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21.
Fayez H. Osman Naglaa M. Abd El-Rahman Fatma A. El-Samahy I. S. Ahmed Farag 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):531-538
3-Acetyl coumarin ( 1 ) reacts with dialkyl phosphites at 100°;C for 8 h to give the phosphonates 2 . Under the same experimental conditions, 1 reacts with trialkyl phosphites to form a mixture of the phosphonates 2 and 3 . The molecular structures of these products were elucidated by x-ray crystallography. 相似文献
22.
Salma A. Al-Tamimi Fatma A. Aly Adibah M. Almutairi 《Journal of Analytical Chemistry》2013,68(4):313-320
Simple and sensitive kinetic spectrophotometric methods were established for the determination of alfuzosin hydrochloride in bulk and in its pharmaceutical preparations using alkaline potassium permanganate as an oxidizing agent. The methods involve determination of alfuzosin HCl by kinetic studies of its oxidation at room temperature for a fixed time of 15 min. The absorbance of the colored manganate ions was measured at 610 nm. Alternatively, the decrease in the absorbance of permanganate upon addition of the studied drug was also measured at 525 nm. The absorbance-concentration plots in both procedures were rectilinear over the range of 2.0–30.0 μg/mL. The different experimental parameters affecting the development were carefully studied and optimized. The determination of alfuzosin HCl by the fixed concentration and initial rate methods is also feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. Both procedures were applied to the determination of alfuzosin HCl in formulations. The results obtained were in good agreement with those obtained using reference methods. 相似文献
23.
N-Aryl-N,N-diphenacylamine dioximes were prepared by the reaction of corresponding arylamines with α-bromoacetophenone oxime in ethanol-water at room temperature. These compounds reacted with aryl isocyanates in acetonitrile to give imidazooxadiazolones 9. The probable mechanism of the reaction is discussed. 相似文献
24.
An environmentally benign, three-component, one-pot integrated chemical process has been developed for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzoxanthene-11-one by nucleophilic addition reaction between aldehyde and β-naphthol followed by Michael addition of dimedone, catalyzed by thiamine hydrochloride in aqueous micellar medium with excellent yield. Simple reaction conditions, no requirement of chromatographic separation, short reaction time, ease of isolation, use of inexpensive, easily recoverable and reusable catalyst makes this protocol very interesting from an economic and environmental perspective. 相似文献
25.
Uğur Oflaz Fatma Yurt Lambrecht Osman Yilmaz Çetin Pekçetin 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):959-964
This study aims to investigate effects of adenine on bacterial translocation (BT) using 99mTc-labeled E. coli in an intestinal obstruction rat model. In the study twenty-one rats were used. The rats were divided into three groups according to different feeding patterns. The control group (CG) was fed with a standard chow diet for 7 days. Group A1 and group A2 were fed with adenine supplemented chow diet for 7 days. At the end of the feeding period, after all groups was submitted intestinal obstruction. 99mTc-E. coli was injected into the rats’ terminal ileum under anesthetic. The rats were sacrificed under aseptic conditions at 24th h after the surgery. The uptake of 99mTc-E. coli was determined in organs such as the liver, mesenteric lymph nodes, spleen and ileum. Group A1 and group A2 results show that the uptake of 99mTc-E. coli decreased in the blood and organs comparing to the CG. As a result, it was observed that adenine reduced the level of BT when compared with CG. The beneficial effect of adenine on BT in intestinal obstruction was observed. However, further studies are needed to more clearly assess how this benefit can be achieved. 相似文献
26.
An inverse coefficient problem for a quasilinear parabolic equation with periodic boundary and integral overdetermination condition 下载免费PDF全文
In this paper, the inverse problem of finding the time‐dependent coefficient of heat capacity together with the solution periodic boundary and integral overdetermination conditions is considered. Under some natural regularity and consistency conditions on the input data, the existence, uniqueness, and continuous dependence upon the data of the solution are shown. Some considerations on the numerical solution for this inverse problem are presented with an example. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
27.
Queiroz Ana Luiza P. Kerins Brian M. Yadav Jayprakash Farag Fatma Faisal Waleed Crowley Mary Ellen Lawrence Simon E. Moynihan Humphrey A. Healy Anne-Marie Vucen Sonja Crean Abina M. 《Cellulose (London, England)》2021,28(14):8971-8985
Cellulose - Microcrystalline cellulose (MCC) is a semi-crystalline material with inherent variable crystallinity due to raw material source and variable manufacturing conditions. MCC crystallinity... 相似文献
28.
Fabrication of a Single Layer and Bilayer Potentiometric Biosensors for Penicillin by Galvanostatic Entrapment of Penicillinase into Polypyrrole Films 总被引:1,自引:0,他引:1 下载免费PDF全文
A single layer and bilayer potentiometric biosensors for the detection of penicillin have been developed. The favourable conditions that were established for the polypyrrole‐penicillinase ((PPy‐P’nase) single layer biosensor were 0.03 M pyrrole, 50 U/mL P’nase, 0.01 M penicillin, applied current density of 0.9 mA/cm2 and a polymerisation time of 40 s. The optimum conditions for the formation of the outer layer of the bilayer were: (a) 0.1 M Py, 19 U/mL P’nase, 0.01 M pen, current density of 0.9 mA/cm2 and a polymerisation time of 40 s. The minimum detectable penicillin concentration with the bilayer potentiometric biosensor was 0.3 µM and the linear concentration range was 7.5–146 µM. The average percentage recovery of penicillin that was found in amoxycillin 500 mg was 113±24 %. The determination of penicillin in milk was fraught with problems of non‐specific binding of penicillin to the milk. 相似文献
29.
Fatma KARA Duygu ADIGÜZEL Ufuk ATMACA Murat ELK Jale NAKTYOK 《Turkish Journal of Chemistry》2020,44(6):1483
A humic substance was obtained from hazelnut husk using an alkali extraction. The chemical and morphological structure of the humic matter was characterized via elemental analysis, Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance, Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), and thermogravimetric-FTIR (TG-FTIR). In addition, thermal analysis measurements TG analysis-differential thermogravimetry/differential scanning calorimetry (TGA-DTG/DSC) were performed under dynamic air conditions to better determine the origin, physical and chemical structure, and decomposition process of the humic matter. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were used to calculate the kinetic parameters of the high-temperature decomposition process. It was observed that the activation energy values were almost constant at certain conversion and temperature intervals. In addition, the structure of the humic substance at different temperatures was also investigated via FTIR analysis. It was found that the obtained humic substance had a very stable structure and decomposed at a high temperature. The stability of the humic matter can be a useful tool in the environmental quality research of soil. 相似文献
30.
The large ring cyclodextrins (with more than 8 glucose units) existence was first described in the 1950s. Because of their hard purification and low yield, these molecules were little studied until recently. Since large ring cyclodextrins have unique structures compared to α-, β- and γ-cyclodextrin, they could offer new opportunities for specific host-guest complex and thus enlarge the area of cyclodextrin applications. This paper gives a literature survey regarding the synthesis, the purification and the applications of cyclodextrins containing more than eight glucose units. 相似文献