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61.
The parallel synthesis of chiral bidentate ligands and their subsequent use in situ for a catalytic process is described. The ligands thus prepared gave comparable results to those obtained when the ligands were synthesized and purified by conventional means. This includes oxazolines and other compounds of similar complexity, meaning that for the first time these valuable compounds have been brought into the field of combinatorial catalysis. 相似文献
62.
Type-I coil planet centrifuge produces a uniformly circulating centrifugal force field to produce vortex motion of two immiscible solvent phases in a cylindrical cavity of the separation column to perform efficient countercurrent chromatography. The partition efficiency obtained from the original vortex column was substantially improved by threading the cylindrical cavity to increase the area of mass transfer between the two phases. Partition efficiency of the threaded column was evaluated by three different two-phase solvent systems with a broad range of hydrophobicity each with a set of suitable test samples. Overall results of the present studies indicated that the threaded cylindrical column substantially improves the partition efficiency in terms of theoretical plate number, peak resolution, and height equivalent of one theoretical plate. The results also indicated that higher peak resolution is produced by eluting either the upper phase in the head to tail direction or the lower phase in the reversed direction. When there is a choice in the mobile phase, a better separation is achieved by using the less viscous phase as the mobile phase. Since the present system gives extremely low column pressure, it may be a potential alternative to the conventional type-J HSCCC system for a large-scale preparative separation. 相似文献
63.
In this paper we use the combinatorics of alcove walks to give uniform combinatorial formulas for Macdonald polynomials for all Lie types. These formulas resemble the formulas of Haglund, Haiman and Loehr for Macdonald polynomials of type GLn. At q=0 these formulas specialize to the formula of Schwer for the Macdonald spherical function in terms of positively folded alcove walks and at q=t=0 these formulas specialize to the formula for the Weyl character in terms of the Littelmann path model (in the positively folded gallery form of Gaussent and Littelmann). 相似文献
64.
A regioselective synthesis of 2,4,6-trisubstituted pyridine is described starting from 2,6-dibromo-4-nitropyridine. All three different regioisomers of the 2,4,6-triamino substituted pyridine have been synthesized in four to five steps. The method described is a general route to unsymmetrical 2,4,6-trisubstituted amino pyridines. 相似文献
65.
Ferenc Vajda Edward Della Torre Martha Pardavi-Horvath 《Journal of magnetism and magnetic materials》1993,120(1-3):289-291
It has been shown that the scalar properties of recording media can be characterized by a moving model that includes reversible and irreversible magnetizing processes. A test of this model for various media is reported in this paper. It is found that the model is capable of calculating accurate major and minor loops. 相似文献
66.
Mary M. Gilbert Jack J. Donn Martha Peirce Kenneth R. Sundberg Klaus Ruedenberg 《Journal of computational chemistry》1985,6(3):209-215
A method of graphically exhibiting detailed information about a three-dimensional electron distribution function f(x,y,z) is described. Contour lines f = constant are drawn on a set of equidistant parallel planes that intersect the distribution, and a perspective view of all contours on all planes is displayed. Representative examples are given. 相似文献
67.
Martha Rzedowski-Calderón Gabriel Villa Salvador Manohar L. Madan 《Mathematische Zeitschrift》1997,224(1):77-101
Dedicated to Professor Peter Roquette
Received 1 February 1996; in final form 26 April 1996 相似文献
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