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231.
In this work, we present some existence theorems of weighted pseudo almost periodic solutions for N-th order neutral differential equations with piecewise constant argument by means of weighted pseudo almost periodic solutions of relevant difference equations. 相似文献
232.
233.
Lin XU En Bo WANG* Zhuang LI Hong Yu ZHANG Chao QIN Department of Chemistry Northeast Normal University Changchun Changchun Institute of Applied Chemistry Academia Sinica Changchun 《中国化学快报》2001,(12)
In recent years, there has been considerable interest in the fabrication of self-assembled ultrathin multilayer films, because of their availability to form nanostructured materials with tailored architecture and properties1. The layer-by-layer (LBL) self-assembly, initially developed for pairs of oppositely charged polyelectrolytes2, is an unusually simple and versatile technique to built up of ultrathin multilayer films. A special feature of the multilayer films is that the composition, t… 相似文献
234.
Ying‐Hui Wang Li‐Jing Gong Wen‐Yue Dong Ping Lu Zhi‐Hui Kang Tian‐Hao Huang Yu‐Guang Ma Han‐Zhuang Zhang 《Journal of Polymer Science.Polymer Physics》2013,51(12):992-997
The photoexcitation processes of two donor–acceptor‐type copolymers PCFBT with different ratios between the donor and the acceptor ( PCFBT0.5 and PCFBT0.1 ) in the solution system are systematically studied. If the number of the donor is equal to that of the acceptor in one repeat unit (such as PCFBT0.5 ), intrachain charge transfer (ICT) can occur and participate in the relaxation of the excited state after photoexcitation. When the number of donors is much larger than that of acceptors (such as PCFBT0.1 ) in one repeat unit, the ICT character can disappear, and the localized exciton decay process is dominant in the relaxation of the copolymer, which also involves an excitation intensity‐independent vibrational thermal relaxation process at the initial time. The results further the understanding of the basic structure‐property relationship. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 992–996 相似文献
235.
In the paper,an experiment investigation was conducted for one-and two-degree of freedom vortex-induced vibration(VIV) of a horizontally-oriented cylinder with diameter of 11 cm and length of 120 cm.In the experiment,the spring constants in the cross-flow and in-line flow directions were regulated to change the natural vibration frequency of the model system.It was found that,in the one-degree of freedom VIV experiment,a "double peak" phenomenon was observed in its amplitude within the range of the reduced velocities tested,moreover,a "2T" wake appeared in the vicinity of the second peak.In the two-degree of freedom VIV experiment,the trajectory of cylinder exhibited a reverse "C" shape,i.e.,a "new moon" shape.Through analysis of these data,it appears that,besides the non-dimensional in-line and cross-flow natural vibration frequency ratios,the absolute value of the natural vibration frequency of cylinder is also one of the important parameters affecting its VIV behavior. 相似文献
236.
Wenling Zhang Jinlin He Zhuang Liu Peihong Ni Xiulin Zhu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):1079-1091
A series of well‐defined amphiphilic triblock copolymers [polyethylene glycol monomethyl ether]‐block‐poly(ε‐caprolactone)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] (mPEG‐b‐PCL‐b‐PDMAEMA or abbreviated as mPEG‐b‐PCL‐b‐PDMA) were prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization. The chemical structures and compositions of these copolymers have been characterized by Fourier transform infrared spectroscopy, 1H NMR, and thermogravimetric analysis. The molecular weights of the triblock copolymers were obtained by calculating from 1H NMR spectra and gel permeation chromatography measurements. Subsequently, the self‐assembly behavior of these copolymers was investigated by fluorescence probe method and transmission electron microscopy, which indicated that these amphiphilic triblock copolymers possess distinct pH‐dependent critical aggregation concentrations and can self‐assemble into micelles or vesicles in PBS buffer solution, depending on the length of PDMA in the copolymer. Agarose gel retardation assays demonstrated that these cationic nanoparticles can effectively condense plasmid DNA. Cell toxicity tests indicated that these triblock copolymers displayed lower cytotoxicity than that of branched polyethylenimine with molecular weight of 25 kDa. In addition, in vitro release of Naproxen from these nanoparticles in pH buffer solutions was conducted, demonstrating that higher PCL content would result in the higher drug loading content and lower release rate. These biodegradable and biocompatible cationic copolymers have potential applications in drug and gene delivery. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1079–1091, 2010 相似文献
237.
Mei Wan Zhenjing Zhuang Jianyuan Dai Dan Xiao 《Russian Journal of Electrochemistry》2011,47(1):96-101
An amperometric sensor using foam nickel electrode as the working electrode for the measurement of ethanol in alkaline solution
has been developed. Cyclic voltammetry and chronoamperometry are employed to analyze electrochemical behavior of the electrode.
The results show that the oxidation of ethanol is more efficient on the foam nickel electrode than that on the nickel foil
electrode. The sensor exhibits a good linear relationship between response current and ethanol concentration in the range
of 4 to 1400 ppm with a detection limit of 0.8 ppm. The sensitivity and the response time of the sensor are 4.63 μA/ppm and
10 s respectively. Additionally, the sensor has 60 days shelf-life time at least. 相似文献
238.
239.
Zhuang Peng-fei Wang Zheng-qing Liu Lian-sou 《Zeitschrift fur Physik C Particles and Fields》1986,32(1):93-99
The mechanism of high-energyA′?A collisions (A>A′, A′ 1/3?1) and the space-time evolution of the fluid formed in the collision are analysed. The corresponding 1+1 dimensional hydrodynamic equations are set up. The average rapidity distributions are estimated and compared with cosmic ray data. The origin of the unsymmetry of rapidity distributions is explained. 相似文献
240.
Yufang Zheng Zhengfang Yu Z. N. Liang Yan Zhuang Fenen Hu 《Hyperfine Interactions》1992,68(1-4):169-172
The relations between the electrical characteristics of BaSn1?x Sb x O3 perovskite system and the contents of BaO, Sb2O3 and silicate sintering agent were studied by X-ray diffraction analysis and Mössbauer spectroscopy. It was found that the electrical conductivity is related to the substitution of Sb3+ for Sn4+, the content of sintering agent and the phase constitutents in samples. BaSnO3, Ba3Sn2O7, Ba2SnO4 and SnO2 phases might appear in different fractions when the contents of BaO change from 0.5 mole to 3.5 mole. In low antimony percentage condition, pentavalent Sb3+ ions inserted in Sn4+ sites and formed the donor center. In high antimony percentage (x≥0.20) condition, the existence of an insulating phase (BaSb2O6) was confirmed. 相似文献