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991.
A quick, accurate, reproducible high performance liquid chromatographic (HPLC) method for the determination of clenbuterol in the presence of some common pharmaceutical preservatives (i.e., methyl and propyl paraben) is described. The method is specific enough to separate and determine clenbuterol in the presence of degradation products of the formulation components. Extraction of interfering formulation components provides the necessary clean-up to determine clenbuterol via HPLC. 相似文献
992.
This article is concerned with translation planesP of orderq 2 and kernelK isomorphic toG F(q). IfP admits a collineation groupG in the linear translation. complement and the order ofG K/K isq 2(q?1) then it is shown thatP is either a semifield plane or is a Lüneburg-Tits, Walker or Betten plane. This generalizes earlier work of Bartolone. 相似文献
993.
In an ordinary list multicoloring of a graph, the vertices are “colored” with subsets of pre‐assigned finite sets (called “lists”) in such a way that adjacent vertices are colored with disjoint sets. Here we consider the analog of such colorings in which the lists are measurable sets from an arbitrary atomless, semifinite measure space, and the color sets are to have prescribed measures rather than prescribed cardinalities. We adapt a proof technique of Bollobás and Varopoulos to prove an analog of one of the major theorems about ordinary list multicolorings, a generalization and extension of Hall's marriage theorem, due to Cropper, Gyárfás, and Lehel. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 179–193, 2007 相似文献
994.
H.M. Widatallah C. Johnson A.M. Gismelseed J.F. Marco M. Pekala 《Journal of Physics and Chemistry of Solids》2006,67(8):1817-1822
Single-phased Cu2+-substituted spinel-related Li0.5Fe2.5O4 was synthesized by sintering a mixture of Cu2+-substituted corundum-related α-Fe2O3 and Li2CO3 at 700 °C which is ∼325-400 °C lower than the temperature at which the material is prepared by the conventional ceramic methods. X-ray powder diffraction, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and magnetic measurements were used to characterize the material. In contrast to high-temperature synthetic routes, the present one leads to a Cu+-and Fe2+-cation free material, thereby optimizing its technological value. Rietveld refinement of the XRD data favors a structural model in which Cu2+ substitutes for both Fe3+ and Li+ at the octahedral sites. Mössbauer and magnetic data are consistent with this model if spin thermal reversal and/or spin canting are taken into account for the later. 相似文献
995.
Weak Cayley table functions between groups are generalized conjugacy-preserving homomorphisms, under which products of images
are conjugate to images of products. There is a weak Cayley table bijection between two groups iff they have the same 2-characters.
In this paper, weak Cayley table functions are augmented to include the specific conjugating elements, leading to the concept
of a weak (Cayley table) morphism. If the conjugating elements are chosen subject to a crossed-product condition, then the
weak morphisms between groups form a category. The forgetful functor to this category from the category of group homomorphisms
is shown to possess a left adjoint. Two weak morphisms are said to be homotopic if they project to the same weak Cayley table
function. As a first step in the analysis of the category of weak morphisms, the group of units of the monoid of weak morphisms
homotopic to the identity automorphism of a group is described. 相似文献
996.
The FIRST FIT DECREASING algorithm for bin packing has long been famous for its guarantee that no packing it generates will use more than times the optimal number of bins. We present a simple modified version that has essentially the same running time, should perform at least as well on average, and yet provides a guarantee of . 相似文献
997.
998.
A microwave-induced discharge spectrometric method is described for determining temperature profiles of oxygen and carbon evolution from solids. Profiles of oxygen and carbon evolved from Ba2YCu3O7 over the temperature range 50–1000° C are obtained by chemiluminescent formation of NO and CN resulting from reactions with active nitrogen. Intensity profiles measured at 304.3 and 388.3 nm respectively show coincident maxima at 750 and 930° C for O2 and COx evolution. In the case of oxygen, evolution is observed also over the broad range 175 to 975° C with an additional maximum at approximately 490° C. Integration of NO intensity over time compared to results from calibration graphs using known gases provided a means of determining the mass of oxygen evolved from samples. Comparisons showed these results to be within ± 10% of the gravimetric result with a correlation coefficient greater than 0.95. 相似文献
999.
1000.
A submersible chemical analyzer (SCANNER) has been developed which can perform analyses in situ in the ocean. The SCANNER is based on a modified flow-injection system and can be used to automate virtually any spectrophotometric determination that can be done by flow injection analysis. The SCANNER consists of a multichannel peristaltic pump, solid-state colorimeters, manifold tubing, valves, and an electronic module. All of the components are pressure-tolerant, except the electronics module, which is placed in a pressure housing. Typical detection limits are of the order of 0.1 μM. Sample introduction is continuous. The SCANNER has been tested successfully to pressures of 3300 dbar in the laboratory and to depths of 2500 m in the ocean. Examples of silicate and sulfide determinations around animal communities in a deep-sea hydrothermal vent field are presented. 相似文献