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991.
IntroductionAsoneofthemostimportantC—Cformationreactionsandone stepmethodforthearylationofolefins ,Heckre actionhasattractedmuchinterest.1However ,thereactionusuallyneedsarelativelylargeamountofpalladiumcata lyst (>1mol%)forsatisfactoryconversions .Recently ,avarietyofpalladacyclesincorporatingcyclometallatedphos phine ,2 phosphite ,3 carbene ,4 imine5andoxime6havebeenreported .Theuseofcatalystswithnitrogen basedligandswasdemonstratedtopossessveryhighactivity .Wehavereportedthecyclopalladat… 相似文献
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Rui GUO. En Yong DING* Key Laboratory of Cellulose Lignocellulosics Chemistry Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou Graduate School of the Chinese Academy of Sciences Beijing 《中国化学快报》2006,(5)
The κ-carrageenan comes from a family of linear water-soluble polysaccharides extracted from different species of marine red algae with a primary structure of an alternating disaccharide with repeating unit of 3-linked β-D-galactose 4-sulfate and 4-link… 相似文献
995.
LAN Congqing CHEN Yanhua Wuhan Institute of Physics Academia Sinica Wuhan )with the Institute of Acoustics Academia Sinica. 《声学学报:英文版》1993,(1)
For ultrasonic reflective tomographic imaging of differenttransmitter-receiver mode,we demonstrate that the Fourier slice theorem canbe used when the distance between the transducer and origin becomes muchlarger than the object to be reconstructed.Iterative reconstruction formulabased on the Fourier slice theorem is proposed for the case in which theparaxial approximation holds.The effect caused by the curvature of integrallines may be eliminated iteratively and better reconstructed images can be ex-pected. 相似文献
996.
The H Collaboration 《The European Physical Journal C - Particles and Fields》2005,41(4):453-467
A measurement of the beauty production cross section in ep collisions at a centre-of-mass energy of 319 GeV is presented. The data were collected with the H1 detector at the HERA collider in the years 1999-2000. Events are selected by requiring the presence of jets and muons in the final state. Both the long lifetime and the large mass of b-flavoured hadrons are exploited to identify events containing beauty quarks. Differential cross sections are measured in photoproduction, with photon virtualities Q2 < 1 GeV2, and in deep inelastic scattering, where 2 < Q2 < 100 GeV2. The results are compared with perturbative QCD calculations to leading and next-to-leading order. The predictions are found to be somewhat lower than the data.Received: 7 February 2005, Revised: 26 April 2005, Published online: 31 May 2005 相似文献
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There is a common hypothesis for the presently popular mild-slope equations that wave particle motion is irrotational. In this paper, an attempt is made to abandon the irrotational assumption and to set up new sea wave packet equations on slowly varying topography by use of the WKBJ method. To simplify the deduction, the two-dimensional shallow water equations are used to describe the sea wave particle motion in the very shallow nearshore area. The established equations can give some characteristics of wave propagation near shore. 相似文献
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Enrique Zas for the Pierre Auger Collaboration 《Czechoslovak Journal of Physics》2006,56(1):A231-A240
The southern Auger Observatory which is being constructed in Malargüe, Mendoza, Argentina, is already the largest cosmic ray detector in operation. It has been collecting data at an ever increasing rate since January 2004. The detector concept, its design and a status report of the construction progress are presented. The first results obtained with the data taken up to June 2005, which make use of the hybrid capabilities of the detector to establish the energy of the detected events, are summarized. 相似文献