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961.
962.
Improper choosability of planar graphs has been widely studied. In particular, ?krekovski investigated the smallest integer gk such that every planar graph of girth at least gk is k‐improper 2‐choosable. He proved [9] that 6 ≤ g1 ≤ 9; 5 ≤ g2 ≤ 7; 5 ≤ g3 ≤ 6; and ? k ≥ 4, gk = 5. In this article, we study the greatest real M(k, l) such that every graph of maximum average degree less than M(k, l) is k‐improper l‐choosable. We prove that if l ≥ 2 then . As a corollary, we deduce that g1 ≤ 8 and g2 ≤ 6, and we obtain new results for graphs of higher genus. We also provide an upper bound for M(k, l). This implies that for any fixed l, . © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 181–199, 2006 相似文献
963.
We combined the ultrabroadband supercontinuum of a photonic crystal fiber with a pulse shaper, resulting in a highly flexible light source for multiplex coherent anti-Stokes Raman microscopy. Implemented as the Stokes pulse, it provides tailored selection of the relevant Raman transitions, resulting in a reduced photon load and partial suppression of the nonresonant background. This experiment exploits the advantages of multiplex excitation with the increased acquisition speed of single-channel detection. The molecule-specific Stokes pulses are demonstrated for chemical mapping of a polymer blend. 相似文献
964.
Itô semimartingales are the semimartingales whose characteristics are absolutely continuous with respect to Lebesgue measure. We study the importance of this assumption for statistical inference on a discretely sampled semimartingale in terms of the identifiability of its characteristics, their estimation, and propose tests of the Itô property against the non-Itô alternative when the observed semimartingale is continuous, or discontinuous with finite activity jumps, and under a number of technical assumptions. 相似文献
965.
Fernando Ruiperez Cecile Danilo Florent Real Jean‐Pierre Flament Valerie Vallet Ulf Wahlgren 《ChemInform》2009,40(19):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
966.
967.
An efficient method for preparation of 4,6 or 5,6 disubstituted 3-aminopyridazines was easily carried out starting from easily available 4-bromo-pyridazine-3,6-dione, and using combination of both amination and Pd(0) cross-coupling reactions under microwave irradiation. 相似文献
968.
969.
970.
Abstract We have investigated Cu, Zn Superoxide Dismutase (Cu, Zn SOD) metal sites at high pressure using X-ray absorption. XAS (X-ray Absorption Spectroscopy) gives information on local structure and it is particularly suited to metal site investigation. To the best of our knowledge, this is the first time that protein conformational states have been investigated using the high pressure XAS technique. Cu, Zn SOD catalyses the dismutation of toxic oxygen radicals produced in cells; this reaction occurs at the copper metal site. Structural changes around the copper, induced by pressure, can be directly related to protein substates. Their characterisation is thus important in the understanding of protein activity. The high-pressure device was a Paris-Edinburgh large volume cell. Experiments were performed on lyophilised Cu, Zn SOD between 0 and 48 kbar at the copper and zinc K-edges. The two metal local atomic environments have a different behaviour as pressure increases: copper exhibits a more flexible environment; on the contrary, zinc shows small structural modifications. We have identified a state, formed between 3 and 8 kbar, which is stable up to 48 kbar. 相似文献