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101.
Ping Chen Yanhong Hao Xinxin Wang Prof. Dr. Dan Yuan Prof. Dr. Yingming Yao Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7292-7297
Highly position selective alkylations of N-alkylindoles at C7-positions have been enabled by cationic zirconium complexes. The strategy provides a straightforward access to install alkyl groups at C7-positions of indoles without a complex directing group. Mechanistic studies provided support for the importance of Brønsted acids in the catalytic manifold. 相似文献
102.
《Physics letters. A》2019,383(17):2090-2092
In this paper, we have used Monte Carlo (MC) method to simulate and study the temperature and doping effects on the electric conductivity of fullerene (C60). The results show that the band gap has reduced by the doping and the charge carrier transport is facilitated from valence band to conduction band by the temperature where is touched a 300 K. In this case, the conductivity reached a value of . The electric conductivity of C60 can increase by the triphenylmethane dye crystal violet (CV) alkali metal to reach at 303 K. Our results of MC simulation have a good agreement with those extracted from literature [10], [33]. 相似文献
103.
Gallai’s path decomposition conjecture states that the edges of any connected graph on vertices can be decomposed into at most paths. We confirm that conjecture for all graphs with maximum degree at most five. 相似文献
104.
We consider the question whether, given a countable family of lattices in a locally compact abelian group G, there exist functions such that the resulting generalized shift-invariant system is a tight frame of . This paper develops a new approach to the study of generalized shift-invariant system via almost periodic functions, based on a novel unconditional convergence property. From this theory, we derive characterizing relations for tight and dual frame generators, we introduce the system bandwidth as a measure of the total bandwidth a generalized shift-invariant system can carry, and we show that the so-called Calderón sum is uniformly bounded from below for generalized shift-invariant frames. Without the unconditional convergence property, we show, counter intuitively, that even orthonormal bases can have arbitrary small system bandwidth. Our results show that the question of existence of frame generators for a general lattice system is rather subtle and depends on analytical and algebraic properties of the lattice system. 相似文献
105.
Sameerah Jamal 《Journal of Differential Equations》2019,266(7):4018-4026
A manifold that contains small perturbations will induce a perturbed partial differential equation. The partial differential equation that we select is the Poisson equation – in order to explore the interplay between the geometry of the manifold and the perturbations. Specifically, we show how the problem of symmetry determination, for higher-order perturbations, can be elegantly expressed via geometric conditions. 相似文献
106.
Ze-Kun Yang Ning-Xin Xu Dr. Chao Wang Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(21):5433-5439
Herein we report a versatile Mizoroki–Heck-type photoinduced C(sp3)−N bond cleavage reaction. Under visible-light irradiation (455 nm, blue LEDs) at room temperature, alkyl Katritzky salts react smoothly with alkenes in a 1:1 molar ratio in the presence of 1.0 mol % of commercially available photoredox catalyst without the need for any base, affording the corresponding alkyl-substituted alkenes in good yields with broad functional-group compatibility. Notably, the E/Z-selectivity of the alkene products can be controlled by an appropriate choice of photoredox catalyst. 相似文献
107.
Khaled Tawfik Alali Dr. Jingyuan Liu Dr. Rongrong Chen Dr. Qi Liu Dr. Hongsen Zhang Jundong Li Jindi Hou Prof. Rumin Li Prof. Jun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11892-11902
Semiconductor metal oxides (SMO)-based gas-sensing materials suffer from insufficient detection of a specific target gas. Reliable selectivity, high sensitivity, and rapid response–recovery times under various working conditions are the main requirements for optimal gas sensors. Chemical warfare agents (CWA) such as sarin are fatal inhibitors of acetylcholinesterase in the nerve system. So, sensing materials with high sensitivity and selectivity toward CWA are urgently needed. Herein, micro-nano octahedral Co3O4 functionalized with hexafluoroisopropanol (HFIP) were deposited on a layer of reduced graphene oxide (rGO) as a double-layer sensing materials. The Co3O4 micro-nano octahedra were synthesized by direct growth from electrospun fiber templates calcined in ambient air. The double-layer rGO/Co3O4-HFIP sensing materials presented high selectivity toward DMMP (sarin agent simulant, dimethyl methyl phosphonate) versus rGO/Co3O4 and Co3O4 sensors after the exposure to various gases owing to hydrogen bonding between the DMMP molecules and Co3O4-HFIP. The rGO/Co3O4-HFIP sensors showed high stability with a response signal around 11.8 toward 0.5 ppm DMMP at 125 °C, and more than 75 % of the initial response was maintained under a saturated humid environment (85 % relative humidity). These results prove that these double-layer inorganic–organic composite sensing materials are excellent candidates to serve as optimal gas-sensing materials. 相似文献
108.
Yanmin Yu 《Molecular physics》2019,117(9-12):1360-1366
ABSTRACTPotential energy surfaces and molecular dynamics of the intramolecular 1, 3-dipolar cycloaddition and ene reaction of a nitrile oxide with an alkene were performed in the gas phase and in dichloromethane with density functional theory. One hundred trajectories were propagated in the gas phase and in dichloromethane, respectively. Twenty percent of the trajectories in the gas phase involve bicyclic intermediate and the mean time gap is 472fs. A dynamically stepwise reaction is observed. In dichloromethane, more reactive trajectories were obtained and the time gap is larger than that in the gas phase. 相似文献
109.
110.