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61.
Bai Zhengguo 《数学年刊B辑(英文版)》1985,6(4):409-426
In this paper the term“Riemannian manifold”means that the fundamental quadraticdifferential form may be indefinite. 相似文献
62.
New polymers having high solid-state fluorescence quantum yields and the ability to tune their electron affinity without effecting their band gap using hyperconjugative interactions is reported. The novel three-dimensional poly(phenylene vinylenes) having [2.2.2] bicyclic ring systems shown were synthesized, and the different hyperconjugative perturbations provide differential fluorescence sensory quenching responses to electron-rich and electron-deficient analytes in solution and solid thin films. 相似文献
63.
Xiaoming Fang Zhengguo Zhang Qinglin Chen Hongbing Ji Xuenong Gao 《Journal of solid state chemistry》2007,180(4):1325-1332
N-doped TiO2 photocatalysts were prepared by annealing two different precursors, P25 and a TiO2 xerogel powder under NH3/Ar flow at 500, 550, and 600 °C. The xerogel powder prepared by peptizing Ti(OH)4 with HNO3 was composed of nanoparticles and had large specific surface area. During the annealing process, the xerogel powder underwent increase in crystallinity, grain growth and phase transformation, whereas P25 did not show obvious changes. Compared with the N-doped TiO2 photocatalysts from P25, the N-doped TiO2 photocatalysts from the xerogel powder possessed higher concentrations of the substitutional nitrogen and exhibited more obvious absorption in the visible light region. The N-doped TiO2 photocatalysts from the xerogel powder exhibited obvious visible-light activities for photodegrading methylene blue and the sample prepared at 500 °C achieved the best performance with a rate constant (k) about 0.44 h−1, whereas those from P25 did not exhibit improved visible-light activities. 相似文献
64.
Discrete Silver(I)‐Palladium(II)‐Oxo Nanoclusters, {Ag4Pd13} and {Ag5Pd15}, and the Role of Metal–Metal Bonding Induced by Cation Confinement
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Dr. Peng Yang Dr. Yixian Xiang Dr. Zhengguo Lin Zhongling Lang Dr. Pablo Jiménez‐Lozano Dr. Jorge J. Carbó Prof. Josep M. Poblet Dr. Linyuan Fan Prof. Changwen Hu Prof. Ulrich Kortz 《Angewandte Chemie (International ed. in English)》2016,55(51):15766-15770
We introduce the class of discrete silver(I)‐palladium(II)‐oxo nanoclusters with the preparation of {Ag4Pd13} and {Ag5Pd15}. Both polyanions represent the first examples of noble metal‐capped polyoxo‐noble‐metalates in a fully inorganic assembly, featuring an unprecedented host–guest mode containing hetero‐ and homometallic Ag–Pd and Ag–Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag–Pd metallic bonds originate partially from surface confinement of AgI guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver‐palladium‐oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core–shell nanoparticles, with high relevance for catalysis. 相似文献
65.
Platinum‐Containing Polyoxometalates: syn‐ and anti‐[PtII2(α‐PW11O39)2]10− and Formation of the Metal–Metal‐Bonded di‐PtIII Derivatives
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Dr. Zhengguo Lin Dr. Natalya V. Izarova Aleksandar Kondinski Xiaolin Xing Dr. Ali Haider Linyuan Fan Dr. Nina Vankova Prof. Thomas Heine Dr. Bineta Keita Prof. Jie Cao Prof. Changwen Hu Prof. Ulrich Kortz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5514-5519
The first examples of dimeric, di‐PtII‐containing heteropolytungstates are reported. The two isomeric di‐platinum(II)‐containing 22‐tungsto‐2‐phosphates [anti‐PtII2(α‐PW11O39)2]10? ( 1 a ) and [syn‐PtII2(α‐PW11O39)2]10? ( 2 a ) were synthesized in aqueous pH 3.5 medium using one‐pot procedures. Polyanions 1 a and 2 a contain a core comprising two face‐on PtO4 units, with a Pt???Pt distance of 2.9–3 Å. Both polyanions were investigated by single‐crystal XRD, IR, TGA, UV/Vis, 31P NMR, ESI‐MS, CID‐MS/MS, electrochemistry, and DFT. On the basis of DFT and electrochemistry, we demonstrated that the {Pt2II} moiety in 1 a and 2 a can undergo fully reversible two‐electron oxidation to {Pt2III}, accompanied by formation of a single Pt?Pt bond. Hence we have discovered the novel subclass of PtIII‐containing heteropolytungstates. 相似文献
66.
Yuushou Nakayama Yuuichi Sogo Zhengguo Cai Takeshi Shiono 《Journal of polymer science. Part A, Polymer chemistry》2013,51(5):1223-1229
A series of titanium complexes with ansa‐(fluorenyl)(cyclododecylamido) ligands, Me2Si(η3‐R)(N‐c‐C12H23)TiMe2 [R = fluorenyl ( 5 ), 2,7‐tBu2fluorenyl ( 6 ), 3,6‐tBu2fluorenyl ( 7 )], was synthesized. The crystal structure of complex 6 revealed η3‐coordination of the fluorenyl moiety to the metal. Upon activation with trialkylaluminum‐free modified methylaluminoxane, complexes 5 – 7 as well as the corresponding tBu amide complexes, Me2Si(η3‐R)(NtBu)TiMe2 [R = fluorenyl ( 2 ), 2,7‐tBu2fluorenyl ( 3 ), 3,6‐tBu2fluorenyl ( 4 )], were adopted as the catalysts for the copolymerization of ethylene (E) and isobutylene (IB). Among these complexes, complex 6 was found to achieve the highest IB incorporation to produce alternating E‐IB copolymers. Complex 6 system also achieved copolymerization of E and limonene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
67.
68.
Chen B Wang B Lin Z Fan L Gao Y Chi Y Hu C 《Dalton transactions (Cambridge, England : 2003)》2012,41(23):6910-6913
Four novel organic functionalized polyoxovanadates are solvothermally synthesized by altering the reaction temperature and using different organoarsonic acids. These POVs are fully characterized and the phase transitions between different POVs structures are confirmed by X-ray diffraction analyses. Such a transition is temperature-dependent and thus controlled synthesis of new POVs can be achieved. 相似文献
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