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151.
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
152.
Guy Solladié Christine Greck Gilles Demailly Arlette Solladié-Cavallo 《Tetrahedron letters》1982,23(48):5047-5050
It is shown that reductions of β-ketosulfoxides of identical chirality (R) at sulfur, lead to reduction products of opposite stereochemistry according to the reducing agent used. The high enantiomeric excesses obtained (80 to 100%) provide a general route to both enantiomers of methylcarbinols from the corresponding esters. 相似文献
153.
Christine?Hartwig Andres?Veske Sarka?Krejcova Georg?Rosenberger Ulrich?FinckhEmail author 《BMC neuroscience》2005,6(1):53
Background
Plexins, known to date as receptors of semaphorins, are implicated in semaphorin-mediated axon repulsion and growth cone collapse. However, subtype-specific functions of the majority of the nine members of the mammalian plexin family are largely unknown. In order to investigate functional properties of B-plexins, we analyzed the expression of human and murine plexin B3 and expressed full-length human plexins B2 (B2) and B3 (B3) in NIH-3T3 cells. 相似文献154.
155.
Allison IF Davies CT Gray A Kronfeld AS Mackenzie PB Simone JN;HPQCD;Fermilab Lattice;UKQCD 《Physical review letters》2005,94(17):172001
We use lattice QCD to predict the mass of the Bc meson. We use the MILC Collaboration's ensembles of lattice gauge fields, which have a quark sea with two flavors much lighter than a third. Our final result is mBc = 6304+/-12(+18)(-0) MeV. The first error bar is a sum in quadrature of statistical and systematic uncertainties, and the second is an estimate of heavy-quark discretization effects. 相似文献
156.
This study examined combinations of energetic and informational maskers in speech identification. Speech targets and maskers (speech or noise) were processed and filtered into sets of 15 narrow frequency bands. The target was the sum of eight randomly selected bands. More masking occurred for speech maskers than for spectrally matched noise maskers regardless of whether the masker bands overlapped the target bands. The greater effect of the speech maskers was interpreted as due to informational masking. When the masker was comprised of nonoverlapping bands of speech, the addition of bands of noise overlapping the speech masker, but not the speech target, reduced the overall amount of masking. Surprisingly, presenting the noise to the ear contralateral to the target and masker produced an even greater release from masking. The contralateral noise was apparently sufficient to cause a slight change in the image of the ipsilateral speech masker, possibly pulling it away from the target enough to allow the focus of attention on the target. This finding is consistent with the interpretation that in some conditions small binaural differences may be sufficient to cause, or significantly strengthen, the perceptual segregation of sounds. 相似文献
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159.
Alain Tressaud Etienne Durand Christine Labrugère 《Journal of fluorine chemistry》2004,125(11):1639-1648
Due to their extreme reactivity, fluorine and fluorinated gases may be used to modify the surface properties of numerous materials. In the following, the surface fluorination of some carbon-based compounds (graphite, graphitised carbon fibres, carbon blacks and elastomers) using CF4 rf plasma technique and direct F2-gas fluorination is proposed. From XPS studies, the different types of CF bonding obtained in the materials after treatment have been correlated either to the physico-chemical characteristics of the pristine material or to the experimental parameters of the fluorination. Reaction mechanisms are proposed. 相似文献
160.
Modular polyketide synthases biosynthesise natural products through successive Claisen-type condensations, where one module is responsible for one round of chain extension. This review describes recent findings where this rule of co-linearity is broken, either by one module being bypassed (skipping) or through one module being used for multiple chain extension events (stuttering). 相似文献