排序方式: 共有33条查询结果,搜索用时 15 毫秒
1.
Claudia Mureşanu Lucian Copolovici Florina Pogącean 《Central European Journal of Chemistry》2005,3(4):592-604
The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from
Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the
Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction:
in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots
of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed. 相似文献
2.
We prove the almost sure existence of absolutely continuous spectrum at low disorder for the Anderson model on the simplest example of a product of a regular tree with a finite graph. This graph contains loops of unbounded size. 相似文献
3.
Victor Bulacovschi Aurelian Stanciu Iulian Rusu Adrian C
ilean Florina Ungureanu 《Polymer Degradation and Stability》1998,60(2-3):487-491
Three new chemically crosslinked polyurethanes were synthesized. Their behaviour in organic solvents and in dynamic heating conditions was studied. Predictions regarding the thermal stability have been made by using the isoconversion kinetic method. 相似文献
4.
Gheorghe Daniela Neacsu Ana Contineanu Iulia Anghel Elena Maria Teodorescu Florina Chican Irina Elena Perisanu Stefan Tanasescu Speranta 《Journal of Thermal Analysis and Calorimetry》2019,138(2):1233-1242
Journal of Thermal Analysis and Calorimetry - A systematic thermodynamic study has been performed for a series of nitrates having cations derived from the α-amino acids glycine (Gly),... 相似文献
5.
A base-free rhodium-catalyzed Mizoroki-Heck (M-H) reaction using potassium aryltrifluoroborates as the arylating agent of alkenes and acetone as a green "oxidant" is described. Thanks to the ready availability of organoboranes, this reaction should constitute an interesting alternative to conventional M-H reactions using aryl halides. 相似文献
6.
We prove persistence of absolutely continuous spectrum for the Anderson model on a general class of tree-like graphs. 相似文献
7.
8.
Catalin Schiopu Corina Flangea Florina Capitan Alina Serb Željka Vukelić Svjetlana Kalanj-Bognar Eugen Sisu Michael Przybylski Alina D. Zamfir 《Analytical and bioanalytical chemistry》2009,395(8):2465-2477
We report here on a preliminary investigation of ganglioside composition and structure in human hemangioma, a benign tumor
in the frontal cortex (HFC) in comparison to normal frontal cortex (NFC) tissue using for the first time advanced mass spectrometric
methods based on fully automated chip-nanoelectrospray (nanoESI) high-capacity ion trap (HCT) and collision-induced dissociation
(CID). The high ionization efficiency, sensitivity and reproducibility provided by the chip-nanoESI approach allowed for a
reliable MS-based ganglioside comparative assay. Unlike NFC, ganglioside mixture extracted from HFC was found dominated by
species of short glycan chains exhibiting lower overall sialic acid content. In HFC, only GT1 (d18:1/20:0), and GT3 (d18:1/25:1)
polysialylated species were detected. Interestingly, none of these trisialylated forms was detected in NFC, suggesting that
such components might selectively be associated with HFC. Unlike the case of previously investigated high malignancy gliosarcoma,
in HFC one modified O-Ac-GD2 and one modified O-Ac-GM4 gangliosides were observed. This aspect suggests that these O-acetylated structures could be associated with cerebral tumors having reduced malignancy grade. Fragmentation analysis by
CID in MS2 mode using as precursors the ions corresponding to GT1 (d18:1/20:0) and GD1 (d18:1/20:0) provided data corroborating for
the first time the presence of the common GT1a and GT1b isomers and the incidence of unusual GT1c and GT1d glycoforms in brain
hemangioma tumor.
相似文献
9.
Florina D. Covaciu D. Alina Magdas Olivian Marincas Zaharie Moldovan 《Analytical letters》2017,50(17):2665-2676
ABSTRACTA sensitive and selective method was developed to determine pesticides in carrots by gas chromatography–mass spectrometry following the development of an optimized extraction procedure. The method was validated for 30 organochlorine pesticides for gas chromatography with electron capture detection obtaining limit of detection from 0.18 to 0.92?µg/kg except for cis- and trans-permenthrin. Twenty-six carrot samples were analyzed and six pesticides were detected. The results compared with the accepted maximum residue levels in correlation to crop origin. 相似文献
10.
Dr. Stela Pruneanu Dr. Alexandru R. Biris Dr. Florina Pogacean Dr. Diana Mihaela Lazar Dr. Stefania Ardelean Dr. Fumyia Watanabe Dr. Enkeleda Dervishi Dr. Alexandru S. Biris 《Chemphyschem》2012,13(16):3632-3639
This work is the first presentation of the synthesis of few‐layer graphene decorated with gold and silver nanoparticles (Gr–Au–Ag) by chemical vapor deposition over a catalytic system formed of bimetallic Au–Ag nanoclusters supported on MgO and with methane used as the source of carbon. The sheetlike morphology of the graphene nanostructures, with mean sizes in the range of hundreds of nanometers, was observed by high‐resolution electron microscopy. The distinctive feature found in all the samples was the regular rectangular or square shapes. This multi‐component organic–inorganic nanomaterial was used to modify a platinum substrate and subsequently employed for the detection of carbamazepine, an anti‐convulsion drug. UV/Vis spectroscopy revealed that a strong hypochromism occurred over time, after mixing solutions of graphene–Au–Ag with carbamazepine. This can be attributed to π–π stacking between the aromatic groups of the two compounds. Linear sweep voltammetry (LCV) provided evidence that the modified platinum substrate presented a significant electrocatalytic reaction toward the oxidation of carbamazepine. The intensity of the current was found to increase by up to 2.5 times, and the oxidation potential shifted from +1.5 to +1.35 V(Ag/AgCl) in comparison with the unmodified electrode. Electrochemical impedance spectroscopy (EIS) was further used to thoroughly assess the activity of the platinum electrode that was modified by the deposition of the Gr‐Au‐Ag composites in the presence of various concentrations of carbamazepine. The experimental EIS records were used for the generation of an equivalent electrical circuit, based on the charge‐transfer resistance (Rct), Warburg impedance (ZD), solution resistance (Rs), and a constant phase element (CPE) that characterizes the non‐ideal interface capacitive responses. 相似文献