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71.
Frank Morgan Wacharin Wichiramala 《Proceedings of the American Mathematical Society》2002,130(9):2745-2751
We prove that the only equilibrium double bubble in which is stable for fixed areas is the standard double bubble. This uniqueness result also holds for small stable double bubbles in surfaces, where it is new even for perimeter-minimizing double bubbles.
72.
Sculimbrene BR Morgan AJ Miller SJ 《Journal of the American Chemical Society》2002,124(39):11653-11656
Peptide-based catalysts have been found that catalyze the enantiodivergent phosphorylation of a meso myo-inositol-derived triol (1). The sequential screening of random peptide libraries, followed by the evaluation of a focused library, led to the identification of two peptides (2 and 24) that are complementary in producing enantiomeric D-myo-inositol-1-phosphate and D-myo-inositol-3-phosphate derivatives. The catalysts were then used to complete efficient total syntheses of both D-I-1P and D-I-3P in optically pure form. Additional information is gleaned from relative rate experiments that unambiguously show the catalysts to afford enantioselection through rate accelerative pathways with respect to simple achiral alkylimidazole catalysts. Furthermore, solvent effect studies show that the two enantiodivergent catalysts exhibit different tolerances of polar media. The systematic discovery of site-selective catalysts establishes a basis for future studies of chiral catalysts that differentiate unique functional groups in polyfunctional molecules. 相似文献
73.
Bailey PD Boyd CA Bronk JR Collier ID Meredith D Morgan KM Temple CS 《Angewandte Chemie (International ed. in English)》2000,39(3):505-508
By building key structural features into hydrophilic drugs, they can be recognized by the PepT1 transporter system of the small intestine and rendered orally active. The model shown provides, for the first time, a 3D template for all known substrates of PepT1. 相似文献
74.
75.
M. Convery W. L. Davis K. DelSignore T. L. Jenkins E. Kangas M. Knepley K. L. Kowalski C. C. Taylor C. H. Wang S. H. Oh W. D. Walker P. L. Colestock B. Hanna M. A. Martens J. M. Streets R. C. Ball H. R. Gustafson L. W. Jones M. J. Longo J. D. Bjorken N. Morgan C. Pruneau 《Il Nuovo Cimento C》1996,19(6):1045-1049
Summary A small experiment, ?MiniMax?, has been set up in the C0 intersection region of the Fermilab Tevatron to seek evidence for
disoriented chiral condensates and to study other forward physics phenomena. The experiment consists of a proportional wire
chamber telescope accompanied by scintillation (trigger) counters, a lead converter, and followed by an electromagnetic calorimeter.
The solid angle accepted is a cone centered at pseudorapidity (η) of 4.1 and of radius (in η-ϕ space) of about 0.6. Over 2.5
million events thus far have demonstrated the successful operation of the apparatus, however to date the analysis has not
progressed sufficiently to permit any conclusions concerning disoriented chiral condensates.
presented byL. W. Jones
Paper presented at the Special Session on very high-energy cosmic-ray interactions (superfamilies) of the XXIV International
Cosmic-Ray Conference, Rome, August 28–September 8, 1995. 相似文献
76.
Modelling flow over a backward–facing step using the F.E.M. and the two-equation model of turbulence
Flow over a downstream-facing step is predicted using the F.E.M. A two-equation model of turbulence is employed where the transport of turbulence kinetic energy and dissipation rate are depicted using transport-type equations, i.e. the two-equation model of turbulence. The results obtained are compared with other models and experimental results. Generally, the model was found to be under-predictive with regard to the reattachment length when previous empirical data was used in the transport equations. 相似文献
77.
The best operating conditions that yield maximum sensitivity at minimum source pressure have been evaluated for the chemical ionization source in a Kratos MS-25 mass spectrometer. The best reagent gas pressure is shown to be different for each gas and is significantly lower than is usually reported in the literature. 相似文献
78.
David M. Rackham Sarah E. Morgan W. R. Nigel Williamson 《Magnetic resonance in chemistry : MRC》1980,14(6):515-516
The 13C NMR spectra of four pairs of 1,3,4-thiadiazole/thiadiazoline isomers have been recorded using broad band and off-resonance proton decoupling techniques and in the coupled mode. Differences in the chemical shifts of the heterocyclic ring and the carbonyl carbons allow identification of the isomer present. Their IR and UV spectra are in agreement with literature reports for azole/azoline analogues. 相似文献
79.
Christine A Morgan Peter J Slater 《Journal of Algorithms in Cognition, Informatics and Logic》1980,1(3):247-258
A core of a graph G is a path P in G that is central with respect to the property of minimizing d(P) = Συ?V(G)d(υ, P), where d(υ, P) is the distance from vertex υ to path P. We present a linear algorithm for finding a core of a tree. Since the core of a graph is not necessarily unique, we also output a list of all the vertices which are in some core. 相似文献
80.
A passive layer, of several thousand ? thickness, formed on a polycrystalline nickel electrode, has been examined using secondary
ion mass spectrometry (SIMS) by spottering with a 5.5 keV, 13μA·cm−2,40Ar+ primary beam. Concentration profiles were detived by monitoring the intensities of atomic and molecular mass peaks as a function
of sputtering time (i.e. depth). Nickel was present throughout the layer but not as the element since the relative intensities
of the Ni
n
+
(n=1, 2, 3, 4) peaks, constituting part of its fingerprint spectrum, differed from those in the fingerprint spectrum of elemental
nickel. These values were eventually reached, signifying piercing of the layer and thus providing a means of estimating its
thickness. Imaging of58Ni+ showed the presence of nickel in at least two different modifications in the layer, both with higher Ni+ yields than the bulk nickel. Their fractional coverages were estimated from the images taken at various depths. The resulting
profile of the Ni+ originating from one of these modifications was found to be proportional to the16O− profile, indicating that these ions originate from the same molecule.
This example demonstrates the advantage of combining different SIMS modes (viz. depth profiles, fingerprint spectra and imaging)
in tackling certain analytical problems. 相似文献