检索结果-南通市图书馆

Cobalt-catalyzed reductive alkynylation to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))bonds

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

Chinese Chemical Letters 2024年第7期35卷 253-258页

作者： Lei wan Yizhou Tong xi Lu Yao Fu Hefei National Research Center for Physical Sciences at the Microscale iChEMCAS Key Laboratory of Urban Pollutant ConversionAnhui Province Key Laboratory of Biomass Clean EnergyUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China

Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon ***,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))*** presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)*** presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.

关键词： Cobalt-catalysis Cross-electrophile coupling Carbon-carbon bond formation Reductive alkynylation Alkyne synthesis

Insulating process for HT-7U central solenoid model coils

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2003年第1期14卷 72-75页

作者： CUI Yi-Min, PAN wan-Jiang, WU Song-Tao, wan yuan-xi (Institute of Plasma Physics, the Chinese Academy of Sciences, Hefei 230031) Institute of Plasma Physics the Chinese Academy of Sciences Hefei 230031

The HT-7U superconducting Tokamak is a whole superconducting magnetically confined fusion device. The insulating system of its central solenoid coils is critical to its properties. In this paper the forming of the insulating system and the vacuum-pressure-impregnating (VPI) are introduced, and the whole insulating process is verified under the superconducting experiment condition.

关键词： HT-7U 托卡马克装置 CS VPI 真空技术绝缘体系螺线管线圈

Spatial correlations in time and frequency domains between chlorophyll-a concentration and environmental factors in the Bohai Sea

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2024年第4期42卷 1143-1156页

作者： wan XU Di MU Zhenteng YANG Dekui yuan Department of Mechanics Tianjin UniversityTianjin 300350China Engineering Research Center of Seawater Utilization of Ministry of Education School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China

Based on the reconstructed MODIS data and ECMWF reanalysis data from 2003 to 2021,spatial correlations between chlorophyll a(Chl a)and sea surface temperature(SST),photosynthetically available radiation(PAR),aerosol optical thickness(AOT),and wind speed(WS)in the Bohai Sea were analyzed from the perspective of time domain and frequency *** indicate that the frequency domain analysis was more conducive to revealing the correlations between Chl a and environmental *** spatial pattern of time-domain correlations was similar to the isobaths of the Bohai Sea,which was positive in shallow waters and negative in deep waters for SST,PAR,and AOT,and was reversed for ***-domain correlations were obtained by performing Fourier Transform and were higher than correlations in time *** spatial distributions indicated that the effects of SST and PAR on Chl a were greater than AOT and WS in the Bohai ***,cross-spectrum analysis was applied to explore the response relationships.A depth-dependent pattern was shown in correlations and time lags,indicating that the influential mechanism of environmental factors on Chl-a concentration is related to seawater depth.

关键词： chlorophyll a(Chl a) frequency domain spatial correlation Bohai Sea

Comparison of irradiation-induced void formations in tungsten with equiaxed and columnar structures

在线全文

学校读者我要写书评

暂无评论

Tungsten 2024年第4期6卷 794-805页

作者： Liu xi Jia-Jun Zhao Ji-Jun Zhao yuan-yuan wang Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education) Dalian University of Technology

Tungsten(W) has been received much attention,since it is regarded as one of the most promising plasma facing materials for fusion *** are two typical morphologies of unirradiated polycrystalline W,which have the equiaxed and columnar grains,***,the role of arrangement of grain boundary(GB) in absorbing irradiation-generated point defects is still waiting to be *** current investigation,irradiation-induced void formations in W with equiaxed and columnar microstructures are predicted,respectively,using the developed phase-field *** significant kinetic behavior,such as the generation and annihilation of point defects and the interaction between point defects and GB,is reasonably *** density,size and porosity of void formed in these two microstructures are examined and analyzed according to the effects of GB ratio,temperature and damage *** analytical results show that higher GB ratio can effectively reduce void porosity,and the columnar-grained structure has better irradiation resistance than that of the equiaxed one in the case of small grain *** importantly,the predicted void sizes changed with temperature and damage rate agree well with the experimentally measured *** work has a more beneficial contribution to the microstructural improvement of International Thermonuclear Experimental Reactor-grade W.

关键词： Grain morphology Irradiation-induced void Phase-field Tungsten

Tuning the surface electronic structure of noble metal aerogels to promote the electrocatalytic oxygen reduction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第2期89卷 557-564,I0013页

作者： Hongxing yuan Wei Gao xinhao wan Jianqi Ye Dan Wen State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072ShaanxiChina

The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion *** the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR ***,the surface electronic structure of Ptbased noble metal aerogels(NMAs)was modulated by various organic ligands,among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR *** calculations suggested the smaller energy barrier for the transformation of O^(*) to OH^(*) and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals,thus enhancing the ORR intrinsic *** Pt3Ni and Pt Pd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different ***,the 4-methylphenylene modified Pt Pd aerogel exhibited the higher halfwave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/*** work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.

关键词： Noble metal aerogels Surface electronic structure ORR Electrocatalyst Organic ligands

Numerical analysis of the correlation between fluid dynamic modes and hydrodynamic noise in flows around a three-dimensional circular cylinder

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第1期36卷 119-129页

作者： Jia-jia Qin Ming-xin Zou yuan Zhuang De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Wuhan Second Ship Design and Research Institute Wuhan430205China

The flow around a circular cylinder for Re=1000 is characterized by flow separation and Karman vortex *** typical flow features can be captured to study the correlation between fluid fields and sound *** this paper,the three-dimensional circular cylinder is taken as the research object,and the probes of surface fluctuating pressure and far field sound pressure are arranged every 10°.The directional diagram and the coherence of fluctuating pressure and sound pressure are *** relationship between the flow mode and hydrodynamic noise is studied by using dynamic mode decomposition(DMD).The characteristics of the dipole and quadrupole sound source term of a long span cylinder are *** results show that at the angles between 30°–120°and 190°–350°,the fluctuating pressure contributes more to the generation of dipole *** quadrupole sound source shows three-dimensional effects,which is more obvious in a cylinder with large spanwise length.

关键词： Pressure coherence dynamic mode decomposition flow-sound correlation circular cylinder

Gamma Approximation Based Multi-Antenna Covert Communication Detection

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

China Communications 2024年第9期21卷 90-97页

作者： wan Pengwu Chen Dongrui wang Danyang Hui xi Peng Kang School of Communications and Information Engineering&School of Artificial Intelligence Xi’an University of Posts and TelecommunicationsXi’an 710121China Key Laboratory of Integrated Service Networks School of Telecommunications EngineeringXidian UniversityXi’an 710071China

Covert communication technology makes wireless communication more secure,but it also provides more opportunities for illegal users to transmit harmful *** order to detect the illegal covert communication of the lawbreakers in real time for subsequent processing,this paper proposes a Gamma approximation-based detection method for multi-antenna covert communication ***,the Gamma approximation property is used to calculate the miss detection rate and false alarm rate of the monitor *** the optimization problem to minimize the sum of the missed detection rate and the false alarm rate is *** optimal detection threshold and the minimum error detection probability are solved according to the properties of the Lambert W ***,simulation results are given to demonstrate the effectiveness of the proposed method.

关键词： covert communication detection Gamma approximation Lambert W function multi-antenna technique

非计算机本科专业计算机程序设计课程的改革思考

在线全文

学校读者我要写书评

暂无评论

计算机工程与科学 2014年第A1期36卷 56-59页

作者：宛西原汪霞后勤工程学院后勤信息与军事物流工程系重庆401311

针对军队院校非计算机专业计算机程序设计课程教学中存在的问题,分析了计算机程序设计课程的特点,利用现代教育观点,探讨了大学计算机程序设计课程改革的要求与原则,并对该课程的教学内容、教学组织与教学评价体系等方面改革进行了阐述... 详细信息

针对军队院校非计算机专业计算机程序设计课程教学中存在的问题,分析了计算机程序设计课程的特点,利用现代教育观点,探讨了大学计算机程序设计课程改革的要求与原则,并对该课程的教学内容、教学组织与教学评价体系等方面改革进行了阐述,最后提出了相应的教学改革的思路与措施。

关键词：程序设计教学改革教学内容课程

Improved Confinement by Edge Multi-pulse Turbulent Heating on HT-6M Tokamak

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1997年第10期14卷 752-755页

作者： MAO Jian-shan LUO Jia-rong LI Jian-gang PAN yuan wanG Mao-quan LIU Bao-hua wan yuan-xi LI Qiang WU xin-chao LIANG Yun-feng XU Yu-hong YU Chang-xuan Institute of Plasma Physics Chinese Academy of SciencesHefei 230031 Department of Modern Physics University of Science and Technology of ChinaHefei 230026

In the recent experiment on HT-6M tokamak,an improved ohmic confinement phase has been observed after application of the edge multi-pulse turbulent heating,and variance of plasma currentΔI_(p)/I_(p) is about 14-20%;.The improved edge plasma confinement phase is characterized by(a)increased average electron density N_(e) and electron temperature T_(e);(b)reduced Hαradiation from the edge;(c)steeper density and temperature profiles at the edge;(d)a more negative radial electric field over a region of~5mm deep inside the limiter;(e)a deeper electrostatic potential well at the edge;(f)reduced magnetic fluctuations at the edge.

关键词： pulse tokamak electrostatic