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排序方式: 共有2327条查询结果,搜索用时 15 毫秒
1.
Nonlinear Dynamics - In this paper, we study a delayed diffusive predator–prey model with nonlocal competition in prey and habitat complexity. The local stability of coexisting equilibrium is... 相似文献
2.
Zihao Yang Junzhi Cui Yufeng Nie Zhiqiang Huang Meizhen Xiang 《Acta Mechanica Sinica》2015,31(5):762-776
In this paper,a statistical second-order twoscale(SSOTS) method is developed to simulate the dynamic thcrmo-mechanical performances of the statistically inhomogeneous materials.For this kind of composite material,the random distribution characteristics of particles,including the shape,size,orientation,spatial location,and volume fractions,are all considered.Firstly,the repre.sentation for the microscopic configuration of the statistically inhomogeneous materials is described.Secondly,the SSOTS formulation for the dynamic thermo-mechanical coupled problem is proposed in a constructive way,including the cell problems,effective thermal and mechanical parameters,homogenized problems,and the SSOTS formulas of the temperatures,displacements,heat flux densities and stresses.And then the algorithm procedure corresponding to the SSOTS method is brought forward.The numerical results obtained by using the SSOTS algorithm are compared with those by classical methods.In addition,the thermo-mechanical coupling effect is studied by comparing the results of coupled case with those of uncoupled case.It demonstrates that the coupling effect on the temperatures,heat flux densities,displacements,and stresses is very distinct.The results show that the SSOTS method is valid to predict the dynamic thermo-mechanical coupled performances of statistically inhomogeneous materials. 相似文献
3.
Dr. Qiao Chen Xin Yi Meirong Huang Wenjia Wu Qiyang Song Changjiang Nie Prof. Shun Wang Prof. Hongwei Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(33):7463-7469
Precursors and catalysts play vital roles in chemical reactions. Considerable efforts have been devoted to the investigation of catalysts for graphene growth by chemical vapor deposition in recent years. However, there has been little research on precursors because of a lack of innovation in term of creating a controllable feeding method. Herein, we present a novel sustained and controlled release approach, and develop a convenient, safe, and potentially scalable feeding system with the assistance of matrix materials and a simple portable feeder. As a result, a highly volatile liquid precursor can be fed accurately to grow large-area, uniform graphene films with optimal properties. This feeding approach will further benefit the synthesis of other two-dimensional materials from various precursors. 相似文献
4.
A series of novel diaroylhydrazone aluminum complexes have been synthesized and well-defined structurally, and their catalytic performance in the polymerization of ε-caprolactone and lactides have also been evaluated. Complexes [(L1–4)2AlMe] ( 1 – 4 ) {[L1 = (3,5-tBu2–2-OMe-C6H2)CH=NNCOC6H5], [L2 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-OCH3)], [L3 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-Br)] and [L4 = (2-OMe-C6H4)CH=NNCO(C6H4–4-tBu)]} were prepared through treatment of AlMe3 with the corresponding proligands L1–4H in molar ratios of 1: 1 or 1: 2. Chemical structures of all the complexes were well-defined by elemental analysis, NMR spectra as well as single-crystal X-ray study. Complexes [(L1–4)2AlMe] ( 1 – 4 ) in this work represent the first examples of aluminum complexes of aroylhydrazone ligands with crystallographic characterization. Specifically, they are all in monomeric form with a penta-coordinated aluminum center, including two approximately co-planar five-membered metallacycles with aluminum. Introduced bulky tert-butyl substituents in aroylhydrazone ligands could affect the geometry around the central metal which is a distorted square-based pyramid in complexes 1 – 3 while being a trigonal bipyramidal in complex 4 , thus affecting their catalytic behaviors. The complexes can successfully catalyze the ring-opening polymerization of ε-caprolactone and L-lactide under mild conditions without any activator. In addition, complexes 1 – 4 could also polymerize rac-lactide, affording atactic polylactides with high conversions and good controllability in relatively short reaction time. 相似文献
5.
Nie Zhuo-Yun Liu Rui-Juan Wang Qing-Guo Guo Dong-Sheng Ma Yi-Jing Lan Yong-Hong 《Nonlinear dynamics》2019,95(2):1053-1066
Nonlinear Dynamics - A new identification approach for a nonlinear system with hysteresis, namely a cascading Bouc–Wen hysteresis model with linear dynamics, is proposed in this study. The... 相似文献
6.
Wei-Zhen Sun Lin-Lin Dai Xiang-He Kong Yu Mao Zhi-Lin Wu Li-Fu Liao Xi-Lin Xiao Chang-Ming Nie 《应用有机金属化学》2020,34(4):e5486
The design of new uranyl-ligands (uranyl-Ls) is of great significance for the separation and utilization of uranium. In this paper, the triazole group was introduced into uranyl-salophen (uranyl-S) to form new asymmetric uranyl-unilateral benzotriazole salophen (uranyl-UBS); we further replaced two oxygen atoms of uranyl-UBS with two sulfur atoms to generate uranyl-unilateral benzotriazole thio-salophen (uranyl-UBTS) as a new receptor. Then, we comprehensively explored coordination models of uranyl-UBS and uranyl-UBTS with R/S-triadimefons (R/S-TDFs) enantiomers as the guests using density functional theory calculations at the B3LYP//RECP/6-311G** level; we then investigated enantioselectivity recognition of the new receptors to the guests R/S-TDFs. The results indicated that the uranium atoms of the receptors uranyl-S, uranyl-UBS and uranyl-UBTS could coordinate with the carbonyl oxygens in guests R/S-TDFs to form complexes of guest-receptors R/S-TDFs-uranyl-Ls that exhibited two stable V-shaped structures with quite different properties. It was found that the coordination ability to the guests R/S-TDFs is uranyl-UBTS > uranyl-UBS > uranyl-S, while the enantioselectivity for the guests is uranyl-UBTS > uranyl-S > uranyl-UBS and, when the receptor is the same, R-TDF has stronger coordination ability than S-TDF. These results provide information and theoretical supports for the experiments of asymmetric uranyl-UBS with R/S-TDFs, and produce a reference for further exploring the coordination characteristics of asymmetric uranyl-salophen with the triazole derivatives. 相似文献
7.
Huang Ting Zhou Yaohong Zhang Xiaohua Peng Dayong Nie Xuliang Chen Jing Xiong WanMing 《Cellulose (London, England)》2022,29(3):1419-1433
Cellulose - A furfuryl alcohol resin-based solid acid (SC-FAR-800) was prepared and applied in the conversion of carbohydrates into furan platform compounds in microwave. The results showed that... 相似文献
8.
We consider the following system with critical exponent in : where , and . Using finite dimensional reduction method, we prove the existence of multi-bump solutions. Their bumps can be placed on arbitrarily many or even infinitely many lattice points in . Since or , we introduce two new norms to avoid singularity. 相似文献
9.
<正>绿色化工技术是实现化工行业可持续发展的关键~1。作为一种先进高效的低碳能源转化技术,化学链工艺在节能和减排等方面具有诸多优势~2。在化学链工艺中,氧化还原催化剂作为氧载体,实现不同反应器之间的晶格氧和热量传递。载氧体的晶格氧释放动力学是决定其反应性能的关键因素~3。ABO3钙钛矿型复合金属氧化物由于其优良的结构循环稳定性和氧离子迁移能力,是一类具有潜在应用价值的催化材料,被广泛研究用于化学链、 相似文献
10.