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排序方式: 共有232条查询结果,搜索用时 31 毫秒
1.
Yeong‐Tarng Shieh Pei‐Yu Tai Chih‐Chia Cheng 《Journal of polymer science. Part A, Polymer chemistry》2019,57(21):2149-2156
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156 相似文献
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In this paper, a hybrid control based on pulse width modulator (PWM) is proposed to synchronize a class of master–slave chaotic systems with uncertainties. We use the Genetic Algorithm (GA) together with fuzzy logic to tune the switching time of PWM mode controller such that the output response of master–slave chaotic system can be synchronized. Finally, an example, uncertain master–slave Duffing–Holmes chaos system, is proposed to show the proposed method’s effectiveness for chaotic synchronization. 相似文献
4.
An inverse nodal problem is studied for the diffusion operator with real-valued coefficients on a finite interval with Dirichlet boundary conditions. The oscillation of the eigenfunctions corresponding to large modulus eigenvalues is established and an asymptotic of the nodal points is obtained. The uniqueness theorem is proved and a constructive procedure for solving the inverse problem is given. 相似文献
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Spencer Knapp Andrew B. J. Naughton Paivi J. Kukkola Wen-Chung Shieh 《Journal of carbohydrate chemistry》2013,32(6):981-993
ABSTRACT For five carbohydrate substrates [methyl 4,6-O-(phenylmethylene)-1-thio-α-D-glucopyranoside 1a, 1-cyano-1-deoxy-4,6-O-(phenylmethylene)-α-D-galactopyranose 2a, methyl α-D-xylopyranoside 3a, methyl β-D-arabinopyranoside 4a, and methyl 5-O-(tert-butyldiphenylsilyl)-α-D-ribofuranoside 5a], selective mono-triflation was achieved where the reacting hydroxyl is cis and vicinal to a heteroatom. 相似文献
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3, 4′-Bipyridine was synthesized from 6-methoxy-3, 4′-bipyridine or 6-benzyloxy-3, 4′-bipyridine via 6-chloro-3, 4′-bipyridine. The chloro derivative was catalytically dechlorinated into the corresponding 3, 4′ -bipyridine. 相似文献
8.
Prof. Dr. Minghuey Shieh Chun‐Hsien Yu Yen‐Yi Chu Yu‐Wen Guo Chung‐Yi Huang Kai‐Jieah Hsing Pei‐Chi Chen Chung‐Feng Lee 《化学:亚洲杂志》2013,8(5):963-973
The reactions of E powder (E=S, Se) with a mixture of Cr(CO)6 and Mn2(CO)10 in concentrated solutions of KOH/MeOH produced two new mixed Cr? Mn? carbonyl clusters, [E2CrMn2(CO)9]2? (E=S, 1 ; Se, 2 ). Clusters 1 and 2 were isostructural with one another and each displayed a trigonal‐bipyramidal structure, with the CrMn2 triangle axially capped by two μ3‐E atoms. The analogous telluride cluster, [Te2CrMn2(CO)9]2? ( 3 ), was obtained from the ring‐closure of Te2Mn2 ring complex [Te2Mn2Cr2(CO)18]2? ( 4 ). Upon bubbling with CO, clusters 2 and 3 were readily converted into square‐pyramidal clusters, [E2CrMn2(CO)10]2? (E=Se, 5 ; Te, 6 ), accompanied with the cleavage of one Cr? Mn bond. According to SQUID analysis, cluster 6 was paramagnetic, with S=1 at room temperature; however, the Se analogue ( 5 ) was spectroscopically proposed to be diamagnetic, as verified by TD‐DFT calculations. Cluster 6 could be further carbonylated, with cleavage of the Mn? Mn bond to produce a new arachno‐cluster, [Te2CrMn2(CO)11]2? ( 7 ). The formation and structural isomers, as well as electrochemistry and UV/Vis absorption, of these clusters were also elucidated by DFT calculations. 相似文献
9.
Shih-Kuen Changchien Chuan-Kuei Huang Hsiau-Hsian Nien Hong-Wei Shieh 《Chaos, solitons, and fractals》2009,39(4):1578-1587
In this paper, we utilize a proper Lyapunov function and Lyapunov theorem, combined with LMIs method, in order to design a controller L, which ensures the synchronization between the transmission and the reception ends of the chaotic secure communication system with time-delay of output state. Meanwhile, for the purpose of increasing communication security, we encrypt and decrypt the original to-be-transmitted message with the techniques of n-shift cipher and public key. The result of simulation shows that the proposed method is able to synchronize the transmission and the reception ends of the system, and moreover, to recover the original message at the reception end. Therefore, the method proposed in this paper is effective and feasible to apply in the chaotic secure communication system. 相似文献
10.
Inverse nodal and inverse spectral problems are studied for second-order differential operators on a finite interval with discontinuity conditions inside the interval. Uniqueness theorems are proved, and a constructive procedure for the solution is provided. 相似文献