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排序方式: 共有199条查询结果,搜索用时 359 毫秒
191.
192.
This paper describes a GC–MS method for the determination of naproxen in human plasma. Naproxen and internal standard ibuprofen were extracted from plasma using a liquid–liquid extraction method. Derivatization was carried out using N‐methyl‐N‐(trimethylsilyl)trifluoroacetamide. The calibration curve was linear between the concentration range of 0.10–5.0 μg/mL. Intra‐ and interday precision values for naproxen in plasma were <5.14, and accuracy (relative error) was better than 4.67%. The extraction recoveries of naproxen from human plasma were between 93.0 and 98.9%. The LOD and LOQ of naproxen were 0.03 and 0.10 μg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of naproxen in six healthy Turkish volunteers who had been given 220 mg naproxen. 相似文献
193.
Maria-João R.P. Queiroz Elisabete M.S. Castanheira Ana S. Abreu Paula M.T. Ferreira Arzum Erdem 《Tetrahedron》2008,64(2):382-391
A benzothienoindole (BTIN) and a benzofuroindole (BFIN) were synthesized in high yields, as potential new DNA target compounds, using a metal-assisted intramolecular C-N cyclization of the methyl esters of N-(tert-butoxycarbonyl)-β,β-bis(dibenzothien-4-yl or dibenzofur-4-yl)dehydroalanines. The latter were obtained by a bis-Suzuki coupling of a β,β-dibromodehydroalanine with the corresponding heteroarylboronic acids. The absorption and fluorescence properties of the new tetracyclic compounds were studied in different solvents and in the presence of salmon sperm DNA. The results in several solvents show that either BTIN or BFIN can be used as fluorescence solvent sensitive probes. Spectroscopic studies of their interaction with dsDNA allowed to determine binding constant (Ki) values and binding site sizes (n). Fluorescence quenching experiments using iodide ion showed that intercalation is the preferred mode of binding to DNA. From the results obtained, BTIN is the more intercalative compound and has a higher affinity to DNA. The interaction of BTIN with DNA was also studied electrochemically, by using differential pulse voltammetry (DPV) in connection with disposable pencil graphite electrode (PGE). After the interaction of BTIN with DNA, the oxidation signals of BTIN and adenine strongly decreased. The latter result was attributed to the binding of BTIN to DNA and the former points to a possible damage of the oxidizable groups of BTIN after intercalation into DNA. The results of spectroscopic and electrochemical studies of BTIN interaction with DNA are in good agreement. 相似文献
194.
The mathematical model related to controlled potential experiments in electrochemistry is studied. Ion transport is regarded
as the superposition of diffusion and migration under the influence of an electric field. Modeling of the experiment leads
to the nonlocal identification problem for nonlinear parabolic equation. It is shown that in some cases the nonlocal identification
problem can be transformed to an initial value problem for nonlinear parabolic equation. The finite diference approximation
of this problem, with the appropriate iteration algorithm, is derived. Based on these algorithms the solution of the identification
problem is presented. The obtained results permits one to derive the behaviour of the current response , depending on time, also the relationship between the current response and Gottrellian is obtained in explicit form. An influence of the valences oxidised and reduced species is also analyzed.
相似文献
195.
Nazan Ocak İskeleli Hasan Karabıyık Çiğdem Albayrak Erbil Ağar İsmail Erdem Gümrükçüoğlu 《Structural chemistry》2008,19(4):565-570
The molecular and crystal structures of the title compound, C16H18N2O, were characterized and determined by single crystal X-ray diffraction method in addition to spectroscopic means such as IR, UV–VIS and 1H NMR. The compound crystallizes in orthorhombic space group P bca, with a = 9.3350(5) Å, b = 23.4878(13) Å, c = 26.5871(12) Å, Z = 16, D calc. = 1.1591(1) g/cm3, μ (MoKα) = 0.073 mm?1. Monomers of the compound in the crystal structure are linked into C(7) and C(8) chains generated by translation along the [1 0 0] direction with the aid of O–H···N type H-bonds which serve to the stabilization of periodic organization of the molecules beside major and minor component in the disordered azo fragment. In order to describe conformational flexibility and the crystal packing effects on the molecular conformation, potential barriers regarding the rotation along both Ar–N bonds were calculated by varying the related torsional degrees of freedom in every 10° ranging from ?180° to +180° via quantum chemical calculations at DFT/B3LYP level. 相似文献
196.
A new surface based on the natural clay mineral sepiolite and a single-walled carbon nanotubes-modified graphite electrode was developed for the electrochemical detection of DNA, and also for anticancer drug-DNA interactions. 相似文献
197.
Bedri Erdem E. David Sudol Victoria L. Dimonie Mohamed S. El‐Aasser 《Macromolecular Symposia》2000,155(1):181-198
The encapsulation of TiO2 particles via miniemulsion polymerization is strongly dependent on the size and stability of the inorganic particles in the monomer medium in which they are initially dispersed. It was found from XPS and FT‐IR studies that both the hydrophilic and hydrophobic TiO2 particles, which were studied, have hydroxyl groups present on their surfaces, which can strongly interact with the amine end‐groups of the polymeric stabilizer, OLOA370 (polybutene‐succinimide diethyl triamine). It was found from the dispersion and adsorption studies that the amount of OLOA370 retained on the TiO2 particles is strongly dependent on the area exposed by the sonification that is applied to break up the aggregates in the dispersion process. The TiO2 dispersions in styrene monomer were themselves dispersed as miniemulsion droplets and subsequently polymerized. It was concluded from the density gradient column (DGC) analysis of the latexes obtained from the encapsulation polymerizations, that the stability of the inorganic particles in the monomer, as well as their particle size, significantly influence the encapsulation efficiencies. The use of the hydrophilic titanium dioxide particles in combination with the stabilizer, OLOA370, resulted in a good dispersibility, dispersion stability, and small TiO2 particle size. This lead to better encapsulation efficiencies compared to the hydrophobic particles. The poorer results obtained with the hydrophobic TiO2 particles were attributed to their larger particle size, which resulted from the reduced adsorption of the OLOA370. Fewer hydroxyls and the presence of the trimethoxy octyl silane (TMOS) groups, which themselves are unable to provide sufficient steric stability, are proposed to explain these findings. 相似文献
198.
We have developed a method to measure living chain molecular weight distributions (MWDs) in free radical polymerization (FRP). By laser photolysis of photoinhibitor molecules included in the polymerizing mixture, the living chains are instantaneously flooded with small molecule radicals carrying fluorescent labels. These radicals react with living chain radical end groups, kinetically freezing growth of living chains and simultaneously end -labelling them: the living chain population has been photocopied. The living MWD is obtained from subsequent analysis by GPC equipped with fluorescence detection. We have measured low conversion thermally initiated PMMA living MWDs, Exponential behaviour is found for large chain length N, in accord with classical Flory-Schultz theory, but at smaller N we establish strong deviations, consistent with the stretched exponential predicted by modern FRP theory incorporating first principles chain length dependencies of termination rate constants. However, this behaviour may derive at least partially from distortions produced by the photocopying technique which can generate power law or logarithmic forms at small N. 相似文献
199.