排序方式: 共有13条查询结果,搜索用时 137 毫秒
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The diastereoselective synthesis of azabicyclo[3.1.0]hexanes bearing different substituents on all positions of the cyclopropane ring has been achieved in moderate to good yields. 相似文献
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Xinjie GaiRonald Grigg Ines KöppenJohn Marchbank Visuvanathar Sridharan 《Tetrahedron letters》2003,44(40):7445-7448
A novel palladium catalysed three-component cascade process is described involving allenylation of an aryl iodide to generate a (π-allyl)palladium species which is intercepted by a carbon or nitrogen nucleophile followed by intramolecular Michael addition to afford carbo- and heterocycles in good yield. 相似文献
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J. K. Brooks Kazuyuki Saitô JD Maitland Wright 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):5-14
LetA be aC*-algebra with second dualA″. Let (φ
n)(n=1,...) be a sequence in the dual ofA such that limφ
n(a) exists for eacha εA. In general, this does not imply that limφ
n(x) exists for eachx εA″. But if limφ
n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ
n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for
positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem. 相似文献
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The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we
use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained
from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized
neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star
masses is minimal. 相似文献
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Mahenthiralingam E Song L Sass A White J Wilmot C Marchbank A Boaisha O Paine J Knight D Challis GL 《Chemistry & biology》2011,18(5):665-677
Gram-negative Burkholderia cepacia complex (Bcc) isolates were screened for antimicrobial activity against cystic fibrosis microbial pathogens, and the ability of B.?ambifaria to inhibit B.?multivorans was identified. The activity was mapped to a cluster of cryptic, quorum-sensing-regulated modular polyketide synthase (PKS) genes. Enacyloxin IIa and its stereoisomer designated iso-enacyloxin IIa were identified as metabolic products of the gene cluster, which encoded an unusual hybrid modular PKS consisting of multiple proteins with sequence similarity to cis-acyltransferase (cis-AT) PKSs and a single protein with sequence similarity to trans-AT PKSs. The discovery of the potent activity of enacyloxins against drug-resistant bacteria and the gene cluster that directs their production provides an opportunity for engineered biosynthesis of innovative enacyloxin derivatives and highlights the potential of Bcc bacteria as an underexploited resource for antibiotic discovery. 相似文献
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