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安徽沼虾和米虾的同步辐射X射线荧光分析及对水环境污染的监测作用 总被引:2,自引:0,他引:2
同步辐射X射线荧光分析了安徽省4个地区的沼虾(Macrobrachium nipponesis)和米虾(Caridina denticulate sinensis)尾扇9个样品中重元紊含量;比较了7种不同水环境中沼虾的元素含量,显示出虾中元素含量随水环境的不同而改变,其中Mn/Fe或Cu/Zn元素的比值强烈地与水环境富营养污染程度相关。生活在同一水环境中米虾的重元素Br、Hg和Pb的富集量分别是沼虾的5.0倍、2.7倍和2.3倍。测量了老龄沼虾和成年沼虾的元素含量,发现老龄沼虾富集的Hg和Pb分别是成年虾的5倍和4倍,而Cu和Zn的含量却降低到成年虾的1/8和1/2。 相似文献
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The strong interactions of the negative-parity heavy mesons with ρ meson may be described consistently in the context of an effective Lagrangian, which is invariant under isospin SU(2) transformation. Four coupling constants gHHρ, fH∗Hρ, gH∗H∗ρ and fH∗H∗ρ enter the effective Lagrangian, where H (H∗) denotes a pseudoscalar bottom or charm meson (the corresponding vector meson). Using QCD light cone sum rule (LCSR) method and, as inputs, the hadronic parameters updated recently, we give an estimate of gH∗H∗ρ and fH∗H∗ρ, about which little was known before, and present an improved result for gHHρ and fH∗Hρ. Also, we examine the heavy quark asymptotic behavior of these nonperturbative quantities and assess the two low energy parameters β and λ of the corresponding effective chiral Lagrangian. 相似文献
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Tao Huang Zuo-Hong Li Fen Zuo 《The European Physical Journal C - Particles and Fields》2009,60(1):63-71
The light-cone QCD sum rules approach improved by using the chiral current correlator is systematically reviewed and applied
to the calculation of all the heavy-to-light form factors, including all the semileptonic and penguin ones. By choosing suitable
chiral currents, the light-cone sum rules for all the form factors are greatly simplified and depend mainly on one leading-twist
distribution amplitude of the light meson. As a result, relations between these form factors arise naturally. At the considered
accuracy, these relations reproduce the results obtained in the literature. Moreover, since the explicit dependence on the
leading-twist distribution amplitudes is preserved, these relations may be more useful to simulate the experimental data and
extract information on the distribution amplitude. 相似文献
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