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741.
Sayed Zia Mohammadi Daryoush Afzali Zahra Fallahi 《International journal of environmental analytical chemistry》2013,93(8):765-773
In the present study, an environment-friendly sample preparation method termed ionic liquid-based dispersive liquid–liquid microextraction combined with flame atomic absorption spectrometry has been developed for the determination of Pb(II) ion in water samples prior to flame atomic absorption spectrometry determination. In this method, ionic liquid was used as an extraction solvent instead of the organic solvent used in the conventional dispersive liquid–liquid microextraction (DLLME) assay, and there is no need for a chelating agent. Several variables that may affect extraction efficiencies, including pH, the volume of ionic liquid, the type and volume of disperser solvent, salt addition, and the time for centrifugation and extraction were studied and optimised. Under the optimised conditions, the calibration curve exhibited linearity over the range of 20.0–1000.0 μg L?1. The enrichment factor and the limit of detection based on 3Sb/m were 35.0 and 5.9 μg L?1, respectively. Seven replicate determination of a solution containing of 100.0 μg L?1 Pb(II) ions gave a relative standard deviation of ±2.1%. Finally, the feasibility of the proposed method for Pb(II) determination was assessed by the analysis of certi?ed reference material and various water samples and the satisfactory results were obtained. 相似文献
742.
Ali Ramazani Nader Noshiranzadeh Bagher Mohammadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):761-765
Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine (or tributylphosphine) and dialkyl acetylenedicarboxylates by acetylacetone leads to sterically congested phosphorus ylides, which undergo an intermolecular Wittig reaction with ninhydrin and concomitant annulation in CH 2 Cl 2 at room temperature to produce dialkyl 3,3-diacetyl-3 a -hydroxy-8-oxo-2,3,3 a ,8-tetrahydrocyclopenta[ a ]indene-1,2-dicarboxylates in fairly high yields. 相似文献
743.
Farhad Shirini Mohammad Ali Zolfigol Kamal Mohammadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1567-1570
Reaction of alcohols with hexamethyldisilazane in the presence of silica chloride provides efficiently the corresponding trimethylsilyl ethers. This system discriminates absolutely amines and thiols from alcohols. 相似文献
744.
Hassan Kefayati Maryam Fakhriyannejad Ali A. Mohammadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1796-1804
New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) 2 .4H 2 O as an efficient Lewis acid catalyst. 相似文献
745.
Leili Jalili‐Baleh Narges Mohammadi Mehdi Khoobi Leila Ma'mani Alireza Foroumadi Abbas Shafiee 《Helvetica chimica acta》2013,96(8):1601-1609
Various monospiro‐2‐amino‐4H‐pyran derivatives have been synthesized in high yields (via three‐component coupling of ninhydrin or different isatins with malononitrile and 1,3‐dicarbonyl compounds) in the presence of catalytic amount of propane‐1‐sulfonic acid‐modified magnetic hydroxyapatite nanoparticles in H2O. Due to easy magnetic removal of nanocatalyst and applying of H2O as solvent, this protocol enhanced product purity, and promised economic as well as environmental benefits, exemplifying a waste‐free chemistry. More importantly, the catalyst could be easily recycled for more than five times without loss of activity. 相似文献
746.
Ali A. Mohammadi Hamed Rohi Ali Abolhasani Soorki 《Journal of heterocyclic chemistry》2013,50(5):1129-1133
An efficient synthesis of novel 2‐aryl‐3‐(phenylamino)‐2,3‐dihydroquinazolin‐4(1H)‐one derivatives using KAl(SO4)2.12H2O (Alum) as a catalyst from an aldehyde and 2‐amino‐N‐phenylbenzohydrazine in ethanol is described. All synthesized derivatives were screened for anti‐bacterial activity. Some compounds exhibited promising anti‐bacterial activity with reference to standard antibiotics. 相似文献
747.
Homeira Ebrahimzadeh Najmeh Tavassoli Omid Sadeghi Mostafa M. Amini Moein Jamali 《Mikrochimica acta》2011,172(3-4):479-487
A technique for solid-phase extraction utilizing pyridine-functionalized nanoporous silica (MCM-41, MCM-48 and SBA-15) was developed for the determination of gold in different samples using flame atomic absorption spectrometry. The effects of concentration and volume of eluent, pH of the solution, flow rate of extraction, sample volume and of potentially interfering ions on the efficiency of preconcentration and recovery was investigated. The limit of detection is lower than 45 pg mL?1. Under optimal conditions, the accuracy and precision (RSD%) of the method were calculated to be >99.5% and <0.7% for the two MCMs (41 and 48) and >89.5%, and <1.5% for SBA-15, respectively. The SPE technique was used to determine the concentration of gold in natural and industrial wastewater with satisfactory results. Figure
A schematic model of modified mesoporous (MCM-41, MCM-48, SBA-15) with pyridine, and adsorption of Au(III) 相似文献
748.
Twenty 2,3‐disubstituted‐4(3H)‐quinazolinones were synthesed by one‐pot three‐component method with isatoic anhydride, orthoesters and amines as raw materials in the presence of KAl(SO4)2·12H2O (Alum) under microwave irradiation and solvent‐free conditions. 6‐Bromo‐2‐propyl‐3‐p‐tolylquinazolin‐4(3H)‐one ( 4m ), 6‐bromo‐2‐methyl‐3‐phenethylquinazolin‐4(3H)‐one ( 4n ) and 6‐bromo‐2‐ethyl‐3‐phenethylquinazolin‐4(3H)‐one ( 4o ) were characterized by IR, 1H NMR, 13C NMR and elemental analysis. 相似文献
749.
M. Mohammadi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(2):255-260
The temporal evolution of both the atomic population inversion of an effective two-level atom and the cross correlation between
the two modes in two-photon Jaynes-Cummings model in the presence of a classical homogeneous gravitational field are investigated.
To analyse the dynamical evolution of the atom-radiation system a quantum treatment of the internal and external dynamics
of the atom is presented based on an alternative su(2) dynamical algebraic structure. By solving the Schr?dinger equation
in the interaction picture, the evolving state of the system is found by which the influence of the gravitational field on
the dynamical behavior of both the atomic population inversion of an effective two-level atom and the cross correlation between
the two modes of the radiation field are explored. Assuming that initially the radiation field is prepared in the coherent
state for each mode and an effective two-level atom is in a coherent superposition of the excited and ground states, the influence
of gravity on both the atomic population inversion of an effective two-level atom and the cross correlation between the two
modes of the radiation field are studied. 相似文献
750.
Rastegari Arezoo Safavi Maliheh Vafadarnejad Fahimeh Najafi Zahra Hariri Roshanak Bukhari Syed Nasir Abbas Iraji Aida Edraki Najmeh Firuzi Omidreza Saeedi Mina Mahdavi Mohammad Akbarzadeh Tahmineh 《Molecular diversity》2022,26(1):409-428
Molecular Diversity - Alzheimer’s disease (AD) is now ranked as the third leading cause of death after heart disease and cancer. There is no definite cure for AD due to the multi-factorial... 相似文献