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991.
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Yuri Tomisaka Aya Yoshimura Akihiro Nomoto Motohiro Sonoda Akiya Ogawa 《Research on Chemical Intermediates》2013,39(1):43-48
The reduction of dodecyl iodide, as model compound, with a series of lanthanoid (Ln) metals in the presence of catalytic amounts of samarium diiodide (SmI2) has been investigated in detail. The reducing activity of SmI2/Ln and the kinds of reduced products were found to be dependent on the individual Ln, but not on SmI2. 相似文献
995.
Umut Aydemir Alim Ormeci Horst Borrmann Bodo Bhme Fabio Zürcher Burcu Uslu Thorsten Goebel Walter Schnelle Paul Simon Wilder Carrillo‐Cabrera Frank Haarmann Michael Baitinger Reinhard Nesper Hans Georg von Schnering Yuri Grin 《无机化学与普通化学杂志》2008,634(10):1651-1661
The Zintl phase Ba3Si4 has been synthesized from the elements at 1273 K as a single phase. No homogeneity range has been found. The compound decomposes peritectically at 1307(5) K to BaSi2 and melt. The butterfly‐shaped Si46− Zintl anion in the crystal structure of Ba3Si4 (Pearson symbol tP28, space group P42/mnm, a = 8.5233(3) Å, c = 11.8322(6) Å) shows only slightly different Si‐Si bond lengths of d(Si–Si) = 2.4183(6) Å (1×) and 2.4254(3) Å (4×). The compound is diamagnetic with χ ≈ −50 × 10−6 cm3 mol−1. DC resistivity measurements show a high electrical resistivity (ρ(300 K) ≈ 1.2 × 10−3 Ω m) with positive temperature gradient dρ/dT. The temperature dependence of the isotropic signal shift and the spin‐lattice relaxation times in 29Si NMR spectroscopy confirms the metallic behavior. The experimental results are in accordance with the calculated electronic band structure, which indicates a metal with a low density of states at the Fermi level. The electron localization function (ELF) is used for analysis of chemical bonding. The reaction of solid Ba3Si4 with gaseous HCl leads to the oxidation of the Si46− Zintl anion and yields nanoporous silicon. 相似文献
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Ida Berts Yuri Gerelli Jöns Hilborn Adrian R. Rennie 《Journal of Polymer Science.Polymer Physics》2013,51(6):421-429
Knowledge of the structure of a biomaterial is usually vital to control its function. This article provides a structural characterization of a hyaluronan scaffold that has demonstrated good biocompatibility and is used to induce bone regeneration. Hyaluronan hydrogels are appealing materials that can function as a matrix to incorporate both organic and inorganic substances to enhance tissue growth. Because of the intrinsic properties of this swollen matrix, one needs a very sensitive technique that can be applied in situ to determine the organization of the polymers in a gel. Small-angle neutron scattering is used to determine the characteristics of the inhomogeneous structure of the hydrogel both with and without added particles. The results are interpreted using models of structure with two length scales that are beyond the traditional picture of homogeneous gels. The observed structure and the dimensions can explain the previously reported rheological properties of gels containing different amount of polymers. Hydroxyapatite nanoparticles added to the gel are frozen in the gel matrix. We are able to determine the distribution and shape of these particles as they aggregate around the polymer chains. We have also concluded, in this case, that the particle structure is concentration independent. Information about the nanostructure for an applicable biomaterial guides the formulation, preparation, and use that should lead to further understanding of its exploitation. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
998.
The scope of the Groebke-Blackburn reaction of 2-aminoazines is limited by the availability of isocyanides. To prepare the Groebke-Blackburn type 2-phenyl-3-(hetero)arylaminoimidazo[1,2-a]azines, for which the respective (hetero)arylisocyanides are scarce or unavailable, a general Pd-catalyzed protocol has been developed that is useful for the arylation of known 2-phenylimidazo[1,2-a]pyridin-3-amine and 2-phenylimidazo[1,2-a]pyrazin-3-amine with various electron-deficient aryl and heteroaryl halides. 相似文献
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I Vayá T Gustavsson T Douki Y Berlin D Markovitsi 《Journal of the American Chemical Society》2012,134(28):11366-11368
Transfer of the electronic excitation energy in calf thymus DNA is studied by time-resolved fluorescence spectroscopy. The fluorescence anisotropy, after an initial decay starting on the femtosecond time scale, dwindles down to ca. 0.1. The in-plane depolarized fluorescence decays are described by a stretched exponential law. Our observations are consistent with one-dimensional transfer mediated by charge-transfer excited states. 相似文献