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61.
Yunyun Wang Yajun Jian Ya Wu Huaming Sun Guofang Zhang Weiqiang Zhang Ziwei Gao 《应用有机金属化学》2019,33(7)
Bifunctional catalysts bearing two catalytic sites, Lewis acidic organometallic titanocene and Brønsted acidic COOH, have been assembled in situ from Cp2TiCl2 with carboxylic acid ligands, showing high catalytic activity over an intramolecular Mannich reaction towards synthesis of 2‐aryl‐2,3‐dihydroquinolin‐4(1H)‐ones. The determination of the bifunctional catalyst Cp2Ti(C8H4NO6)2 was elucidated by single X‐ray HR‐MS and investigation of catalytic behavior. In particular, masking the Brønsted acidic COOH catalytic site with dormant COOMe lowered the reaction yield greatly, indicating that two catalytic sites work together to maintain high catalytic efficiency. 相似文献
62.
Wang Jing-Xian Liu Nan Wang Chen Xu Jian 《International Journal of Theoretical Physics》2019,58(8):2654-2663
International Journal of Theoretical Physics - Quantum secure communication is the key development object of current communication technology. There are many branches, among which the most... 相似文献
63.
Research on Chemical Intermediates - The low Mg 2p value (47.0 eV) of MgO reported in Res Chem Intermed 44(2018)829 is carefully analyzed and discussed based on a series of X-ray... 相似文献
64.
Numerical Algorithms - Studying the dynamics of runaway electrons has theoretical and practical significance. As the system is highly relativistic, multi-scale and nonlinear, accurate and efficient... 相似文献
65.
Jian Wang 《Comptes Rendus Mathematique》2019,357(3):284-290
The goal of this paper is to investigate the topological structure of open simply connected 3-manifolds whose scalar curvature has a slow decay at infinity. In particular, we show that the Whitehead manifold does not admit a complete metric whose scalar curvature decays slowly, and in fact that any contractible complete 3-manifolds with such a metric is diffeomorphic to . Furthermore, using this result, we prove that any open simply connected 3-manifold M with and a complete metric as above is diffeomorphic to . 相似文献
66.
Given a planar continuum Gaussian free field h𝒰 in a domain 𝒰 with Dirichlet boundary condition and any δ > 0, we let be a real-valued smooth Gaussian process where is the average of h𝒰 along a circle of radius δ with center v. For γ > 0, we study the Liouville first-passage percolation (in scale δ), i.e., the shortest path distance in 𝒰 where the weight of each path P is given by . We show that the distance between two typical points is for all sufficiently small but fixed γ > 0 and some constant c* > 0. In addition, we obtain similar upper bounds on the Liouville first-passage percolation for discrete Gaussian free fields, as well as the Liouville graph distance, which roughly speaking is the minimal number of euclidean balls with comparable Liouville quantum gravity measure whose union contains a continuous path between two endpoints. Our results contradict some reasonable interpretations of Watabiki's prediction (1993) on the random distance of Liouville quantum gravity at high temperatures.© 2019 Wiley Periodicals, Inc. 相似文献
67.
Jian Wang Jinjin Zhou Yu Xu Bingqi Zhu Huiyi Li 《Rapid communications in mass spectrometry : RCM》2019,33(17):1410-1419
68.
Na-Na Jiang Shu-Zong Du Yan-Song Ye Hui Yan Xing-Wei Yang Jian Yang Yin Nian Gang Xu 《Tetrahedron letters》2019,60(45):151220
Hyphenone A (1), a new type of bicyclic polyprenylated acylphloroglucinols (BPAPs) featured with an unprecedented 3,3-diisoprenylated 1,3,5-trione core, were characterized from the roots of Hypericum henryi together with two new congeners (hyphenones B–C, 2–3) and five known biosynthetic related PPAPs. Biogenetically, 1 should be derived from a novel 3,3,5,5-tetraisoprenylated MPAPs precursor. Their structures were elucidated by comprehensive spectroscopic data and X-ray diffraction. Moreover, 1–3 were identified as the first PPAPs type Cav3.1 T-type calcium channel (TTCC) inhibitors, with IC50 values of 7.07, 6.19, and 5.47 μM, respectively. 相似文献
69.
70.
针对设计的一种场畸变气体开关,研究中间电极材料分别为不锈钢和黄铜条件下的烧蚀特性,结合开关寿命期间静态与触发特性的变化规律,获得决定开关寿命的关键因素,为三电极场畸变气体开关的性能优化提供理论支撑。研究结果表明,采用不锈钢和黄铜作为中间电极的烧蚀区域以及表面粗糙度均随着放电次数增加而增大,黄铜电极烧蚀较为严重且表面有明显的烧蚀圆斑,不锈钢电极则具有更高的表面粗糙度,阴阳极表面烧蚀存在明显差异,随着放电次数的增加,击穿点向电极边缘区域集中,影响开关的沿面绝缘特性,是导致开关寿命终结的主要原因。 相似文献