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921.
HoU Baoxiu MA Linlin ZANG Xiaohuan SHANG Ningzhao SONG Jianmin ZHAO Xiaoxian WANG Chun QI Jian WANG Jiangyan YU Ranbo 《高等学校化学研究》2021,37(2):265-273
An easy and delicate approach using cheap carbon source as conductive materials to construct 3D sequential porous structural Na3V2(PO4)3/C(NVP/C)with high performance for cathode materials of sodium ion battery is highly desired.In this paper,the NVP/C with 3D sequential porous structure is constructed by a delicate approach named as“cooking porridge”including evaporation and calcination stages.Especially,during evaporation,the viscosity of NVP/C precursor is optimized by controlling the adding quantity of citric acid,thus leading to a 3D sequential porous structure with a high specific surface area.Furthermore,the NVP/C with a 3D sequential porous structure enables the electrolyte to interior easily,providing more active sites for redox reaction and shortening the diffusion path of electron and sodium ion.Therefore,benefited from its unique structure,as cathode material of sodium ion batteries,the 3D sequential porous structural NVP/C exhibits high specific capacities(115.7,88.9 and 74.4 mA·h/g at current rates of 1,20 and 50 C,respectively)and excellent cycling stability(107.5 and 80.4 mA·h/g are remained at a current density of 1 C after 500 cycles and at a current density of 20 C after 2200 cycles,respectively). 相似文献
922.
923.
YANG Liming GUO Lixin YU Hao WANG Guan SUN Jiangman ZHANG Pengfei GU Xinggui TANG Ben Zhong 《高等学校化学研究》2021,37(1):129-136
The development of fluorescent nanocrystals based on organic small molecules is of great importance in bioimaging due to the merits of easy modification,high brightness and excellent photostability,however suffering from the emission-detrimental aggregation-caused quenching(ACQ)effect.Herein,we successfully designed and synthesized an AIE-active di(N,N-dimethylaniline)-dibenzofulvene(named as NFTPE),which exhibits the crystallization-induced emission enhancement(CIEE)effect.Interestingly,two types of yellow-and orange-emissive crystals for NFTPE were obtained,exhibiting aggregation microenvironment-dependent emission tuning in the solid state.Single-crystal analysis and density functional theory(DFT)calculations reveal that different aggregation microenvironments result in the distinct molecular conformation for various emission.Excitingly,the crystallization of NFTPE in an aqueous solution under the assistance of amphiphilic PEG polymer matrices could be monitored in situ by the fluorescence changes,facilitating the preparation of NFTPE nanocrystals(NFTPE-NCs)by adjusting the aggregation microenvironment.The obtained NFTPE-NCs exhibit the superior performance in cell imaging in respect to high brightness,photostability,and biocompatibility,thus demonstrating the potential in bioimaging applications. 相似文献
924.
925.
The reactive intermediate cyclopropylidene, generated quickly by the reactions of dihalocyclopropanes with lithium or magnesium under ultrasonic irradiation, can be trapped by olefins and the corresponding spriopentane derivatives are obtained, Based on the identification of the intermediate and the products of the reaction, a mechanism is proposed that the radical intermediate should be generated at first via a single electron transfer process, sequentially it gains another electron from the metals to form the carbenoid intermediate which then leads to the main products by insertion, addition or rearrangement. On the other hand, it can also abstract the hydrogen atom from the solvent to form the corresponding monohalide which then converts into the cyclopropane derivatives. Discussions on and verifications for the reaction mechanism are given in this paper. 相似文献
926.
The molecular weight distribution function (MWD) of AB, B type condensation polymers obtained by adding AB monomers in batches has been derived by statisticaland kinetic methods. Calculations show that the MWD of condensation polymers obtained by this process is much narrower than the Flory distribution and agrees with the Monte Carlo results very well. 相似文献
927.
This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed 相似文献
928.
YU Biao HUI Yong-ZhengState Key Laboratory of Bio-organic Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai China 《中国化学》1996,14(2):171-179
Three types of single-chain hydrocarbon fluorocarbon hybrid bolaamphiphiles were synthesized.They readily formed different kinds of organized supramolecular assemblies,including vesicles,tapes,and micellar fibers,in aqueous solution.The aggregates morphology was characterized by transmission electron microscopy (TEM) after negative staining.The superstructures of these aggregates seemed to be determined by the geometry and the head group's properties of the corresponding amphiphiles. 相似文献
929.
930.