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91.
Gade Srinivas Reddy Kadaboina Rajasekhar Cherukupally Praveen Kaga Mukkanti 《合成通讯》2013,43(22):3884-3893
3,4-Dihydro-1,4,4a,6a-tetraaza-benzo[a]fluoren-2-one, a new tetracyclic heterocyclic framework, is designed through a simple and convenient synthetic sequence. Its 6-aryl derivatives are synthesized starting from 1H-indole-2-carboxylic acid. The reaction of differently substituted phenacyl bromides with 1H-indole-2-carboxylic acid and POCl3-mediated cyclization of the resultant 1H-indole-2-carboxylic acid phenacyl ester provided 2-oxa-4a-aza-fluoren-1-one, and its sequential reaction with hydrazine and 2-chloro-acetamide furnished the desired new heterocyclic compounds 7a–f. 相似文献
92.
An efficient and mild approach for the synthesis of pyrrolidine‐benzimidazoles has been reported. They were further employed for the aldol and Michael addition reactions to afford the corresponding products with good yields and moderate enantioselectivities. 相似文献
93.
Pilli NR Inamadugu JK Kondreddy N Karra VK Damaramadugu R Rao JV 《Biomedical chromatography : BMC》2011,25(8):943-951
A rapid and sensitive liquid chromatography–tandem mass spectrometric (LC‐MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6‐o‐desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid–liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n‐hexane. The reconstituted samples were chromatographed on a C18 column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm , pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09–24.2 ng/mL for donepezil and 0.03–8.13 ng/mL for 6‐o‐desmethyl donepezil. The results of the intra‐day and inter‐day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
94.
A cloud point extraction method has been developed using an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMiM PF(6)) for the determination of a widely studied cyanotoxin (microcystin leucine-arginine, MCLR) in natural waters. Extraction parameters such as sample pH, extraction temperature, extraction time, the amount of ionic liquid and the amount of extraction volume were investigated and optimized to achieve the maximum extraction efficiency. The results obtained indicated a good linearity with the correlation coefficient of 0.995 over the range of 0.5-50 μg L(-1). The relative standard deviation (RSD) of the method was 7.5% (n=6). The calculated method detection limit was 0.03 μg L(-1) (n=6). The practical applicability of the technique was demonstrated by analyzing water samples (n=9) collected from three different sites in local reservoirs. 相似文献
95.
Hundred and forty-five novel molecules of Wittig-based Schiff-base (WSB), including copper(II) complex and precursors, were computationally screened for nonlinear optical (NLO) properties. WSB ligands were derived from various categories of amines and aldehydes. Wittig-based precursor aldehydes, (E)-2-hydroxy-5-(4-nitrostyryl)benzaldehyde (f) and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl) benzaldehyde (g) were synthesised and spectroscopically confirmed. Schiff-base ligands and copper(II) complex were designed, optimised and their NLO property was studied using GAUSSIAN09 computer program. For both optimisation and hyperpolarisability (finite-field approach) calculations, Density Functional Theory (DFT)-based B3LYP method was applied with LANL2DZ basis set for metal ion and 6-31G* basis set for C, H, N, O and Cl atoms. This is the first report to present the structure–activity relationship between hyperpolarisability (β) and WSB ligands containing mono imine group. The study reveals that Schiff-base ligands of the category N-2, which are the ones derived from the precursor aldehyde, 2-hydroxy-5-(4nitro-styryl)benzaldehyde and pre-polarised WSB coordinated with Cu(II), encoded as Complex-1 (β = 14.671 × 10?30 e.s.u) showed higher β values over other categories, N-1 and N-3, i.e. WSB derived from precursor aldehydes, 2-hydroxy-5-styrylbenzaldehyde and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl)benzaldehyde, respectively. For the first time here we report the geometrical isomeric effect on β value. 相似文献
96.
K. Jalaiah K. Vijaya Babu K. Rajasekhar Babu V. Venkat Kumar R.V. Krishnaiah 《Chinese Journal of Physics (Taipei)》2018,56(5):2039-2051
The zirconium and copper co-substituted Ni0.75Zn0.25ZrxCuxFe2-2xO4 (where x?=?0.05, 0.1, 0.15, 0.2) ferrites have been prepared by sol-gel auto-combustion method. The XRD patterns provide the evidence of single phase cubic spinel structure. The theoretical and experimental lattice parameters have resemblance with increase dopant concentration. The sintered density and porosity show the opposite trend with dopant concentration. The FT-IR spectrum of prepared samples reveal cubic spinel with () space group. The wave numbers of tetrahedral and octahedral sites show agnate trend. The dielectric constant and loss factors decreased with increasing dopant concentration. The saturation magnetization and net magnetic moment have the identical trend with increasing dopant concentration. The coercive field is decreased with increasing dopant concentration. The Y–K angles are increased with increasing dopant concentration. The Q-factor in prepared samples, exhibit narrower frequency bands with increasing frequency. 相似文献