期刊文献+
共找到4,086篇文章
< 1 2 205 >
每页显示 20 50 100
水稻需水量及其影响因素研究
1
作者 王彬 杨丞 +1 位作者 吴朋浩 李小坤 《中国稻米》 北大核心 2025年第4期79-85,共7页
采用ET_(0) Calculator和单作物系数法计算水稻需水量,分析近41年种植区域、季型和种植时期对水稻需水量的影响,比较影响需水量气候因素的相对重要性,为水稻的水分高效利用提供理论依据。水稻需水量随生育进程推进呈逐渐增加的趋势,全... 采用ET_(0) Calculator和单作物系数法计算水稻需水量,分析近41年种植区域、季型和种植时期对水稻需水量的影响,比较影响需水量气候因素的相对重要性,为水稻的水分高效利用提供理论依据。水稻需水量随生育进程推进呈逐渐增加的趋势,全生育期需水总量变异性较大,最小值为4 057.0 t/hm^(2),最大值为9 788.0 t/hm^(2),平均值为6 621.0t/hm^(2)。日均需水量呈先增加后降低的趋势,返青期、分蘖期、拔节孕穗期、抽穗灌浆期和黄熟期的日均需水量分别为50.0、63.0、75.0、64.0和37.0 t/(hm^(2)·d)。水稻种植区域、季型、种植时期等因素对需水量都具有一定的影响:东北地区、西北地区、长江中下游地区、华南地区和西南地区水稻需水量分别为5 161.0~6 111.0 t/hm^(2)、8 845.0~9 788.0 t/hm^(2)、5 211.0~9 591.0 t/hm^(2)、4 057.0~5 676.0 t/hm^(2)、7 658.0~8 347.0 t/hm^(2);早稻、晚稻和单季稻需水量分别为5 211.0~5 891.0 t/hm^(2)、6 074.0~6 990.0 t/hm^(2)和8 428.0~9 545.0 t/hm^(2);随种植时间的推移水稻需水量呈增加的趋势。影响水稻需水量的气候因素中,平均温度、最高温度、日照时数、最低温度、相对湿度、降水和风速的相对重要性占比分别为25.5%、22.9%、22.6%、20.9%、4.9%、1.7%和1.5%。 展开更多
关键词 水稻 需水量 气候 ET_(0)Calculator
在线阅读 下载PDF
Defect regulation of p-n scheme Cu_(2)N_(x)O_(1–x)/PDINH composites for enhanced photocatalytic antibacterial activities 被引量:2
2
作者 Chengcheng Ma Shougang Chen +3 位作者 Chaoqun Wang Zhipeng Zhao Wei Wang Wen Li 《Journal of Materials Science & Technology》 2025年第6期149-160,共12页
The defect regulation and p-n heterojunction of composites have gained significant attention due to their potential applications.Nitrogen(N)as doping heteroatoms and perylene-3,4,9,10-tetracarboximide(PDINH)as an appr... The defect regulation and p-n heterojunction of composites have gained significant attention due to their potential applications.Nitrogen(N)as doping heteroatoms and perylene-3,4,9,10-tetracarboximide(PDINH)as an appropriate n-type semiconductor were innovatively and reasonably selected to enhance the photocatalytic performance of pristine p-type cuprous oxide(Cu_(2)O).In this study,the defect regula-tion of N doping(1)achieved the small-size effect of Cu_(2)O,(2)optimized the electron features,and(3)improved the kinetics of reactive oxygen species.The p-n heterojunction with PDINH was developed to sharply improve the light utilization of Cu_(2)O,from the UV region to the near-infrared region.As expected,the optimized Cu_(2)N_(x)O_(1–x)/PDINH(x=0.02)exhibited excellent long-term photocatalytic antibacterial ac-tivities,with antibacterial rates exceeding 91%against Staphylococcus aureus and Pseudomonas aeruginosa.Defect regulation and p-n heterojunction of Cu_(2)O-based composites thus provide a great deal of potential for future advancements in photocatalysis. 展开更多
关键词 N doping O vacancy PHOTOCATALYTIC ANTIBACTERIAL DFT calculation
原文传递
High temperature oxidation behavior of TiNbMoAlSi refractory high entropy alloy developed by electron beam additive manufacturing 被引量:2
3
作者 Zhe Li Liang Wang +9 位作者 Yong Yang Chen Liu Baoxian Su Qingda Zhang Zhiwen Li Jiaqi Huang Binbin Wang Liangshun Luo Ruirun Chen Yanqing Su 《Journal of Materials Science & Technology》 2025年第12期131-146,共16页
Up-and-coming high-temperature materials,refractory high entropy alloys,are suffering from lower oxidation resistance,restricting their applications in the aerospace field.In this study,two novel treatments of Al-depo... Up-and-coming high-temperature materials,refractory high entropy alloys,are suffering from lower oxidation resistance,restricting their applications in the aerospace field.In this study,two novel treatments of Al-deposited and remelted were developed to refine the microstructure and enhance the oxidation resistance of refractory high entropy alloy using electron beam freeform fabrication(EBF3).Finer and short-range ordering structures were observed in the remelted sample,whereas the Al-deposited sample showcased the formation of silicide and intermetallic phases.High-temperature cyclic and isothermal oxidation tests at 1000℃ were carried out.The total weight gain after 60 h of cyclic oxidation decreased by 17.49%and 30.46%for the remelted and deposited samples,respectively,compared to the as-cast state.Oxidation kinetics reveal an evident lower mass gain and oxidation rate in the treated samples.A multilayer oxide consisting of TiO_(2)+Al_(2)O_(3)+SiO_(2)+AlNbO_(4) was studied for its excellent oxidation resistance.The oxidation behavior of rutile,corundum and other oxides was analyzed using first principles calculations and chemical defect analysis.Overall,this research,which introduces novel treatments,offers promising insights for enhancing the inherent oxidation resistance of refractory high entropy alloys. 展开更多
关键词 Refractory high entropy alloy OXIDATION Electron beam freeform fabrication Multilayer oxide First principles calculations
原文传递
Interfacial Pt-N coordination for promoting oxygen reduction reaction 被引量:1
4
作者 Jialin Cai Yizhe Chen +5 位作者 Ruiwen Zhang Cheng Yuan Zeyu Jin Yongting Chen Shiming Zhang Jiujun Zhang 《Chinese Chemical Letters》 2025年第2期481-485,共5页
Nitrogen-doping of carbon support(N-C)for platinum(Pt)nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction(ORR)in proton exchange... Nitrogen-doping of carbon support(N-C)for platinum(Pt)nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells.For fundamental understanding,clearly identifying the metalsupport effect on enhancement mechanisms of ORR electrocatalysis is definitely needed.In this work,the impact of Pt-support interaction via interfacial Pt-N coordination on electrocatalytic ORR activity and stability in Pt/N-C catalyst is deeply studied through structural/compositional characterizations,electrochemical measurements and theoretical DFT-calculations/AIMD-simulations.The resulting Pt/N-C catalyst exhibits a superior electrocatalytic performance compared to the commercial Pt/C catalyst in both half-cell and H_(2)-O_(2)fuel cell.Experimental and theoretical results reveal that the interfacial Pt-N coordination enables electron transfer from N-C support to Pt nanoparticles,which can weaken the adsorption strength of oxygen intermediates on Pt surface to improve ORR activity and induce the strong Pt-support interaction to enhance electrochemical stability. 展开更多
关键词 Oxygen reduction reaction N-doped carbon PLATINUM Pt-N Theoretical calculations
原文传递
Evading efficiency-voltage trade-off in magnesium-air batteries through solute atoms and second phases synergy 被引量:1
5
作者 Hongxing Liang Liang Wu +2 位作者 Chenchen Zhao Chuantian Zhai Wenbo Du 《Journal of Magnesium and Alloys》 2025年第2期719-730,共12页
The quest for high-energy-density magnesium-air batteries is hindered by the efficiency-voltage trade-off,ultimately leading to an unsatisfactory energy density.Here,we effectively mitigate the inherent efficiency-vol... The quest for high-energy-density magnesium-air batteries is hindered by the efficiency-voltage trade-off,ultimately leading to an unsatisfactory energy density.Here,we effectively mitigate the inherent efficiency-voltage trade-off by introducing a novel anode material,specifically,Mg-0.5Sn-0.5In-0.5Ga.This anode demonstrates exceptional anodic efficiency,achieving 60.5±2.5%at 1 mA cm^(-2),65.3±2.7%at 10 mA cm^(-2),and 71.4±1.2%at 20 mA cm^(-2).Furthermore,the discharge voltage is significantly enhanced,reaching 1.76±0.01 V at 1 mA cm^(-2),1.44±0.02 V at 10 mA cm^(-2),and 1.21±0.08 V at 20 mA cm^(-2).Consequently,our newly developed anode exhibits a remarkable energy density of 2312±98 W h kg^(-1),placing it among the top-performing magnesium anodes documented in the literature.Density functional theory calculations and experimental investigations have unveiled that the exceptional performance can be attributed to the inhibition of water reduction,facilitated by the hybridization between solute atoms and neighboring Mg atoms.Furthermore,the activation of the second phase,introducing additional galvanic couples,significantly contributes to this performance.This study presents valuable insights that can guide the design of novel anodes,contributing to the advancement of high-performance magnesium-air batteries. 展开更多
关键词 Magnesium anode Corrosion Discharge mechanism Theoretical calculation
在线阅读 下载PDF
Sensitivity analysis of the lithospheric magnetic field at satellite altitude:the effects of the inducing field and the shape of the magnetic lithosphere 被引量:1
6
作者 JinSong Du YuKun Li +5 位作者 HouPu Li ChangQing Yuan KangAn Zhao JiangSong Gui Pan Zhang ShaoFeng Bian 《Earth and Planetary Physics》 2025年第3期642-652,共11页
As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal vari... As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal variations in the lithosphere.Traditional approaches either do not consider the non-axial dipolar terms of the inducing field and its radial variation or do so by means of complicated formulae.Moreover,existing methods treat the magnetic lithosphere either as an infinitesimally thin layer or as a radially uniform spherical shell of constant thickness.Here,we present alternative forward formulae that account for an arbitrarily high maximum degree of the inducing field and for a magnetic lithosphere of variable thickness.Our simulations based on these formulae suggest that the satellite magnetic anomaly field is sensitive to the non-axial dipolar terms of the inducing field but not to its radial variation.Therefore,in forward and inverse calculations of satellite magnetic anomaly data,the non-axial dipolar terms of the inducing field should not be ignored.Furthermore,our results show that the satellite magnetic anomaly field is sensitive to variability in the lateral thickness of the magnetized shell.In particular,we show that for a given vertically integrated susceptibility distribution,underestimating the thickness of the magnetic layer overestimates the induced magnetic field.This discovery bridges the greatest part of the alleged gap between the susceptibility values measured from rock samples and the susceptibility values required to match the observed magnetic field signal.We expect the formulae and conclusions of this study to be a valuable tool for the quantitative interpretation of the Earth's global lithospheric magnetic field,through an inverse or forward modelling approach. 展开更多
关键词 lithospheric magnetic field forward calculation spherical harmonic analysis sensitivity analysis satellite magnetism
在线阅读 下载PDF
NiMo-based alloy and its sulfides for energy-saving hydrogen production via sulfion oxidation assisted alkaline seawater splitting 被引量:1
7
作者 Miaosen Yang Junyang Ding +3 位作者 Zhiwei Wang Jingwen Zhang Zimo Peng Xijun Liu 《Chinese Chemical Letters》 2025年第9期595-601,共7页
Establishing an energy-saving and affordable hydrogen production route from infinite seawater presents a promising strategy for achieving carbon neutrality and low-carbon development.Compared with the kinetically slug... Establishing an energy-saving and affordable hydrogen production route from infinite seawater presents a promising strategy for achieving carbon neutrality and low-carbon development.Compared with the kinetically sluggish oxygen evolution reaction(OER),the thermodynamically advantageous sulfion oxidation reaction(SOR)enables the S^(2-)pollutants recovery while reducing the energy input of water electrolysis.Here,a nanoporous NiMo alloy ligament(np-NiMo)with AlNi_(3)/Al_(5)Mo heterostructure was prepared for hydrogen evolution reaction(HER,-0.134V versus reversible hydrogen electrode(vs.RHE)at 50mA/cm^(2)),which needs an Al_(89)Ni_(10)Mo_(1)as a precursor and dealloying operation.Further,the np-NiMo alloy was thermal-treated with S powder to generate Mo-doped NiS_(2)(np-NiMo-S)for OER(1.544V vs.RHE at 50mA/cm^(2))and SOR(0.364 V vs.RHE at 50mA/cm^(2)),while still maintaining the nanostructuring advantages.Moreover,for a two-electrode electrolyzer system with np-NiMo cathode(1M KOH+seawater)coupling np-NiMo-S anode(1mol/L KOH+seawater+1 mol/L Na_(2)S),a remarkably ultra-low cell potential of 0.532 V is acquired at 50mA/cm^(2),which is about 1.015 V below that of normal alkaline seawater splitting.The theory calculations confirmed that the AlNi_(3)/Al_(5)Mo heterostructure within np-NiMo promotes H_(2)O dissociation for excellent HER,while the Mo-dopant of np-NiMo-S lowers energy barriers for the rate-determining step from^(*)S_(4)to^(*)S_(8).This work develops two kinds of NiMo alloy with tremendous prominence for achieving energy-efficient hydrogen production from alkaline seawater and sulfur recycling from sulfion-rich sewage. 展开更多
关键词 NiMo alloy Alkaline seawater electrolysis Hydrogen production Sulfion oxidation reaction Theoretical calculation
原文传递
In situ constructing lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x) as bifunctional electrocatalyst for high-current-density water splitting 被引量:1
8
作者 Yue Deng Jin Wang +6 位作者 Shao-Fei Zhang Zhi-Jia Zhang Jin-Feng Sun Tian-Tian Li Jian-Li Kang Hao Liu Shi Bai 《Rare Metals》 2025年第2期1053-1066,共14页
The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-... The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x),in situ grown on nickel foam(NF),holds great promise as a high-efficient bifunctional electrocatalyst(named R-CoFe/Ce/NF)for water splitting.Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization.By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_(2−x) heterostructure interfaces,the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution(η_(10)=227 mV;η_(500)=450 mV)and hydrogen evolution(η_(10)=35 mV;η_(408)=560 mV)reactions with high normalized electrochemical active surface areas,respectively.Additionally,the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm^(−2) only at 1.75 V;the decline of activity is satisfactory after 100-h durability test at 300 mA·cm^(−2).Density functional theory also demonstrates that the electron can transfer from CeO_(2−x) by virtue of O atom to CoFeOOH at CoFeOOH/CeO_(2−x) heterointerfaces and enhancing the adsorption of reactant,thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting. 展开更多
关键词 Lamellar nanoporous structure Electronic structure regulation High current density Theoretical calculation Overall water splitting
原文传递
美国《保健物理》(Health Physics)杂志英文摘要
9
《辐射防护》 北大核心 2025年第6期655-658,共4页
INTERNAL DOSE RESEARCH PAPERS INTDOSKIT:An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties Bastian Breustedt 1,Niranjan Chavan 2,Thomas Makumbi 2(1.Karlsruhe Institute of Technology,Instit... INTERNAL DOSE RESEARCH PAPERS INTDOSKIT:An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties Bastian Breustedt 1,Niranjan Chavan 2,Thomas Makumbi 2(1.Karlsruhe Institute of Technology,Institute of Biomedical Engineering(IBT),Fritz-Haber-Weg 1,D-76131 Karlsruhe,Germany;2.Karlsruhe Institute of Technology,Institute for Thermal Energy Technology and Safety(ITES),Hermann-von-Helmholtz-Platz 1,76344 EggensteinLeopoldshafen,Germany)Abstract:An R-code,which allows the calculation of the time dependent activity distribution based on ICRP reference models,the number of decays in a commitment period,and the dose coefficients for tissues and organs of the human body,has been developed.R Language was chosen due to its powerful mathematical and statistical modeling features,as well as its graphical capabilities. 展开更多
关键词 CALCULATION internal dose dose coefficients internal dose research papers calculation dose coefficients calculation ti UNCERTAINTIES R code
暂未订购
Numerical Simulation of Microstructure Refinement of Al-Cu-Mg-Ag Alloy During Solidification
10
作者 ZHU Shiqing ZHANG Hong CHEN Linghao 《材料科学与工程学报》 北大核心 2025年第4期513-519,524,共8页
Al-Cu-Mg-Ag alloys have become a research hotspot because of its good heat resistance.Its excellent mechanical properties are inseparable from the regulation of the structure by researchers.The method of material stru... Al-Cu-Mg-Ag alloys have become a research hotspot because of its good heat resistance.Its excellent mechanical properties are inseparable from the regulation of the structure by researchers.The method of material structure simulation has become more and more perfect.This study employs numerical simulation to investigate the microstructure evolution of Al-Cu-Mg-Ag alloys during solidification with the aim of controlling its structure.The size distribution of Ti-containing particles in an Al-Ti-B master alloy was characterized via microstructure observation,serving as a basis for optimizing the nucleation density parameters for particles of varying radii in the phase field model.The addition of refiner inhibited the growth of dendrites and no longer produced coarse dendrites.With the increase of refiner,the grains gradually tended to form cellular morphology.The refined grains were about 100μm in size.Experimental validation of the simulated as-cast grain morphology was conducted.The samples were observed by metallographic microscope and scanning electron microscope.The addition of refiner had a significant effect on the refinement of the alloy,and the average grain size after refinement was also about 100μm.At the same time,the XRD phase identification of the alloy was carried out.The observation of the microstructure morphology under the scanning electron microscope showed that the precipitated phase was mainly concentrated on the grain boundary.The Al_(2)Cu accounted for about 5%,and the matrix phase FCC accounted for about 95%,which also corresponded well with the simulation results. 展开更多
关键词 Al-Cu-Mg-Ag alloy Phase field simulation Dendrite refinement Phase diagram calculation
在线阅读 下载PDF
Electrocatalytic Nitric Oxide Reduction to Yield Ammonia over Fe_(3)C Nanocrystals
11
作者 Sen Lin Lang Zhang +4 位作者 Tong Hou Jun-Yang Ding Zi-Mo Peng Yi-Fan Liu Xi-Jun Liu 《电化学(中英文)》 北大核心 2025年第4期1-11,共11页
Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atm... Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atmospheric pollutant NO but also produces valuable ammonia(NH_(3)).Hence,through the synthesis and modification of Fe_(3)C nanocrystal cata-lysts,the as-obtained optimal sample of Fe_(3)C/C-900 was adopted as the NORR catalyst at ambient conditions.As a result,the Fe_(3)C/C-900 catalyst showed an NH_(3)Faraday efficiency of 76.5%and an NH_(3)yield rate of 177.5μmol·h^(-1)·cm^(-2)at the working potentials of-0.8 and-1.2 V versus reversible hydrogen electrode(vs.RHE),respectively.And it delivered a stable NORR activity during the electrolysis.Moreover,we attribute the high NORR properties of Fe_(3)C/C-900 to two aspects:one is the enhanced intrinsic activity of Fe_(3)C nanocrystals,including the lowering of the energy barrier of rate-limiting step(*NOH→*N)and the inhibition of hydrogen evolution;on the other hand,the favorable dispersion of active components,the effective adsorption of gaseous NO,and the release of liquid NH_(3)products facilitated by the porous carbon substrate. 展开更多
关键词 Nitric oxide reduction NH3 synthesis Fe_(3)C nanocrystal ELECTROLYSIS Theoretical calculation
在线阅读 下载PDF
Photocatalytic oxidation of high concentration NO over SnS_(2)/g-C_(3)N_(4): A mechanistic study
12
作者 WANG Haocun ZHANG Qixin +2 位作者 YANG Yifan BIAN Junjie LI Chunhu 《燃料化学学报(中英文)》 北大核心 2025年第3期323-335,共13页
This study aims to enhance the photocatalytic performance of 2D/2D heterojunctions for NO removal from marine vessel effluents.SnS_(2)/g-C_(3)N_(4) composites were successfully constructed via a facile solvothermal me... This study aims to enhance the photocatalytic performance of 2D/2D heterojunctions for NO removal from marine vessel effluents.SnS_(2)/g-C_(3)N_(4) composites were successfully constructed via a facile solvothermal method,demonstrating a significant improvement in photocatalytic NO removal under visible light irradiation.For high-flux simulated flue gas,the composite with 10%SnS_(2)(denoted as SNCN-10)showed exceptional NO removal efficiency,reaching up to 66.8%,along with excellent reusability over five consecutive cycles.Detailed band structure and density of states(DOS)calculations confirmed the formation of a characteristic heterojunction.Spin-trapping ESR spectroscopy identified·O_(2)^(-)−as the key reactive species driving NO oxidation.Additionally,in situ DRIFT spectroscopy revealed that SNCN-10 facilitated the conversion of NO to nitrate through intermediate species,including bridging nitrite and cis-nitrite(N_(2)O_(2)^(2-)).Kinetic studies further indicated that NO oxidation followed the Langmuir-Hinshelwood(L-H)mechanism.Based on density functional theory(DFT)calculations of free energy changes,a comprehensive reaction pathway for NO oxidation was proposed.These findings provide valuable insights for the development of efficient photocatalytic strategies for NO removal. 展开更多
关键词 polymeric g-C_(3)N_(4) charge separation PHOTOCATALYSIS NO removal DFT calculations
在线阅读 下载PDF
Syntheses,crystal structures,and characterizations of two cadmium(Ⅱ)coordination polymers
13
作者 LI Xiumei LI Linlin +1 位作者 LIU Bo PAN Yaru 《无机化学学报》 北大核心 2025年第3期613-623,共11页
Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfull... Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2. 展开更多
关键词 coordination polymer cadmium(Ⅱ)complex crystal structure quantum⁃chemical calculations
在线阅读 下载PDF
A Pillar[5]arene-Based π-Conjugated Dye Used for Fluorescence Sensing of L-Arginine
14
作者 Ling Xiaopeng Tao Shaoping +4 位作者 Lin Qi Shi Bingbing Yao Hong Wei Taibao Chen Jinfa 《有机化学》 北大核心 2025年第7期2480-2485,共6页
In the past decade,people have conducted extensive research on the synthesis and application properties of various functionalized pillararenes.Pillararenes show good application prospects in the field of sensors due t... In the past decade,people have conducted extensive research on the synthesis and application properties of various functionalized pillararenes.Pillararenes show good application prospects in the field of sensors due to the rich host-vip recognition in their rigid electron-rich cavities.However,most reported pillararenes are functionalized by alkoxy modification,which results in poor charge transfer nature and weak fluorescence response.A π-conjugated charge-transfer system P5BN was obtained by introducing electron-donating triarylamine(Ar_(3)N)and electron-deficient triarylborane(Ar_(3)B)into pillar[5]arene skeleton,which significantly improved its luminescence behavior and was further used for fluorescence detection applications.The molecular structure showed that P5BN provided a good macrocyclic cavity to encapsulate amino acids molecules of suitable size.It was found that P5BN,as a fluorescent sensor,showed a highly sensitive and selective response to L-arginine(L-Arg),resulting in a significant enhancement of the fluorescence at 408 nm of P5BN with the lowest detection concentration being 2.21×10^(-8) mol/L.The recognition mechanism was demonstrated through experiments and DFT theoretical calculations. 展开更多
关键词 fluorescent sensor host-vip recognition arene L-ARGININE density functional theory(DFT)calculations
原文传递
Mechanistic understanding of the selective C=C and C=O hydrogenation catalyzed by frustrated Lewis pairs on CeO_(2)(110)from theoretical perspectives
15
作者 MA Hong CHEN Siqing +7 位作者 CHEN Jiamin DING Runlong LIU Shaoli TIAN Xinxin WU Jianbing LI Haitao WANG Yongzhao ZHAO Yongxiang 《燃料化学学报(中英文)》 北大核心 2025年第10期1528-1539,I0013-I0019,共19页
Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Co... Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts. 展开更多
关键词 CeO_(2)(110) frustrated Lewis pairs(FLP) CH_(2)=CH_(2)/CH_(3)CH=O the mechanism of hydrogenation DFT calculation
在线阅读 下载PDF
First-principles Investigation of Heavy Metal Adsorption on C-lignin
16
作者 WANG Juan JIA Leiyu +3 位作者 XU Yao ZHANG Zhenzhen DUAN Ziyu ALBINA Jan-Michael 《Journal of Wuhan University of Technology(Materials Science)》 2025年第6期1790-1794,共5页
We investigated the adsorption mechanisms including physical and chemical adsorption for heavy metals(Cd,Pb,Zn,Co,Cu)on C-lignin using density functional theory(DFT)simulations.Physical adsorption,involving metal atom... We investigated the adsorption mechanisms including physical and chemical adsorption for heavy metals(Cd,Pb,Zn,Co,Cu)on C-lignin using density functional theory(DFT)simulations.Physical adsorption,involving metal atoms near carbon atoms,is found to be endothermic;meanwhile,chemical adsorption,where hydroxyl groups replace metal ions,is exothermic and spontaneous.Pb exhibits the highest physical adsorption potential,while Cu and Co demonstrate the strongest chemical adsorption due to their highly negative adsorption energies.These findings provide valuable insights into the design of eco-friendly nano lignocellulosic composite films for effective heavy metal removal from contaminated water sources.Key words:C-lignin;adsorption;We investigated the adsorption mechanisms including physical and chemical adsorption for heavy metals(Cd,Pb,Zn,Co,Cu)on C-lignin using density functional theory(DFT)simulations.Physical adsorption,involving metal atoms near carbon atoms,is found to be endothermic;meanwhile,chemical adsorption,where hydroxyl groups replace metal ions,is exothermic and spontaneous.Pb exhibits the highest physical adsorption potential,while Cu and Co demonstrate the strongest chemical adsorption due to their highly negative adsorption energies.These findings provide valuable insights into the design of eco-friendly nano lignocellulosic composite films for effective heavy metal removal from contaminated water sources. 展开更多
关键词 C-lignin ADSORPTION heavy metal ions first principles calculations metal ions first principles calculations
原文传递
Asymmetric Nozaki-Hiyama-Kishi(NHK)-type reaction of isatins with aromatic iodides by cobalt catalysis
17
作者 Jieshuai Xiao Yuan Zheng +2 位作者 Yue Zhao Zhuangzhi Shi Minyan Wang 《Chinese Chemical Letters》 2025年第5期243-251,共9页
The asymmetric addition of aromatic organometallic compounds to the carbonyl group(C-3)of isatins,catalyzed by transition metals,has emerged as a remarkably efficient method for the synthesis of chiral 3-hydroxyoxindo... The asymmetric addition of aromatic organometallic compounds to the carbonyl group(C-3)of isatins,catalyzed by transition metals,has emerged as a remarkably efficient method for the synthesis of chiral 3-hydroxyoxindoles.Here,an exceptionally enantioselective approach was developed for the first time to achieve a catalytic NHK reaction of isatins with aromatic halides(both aryl and heteroaryl).Utilizing chiral cobalt complexes as catalysts,and the presence of a diboron reagent B_(2)nep_(2)as both a reducing agent and determinant in enantiocontrol,has resulted in the triumphantly achieved synthesis of enantioenriched products.Compared to reported strategies,this approach exhibits remarkable compatibility with substrates bearing sensitive functional groups,such as halides and borate esters,while also eliminating the need for organometallic reagents as required in previous strategies.Through experimental investigations,the presence of aryl-cobalt species during the addition process was confirmed,rather than in-situ generation of an arylboron reagent.Furthermore,the successful attainment of the R absolute configuration through aryl addition was demonstrated. 展开更多
关键词 ENANTIOSELECTIVITY ISATIN Cobalt Addition DFT calculations
原文传递
Research and Application Progress of Intraocular Lens Power Calculation Formulas in the Era of Refractive Cataract Surgery
18
作者 Bowei Liang Jinhua Wang +1 位作者 Yao Chen Pan Liu 《Journal of Biosciences and Medicines》 2025年第2期348-356,共9页
As cataract surgery progresses from “restoration of sight” to “refractive correction”, precise prediction of intraocular lens (IOL) power is critical for enhancing postoperative visual quality in patients. IOL pow... As cataract surgery progresses from “restoration of sight” to “refractive correction”, precise prediction of intraocular lens (IOL) power is critical for enhancing postoperative visual quality in patients. IOL power calculation methods have evolved and innovated throughout time, from early theoretical and regression formulas to nonlinear formulas for estimating effective lens position (ELP), multivariable formulas, and innovative formulas that use optical principles and AI-based online formulas. This paper thoroughly discusses the development and iteration of traditional IOL calculation formulas, the emergence of new IOL calculation formulas, and the selection of IOL calculation formulas for different patients in the era of refractive cataract surgery, serving as a reference for “personalized” IOL implantation in clinical practice. 展开更多
关键词 Cataract Surgery Intraocular Lens Power Calculation Formula Refractive Cataract Lens Power Calculation
在线阅读 下载PDF
First-principles analysis of effects of cerium doping on electrochemical corrosion behaviors of steel
19
作者 Xiangjun Liu Zhongqiao Ma +4 位作者 Changqiao Yang Xiang Li Jichun Yang Huiping Ren Hui Ma 《Journal of Rare Earths》 2025年第8期1758-1768,I0006,共12页
Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the infl... Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the influencing mechanism Ce doping on the corrosion resistance of Fe-Ce system in the Cl medium environment was analyzed.The results show that Ce doping on the first surface and subsurface inhibits the ionization of Fe atoms and greatly promotes the repassivation process of Fe matrix.Ce doping on the first layer is conducive to preventing the detachment of surface Fe atoms from Fe matrix and delaying the occurrence of corrosion.Ce atoms in the subsurface effectively increase the difficulty of Fe atoms detaching from the matrix at high Cl concentrations.When O diffusion is the controlling link of oxygen absorption reaction,Ce doping has no effects on the reaction rate of cathodic oxygen absorption.Ce doping enhances the electrochemical stability of Fe(100)1and reduces the anodic dissolution rate of Fe matrix,thereby improving its corrosion resistance. 展开更多
关键词 First-principles calculations STEEL Corrosion modeling Rare earths CHLORINE
原文传递
Machine learning accelerated catalysts design for CO reduction:An interpretability and transferability analysis
20
作者 Yuhang Wang Yaqin Zhang +4 位作者 Ninggui Ma Jun Zhao Yu Xiong Shuang Luo Jun Fan 《Journal of Materials Science & Technology》 2025年第10期14-23,共10页
Developing machine learning frameworks with predictive power,interpretability,and transferability is crucial,yet it faces challenges in the field of electrocatalysis.To achieve this,we employed rigorous feature engine... Developing machine learning frameworks with predictive power,interpretability,and transferability is crucial,yet it faces challenges in the field of electrocatalysis.To achieve this,we employed rigorous feature engineering to establish a finely tuned gradient boosting regressor(GBR)model,which adeptly captures the physical complexity from feature space to target variables.We demonstrated that environmental electron effects and atomic number significantly govern the success of the mapping process via global and local explanations.The finely tuned GBR model exhibits exceptional robustness in predicting CO adsorption energies(R_(ave)^(2)=0.937,RMSE=0.153 eV).Moreover,the model demonstrated remarkable transfer learning ability,showing excellent predictive power for OH,NO,and N_(2) adsorption.Importantly,the GBR model exhibits exceptional predictive capability across an extensive search space,thereby demonstrating profound adaptability and versatility.Our research framework significantly enhances the interpretability and transferability of machine learning in electrocatalysis,offering vital insights for further advancements. 展开更多
关键词 Machine learning First-principles calculation INTERPRETABILITY Transferability CO reduction
原文传递
上一页 1 2 205 下一页 到第
使用帮助 返回顶部