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41.
42.
Valentina Uivarosi Mihaela Badea Rodica Olar Dana Marinescu Teodor Octavian Nicolescu George Mihai Nitulescu 《Journal of Thermal Analysis and Calorimetry》2011,105(2):645-650
Three new complexes with ligands belong to the fluoroquinolone class having the general formula [RuL2Cl2]Cl nH2O ((1) L: norfloxacin (nf), n = 4; (2) L: ciprofloxacin (cp), n = 3; (3) L: enrofloxacin (enro), n = 5) were synthesized and characterized by chemical analysis UV–Vis and IR spectroscopy. In all complexes fluoroquinolone
derivative acts as bidentate chelate ligand. The thermal behavior steps were investigated in synthetic air flow. The thermal
transformations are complex processes according to TG and DTG curves including dehydration, quinolone derivative degradation,
as well as RuCl3 conversion in RuO2. 相似文献
43.
Mihaela Gulea Małgorzata Kwiatkowska Piotr Łyżwa Remi Legay Annie-Claude Gaumont Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2009,20(3):293-297
The Michael addition of selected sulfur and nitrogen nucleophiles to a chiral non-racemic 2-phosphono-2,3-didehydrothiolane S-oxide is fully diastereoselective. The enantiomeric excesses of the adducts obtained could be determined by 31P NMR spectroscopy using (R)-(+)-tert-butyl(phenyl)phosphinothioic acid as a chiral solvating agent. The addition of thiophenol was monitored by 31P NMR spectroscopy which made it possible to observe the formation and evolution of the kinetic and thermodynamic adducts in the reaction mixture. The structures of both enantiomeric thiophenol adducts have been determined by X-ray analysis. 相似文献
44.
Alberto Damiano Daniele Struppa Adrian Vajiac Mihaela Vajiac 《Journal of Geometric Analysis》2009,19(2):288-300
We introduce the notion of antisyzygies, which studies the inverse problem of finding a system of PDEs, given compatibility
conditions. The system obtained possesses the property of removability of compact singularities. We write explicit computations
in the cases of the Cauchy-Fueter system and Maxwell’s system for electromagnetism, and we conclude with a study of systems
of non-maximal rank.
相似文献
45.
Andreas H. Hamel Birgit Rudloff Mihaela Yankova 《Mathematics and Financial Economics》2013,7(2):229-246
New versions of the set-valued average value at risk for multivariate risks are introduced by generalizing the well-known certainty equivalent representation to the set-valued case. The first ’regulator’ version is independent from any market model whereas the second version, called the market extension, takes trading opportunities into account. Essential properties of both versions are proven and an algorithmic approach is provided which admits to compute the values of both versions over finite probability spaces. Several examples illustrate various features of the theoretical constructions. 相似文献
46.
Mihaela Singer Dr. 《ZDM》2001,33(6):204-217
Dominating information by formation seems to be the only realistic solution to overcome the crisis generated by the higher and higher accumulation of information in each domain. The paper is proposing a model of building structured knowledge able to generate in the child's mind strategies for efficient processing of information. 相似文献
47.
Mihaela Frunza Gabriela Lisa M. I. Popa N. D. Miron Denisa Ileana Nistor 《Journal of Thermal Analysis and Calorimetry》2008,93(2):373-379
The thermal behavior of the new inorganic-organic nanohybrid materials obtained by intercalation of chloramphenicol and salicylate
into layered double hydroxides (LDHs) by direct synthesis method, anion exchange reaction and the reconstruction method was
evaluated by dynamic thermogravimetric analysis in air, at heating rates of 5°C min−1. The XRD patterns of the samples are characteristic for those of well crystallized solids with layered double hydroxide structures.
The FTIR spectroscopy results show the presence of the organic compound within the network structure of the synthesized LDHs.
The kinetic parameters (reaction order (n) apparent activation energy (E
a) and pre-exponential factor (lnA) were calculated by the Coats-Redfern method. The compensation effects were determined. 相似文献
48.
49.
Electropolymerization of a new phenothiazine derivative (bis-phenothiazin-3-yl methane, BPhM) on glassy carbon electrodes
leads to electroactive and conducting layers of poly-BPhM. Based on the Laviron method, the kinetic parameters (the heterogeneous
electron transfer rate constants k
s and transfer coefficients α) were calculated out of the experimental and theoretical data. The theoretical data have been
obtained by using the analogical modelling and numerical simulating method. The modified electrodes present high values of
k
s(~50s−1) in phosphate buffer solutions of different pH values. A good correlation of mathematical and numerical simulated kinetic
parameters has been obtained, with the experimental values and the norm of residuals being very close to zero. 相似文献
50.
Cimpoiu C Hosu A Seserman L Sandru M Miclaus V 《Journal of separation science》2010,33(23-24):3794-3799
The aim of this paper is to develop a new simple, fast and economical method for simultaneous quantitative determination of methylxanthine compounds based on TLC combined with image analysis. To obtain certain results, both extraction and chromatographic separation were optimized. The optimum extraction conditions were maceration in ethanol-water 8:2, v/v. The chromatographic separations were done on the silica gel F(254) TLC plates developed with chloroform-dichloromethane-isopropanol, 4:2:1 v/v/v. Detection was performed under UV lamp at 254?nm and the evaluation of the chromatographic plate was based on digital processing of chromatographic images. The developed TLC method was validated for parameters such as specificity, linearity and range, LOD and LOQ, precision, robustness and accuracy. This method was then applied for determination of caffeine, theobromine and theophylline in different types of tea, commercially available. Moreover, the content of methylxanthines detected and determined in commercial tea samples can be used as chemical marker in quality control. 相似文献