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71.
A tris(bromo-methylphenylene)triazine and its corresponding phosphine oxide derivative have been synthesized; the latter compound was found to be a potent ligand for the hydroformylation reaction. Suzuki coupling of the mono-pinacolboronate derivative of the former compound with a tris(iodo-methylphenylene)triazine was possible at two of the three iodine atoms, yielding a bromo- and iodo-methylphenylene periphery-functionalized triazine-based dendritic molecule with a 3,3′-dimethyl-biphenyl linker. 相似文献
72.
Gottfried Pohlentz Ioannis Marlis Heinz Egge 《Journal of carbohydrate chemistry》2013,32(7):1151-1165
Abstract N-Phthaloyl, N-acetyl, N-benzyl, N-acetyl-N-methyl, N,N-dimethyl, N-benzoyl, and N,N-dibenzoyl derivatives of the trisaccharide β-D-glucopyranosyl-(1-3)-O-(2-deoxy-2-amino-β-D-glucopyranosyl)-(1-4)-O-β-D-glucopyranose were synthesized and analyzed by FAB MS. The intensity ratios of the peaks resulting from cleavage of the anomeric bond of the glucosamine residue and the respective molecular ion peaks turned out to be high for the N-acyl derivatives and up to two orders of magnitude lower for the N-alkyl compounds. These results show that fragmentation at the anomeric carbon of the amino sugar may be assisted by the carbonyl group and the resulting cation is stabilized by delocalization of the positive charge. 相似文献
73.
74.
Two Characterizations of Optimality in Dynamic Programming 总被引:1,自引:0,他引:1
It holds in great generality that a plan is optimal for a dynamic programming problem, if and only if it is “thrifty” and
“equalizing.” An alternative characterization of an optimal plan, that applies in many economic models, is that the plan must
satisfy an appropriate Euler equation and a transversality condition. Here we explore the connections between these two characterizations. 相似文献
75.
Ioannis K. Argyros
Ferenc Szidarovszky
《Applied mathematics and computation》1990,40(2):179-185This paper discusses monotonicity concepts to compare iteration sequences and common fixed points of point-to-set mappings. Three particular applications are presented. A new proof of the Gronwall lemma is first introduced, and then the monotonicity of input-output systems is analysed. Matrices with nonnegative inverses are finally examined. 相似文献
76.
Anastassia N. Rissanou Spiros H. Anastasiadis Ioannis A. Bitsanis 《Journal of polymer science. Part A, Polymer chemistry》2009,47(24):2462-2476
When a polymer chain in solution interacts with an atomically smooth solid substrate, its conformational properties are strongly modified and deviate substantially from those of chains in bulk. In this work, the interplay of two competing transitions that affect the conformations of polymer chains near an energetically attractive surface is studied by means of Monte Carlo simulations on a cubic lattice. The transition from an extended to a compact conformation of a polymer chain near an attractive wall, as solubility deteriorates, exhibits characteristics akin to the “coil-to-globule” transition in bulk. An effective θ-temperature is determined. Its role as the transition point is confirmed in a variety of ways. The nature of the coil-to-compact transition is not qualitatively different from that in the bulk. Adsorbed polymer chains may assume “globular” or “pancake” configurations depending on the competition among adsorption strength, cohesive energy, and entropy. In a very relevant range of conditions, the dependence of the adsorbate thickness on chain-length is intermediate between that of 3-d (“semidroplets”) and 2-d (“pancake”) objects. The focus of this study is on rather long polymer chains. Several crucial features of the transitions of the adsorbed chains are N-dependent and various aspects of the adsorption and “dissolution” process are manifested clearly only at the “long chain” limit. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2462–2476, 2009 相似文献
77.
Christodoulos Athanasiadis Gary F. Roach Ioannis G. Stratis 《Mathematische Nachrichten》2003,250(1):3-16
A time domain analysis of the equations governing wave propagation in an unbounded chiral medium is presented by a spectral family approach and by a direct eigenfunction expansion using Beltrami–Moses fields. 相似文献
78.
Ioannis Emmanouil 《Inventiones Mathematicae》1998,132(2):307-330
In this paper, we use the Connes-Karoubi character liftings of the Hattori-Stallings rank in order to obtain examples of
groups satisfying Bass' conjecture. We consider the nilpotence of the periodicity operator in cyclic homology and verify the
conjecture for a certain class of groups which contains properly the ones studied by Eckmann. We also give an application
of this method to the idempotent conjecture.
Oblatum 21-III-1997 & 12-VI-1997 相似文献
79.
Sotirios Zarogiannis Vassilios Liakopoulos Chrissi Hatzoglou Konstantinos Vogiatzidis Marios Salmas Ioannis Stefanidis Konstantinos Gourgoulianis Paschalis Adam Molyvdas Spiros Lafis 《Analytical sciences》2007,23(5):593-595
This article reports on the development of a simple and cost-effective bioassay for the detection of biotin in urine and serum, based on the very selective binding of avidin and biotin. Avidin was allowed to react without isolating it from egg white. Egg white was treated with the dye HABA, which binds to avidin. Upon subsequent treatment with biotin, HABA is released due to the high affinity of biotin to avidin. The amount of HABA released is proportional to the amount of biotin used. 相似文献
80.
Ioannis K. Argyros 《BIT Numerical Mathematics》1990,30(1):92-100
New error bounds for the modified secant method are provided. We show that our error estimates are better than the ones already existing in the literature, under similar assumptions. 相似文献