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81.
Boris A. Trofimov Boris G. Sukhov Svetlana F. Malysheva Natal’ya A. Belogorlova Anatolii P. Tantsirev Lidiya N. Parshina Ludmila A. Oparina Sergey P. Tunik Nina K. Gusarova 《Tetrahedron letters》2004,45(49):9143-9145
Secondary phosphines react readily with a vinyl ether of diacetone-d-glucose under radical initiation conditions to give, in high yield, anti-Markovnikov adducts, diorganyl{2-[3-O-(1,2:5,6-di-O-isopropylidene)-d-glucofuranosyloxy]ethyl}phosphines, which oxidize almost quantitatively upon reacting with air oxygen or elemental sulfur to form the corresponding optically active phosphine oxides or sulfides. 相似文献
82.
Concerning the obstacle-problem-like equation
, where + > 0 and – > 0, we give a complete characterization of all global two-phase solutions with quadratic growth both at 0 and infinity. 相似文献
83.
Häkkinen H Moseler M Kostko O Morgner N Hoffmann MA von Issendorff B 《Physical review letters》2004,93(9):093401
We present high resolution UV-photoelectron spectra of cold mass selected Cun-, Agn-, and Aun- with n=53-58. The observed electron density of states is not the expected simple electron shell structure, but is strongly influenced by electron-lattice interactions. Only Cu55- and Ag55- exhibit highly degenerate states. This is a direct consequence of their icosahedral symmetry, as is confirmed by density functional theory calculations. Neighboring sizes exhibit perturbed electronic structures, as they are formed by removal or addition of atoms to the icosahedron and therefore have lower symmetries. Gold clusters in the same size range show completely different spectra with almost no degeneracy, which indicates that they have structures of much lower symmetry. This behavior is related to strong relativistic bonding effects in gold, as demonstrated by ab initio calculations for Au55-. 相似文献
84.
We propose an efficient method for the prediction of protein folding rate constants and mechanisms. We use molecular dynamics simulation data to build Markovian state models (MSMs), discrete representations of the pathways sampled. Using these MSMs, we can quickly calculate the folding probability (P(fold)) and mean first passage time of all the sampled points. In addition, we provide techniques for evaluating these values under perturbed conditions without expensive recomputations. To demonstrate this method on a challenging system, we apply these techniques to a two-dimensional model energy landscape and the folding of a tryptophan zipper beta hairpin. 相似文献
85.
Optical waveguide sensor for on-line monitoring of bacteria 总被引:2,自引:0,他引:2
A grating-coupled planar optical waveguide sensor is presented for sensing of bacteria by evanescent waves. The waveguide design results in increased depth of penetration into the sample volume, which makes it suitable for detecting micrometer-sized biological objects. We tested the sensor's performance by monitoring the adhesion of Escherichia coli K12 cells to the sensor surface. 相似文献
86.
Vincent KA Tilley GJ Quammie NC Streeter I Burgess BK Cheesman MR Armstrong FA 《Chemical communications (Cambridge, England)》2003,(20):2590-2591
Addition of an equivalent of a polyaminocarboxylate ligand (L) to a solution of a redox protein and the aqua Eu2+ ion results in the instantaneous in situ generation of a very powerful reductant Eu(II)-L that can rapidly drive an electron stoichiometrically onto a redox centre having an extremely negative reduction potential (lower than -1 V): this is exemplified by straightforward generation of the super-reduced state of the Fe-protein of nitrogenase. 相似文献
87.
88.
89.
Nina Zorboska 《Proceedings of the American Mathematical Society》2003,131(3):793-800
We analyze the connection between compactness of operators on the Bergman space and the boundary behaviour of the corresponding Berezin transform. We prove that for a special class of operators that we call radial operators, an oscilation criterion is a sufficient condition under which the compactness of an operator is equivalent to the vanishing of the Berezin transform on the unit circle. We further study a special class of radial operators, i.e., Toeplitz operators with a radial symbol.
90.
Nina P. Gritsan Alexander Yu. Makarov Andrey V. Zibarev 《Applied magnetic resonance》2011,41(2-4):449-466
This paper gives a brief overview of a new approach to chalcogen–nitrogen heterocyclic π-radicals, particularly 1,2,3- and 1,3,2-benzodithiazolyls, based on thermolysis or photolysis of closed-shell precursors (such as 1,3,2,4-benzodithiadiazines and their 1-Se congeners, 1,2,4,3,5- and 1,3,5,2,4-benzotrithiadiazepines, and some other sulfur–nitrogen rings and cages). The approach allows obtaining radicals hardly accessible or inaccessible in other ways, especially, fluorinated radicals. The identity of radicals prepared is confirmed by electron paramagnetic resonance spectroscopy in combination with density functional theory calculations. 相似文献