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131.
Global dynamics of a Filippov plant disease model with an economic threshold of infected-susceptible ratio 下载免费PDF全文
Lihong Huang Huili M Jiafu Wang Chuangxia Huang 《Journal of Applied Analysis & Computation》2020,10(5):2263-2277
This paper presents a Filippov plant disease model incorporating an economic threshold of infected-susceptible ratio, above which control strategies of replanting or removing are needed to be carried out. Based on the Filippov approach, we study the sliding mode dynamics and further the global dynamics. It is shown that there is a unique equilibrium, which is a disease-free equilibrium, an endemic equilibrium or a pseudo-equilibrium. Moreover, the equilibrium is proved to be globally asymptotically stable. Our results indicate that the control goal can be achieved by taking appropriate replanting and removing rate. 相似文献
132.
基质固相分散-高效液相色谱法测定植物油中的痕量苯并[a]芘 总被引:1,自引:0,他引:1
苯并[a]芘是一种强致癌物质,它是有机化合物在高温条件下发生聚合反应产生的,主要在垃圾焚烧、高温炼油等过程中产生。其一旦产生就很难分解,因此危害较大。无公害食品植物油的理化指标中规定苯并[a]芘的含量要低于10μg/kg。本文采用基质固相分散萃取技术处理植物油样品,减少了有机溶剂的用量,缩短了分析时间,提高了分析效率。处理后的样品经高效液相色谱法(HPLC)的快速测定,所得结果完全能满足食品检验的需要。1实验部分1.1仪器与试剂W a ters A lliance2695高效液相色谱仪,配四元泵溶剂淋洗系统、自动进样系统、2475荧光检测器。SUPE… 相似文献
133.
The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_p and orientational order parameter Φ, which are the important parameters to predict d_(33) of poled films, can be calculated by a simple operation from the number of red shift of charge transfer absorption band. The calculated results are in good agreement with the experimental data. 相似文献
134.
Jiafu Wang Shaobo Qu Zhuo Xu Yiming Yang Xiang Wu 《Journal of magnetism and magnetic materials》2009,321(18):2805-2809
In this paper, a polarization-dependent wide-angle three-dimensional metamaterial absorber with a near-unity absorbance was presented. The metamaterial absorber structure is composed of coplanar electric and magnetic resonators. By carefully adjusting the structural dimensions, less-than-unity ε and/or μ can be realized. To match the impedance of free space, the structural dimensions were adjusted so that ε=μ, which guarantees minimum reflection. Since the resonance-based structure is made of metallic resonators and lossy substrates, the imaginary part of refractive index is large, which guarantees strong absorption of transmitted waves. Full-wave simulations confirmed the effectiveness of the proposed three-dimensional metamaterial absorber. 相似文献
135.
以维生素C及常用于其注射液中作稳定剂的焦亚硫酸钠为例, 测定了两组平行反应(维生素C无氧降解和有氧降解; 维生素C和焦亚硫酸钠的氧化反应)的动力学参数, 建立了维生素C的降解动力学方程. 结果表明维生素C无氧降解为零级反应; 在维生素C和焦亚硫酸钠的氧化反应中, 维生素C和焦亚硫酸钠的反应级数都为零, 溶解氧为一级; 维生素C溶液的吸光度变化在一定范围内和浓度降解量成线性关系. 根据建立的动力学方程, 从理论上计算得在维生素C溶液中加(或不加)焦亚硫酸钠时的贮存期分别为444 d(或152 d), 表明加入焦亚硫酸钠能显著延长维生素C溶液的贮存期. 相似文献
136.
137.
In this paper, monodisperse poly(styrene-co-divinylbenzene) (PS-DVB) capsules with a bowl-like morphology were prepared controllably by regulating the content of DVB and dispersant. Using as-prepared PS-DVB capsules as building blocks, two-dimensional (2D) uniform hexagonal close-packed array with same orientation of each bowl was successfully fabricated by solvent evaporation. The size distribution showed that the capsules were still spherical in acetone before assembly and thus certified that the capsules caved in after self-assembly. Many factors including DVB content in capsules, experimental temperature and dispersants play important roles on regularity of orientation. Besides, "local self-assembly" array using multi-caved capsule as building blocks was obtained. More study proceeds with it, further advanced materials with complex functionalities or peculiar behavior could be expected. 相似文献
138.
In this paper, superconvergence of the lowest order Raviart-Thomas mixed finite element approximation for second order Neumann boundary value problem on fishbone shape meshes is analyzed. The main term of the error between the exact solution and the finite element interpolating function is determined by Bramble-Hilbert lemma on the individual finite element. A part of the main term of the error on two adjacent finite elements can be cancelled along the special direction, and thus the higher order error estimate is obtained on the whole domain by summation. Compared with the general finite element error estimate,the convergence rate can be increased from order one to order two in L2-norm by postprocessing superconvergence technique. 相似文献
139.
140.
Yu Chen Prof. Jiafu Shi Dr. Yizhou Wu Zheyuan Guo Shihao Li Wenping Li Zhenhua Wu Dr. Hongjian Wang Dr. Haifei Jiang Prof. Zhongyi Jiang 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310238
Photosynthesis offers a green approach for the recycling of nicotinamide cofactors primarily NADH in bio-redox reactions. Herein, we report an NADH photosynthesis system where the oxidation of biomass derivatives is designed as an electron supply module (ESM) to afford electrons and superoxide dismutase/catalase (SOD/CAT) cascade catalysis is designed as a reactive oxygen species (ROS) elimination module (REM) to inhibit NADH degradation. Glucose as the electron donor guarantees the reaction sustainability accompanied with oxidative products of gluconic acid and formic acid. Meanwhile, enzyme cascades of SOD/CAT greatly eliminate ROS, leading to a ≈2.00-fold elevation of NADH yield (61.1 % vs. 30.7 %). The initial reaction rate and turnover frequency (TOF) increased by 2.50 times and 2.54 times, respectively, compared with those systems without REM. Our study establishes a novel and efficient platform for NADH photosynthesis coupled to biomass-to-chemical conversion. 相似文献