排序方式: 共有87条查询结果,搜索用时 15 毫秒
21.
Azimi Bahareh Maleki Homa Gigante Vito Bagherzadeh Roohollah Mezzetta Andrea Milazzo Mario Guazzelli Lorenzo Cinelli Patrizia Lazzeri Andrea Danti Serena 《Cellulose (London, England)》2022,29(6):3079-3129
Cellulose - Cellulose, a natural, renewable, and environment friendly biopolymer, has been considered as a sustainable feedstock in the near future. However, only 0.3% of cellulose is today... 相似文献
22.
Payman Hashemi Sayyed Mohammad Hosseini Ali Kakanejadifard Gholamhassan Azimi Somayeh Zohrehvand 《中国化学会会志》2010,57(1):111-117
A dispersive liquid‐liquid microextraction (DLLME) technique was proposed for the enrichment and graphite furnace atomic absorption spectrometric (GFAAS) determination of Cu2+ in water samples. In this method a mixture of 480 μL acetone (disperser solvent) containing 26 μg S,S‐bis(2‐aminobenzyl)‐dithioglyoxime (BAT) ligand and 20 μL carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL aqueous sample containing copper ions (analyte). Thereby, a cloudy solution formed. After centrifugation, the fine droplets containing the extracted copper complex were sedimented at the bottom of the conical test tube. This phase was collected by a microsyring and after dilution by methanol, 20 μL of it was injected into the graphite tube of the instrument for analysis. Effects of some parameters on the extraction, such as extraction and disperser solvent type and volume, extraction time, salt concentration, pH and concentration of the chelating agent were optimized. The response surface method was used for optimization of the effective parameters on the extraction recovery. Under these conditions, an enrichment factor of 312 was obtained. The calibration graph was linear in the rage of 2–50 μ L−1 Cu2+ with a detection limit of 0.03 μg L−1 and a relative standard deviation (RSD) for five replicate measurements of 3.4% at 20 μg L−1 Cu2+. The method was successfully applied to the determination of Cu2+ in some spring water samples. 相似文献
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M.A. Elbagerma Gholamhassan Azimi H.G.M. Edwards A.I. Alajtal I.J. Scowen 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1403-1410
Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 °C in a solution of ionic strength 0.96 mol dm?3 (KNO3) and 0.04 mol dm?3 (HNO3). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information. 相似文献
24.
Simultaneous determination of total iron and vanadium by H-point standard addition method (HPSAM) and partial least squares (PLS) is described. Gallic acid (GA) in a cationic micellar solution of CTAB was used for determination of iron and vanadium in different oxidation states at pH 5. The presence of a micellar system enables total iron and vanadium to be determined with improved sensitivities. The total relative standard error for applying the PLS method to 15 synthetic samples in the ranges 0.20–15.00 μg ml−1 iron and 0.20–8.00 μg ml−1 vanadium was 2.2%. The results of applying the H-point standard addition method showed that iron and vanadium can be determined simultaneously with the concentration ratios of iron to vanadium from 10:1 to 1:20 in the mixed sample. Both HPSAM and PLS methods showed suitable abilities to resolve accurately overlapped absorption spectra of the compounds. Both proposed methods were successfully applied to the determination of Fe and V in several synthetic alloy solutions. 相似文献
25.
M. Mazloum Ardakani M. A. Karimi M. H. Mashhadizadeh M. Pesteh M. S. Azimi H. Kazemian 《International journal of environmental analytical chemistry》2013,93(4):285-294
A purge-and-trap method was developed for sensitive and fast determination of trace MTBE in aqueous samples. The sample solutions were added with 10% (w/w) sodium sulfate and adjusted to pH 4 by acetic acid and sodium acetate buffer solution to improve the purge efficiency before the analysis. A CP-4010 purge-and-trap injector (PTI) was used to purge MTBE from water and cool it in the cold-trap kept at m 75°C, then the cooled trap was flash heated to release the analytes onto a HP-1 capillary column and detected by gas chromatography-flame ionization detector (GC-FID). A good linear response was obtained and the detection limit was 0.1 µg L m 1 . This method has been successfully applied to the determination of MTBE in several Chinese river samples. 相似文献
26.
Robabeh Baharfar Zahra Rahmani Mojtaba Mohseni Razieh Azimi 《Natural product research》2015,29(22):2145-2148
This study was designed to examine the total phenolic and flavonoid contents, radical scavenging and antibacterial activity of the ethanolic extracts from leaves, berries and stems of Hedera pastuchovii Woron. ex Grossh. The berry extract, which contained the highest phenolic and flavonoid compounds, showed an appreciable DPPH√ scavenging ability in comparison with leaf and stem extracts. The various extracts exhibited moderate to good activity against both Gram-negative and Gram-positive bacteria, and the effectiveness of leaf extract was higher for all tested bacteria. 相似文献
27.
In situ generated acetone pyrrolidine enamine undergoes [6 + 2] cycloadditions with fulvenes to give 1,2-dihydropentalenes. This ring annulation method works particularly well with 6-monosubstituted fulvenes and is subject to steric hindrance at C-6 of the fulvene. On the basis of mechanistic studies, optimal conditions have been developed for a one-pot synthesis of 1,2-dihydropentalenes using catalytic amounts of pyrrolidine. 相似文献
28.
A series of pyrido[2,3-d]pyrimidine derivatives were easily constructed by cyclocondensation reactions of 6-aminouracils or 6- aminothiouracil withα,β-unsaturated carbonyl compounds(aldehyde,ketone and ester) possessing a leaving group on theβposition,in H2O under reflux conditions. 相似文献
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Abbas Azimi Roshan Manouchehr Mamaghani Nosrat Ollah Mahmoodi Farhad Shirini 《中国化学快报》2012,23(4):399-402
An efficient ultrasound-assisted preparation of a series of novel 4-aryl-3-methyl-4,5-dihydro-l//-pyrazolo[34-b]pyridin-6(7H)ones via the reaction of 5-amino-3-methyl-1H-pyrazole,Meldrum’s acid and various arylaldehydes using one-pot three-component approach is described.This rapid method produced the products in short reaction times(3-4 min) and excellent yields(87-95%). 相似文献