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The histidine functionalized graphene quantum dots(His-GQDs)react with ruthenium trichloride to form a stable ruthenium complex. This complex is treated in a N2 atmosphere at 600 ℃ for 1 h to obtain a ruthenium-graphene quantum dot composite (Ru-His-GQD). The results of scanning electron microscopy (SEM)and transmission electron microscopy(TEM)analysis demonstrate that Ru-His-GOD has one three-dimensional structure. The diameter of ruthenium nanoparticles is between 40 and 60 nm. Ru-His-GQD is rich in functional groups and has high oxidase-like activity. Based on Ru-His-GQD catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine(TMB)to produce blue compounds,a photometric method for the determination of phoxim in carrots is established. Phoxim can inhibit the activity of Ru-His-GQD oxidase,resulting in a decrease in the absorbance of the blue compound. When the concentration of phoxim is between 30~240 μg/ L,the absorbance of the oxidation product of TMB at 652 nm decreases linearly with the increase of phoxim concentration. The detection limit of the method reaches 7. 33 μg/L(S/N=3),and the sensitivity is higher than those in literature. It has been successfully applied to the detection of phoxim in carrots. © 2022, Science Press (China). All rights reserved. 相似文献
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We obtained the Cα continuity for weak solutions of a class of ultraparabolic equations with measurable coeffcients of the form
δt u = δx(a(x, y, t)δx u) + b0(x, y, t)δxu + b(x, y, t)δyu, which generalized our recent results on KFP equations. 相似文献
δt u = δx(a(x, y, t)δx u) + b0(x, y, t)δxu + b(x, y, t)δyu, which generalized our recent results on KFP equations. 相似文献
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