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131.
Juan F García-Reyes Pilar Ortega-Barrales Antonio Molina-Díaz 《Analytical sciences》2007,23(4):423-428
A combined approach based on solid-phase optosensing and multicommutation principles has been applied to develop a method for the simultaneous analysis of two pharmaceuticals (naproxen and salicylic acid) in biological fluids. The multicommuted flow-through optosensor was based on direct native fluorescence measurements of both analgesics using a non-polar sorbent (C18 silica gel) as a solid sensing zone. The flow system was controlled by Java-written home-made software and designed using three-way solenoid valves for an independent automated manipulation of sample and carrier solutions. Using an optimized sampling time, the method was calibrated in the range of 1 - 25 and 5 - 200 ng mL(-1). The obtained detection limits were 0.3 and 1.3 ng mL(-1) for naproxen and salicylic acid, respectively, with RSD (%) values of better than 2% for both analytes. The proposed methodology was successfully applied to urine, serum and pharmaceutical preparations. Recovery percentages ranging from 96.1 to 104% were obtained for both analytes. 相似文献
132.
133.
L. Barral J. Cano A. J. López J. López P. Nogueira C. Ramírez 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1167-1174
Using dynamic mechanical analysis (DMA) we have studied thermal degradation for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcylohexane (1,3-BAC). The changes of dynamic mechanical properties during thermal degradation indicated a shift of the glass transition temperature (T g) to higher temperatures and a decrease in the peak value of the dynamic loss factor (tan δ) with an increasing of aging time. The value of dynamic storage modulus (E′) at the rubbery state showed an increase with aging time, whiteE′ at the glassy state only underwent a moderate change with increased thermal degradation. From these results it can be argued that thermal degradation during the stage prior to the onset of the severe degradation involves structural changes in the epoxy system, as further crosslinking and loss of dangling chains in the crosslinked network. 相似文献
134.
135.
136.
We derive the action of 2D gravity from the two-cocycle of the Virasoro group by using a previously introduced method for constructing a dynamical system from a Lie group. A natural construction and explanation of the hidden SL(2,
)-Kac-Moody symmetry, of general applicability, is provided. We also show how the proper quantization goes beyond the ordinary co-adjoint orbit method, and the possible connection with the Poisson-Lie groups. 相似文献
137.
In this article we prove a local existence and uniqueness theorem for the Kadomtsev-Petviashvili Equation (u
t
+u
xxx
+uu
x
)
x
−u
yy
=0) in the Sobolev spaces of orders≥3, with initial values in the same spaces, and periodic boundary conditions. This theorem improves previous results based
upon the application of singular perturbation techniques. 相似文献
138.
Ferric ferrocyanides synthesized from different sources of ferric cations and ferrocyanide anions and those derived from ferrous ferricyanide, ferrous ferrocyanide and ferric ferricyanide have been studied using Mössbauer and XRD techniques. Structural information of the effect of the provenance on the properties of the final compound is obtained. Significant correlations between isomer shift and quadrupole splitting of inner and outer iron cations have been observed. 相似文献
139.
Using the time differential perturbed angular correlation technique, the hyperfine interactions as titanium sites in ZnTiF6·6H2O and its decomposition products were determined between room temperature (300 K) and 1273 K. The different steps in the decomposition pattern were identified and a simple model is given for it. 相似文献
140.
R García-Flores X Z Wang T F Burgess 《The Journal of the Operational Research Society》2003,54(4):350-361
A project to improve inventory management in a small UK chemical company is described. A research group comprising university academics and company managers for logistics and information technology examined current practices and analysed a database of historical records of business operations of the company. Based on the analysis, a scheme to categorise stock and set ordering policies to optimise inventory costs was developed. Some comments are made on process issues and the learning that took place. 相似文献