排序方式: 共有122条查询结果,搜索用时 15 毫秒
1.
Abdolmohammadi Shahrzad Hossaini Zinatossadat Poor Heravi Mohammad Reza 《Molecular diversity》2022,26(4):1983-1993
Molecular Diversity - A new series of azo chromene dyes were synthesized via a facile cyclocondensation reaction of (E)-1,2-diphenyl-1-diazene and 4-aminocoumarin with 1:2 molar ratio catalyzed by... 相似文献
2.
M. H. Sadr S. Astaraki S. Salehi 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(11):795-807
In developing a neural network technique for a finite element model updating, researchers have been shown that the number
of training samples and their quality, significantly affect the accuracy of the NN predication. In this study, based on the
genetic algorithm (GA) method, we reduce the number of analyses required to develop the training pairs and reduce the amount
of time for training the NN. In the other words, a uniform distribution of design points inside the design space will be obtained
by means of this approach. To validate the efficiency of GA sample selection, random generation (RG) method is used for comparison.
Two comparisons are made based on a numerical and experimental example. One is updated from 10 degrees of freedom lumped parameters
system and the other is updated from a free–free beam using test data. The results indicate that the GA sample selection can
reduce the number of training samples without affecting the accuracy of the NN predication. In our present study, also, the
advantages of using frequency response function (FRF) data as input to the NN are kept and the drawback of having too many
frequency points is overcome by the application of principal component analyses (PCA). 相似文献
3.
Propoxur (Baygon®) is an insecticide with a broad spectrum of activity and a very low order of mammalian toxicity. Radiosynthesis of propoxur was performed by the reaction of acetyl-114C chloride and sodium azide to produce methyl isocyanate which then reacted with o-isopropoxyphenol at 100°C. A two compartment reaction tube with a break seal was utilized. Chromatographic procedures for isolating the N-methylcarbamates from their reaction mixtures are reported. Acetyl-1–14C chloride was prepared from thionyl chloride and sodium acetate-1–14C. Grignard reaction between methyl iodide and carbon –14 dioxide yielded acetic acid –14C which was neutralized by sodium hydroxide solution to give sodium acetate 1-14C. 相似文献
4.
Issa Yavari Zinatossadat Hossaini Maryam Sabbaghan 《Monatshefte für Chemie / Chemical Monthly》2007,8(4):107-110
Protonation of the highly reactive 1:1 intermediates produced in the reaction between alkyl(aryl) isocyanides and dibenzoylacetylene
by isatin, leads to vinylnitrilium cations, which undergo carbon-centered Michael-type addition with the conjugate base of the NH-acid to produce highly functionalized 1-(3-furyl)-1H-indole-2,3-diones. A dynamic NMR effect is observed in the 1H NMR spectra of these compounds as a result of restricted rotation around the single bond linking the indole moiety and the
furan system. The free-energy of activation (ΔG
#) for this process is 69–71 ± 2 kJ mol−1. 相似文献
5.
Isoquinoline reacts with ethyl bromopyruvate in the presence of dialkyl acetylenedicarboxylates or diaryloylacetylenes to produce dialkyl 1-(2-ethoxy-2-oxoacetyl)pyrrolo[2,1-a]isoquinoline-2,3-dicarboxylates or ethyl 2-[2,3-diaryloylpyrrolo[2,1-a]isoquinoline-1-yl]-2-oxoacetates in good yields. 相似文献
6.
The vapor pressures and osmotic coefficients of solutions of (R4N)2[MoS4] (R = ethyl, n-propyl and n-butyl) in acetone have been measured by head space-gas chromatography (HS-GC). Experimental data for the osmotic coefficients have been expressed by three thermodynamic models including the ionic interaction model of Pitzer, the electrolyte non-random two liquid (e-NRTL) model and the non-random factor (NRF) model. The ability of the models to fit the osmotic coefficient was compared on the basis of the standard deviation of the fittings. The results show that the considered models provide reliable results, but the Pitzer's model gives better results than the NRTL and the NRF methods, especially in the dilute region. 相似文献
7.
8.
Mahboubeh Ghasemian Dazmiri Heshmatollah Alinezhad Zinatossadat Hossaini Ahmad R. Bekhradnia 《应用有机金属化学》2020,34(9):e5731
In this research, Fe3O4/ZnO magnetic core-shell nanoparticles (Fe3O4/ZnO MCNPs) were synthesized through a green method using Petasites hybridus rhizome water extract as a reducing and stabilizing agent. The morphology and size of the Fe3O4/ZnO MCNPs was identified by X-ray diffraction, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic activity of the Fe3O4/ZnO MCNPs was evaluated in the efficient and green preparation of pyran derivatives in excellent yield using three-component reactions of dimedone, aldehydes, and malononitrile in ethanol at room temperature. The ability of some synthesized compounds to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical was measured and the results proved this observation. Moreover, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The results for the disk diffusion test showed that compounds ( 4c, 4d, 4f and 4g ) prevented bacterial growth. 相似文献
9.
10.
Summary The reaction between alkyl isocyanides and isopropylidene Meldrum’s acid in the presence of 1,2-ethanediol leads to N
1-(alkyl)-2-(5,7-dioxo-1,4-dioxepane-6-yl)-2-methylpropanamides. 1,3-Propanediol or 1,4-butanediol produce hydroxyalkyl 1-(tert-butyl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxylates. When the reaction was performed in the presence of catechol, bis(2-hydroxyphenyl)
2-[2-(tert-butylamino)-1,1-dimethyl-2-oxoethyl]malonate was obtained. 2-Aminophenols react with alkyl isocyanides in the presence of
isopropylidene Meldrum’s acid to produce 1-alkyl-N
3-(2-hydroxyaryl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxamides in good yields. 相似文献