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排序方式: 共有133条查询结果,搜索用时 281 毫秒
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Forouzan Zonouzi Alireza Shayesteh Taher Alizadeh Hamid Dezhampanah Bahram Ghalami-Choobar Afsaneh Zonouzi 《中国化学会会志》2020,67(1):41-45
The (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes (azo dyes 1–4 ) were synthesized in high purity. As they are insoluble in water, the usual analytical methods cannot be utilized to determine their pKa values. Cyclic voltammetry was experimentally used to determine their pKa values in DMSO solvent. In addition, computational methods and a conductor-like screening model (COSMO) were used to calculate the solvent effect. , , Kexchange, and pKa values were estimated for the azo dyes being studied using the BP86, TPSS, B3LYP, PBE0, TPSSh, and PW6B95 density functionals in def2-TZVP basis sets. The obtained mean absolute deviations (MADs) indicate that the results of BP86, PBE0, and PW6B95 functionals are in good agreement with experimental values. 相似文献
33.
Measurement of S2 emission of the diethyldithiocarbamates of As, Sb, Se and Te extracted into tetrachloromethane gives detection limits of 50, 150, 50 and 70 pg (in 5 μl), respectively. Tellurium in the presence of Se, and Sb in the presence of As, can be determined by extraction at pH 9.0. Calibration graphs are linear up to ca. 1 mg l?1. 相似文献
34.
A rapid and sensitive flow injection chemiluminescence method is described for the determination of sulfide based on the chemiluminescence generated during its reaction with either N-bromosuccinimide (NBS) or N-chlorosuccinimide (NCS) in alkaline medium. The results of investigation of the sensitized and non-sensitized chemiluminescence reactions are presented. The emission intensity is greatly enhanced for both NBS- and NCS-sulfide chemiluminescence systems if dichlorofluorescein (for NBS-sulfide) and fluorescein (for NCS-sulfide) are presented in the reaction solutions. The methods were applied satisfactorily to the determination of sulfide in spring water samples. 相似文献
35.
Fariba Fathi Laleh Majari‐Kasmaee Ahmad Mani‐Varnosfaderani Anahita Kyani Mohammad Rostami‐Nejad Kaveh Sohrabzadeh Nosratollah Naderi Mohammad Reza Zali Mostafa Rezaei‐Tavirani Mohsen Tafazzoli Afsaneh Arefi‐Oskouie 《Magnetic resonance in chemistry : MRC》2014,52(7):370-376
The present study was designed to search for metabolic biomarkers and their correlation with serum zinc in Crohn's disease patients. Crohn's disease (CD) is a form of inflammatory bowel disease that may affect any part of the gastrointestinal tract and can be difficult to diagnose using the clinical tests. Thus, introduction of a novel diagnostic method would be a major step towards CD treatment. Proton nuclear magnetic resonance spectroscopy (1H NMR) was employed for metabolic profiling to find out which metabolites in the serum have meaningful significance in the diagnosis of CD. CD and healthy subjects were correctly classified using random forest methodology. The classification model for the external test set showed a 94% correct classification of CD and healthy subjects. The present study suggests Valine and Isoleucine as differentiating metabolites for CD diagnosis. These metabolites can be used for screening of risky samples at the early stages of CD diagnoses. Moreover, a robust random forest regression model with good prediction outcomes was developed for correlating serum zinc level and metabolite concentrations. The regression model showed the correlation (R2) and root mean square error values of 0.83 and 6.44, respectively. This model suggests valuable clues for understanding the mechanism of zinc deficiency in CD patients. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Afsaneh Amiri Eui Yul Choi Huyn Jeong Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(1-2):185-194
The developments of immunosensors with a variety of formats are increasingly finding applications in clinical diagnostics and biological researches. A strategy for the immunoassay and preparation of Calixcrownchips is proposed. This strategy is based on the immobilization of antigens or antibodies on the surface of Calixcrown and the direct electrochemistry of horseradish peroxidase (HRP) that was labeled to an antibody or antigen, with its activity determined by using tetramethylbenzidine (TMB) as an electrochemical substrate. The present study includes general considerations of the competitive immunoreaction protocols. Alanine aminotransferase (ALT) monoclonal antibody (anti-ALT-mAb) was successfully immobilized on thiol derivative of Calixcrown fixed to a gold surface. ALT antigen was detected by competitive immunoreactions based on microarrays of anti-ALT-mAb or antigen immobilized on the surface of the Calixcrownchip. For the anti-ALT-mAb immobilized microarray the dynamic range is 0.05 ng/mL–10 μg/mL, the detection limit is 0.05 ng/mL and the sensitivity is 10 nA/(ng/mL) respectively. The Calixcrownchip immunosensor microarray provided much better technical performance than a comparable enzyme sensor with immobilized-anti-ALT-mAb. To investigate the complexation site, the structures of the complexes formed between the crown-5-ether moiety of Calix[4]arene and protonated Arginine and Lysine were determined by minimizing the complex formation energies. The complex stability depends on the number of amine groups in the alkyl chain of the amino acid and also the number of methylene groups between the amine groups of the amino acid. 相似文献
38.
Mohammad Hossein Pournaghi-Azar Shahla Kheradmandi Afsaneh Saadatirad 《Journal of Solid State Electrochemistry》2010,14(9):1689-1695
In the present work, the aluminum electrode surface was modified with a thin layer of palladium by dipping its polished surface
in a 25% ammonia solution of PdCl2. The electrocatalytic ability of the modified electrode towards the paracetamol (PCT), ascorbic acid (AA), and codeine (CO)
oxidation was investigated using cyclic voltammetry, chronoamperometry. The number of electrons for rate-determining step
and diffusion coefficient of PCT, AA, and CO were determined. The electro-oxidation pathway and kinetics, including transfer
coefficient α and diffusion coefficient D, are estimated. The results indicated that the simultaneous voltammetry of the three compounds was possible in a mixture
solution. 相似文献
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Aromatic and aliphatic amines and hydrazine in the range 1–30 × lO-5 M are determined by measuring the S2 emission in a carbon cavity held in a hydrogen—nitrogen flame arising from the formation of an addition compound between the amine, formaldehyde and sulphite. As little as 1.8 ng of aniline in 5 μl (4 × 10-6 M) can be detected. 相似文献