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51.
Huld T.A. Pecseli H.L. Rasmussen J.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(1):149-158
The propagation of a low-density-modulated ion beam with finite cross section in a homogeneous plasma is considered. Analytical expressions describing a Cerenkov-like radiation pattern are obtained. An experimental setup is described that is suitable for investigating these phenomena. The results are in qualitative agreement with the analytical expressions 相似文献
52.
Ebbe Rasmussen 《Zeitschrift für Physik A Hadrons and Nuclei》1932,73(11-12):779-790
53.
Two methods for automated analysis of extracts from edible muscle tissue of Atlantic salmon are described. Oxolinic acid and flumequine are extracted with phosphate buffer pH 9, and the extracts are analysed by high-performance liquid chromatography using a column-switching system. One method applies on-line concentration and clean-up of the extracts on a precolumn packed with polystyrene-divinylbenzene. This method was useful for the analysis of oxolinic acid and flumequine in the microgram/g range. The other method was based on on-line dialysis and concentration of the dialysate on the polymeric precolumn. This method was shown to be a reliable method for residue analysis, and the limit of detection was 2 ng/g for oxolinic acid and 3 ng/g for flumequine with fluorescence detection. 相似文献
54.
Vianello N Naulin V Schrittwieser R Müller HW Zuin M Ionita C Rasmussen JJ Mehlmann F Rohde V Cavazzana R Maraschek M;ASDEX Upgrade Team 《Physical review letters》2011,106(12):125002
Magnetically confined plasmas in the high confinement regime are regularly subjected to relaxation oscillations, termed edge localized modes (ELMs), leading to large transport events. Present ELM theories rely on a combined effect of edge current and the edge pressure gradients which result in intermediate mode number (n?10-15) structures (filaments) localized in the perpendicular plane and extended along the field lines. By detailed localized measurements of the magnetic field perturbation associated to type-I ELM filaments, it is shown that these filaments carry a substantial current. 相似文献
55.
56.
In this introductory paper we take partial stock of the current state of field on calculus research, exemplifying both the promise of research advances as well as the limitations. We identify four trends in the calculus research literature, starting with identifying misconceptions to investigations of the processes by which students learn particular concepts, evolving into classroom studies, and, more recently research on teacher knowledge, beliefs, and practices. These trends are related to a model for the cycle of research and development aimed at improving learning and teaching. We then make use of these four trends and the model for the cycle of research and development to highlight the contributions of the papers in this issue. We conclude with some reflections on the gaps in literature and what new areas of calculus research are needed. 相似文献
57.
Jerald K. Rasmussen Steven M. Heilmann Larry R. Krepski Howell K. Smith Alan R. Katritzky Kumars Sakizadeh 《Journal of polymer science. Part A, Polymer chemistry》1986,24(11):2739-2747
The reaction of bisazlactones (2-oxazolin-5-ones) with primary diamines containing additional secondary or tertiary amine functionality (e.g., diethylenetriamine, triethylenetetramine, or N-methyliminobispropylamine) readily produces polyamides which serve as precursors to a new class of heterocyclic polymers. Thermal cyclodehydration takes place under relatively mild conditions (180–200°C) to produce water-soluble polymers containing the 2-imidazolin-5-one heterocycle. Model reactions have been studied to verify this mode of cyclization and confirm the proposed polymer structure. 相似文献
58.
An automated method for the determination of pholcodine in plasma and whole blood is described. The technique combines dialysis and trace enrichment prior to high-performance liquid chromatography. Dialysis, trace enrichment on a weak cation-exchange column, separation on a cyano column and fluorescence detection was shown to be an extremely selective and sensitive method. The method has been used successfully in the analysis of real samples after administration of pholcodine. The automated method can be used, after minor modification, to determine other basic drugs in whole blood and plasma. 相似文献
59.
Lars Eilstrup Rasmussen 《Random Structures and Algorithms》1994,5(2):349-361
In this article, we present an efficient and very simple unbiased estimator for the Permanent of square (0–1) matrices. As the main result, we prove that our estimator, even though its worst case behavior is provably very bad, runs in time polynomial in the size of the input matrix for almost all matrices. We also generalize our technique and apply it to another enumeration problem, that of counting Hamilton cycles in directed graphs. The ease with which this was done suggests that the basic technique may have wide applicability. © 1994 John Wiley & Sons, Inc. 相似文献
60.
It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) ? HOSO(+M), HOSO + H/OH ? SO2 + H2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO2 with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H2, as major products of the HOSO + H reaction is in agreement with a range of experimental results from batch and flow reactors, as well as laminar flames. 相似文献