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81.
Enantiomeric Thin-Layer Chromatographic Assay of Escitalopram in Presence of “In-Process Impurities”
JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid and precise thin-layer chromatographic (TLC) method for analysis of escitalopram oxalate (ESC-OX) (S-enantiomer) in... 相似文献
82.
This paper investigates an optimal sequencing and dynamic pricing problem for a two-class queueing system. Using a Markov
Decision Process based model, we obtain structural characterizations of optimal policies. In particular, it is shown that
the optimal pricing policy depends on the entire queue length vector but some monotonicity results prevail as the composition
of this vector changes. A numerical study finds that static pricing policies may have significant suboptimality but simple
dynamic pricing policies perform well in most situations. 相似文献
83.
Gülsev Dilber Mahmut Durmuş Halit Kantekin Volkan Çakır 《Journal of organometallic chemistry》2011,696(15-16):2805-2814
The synthesis and characterization of peripherally tetra-biphenyl-4-yl-methoxy substituted metal-free (4), Ni(II) (5), Cu(II) (6), Zn(II) (7), Co(II) (8) and Pb(II) (9) phthalocyanine derivatives are reported. These new phthalocyanine derivatives show the enhanced solubility in organic solvents and they have been characterized by a combination of IR, 1H NMR, 13C NMR, UV–vis, mass spectral data, elemental analysis and thermal analysis methods (TG/DTA). The photophysical (fluorescence quantum yield and lifetime) and photochemical (singlet oxygen generation and photodegradation quantum yield) properties of tetra-biphenyl-4-yl-methoxy substituted zinc (II) phthalocyanine derivative (7) are also investigated. The fluorescence of this phthalocyanine derivative (7) is effectively quenched by addition of 1,4-benzoquinone (BQ). 相似文献
84.
We present a method to identify the symmetry class of an elasticity tensor whose components are given with respect to an arbitrarily
oriented coordinate system. The method is based on the concept of distance in the space of tensors, and relies on the monoclinic
or transversely isotropic distance function. Since the orientation of a monoclinic or transversely isotropic tensor depends
on two Euler angles only, we can plot the corresponding distance functions on the unit sphere in ℝ3 and observe the symmetry pattern of the plot. In particular, the monoclinic distance function vanishes in the directions
of the normals of the mirror planes, so the number and location of the zeros allows us to identify the symmetry class and
the orientation of the natural coordinate system. Observing the approximate locations of the zeros on the plot, we can constrain
a numerical algorithm for finding the exact orientation of the natural coordinate system. 相似文献
85.
In this study, the effect of ascorbic acid in the electrochemical behavior of copper has been investigated in 3.5 % NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy. Current-potential curve and Nyquist diagrams were obtained in different concentrations of ascorbic acid. The surface morphology of copper after its exposure to 3.5 % NaCl solution with and without of ascorbic acid was examined by scanning electron microscopy. The obtained results show that ascorbic acid inhibits corrosion of copper in 3.5 % NaCl solution. The inhibition activity of ascorbic acid increases with a decrease in the concentration of ascorbic acid. 相似文献
86.
A. Kiliç K. Kiliç H. Yetiş M. Olutaş A. Altinkok H. Sözeri O. Çetin 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(4):565-569
The flux dynamics in a polycrystalline sample of
Bi1.7Pb0.3Sr2Ca2Cu3Ox with a macroscopic
cylindrical hole (CH) drilled was investigated by slow transport relaxation
(V-t curves) and magnetovoltage measurements (V-H curves). It was monitored that
there are several discontinuities in the time evolution of quenched state in
V-t curves, which was attributed to the leaving of quantized flux lines
trapped through CH together with surface superconducting effects. We
observed that asymmetric V-H curves demonstrate unusual remarkable counter
clockwise hysteresis effects upon cycling of field. This interesting result
was correlated mainly to the flux trapping inside the CH that acts as a
macroscopic attractive pinning center for flux lines. Further, the
hysteresis effects in V-H curves for a fixed transport current provide a direct
evidence that the number of flux lines, measured dissipation and relative
decrease/increase in irreversibilities could be determined by sweeping rate
of external magnetic field (dH/dt) which leads also to peculiar time effects. 相似文献
87.
H. Arkın T. Çelik 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):577-580
To investigate the performance of the energy landscape paving (ELP) procedure for peptides, we apply it here to deltorphin,
a linear heptapeptide with bulky side chains (H-Tyr1-D-Met2-Phe3-His4-Leu5-Met6-Asp7-NH2) and compare the results with the Multicanonical method (MUCA) in regard of finding the low-energy structures. Deltorphin
is modeled in vacuum by the potential energy function ECEPP.
Received 23 July 2002 / Received in final form 18 September 2002 Published online 31 December 2002 相似文献
88.
We discuss the parametrization of quantum groups in terms of independent operators. We find that this consideration leads to the parametrization ofSU q(2) in terms of aq-oscillator plus a commuting phase. The commuting phase is naturally identified with the subgroupU(1) and the remaining cosetSU q(2)/U(1)=CP q(1) consists of aq-oscillator. For unitary quantum groupsSU q (n), the analogous construction results in the quantum projective spaceSU q(n+1)/U q (n)=CP q (n) being identified with then-dimensionalq-oscillator. This yields a nonlinear action of the quantum groupSU q(n+1) on then-dimensionalq-oscillator. 相似文献
89.
The square-wave voltammetric (SWV) behaviour of riboflavin and folic acid was studied at a static mercury drop electrode by square wave voltammetry. In 0.05M KCl (pH 5.89) a cathodic scan gave peaks at — 0.56 and — 0.87 V vs. Ag/AgCl for riboflavin and folic acid, respectively. The reduction peak currents are linearly dependent on the concentration of vitamins. Both vitamins can be simultaneously determined from the same voltammogram. The method proposed for the determination of riboflavin and folic acid in multivitamin tablets is very simple, rapid and does not involve time-consuming separation steps. The average contents of riboflavin and folic acid were found to be 14.8 ± 1.26% and 1.46 ± 2.66%, for tablet A and 9.86 ±1.40% and 1.47 ± 2.0% for tablet B, respectively. 相似文献
90.
Naz Mohammed Aghatabay Yaghub Mahmiani Hüseyin Çevik Fahrettin Gucin Basaran Dulger 《Structural chemistry》2008,19(5):833-842
Series of new mixed aza-oxo-thia macrocyclic ligands {2,6,12,16-tetraaza-1,7,11,17-tetraoxo-9,19-dithia-[(4′-methyl-5′,4,3′)(14′-methyl-15′,14,13′)]ditriazine}cyclocosane
(L
1
); {2,6,13,17-teraaza-1,7,12,18-tetraoxo-9,10,20,21-tetrathia-[(4′-methyl-5′,4,3′)(15′-methyl-14′,16′,15)]di-triazine}cyclodocosane
(L
2
); {2,6,14,18-tetraaza-1,7,13,19-tetraoxo-10,22-dithia-[(4′-methyl-5′,3′,4)(16′-methyl-15′,17′,16)]ditriazine}cyclotetracosane
(L
3
) and {2,6,15,19-tetraaza-1,7,14,12-tetraoxo-10,11,23,24-tetrathia-[(4′-methyl-5′,4,3′)(17′-methyl-8′,17,16′)]ditriazine}cyclohexa-cosane
(L
4
) were synthesized. The structural features of the compounds have been studied by elemental analyses, Mass, FT-Raman, FT-IR,
1H and 13C NMR spectroscopy. The antimicrobial activities of the ligands were evaluated using disk diffusion method in dimethyl sulfoxide
as well as the minimal inhibitory concentration (MIC) dilution method, against 9 bacteria. The obtained results from disk
diffusion method were assessed in side-by-side comparison with those of Penicillin-g, Ampicillin, Cefotaxime, Vancomycin,
Oflaxacin, and Tetracyclin, well-known antibacterial agents. The results from dilution procedure were compared with Gentamycin
as antibacterial and Nystatin as antifungal. The antifungal activities are reported on five yeast cultures namely Candida albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii, and Hanseniaspora guilliermondii, and the results are referenced with Nystatin, Ketaconazole, and Clotrimazole, commercial antifungal agents. In most cases,
the compounds show strong antifungal activity in the comparison tests. 相似文献