排序方式: 共有52条查询结果,搜索用时 46 毫秒
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Rh(III)-catalyzed ortho C-H activation/olefination of phenol carbamates has been developed. High regioselectivity is observed with a range of phenol carbamates enabling efficient coupling with acrylates and styrenes. This reaction exhibits different reactivity as compared to the Pd-catalyzed ortho-arylation reaction of phenol esters and provides a new approach for the synthesis of ortho-substituted phenols. 相似文献
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FENG Tian-Jun 《理论物理通讯》2009,52(5):941-944
A Korteweg-de Vires-type (KdV-type) equation and a modifiedNonlinear Schrödinger equation (NLSE) for the dust lattice wave(DLW) are derived in a weakly inhomogeneous dust plasma crystal. Itseems that the amplitude and the velocity of the dust lattice solitary waves decay exponentially with increasing time in a dust lattice. The modulational instability of this dust lattice envelope waves is investigated as well. It is found that the waves are modulational stable under certain conditions. On the other hand, the waves are modulational unstable if the conditions are not satisfied. 相似文献
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Sr2CeO4蓝色荧光粉体材料的柠檬酸盐分解法合成与表征 总被引:3,自引:0,他引:3
Pure Sr2CeO4 nanosized phosphors has been successfully synthesized via a citrate decomposition method at a temperature as low as 900 ℃. The particle sizes were estimated to be 80~120 nm by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The particle sizes were determined at the temperature of pre-decomposition, and would increase with the annealed temperature. Meanwhile, the photoluminescence properties of nano-Sr2CeO4 were investigated. 相似文献
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LIAN Zhao-Xuna② LIU Pinga ZHANG Jia-Mina LOU Tian-Juna WANG Tian-Xia LI Hao-Hongb a 《结构化学》2008,27(6)
The title compounds, Cu(L1)(C4H8NHO) and Ni(L2)(C4H8NHO) (H2L1 = 5-bro- mosalicylaldehyde-p-nitrobenzoylhydrazone, H2L2 = 5-bromosalicylaldehyde-p-hydroxybenzo- ylhydrazone), have been obtained and characterized by single-crystal X-ray diffraction. Complex 1 belongs to the triclinic system, space group P1 with a = 8.6960(2), b = 9.957(2), c = 11.878(2) , α = 73.36(3), β = 78.25(3), γ = 82.64(3)o, V = 962.1(3) 3, Mr = 512.81, Z = 2, F(000) = 514, Dc = 1.770 g/cm3, μ(MoKα) = 3.251, R = 0.0337 and wR = 0.0846. Complex 2 is of monoclinic, space group P21/c with a = 13.313(2), b = 8.2096(1), c = 21.890(3) , β = 125.737(3)o, V = 1941.9(4) 3, Mr = 478.97, Z = 4, F(000) = 968, Dc = 1.638 g/cm3, μ(MoKα) = 3.085, R = 0.0356 and wR = 0.0817. The ligands form a satisfactory N2O2 square plane around the metal centers in two compounds. Different patterns of hydrogen bonds are observed owing to the presence of different substituents on aromatic ring of the acylhydrazone Schiff bases. In complex 1, square-planar copper(II) complexes are linked by intermolecular hydrogen bonds leading to zigzag infinite chains. In complex 2, the metal complexes are linked via hydrogen bonds to form corrugated sheets in a staggered fashion; 3D channels along the b axis are constructed through other non-covalent interactions between the neighboring layers. 相似文献
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Nonlinear Dynamics - In this study, multi-pulse chaotic dynamics of an unbalanced Jeffcott rotor with gravity effect are investigated. Based on the solvability conditions obtained for the case of... 相似文献
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Chang-Gong Li Yong-Fang Li Jing-Yan Shang Tian-Jun Lou 《Transition Metal Chemistry》2014,39(4):373-378
Carbonyl substitution reactions of [μ-(SCH2)2CHC6H5]Fe2(CO)6 with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph2P)2N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH2)2CHC6H5]Fe2(CO)4(k 2-dppv) and a symmetrically substituted bridging complex [(μ-SCH2)2CHC6H5]Fe2(CO)4[μ-(PPh2)2N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH2)2CHC6H5]Fe2(CO)4(k 2-dppv) was investigated. 相似文献
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Tian-Jun Yue Dr. Gulzar A. Bhat Wen-Jian Zhang Prof. Dr. Wei-Min Ren Prof. Dr. Xiao-Bing Lu Prof. Dr. Donald J. Darensbourg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13735-13739
Topological polymers possess many advantages over linear polymers. However, when it comes to the poly(monothiocarbonate)s, no topological polymers have been reported. Described herein is a facile and efficient approach for synthesizing well-defined branched poly(monothiocarbonate)s in a “grafting through” manner by copolymerizing carbonyl sulfide (COS) with epichlorohydrin (ECH), where the side-chain forms in situ. The lengths of the side-chains are tunable based on reaction temperatures. More importantly, enhancement in thermal properties of the branched copolymer was observed, as the Tg value increased by 22 °C, compared to the linear analogues. When chiral ECH was utilized, semicrystalline branched poly(monothiocarbonate)s were accessible with a Tm value of 112 °C, which is 40 °C higher than that of the corresponding linear poly(monothiocarbonate)s. The strategy presented herein for synthesizing branched polymers provides efficient and concise access to topological polymers. 相似文献
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In this paper, we prove the connectedness of symplectic ball packings in the complement of a spherical Lagrangian, $S^{2}$ or $\mathbb{RP }^{2}$ , in symplectic manifolds that are rational or ruled. Via a symplectic cutting construction, this is a natural extension of McDuff’s connectedness of ball packings in other settings and this result has applications to several different questions: smooth knotting and unknottedness results for spherical Lagrangians, the transitivity of the action of the symplectic Torelli group, classifying Lagrangian isotopy classes in the presence of knotting, and detecting Floer-theoretically essential Lagrangian tori in the del Pezzo surfaces. 相似文献