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661.
662.
Kordyuk AA Borisenko SV Zabolotnyy VB Geck J Knupfer M Fink J Büchner B Lin CT Keimer B Berger H Pan AV Komiya S Ando Y 《Physical review letters》2006,97(1):017002
Applying the Kramers-Kronig consistent procedure, developed earlier, we investigate in detail the formation of the quasiparticle spectrum along the nodal direction of high-Tc cuprates. The heavily discussed "70 meV kink" on the renormalized dispersion exhibits a strong temperature and doping dependence when purified from structural effects such as bilayer splitting, diffraction replicas, etc. This dependence is well understood in terms of fermionic and bosonic constituents of the self-energy. The latter follows the evolution of the spin-fluctuation spectrum, emerging below some doping dependent temperature and sharpening below Tc, and is mainly responsible for the formation of the kink in question. 相似文献
663.
A 1:1 adduct of chloranilic acid with 5,5'-dimethyl-2,2'-bipyridine, in which two kinds of molecules are connected by infinite hydrogen bond chains, exhibits a distinct dielectric phase transition when cooled. Below T(c)(=318 K) the hydrogen atoms participating in hydrogen bonding undergo long-range ordering and form an antiferroelectric-like state, taking a single minimum potential in the high-temperature phase (T>T(c)) due to the bifurcate hydrogen bond system. The proton-transfer phenomenon was clearly observed by electron density distribution analysis using a maximum entropy method of synchrotron x-ray diffraction data. 相似文献
664.
Anion-controlled circular dichroism (CD) spectral changes in Hg(2+) complexes with a chiral bidentate ligand are reported. Although the Hg(CF(3)SO(3))(2) and Hg(CF(3)CO(2))(2) complexes with (R)-(-)-1-(naphthalen-1-yl)-N,N-bis(pyridin-4-ylmethyl)ethanamine, (R)-(-)-1, show significant CD spectral changes, no CD spectral changes were observed in the HgCl(2), HgBr(2), Hg(CN)(2), or Hg(CH(3)CO(2))(2) complexes. X-ray analysis indicates that both the (R)-(-)-1-Hg(CF(3)SO(3))(2) and (R)-(-)-1-HgCl(2) complexes form a coordination polymer and a discrete 2:3 [=(R)-(-)-1/HgCl(2)] complex with a figure-eight structure. X-ray crystallography revealed that (i) the Hg-Hg distances bridged by anions vary depending on the anions used and (ii) a coordination polymer cannot be formed when the Hg-Hg distances are too short. Therefore, the formation of a coordination polymer is required to give the observed significant CD spectral changes. 相似文献
665.
Yohsuke Satoh Dai Kawamura Masashi Yamaura Yoichi Ikeda Yumi Ochiai Ichiro Hayakawa Hideo Kigoshi 《Tetrahedron letters》2012,53(11):1390-1392
Biselides A and B are cytotoxic marine polyketides. We have achieved synthesis of the C-1–C-15 segment of biselides A and B by using Stille coupling and regioselective oxidative cleavage as key steps. Furthermore, we constructed the α,β-unsaturated lactone part of biselide E by using a similar strategy. 相似文献
666.
In this article,we establish the global asymptotic stability of a disease-free equilibrium and an endemic equilibrium of an SIRS epidemic model with a class of nonlinear incidence rates and distributed... 相似文献
667.
668.
Hiroko Shimomura Yutaka Sashida Kazunori Ogawa Yoichi Iitaka 《Tetrahedron letters》1981,22(14):1367-1368
The structure of a new bitter neo-clerodane, ajugamarin, isolated from Makino, has been elucidated by spectroscopic studies and confirmed by X-ray crystallographic analysis. 相似文献
669.
670.
Based on 1H and 13C NMR spectral data and chemical degradation, the structure of capoamycin, a new isotetracenone antibiotic has been determined as shown in Fig. 1. 相似文献