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991.
A new 1D Hg(II) coordination polymer, [Hg4(Chbz)4(4,4′-Bipy)2(NO3)4 · H2O] n (I) (Chbz = 2-chlorophenyl, 4,4′-Bipy = 4,4′-bipyridine), has been synthesized by the in situ synthesis of 2-chlorophenyl from the reaction of 2-chlorobenzoic acid, 4,4′-Bipy and mercury salt under hydrothermal conditions and characterized by elemental analysis, IR, TGA and single-crystal X-ray diffraction. Complex I exhibits an interesting 1D infinite zigzag polymeric chain along the x axis. The photoluminescent measurements reveal that complex I exhibits fluorescent emission in the solid state at room temperature. 相似文献
992.
以乙二胺为模板剂(SDA)合成微孔晶体磷酸钴, 可以得到多种不同的结构. 本文在合成四种不同结构类型的微孔磷酸钴(命名为CoPO-en-1, CoPO-en-2, CoPO-en-3, CoPO-en-4, en 为乙二胺的英文缩写)过程中发现, 它们之间不仅可以在水热合成条件下相互转化, 在焙烧处理条件下也能实现转化. 研究发现, 在水热合成过程中, CoPO-en-2、CoPO-en-4 分别是CoPO-en-1、CoPO-en-3 的晶化中间物, 在较低晶化温度下或者较高温度的晶化初期, 可以发现它们的身影. 一旦晶化温度升高或者晶化时间延长, 它们就分别转化为CoPO-en-1和CoPO-en-3. 在合成产物的热处理过程中发现: CoPO-en-2、CoPO-en-3、CoPO-en-4 都能够通过焙烧转化为CoPO-en-1. 这种现象表明, 几种微孔磷酸钴结构间的稳定性存在递变关系. 相似文献
993.
The equitable tree-coloring can formulate a structure decomposition problem on the communication network with some security considerations. Namely, an equitable tree-k-coloring of a graph is a vertex coloring using k distinct colors such that every color class induces a forest and the sizes of any two color classes differ by at most one. In this paper, we show some theoretical results on the equitable tree-coloring of graphs by proving that every d-degenerate graph with maximum degree at most Δ is equitably tree-k-colorable for every integer k ≥(Δ + 1)/2 provided that Δ≥ 9.818 d,confirming the equitable vertex arboricity conjecture for graphs with low degeneracy. 相似文献
994.
In this paper,the mixed Pólya-Szeg? principle is established.By the mixed Pólya-Szeg? principle,the mixed Morrey-Sobolev inequality and some new analytic inequalities are obtained. 相似文献
995.
This article presents a comprehensive therotical investigation of excited state intramolecular proton transfer (ESIPT) for
some newly-designed diphenylethylene derivatives containing 2-(2-hydroxy-phenyl)-benzotriazole moiety with various substituted
groups. The calculation shows the structural parameters and Mulliken charges of phototautomers enol (E) and keto (K) of these
compounds exhibit no or tiny changes from S0 to S1. The calculated results suggest that HOMO and LUMO + 1 of the compounds displays excellent overlapping nature, and thus the
absorption and emission could be from the electron transition of HOMO→LUMO + 1. The electron density distribution in the frontier
orbital of E and K are influenced remarkably by various substituted groups in S0 and S1 states. Electron density distribution deficiency in 2-(2-hydroxy-phenyl)-benzotriazole part is observed in L + 1 for these
derivatives. The calculation also suggests the potential energy curves of ESIPT are shown to be a strong relationship with
electron donor-acceptor groups. The absorption spectra, normal emission spectra and ESIPT spectra of the derivatives were
also calculated. 相似文献
996.
Passively Q-switched output of a diode-pumped 1.34 μm Nd:GdVO4 laser was demonstrated by using Co2+:MgAl2O4(Co2+:MALO) crystal as the saturable absorber for the first time. When the transmission of output mirror is 15%, the Q-switched
pulse width is 110 ns and a corresponding average output power is 460 mW under the pump power of 9.69 W. The optical-optical
conversion efficiency is 36%. At about 330 kHz repetition rate, the single Q-switched pulse energy and the peak power are
about 1.39 μJ and 12.6 W, respectively. 相似文献
997.
Fuling Wang Jianguo Tang Jixian Liu Yao Wang Rui Wang Lin Niu Linjun Huang Zhen Huang 《Journal of Physical Organic Chemistry》2011,24(11):1101-1109
In this article, a donor–acceptor array consisting of two zinc porphyrin (ZnPOR) units attached to the 1,7‐positions of perylene‐3,4:9,10‐bis(dicarboximide) (PDI) was synthesized and characterized. This double‐wing molecule exhibits very broad absorption in the region from 300 to 900 nm. Especially, its lower energy absorption feature presumably arises from donor–acceptor interactions. The fluorescence emission spectra confirmed that photoinduced electron transfer occurred from POR to perylene bisimide moiety in this triad. In contrast to previously studied systems incorporating POR and PDI groups, this array shows the evidence of a relatively strong ground‐state electronic coupling between the donor and acceptor moieties. Additionally, highest occupied molecular orbital and lowest unoccupied molecular orbital values of the array were acquired by cyclic voltammetry (CV). The results showed that these energy values fulfill the energetic conditions required for the proposed electron transfer. More importantly, the photocurrent measurement showed that this molecule exhibits a high capacity to form a photoinduced charge‐separated state and to produce steady and prompt cathodic photocurrent responses. These results confirmed the role of this new array toward harvesting light energy and generating photocurrent during the operation of a photoelectrochemical cell. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
998.
In this paper, properties of the spherical functions and Hardy-Sobolev inequalities of generalized Baouendi-Grushin vector
fields are established, and then some unique continuation results for generalized Baouendi-Grushin operators with singular
weights are given. 相似文献
999.
1000.
Desynchronization attacks are among the most difficult attacks to resist, for it can desynchronize the location of the watermark and hence cause incorrect watermark detection. The design of an image watermarking scheme that is robust against desynchronization attacks is challenging. Based on a multi-scale SIFT (scale invariant feature transform) detector and Bandelet transform theory, we propose a new content based image watermarking algorithm with good visual quality and reasonable resistance toward desynchronization attacks. Firstly, the stable image feature points are extracted from the original host by using the multi-scale SIFT detector, and the local feature regions (LFRs) are constructed adaptively according to the feature scale theory. The Bandelet transform is then performed on the LFRs. Finally, the digital watermark is embedded into the LFRs by modifying the significant Bandelet coefficients. By binding the watermark with the geometrically invariant image features, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common signal processing such as sharpening, noise adding, JPEG compression, etc., but also robust against the desynchronization attacks such as rotation, translation, scaling, row or column removal, cropping, etc. 相似文献