, plants and *** were two types of trypsin inhibitors in soybean including Bowman-Birk protease inhibitors(BBI) and Kunitz in-hibitors(KTI).The different BBI genes from wild soybean(***) and cultivated soybean(***) formed a multigene *** constructed a cDNA library of cultivar 'SuiNong 14' seed at the R7 growth stage using the SMART *** contigs or singletons were highly homologous to soy-bean protease *** of 5, 35, 8 and 9 were highly homologous to BBI family members BBI-A1, BBI-A2, BBI-C and BBI-D, *** analyses showed there were novel allelic varia-tions among the 4 BBI members in SuiNong *** on the comparison of soybean seed cDNA li-braries from different developmental stages, it was apparent that the expression of trypsin inhibitors increased during seed development in *** analysis of BBI gene sequences among dicotyledonous and monocotyledonous plants demonstrated that these genes shared a common pro-genitor.

关键词： soybean trypsin inhibitor Bowman-Birk proteinase inhibitor Kunitz trypsin inhibitor allelic variation