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641.
Alaa A. Hassan Yusria R. Ibrahim Essmat M. El‐Sheref Alan B. Brown 《Journal of heterocyclic chemistry》2012,49(5):1054-1058
(Z)‐Methyl 2‐[3‐(arylideneamino)‐2‐(arylidenehydrazono)‐4‐oxothiazolidin‐5‐ylidene]acetate prepared during the reaction between thiocarbonohydrazides and dimethyl acetylene dicarboxylate. Rational for there conversations involving the nucleophilic addition on C/C triple bond of dimethyl acetylenedicarboxylate are presented. 相似文献
642.
Alaa A. Hassan Fathy F. Abdel-Latif Ahmed M. Nour El-Din Sara M. Mostafa Martin Nieger Stefan Bräse 《Tetrahedron》2012,68(40):8487-8492
Conjugated alkenylidene-hydrazinecarbothioamides react in high yield with 2,3-diphenylcyclopropenone to give a series of (E)-2,5-disubstituted 1,3,4-thiadiazolyl-2,3-diphenylpropenones. 相似文献
643.
The formation of agglomerates by salt-induced double layer compression of magnetic nanoparticles in the absence and presence of an external magnetic field was investigated experimentally as well as computationally in this study. The structures of the agglomerates were analyzed through scanning electron microscopy and proved to be highly porous and composed of large spaces among the branches of a convoluted network. In the absence of an external magnetic field, the branches of such a network were observed to be oriented in no particular direction. In contrast, when the agglomeration process was allowed to occur in the presence of an external magnetic field, these branches appeared to be oriented predominantly in one direction. A modified Discrete Element Method was applied to simulate the agglomeration process of magnetic nanoparticles both in the absence and presence of an external magnetic field. The simulations show that agglomeration occurred by the formation of random clusters of nanoparticles which then joined to form a network. In the presence of anisotropic magnetic forces, these clusters were rotated to align along the direction of the magnetic field and the final network formed consisted largely of elongated branches of magnetic nanoparticles. 相似文献
644.
A sensitive time- resolved luminescence method for the determination of meloxicam (MX) in methanol and in aqueous solution
is described. The method is based on the luminescence sensitization of europium (Eu3+) by formation of ternary complex with MX in the presence of 1,10- phenanthroline as coligand, Tween-80 as surfactant and
gadolinium ion as a co-luminescence reagent. The signal for Eu- MX-1, 10- phenanthroline is monitored at λex = 360 nm and λem = 620 nm. Optimum conditions for the formation of the complex in aqueous system were 0.01 M TRIS buffer, pH 8.0, 1,10- phenanthroline
(6.0 × 10−6 M) , Gd3+ (7.0 × 10−6 M), Tween-80 (0.28%) and 1.75 mM of Eu3+ which allows the determination of 20–800 ppb of MX with limit of detection (LOD) of 7 ppb. The relative standard deviations
of the method range between 0.1 and 1.1% indicating excellent reproducibility of the method. The proposed method was successfully
applied for the assay of MX in pharmaceutical formulations, plasma and in urine samples. Average recoveries of 99.8 ± 1.1%,
100.2 ± 0.9% and 100.9 ± 1.1% were obtained for MX in tablet, plasma and urine sample respectively. 相似文献
645.
646.
647.
Nemat Nyamoradi Mokhtar Kirane 《Mathematical Methods in the Applied Sciences》2020,43(17):10237-10248
In this paper, we investigate a fractional p-Laplacian system with different critical Sobolev-Hardy exponents. By variational methods and the Mountain-Pass lemma, positive minimizers of the related best Sobolev constants and the existence of positive solutions of the system are found. 相似文献
648.
Huy?Tuan?NguyenEmail author Mokhtar?Kirane Nam?Danh?Hua?Quoc Van?Au?Vo 《Mediterranean Journal of Mathematics》2018,15(1):18
In this paper, we consider the problem of finding the initial distribution for the linear inhomogeneous and nonlinear biparabolic equation. The problem is severely ill-posed in the sense of Hadamard. First, we apply a general filter method to regularize the linear nonhomogeneous problem. Then, we also give a regularized solution and consider the convergence between the regularized solution and the sought solution. Under the a priori assumption on the exact solution belonging to a Gevrey space, we consider a generalized nonlinear problem by using the Fourier truncation method to obtain rigorous convergence estimates in the norms on Hilbert space and Hilbert scale space. 相似文献
649.
Mohamed A. Badawy Sayed A. L. Abdel-Hady Yehia A. Ibrahim Azza M. Kadry 《Journal of heterocyclic chemistry》1985,22(6):1535-1536
The action of hydrazine on 2-mercapto and 2-alkylmercaptoquinazolin-4-ones is reinvestigated. The structure of the isolated products have been revised. 相似文献
650.