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Andreas J. Steiner Georg Schitter Arnold E. Stütz Tanja M. Wrodnigg Chris A. Tarling Stephen G. Withers Don J. Mahuran Michael B. Tropak 《Tetrahedron: Asymmetry》2009,20(6-8):832-835
Cyclisation by double reductive amination of 2-acetamino-2-deoxy-d-xylo-hexos-5-ulose with N-2 protected l-lysine derivatives provided 2-acetamino-1,2-dideoxynojirimycin derivatives without any observable epimer formation at C-5. Modifications on the lysine moiety gave access to lipophilic derivatives that exhibited improved hexosaminidase inhibitory activities. 相似文献
165.
This article examines the ellipsograph of Archimedes, also knownas the locus problem of Franciscus van Schooten, and relatedmechanisms. We not only solve the algebraic system explicitly,but we also reverse engineer the problem and find configurationsthat provide a particular solution. Using the modern techniquesof polynomial Gröbner Bases we show this can be used asa traditional compass, as a straight edge (to draw a straightline) and as an ellipsograph to trace ellipses. 相似文献
166.
Chris C. Stowers J. Brian Robertson Hyunju Ban Robert D. Tanner Erik M. Boczko 《Applied biochemistry and biotechnology》2009,156(1-3):59-75
Four decades of work have clearly established the existence of autonomous oscillations in budding yeast culture across a range of operational parameters and in a few strains. Autonomous oscillations impact substrate conversion to biomass and products. Relatively little work has been done to quantify yield in this case. We have analyzed the yield of autonomously oscillating systems, grown under different conditions, and demonstrate that it too oscillates. Using experimental data and mathematical models of yeast growth and division, we demonstrate strategies to increase the efficient recovery of products. The analysis makes advantage of the population structure and synchrony of the system and our ability to target production within the cell cycle. While oscillatory phenomena in culture have generally been regarded with trepidation in the engineering art of bioprocess control, our results provide further evidence that autonomously oscillating systems can be a powerful tool, rather than an obstruction. 相似文献
167.
Quantised phase filters with binary low and high pass amplitude response: the effect of quantisation for scale and rotation input distortions 总被引:1,自引:0,他引:1
Triantafillos Koukoulas Rupert C.D. Young Chris R. Chatwin 《Optics and Lasers in Engineering》2005,43(9):963
In the field of optical pattern recognition, there are a large number of filters that possess identification capabilities for certain kinds of input distortions. The resolution of the spectral components plays an important role in the overall processing time of a correlator that may employ such filters. In this paper, two different techniques are discussed: low pass phase filtering and high pass phase filtering. This is achieved by binarizing the amplitude information which then allows certain frequencies to pass and others to be blocked. Their response to different kinds of input distortions is presented and the effect of phase quantisation is considered in detail. 相似文献
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Tim B. van Erp Chris T. Reynolds Ton Peijs Johannes A. W. van Dommelen Leon E. Govaert 《Journal of Polymer Science.Polymer Physics》2009,47(20):2026-2035
The time‐dependent yield and failure behavior of off‐axis loaded uniaxially oriented polypropylene tape is investigated. The yield and failure behavior is described with an anisotropic viscoplastic model. A viscoplastic flow rule is used with an equivalent stress, based on Hill's anisotropic yield criterion, and the Eyring flow theory combined with a critical equivalent strain definition. This model is based on factorization of the rate and draw ratio dependence and is capable of quantitatively predicting the rate, angle and draw ratio dependence of the yield stress as well as time‐to‐failure in various off‐axis tensile loading conditions characterized solely from the transverse direction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2026–2035, 2009 相似文献
170.
Frank Roschangar Jianxiu Liu Marine Dufour Vittorio Farina Azad Hossain Heewon Lee Richard Varsolona Pierre Beaulieu Chris H. Senanayake 《Tetrahedron letters》2008,49(2):363-366
A regioselective Larock approach to 3-substituted-2-pyridin-2-ylindoles from 2-alkynylpyridines and 2-iodoanilines is described herein. The unexpectedly high regioselectivity can be rationalized by a combination of steric, coordinative and electronic effects. 相似文献