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排序方式: 共有212条查询结果,搜索用时 15 毫秒
181.
Cyclic voltammetry and electrochemical impedance studies of Fe(tmphen) 3 2+ (where tmphen?=?3,4,7,8-tetramethyl-1,10-phenanthroline)-immobilized Nafion?-modified glassy carbon electrode (GC/Nf/Fe(tmphen) 3 2+ ) are carried out in 0.1?M Na2SO4 solution. Nafion–Fe(tmphen) 3 2+ complex exhibits efficient electrocatalytic oxidation of isoniazid. The linear double reciprocal plot of current and concentration of isoniazid shows a Michaelis–Menten-type catalytic process. The catalytic oxidation currents are proportional to the concentration of isoniazid and show a wide linear calibration range for the quantitative determination of isoniazid. Detection limit and sensitivity are found to be 13?μM and 2.5?μA?mM?1, respectively. 相似文献
182.
183.
Background
The mechanisms that regulate the activity of the nonreceptor tyrosine kinase Ack1 (activated Cdc42-associated kinase) are poorly understood. The amino-terminal region of Ack1 is predicted to contain a sterile alpha motif (SAM) domain. SAM domains share a common fold and mediate protein-protein interactions in a wide variety of proteins. Here, we addressed the importance of the Ack1 SAM domain in kinase activity. 相似文献184.
Fatma Aydin Akgun Azad Bayramov Mehmet Bayramoğlu 《Mediterranean Journal of Mathematics》2013,10(1):277-288
In this paper we study the asymptotic formulas for the eigenvalues and corresponding eigenfunctions of discontinuous boundary value problems with retarded argument and eigenparameter-dependent boundary conditions. 相似文献
185.
Syed?Muhammad?Jawwad?RiazEmail author Azad?A.?Siddiqui 《General Relativity and Gravitation》2011,43(4):1167-1178
In this paper we present non-singular coordinates for the rotating BTZ (Banados–Teitelboim–Zanelli) black hole. The approach
is further extended to construct non-singular coordinates for different cases of general circularly symmetric black holes
in 2 + 1 dimensions. 相似文献
186.
Nicole M. Anders Teresia M. Wanjiku Ping He Nilofer S. Azad Michelle A. Rudek 《Biomedical chromatography : BMC》2016,30(3):494-496
The DNA methyltransferase inhibitor 5‐azacytidine is being evaluated clinically as an oral formulation to treat various solid tumors. A sensitive, reliable method was developed to quantitate 5‐azacytidine using LC‐MS/MS to perform detailed pharmacokinetic studies. The drug of interest was extracted from plasma using Oasis MCX ion exchange solid‐phase extraction 96‐well plates. Chromatographic separation was achieved with a YMC J'sphere M80 C18 column and isocratic elution with a methanol–water–formic acid (15:85:0.1, v/v/v) mobile phase over a 7 min total analytical run time. An AB Sciex 5500 triple quadrupole mass spectrometer operated in positive electrospray ionization mode was used for the detection of 5‐azacytidine. The assay range was 5–500 ng/mL and proved to be accurate (97.8–109.1%) and precise (CV ≤ 9.8%). Tetrahydrouridine was used to stabilize 5‐azacytidine in blood/plasma samples. With the addition of tetrahydrouridine, long‐term frozen plasma stability for 5‐azacytidine at ?70°C has been determined for at least 323 days. The method was applied for the measurement of total plasma concentrations of 5‐azacytidine in a cancer patient receiving a 300 mg oral daily dose. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
187.
Khan AA Hussain HA Iftikhar K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(8-9):2087-2092
The effect of change in the environment upon 4f-4f absorption spectra of nine-coordinate Ho(III) and Er(III) complexes with thiocyanate and 2,2'-bipyridyl in methanol, DMSO, DMF and pyridine have been investigated. The oscillator strength for hypersensitive and non-hypersensitive transitions have been calculated and variation in the intensity and band shape with respect to solvent type is rationalized in terms of solvent structure and coordinating properties. A comparison with 1,10-phenanthroline complexes is investigated and has been found that phen has a larger impact on the transition intensities for these ions. Pyridine has been found most effective in promoting 4f-4f intensity. The results indicate that it is important to consider both the static and dynamic coupling mechanism while analysing the oscillator strength of hypersensitive transition. 相似文献
188.
Polycrystalline Sr2−xNdxFeMoO6 (x=0.0, 0.1, 0.2, 0.4) materials have been synthesized by a citrate co-precipitation method and studied by neutron powder diffraction (NPD) and magnetization measurements. Rietveld analysis of the temperature-dependent NPD data shows that the compounds (x=0.0, 0.1, 0.2) crystallize in the tetragonal symmetry in the range 10-400 K and converts to cubic symmetry above 450 K. The unit cell volume increases with increasing Nd3+ concentration, which is an electronic effect in order to change the valence state of the B-site cations. Antisite defects at the Fe-Mo sublattice increases with the Nd3+ doping. The Curie temperature was increased from 430 K for x=0 to 443 K for x=0.4. The magnetic moment of the Fe-site decreases while the Mo-site moment increases with electron doping. The antiferromagnetic arrangement causes the system to show a net ferrimagnetic moment. 相似文献
189.
The adsorption and reaction of CO and CO(2) on oxidized and reduced SrTiO(3)(100) surfaces have been studied with temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). XPS results indicate that the oxidized SrTiO(3)(100) surfaces are nearly defect-free with predominantly Ti(4+) ions whereas the sputter-reduced surfaces contain substantial amounts of defects. Both CO and CO(2) are found to adsorb weakly on the oxidized SrTiO(3)(100) surfaces. On sputter-reduced surfaces, enhanced reactivity of CO and CO(2) is observed due to the presence of oxygen vacancy sites, which are responsible for dissociative adsorption of these molecules. Our studies indicate that the CO and CO(2) molecules exhibit relatively weaker interactions with SrTiO(3)(100) compared to those with TiO(2)(110) and TiO(2)(100) surfaces. This is most likely an influence of the Sr cations on the electronic structure of the Ti cations in the mixed oxide of SrTiO(3). 相似文献
190.
The adsorption and reaction of methanol (CH(3)OH) on stoichiometric (TiO(2)-terminated) and reduced SrTiO(3)(100) surfaces have been investigated using temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and first-principles density-functional calculations. Methanol adsorbs mostly nondissociatively on the stoichiometric SrTiO(3)(100) surface that contains predominately Ti(4+) cations. Desorption of a monolayer methanol from the stoichiometric surface is observed at approximately 250 K, whereas desorption of a multilayer methanol is found to occur at approximately 140 K. Theoretical calculations predict weak adsorption of methanol on TiO(2)-terminated SrTiO(3)(100) surfaces, in agreement with the experimental results. However, the reduced SrTiO(3)(100) surface containing Ti(3+) cations exhibits higher reactivity toward adsorbed methanol, and H(2), CH(4), and CO are the major decomposition products. The surface defects on the reduced SrTiO(3)(100) surface are partially reoxidized upon saturation exposure of CH(3)OH onto this surface at 300 K. 相似文献