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排序方式: 共有288条查询结果,搜索用时 15 毫秒
21.
Liu CW Hung CM Haia HC Liaw BJ Liaw LS Tsai YF Wang JC 《Chemical communications (Cambridge, England)》2003,(8):976-977
The novel halide-centered Ag(I)8 cubic clusters containing diethyl diselenophosphato ligands are prepared and their solid state structures, a discrete unit or a one-dimensional chain, are dictated by the counter anions. 相似文献
22.
We design an inclination-sensing system based on a fiber-ring laser integrated fiber-Bragg grating (FBG) whose peak wavelength is changed by the axial strain. By replacing a conventional broadband light source with the fiber-ring laser, we raise the sensing power to 3.1 dBm, the peak-to-noise ratio to 65.31 dB, and reduce the 3-dB bandwidth to 0.06 nm. Thus, the sensitivity and resolution of the proposed system are greatly improved. By using an FBG integrated with a pendulum ball used as a sensor head, the resolution of the angular inclination could reach 0.015 nm per degree. These specifications are qualified for the general practice of the pendulum-sensing system. 相似文献
23.
Wong WW Vak D Singh TB Ren S Yan C Jones DJ Liaw II Lamb RN Holmes AB 《Organic letters》2010,12(21):5000-5003
A new class of self-assembling hexa-peri-hexbenzocoronene (HBC)-fullerene hybrid materials has been synthesized and characterized. Photoluminescence experiments indicate that energy transfer processes can be tuned in these donor-acceptor systems by varying the length and nature of the linker group. In preliminary device testing, ambipolar charge transport behavior is observed in organic field effect transistors, while single active component organic photovoltaic devices consisting of these materials achieved a maximum external quantum efficiency of 30%. 相似文献
24.
Cheng‐Hung Chang Kun‐Li Wang Jyh‐Chiang Jiang Der‐Jang Liaw Kueir‐Rarn Lee Juin‐Yih Lai Kuo Yuan Chiu Yuhlong Oliver Su 《Journal of polymer science. Part A, Polymer chemistry》2010,48(24):5659-5669
A series of highly organosoluble polyamides with high modulus having propeller‐shaped triarylamine were synthesized using aromatic diacid chlorides by low‐temperature solution polycondensation. The polyamide films had strong, tough, flexible, and amorphous properties. These polymers revealed electrochromic characteristics both in the visible range and near‐infrared (NIR) region, with a color change from pale yellowish at its neutral state to green and blue at its oxidized state at applied potentials ranging from 0.00 to 1.35 V. Cyclic voltammetry (CV) of the polymer films cast onto an indium tin oxide (ITO)‐coated glass substrate exhibited two reversible redox couples at potentials of 0.80–0.87 V and 1.19–1.25 V, respectively, vs. Ag/Ag+ in acetonitrile solution. From the combination of the experimental and computational study, we proposed an oxidation mechanism based on molecular orbital (MO) theory, which well explains the CV experimental result. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
25.
Yu‐Liang Yang Dr. Wen‐Ying Liao Wan‐Yun Liu Chih‐Chuang Liaw Dr. Chia‐Ning Shen Dr. Zih‐You Huang Shih‐Hsiung Wu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11573-11580
Six photosensitive polyketides, malbranpyrroles A–F, were discovered from the thermophilic fungus Malbranchea sulfurea by using intact‐cell desorption/ionization on silicon mass (ICD‐MS) and LC‐SPE‐NMR. These two strategies facilitate the searching and structural determination of unstable natural products. The ICD‐MS indicated that only brown hyphae of M. sulfurea can produce malbranpyrroles. The biosynthetic pathway of malbranpyrroles was evidenced by 13C isotope precursors and amino acid feeding experiments. The cytotoxicity data revealed that the conformation of the conjugated system in malbranpyrroles does not affect cytotoxic potency against cancer cell lines. In addition, the chlorine atom was shown to be the pharmacophore for cytotoxicity. 相似文献
26.
27.
In this paper, we study the stabilization of nonlinear systems in critical cases by using the center manifold reduction technique. Three degenerate cases are considered, wherein the linearized model of the system has two zero eigenvalues, one zero eigenvalue and a pair of nonzero pure imaginary eigenvalues, or two distinct pairs of nonzero pure imaginary eigenvalues; while the remaining eigenvalues are stable. Using a local nonlinear mapping (normal form reduction) and Liapunov stability criteria, one can obtain the stability conditions for the degenerate reduced models in terms of the original system dynamics. The stabilizing control laws, in linear and/or nonlinear feedback forms, are then designed for both linearly controllable and linearly uncontrollable cases. The normal form transformations obtained in this paper have been verified by using code MACSYMA. 相似文献
28.
Nonlinear heave-roll coupling and ship rolling 总被引:4,自引:0,他引:4
A nonlinear model for simulating the heave-roll motions of ships in following waves is presented. The parametric excitation is modeled by a Hill's type equation, instead of the conventional Mathieu's equation. The model includes not only the linear but also the quadratic coupling term. Instability conditions for parametrically excited rolling motions are derived using the harmonic balance method. The results are verified by numerical analyses. The effects of including the quadratic coupling term on the instability conditions and nonlinear responses are studied. The complex dynamic behaviour of the coupled system in the various instability regions is also investigated. Bifurcations of the flip, fold and pitchfork types are observed in the Poincaré mapping of the numerically simulated responses. Chaotic motions leading to boundary crises and inevitable capsize are also reported. 相似文献
29.
Der‐Jang Liaw 《Journal of polymer science. Part A, Polymer chemistry》2005,43(19):4559-4569
New polyamides were prepared directly from a diamine, bis[4‐(2‐trifluoromethyl 4‐aminophenoxy)phenyl] diphenylmethane, containing an electron‐withdrawing trifluoromethyl group and a kink diphenylmethylene linkage with various aromatic dicarboxylic acids having inherent viscosities ranging from 0.66 to 0.83 dL g?1. All the polyamides showed outstanding solubility and could be easily dissolved in amide‐type polar aprotic solvents (e.g., N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N,N‐dimethylformamide) and even dissolved in less polar solvents (e.g., pyridine, cyclohexanone, and tetrahydrofuran). The dielectric constants of the polyamide films were 3.37–3.87 (100 KHz) and decreased with an increase in the frequency, which ranged from 1 Hz to 100 KHz. A low coefficient of thermal expansion for the polyamides was observed in the range of 54–78 ppm/°C (by thermomechanical analysis). These polyamides showed excellent thermal stability, and the 10% weight loss temperatures were in the range of 484–507 °C in an atmosphere of nitrogen. The polymers had an initial modulus of 1.8–2.2 GPa. The polyamides with kink and electron‐withdrawing trifluoromethyl units afforded light‐color polymer films with high transmittance in the visible region (400–700 nm), and their cutoff wavelength was lower than 362 nm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4559–4569, 2005 相似文献
30.
The first 2D metal-organic framework utilizing PPh2(CH2)2PPh2 (dppe) units as the linkers and tetranuclear silver clusters, [Ag4(micro3)-Cl){S2P(OR)2}3], as the network nodes in the formation of the honeycomb-shaped layer structure is reported. 相似文献