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991.
Dairen Lu Yun Wang Tianyuan Wu Kang Tao Lijia An Ruke Bai 《Journal of polymer science. Part A, Polymer chemistry》2008,46(17):5805-5815
Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization using an ion‐bonded macromolecular RAFT agent (macro‐RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6‐bis(bromomethyl)‐isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion‐bonded supramolecular macro‐RAFT agent was obtained through the interaction between the tertiary amino group and 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methyl propionic acid (DMP). Finally, ion‐bonded amphiphilic miktoarm star copolymer, (PSt)2‐poly(N‐isopropyl‐acrylamide)2, was prepared by RAFT polymerization of N‐isopropylacrylamide (NIPAM) in the presence of the supramolecular macro‐RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of 1H‐NMR, FTIR, and GPC techniques. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5805–5815, 2008 相似文献
992.
A stabilization problem for Burgers' equation is considered. Using linearization, various controllers are constructed which minimize certain weighted energy functionals. These controllers produce the desired degree of stability for the closed-loop nonlinear system. A numerical scheme for computing the feedback gain functional is developed and several numerical experiments are performed to illustrate the theoretical results. 相似文献
993.
The pressure and laser-power dependence of the product distributions in the TEA CO2 laser induced decomposition of trichloroethylene were studied. At moderate pressures molecular elimination of HCl to give CClCCl via intermolecular energy transfer was found to be the major reaction path. At low pressures a pure laser-induced CCl bond fission to give CHCCl was found to be the primary, reaction step. 相似文献
994.
A water-in-oil-in-water emulsion liquid membrane system is used to transport alkali metal and alkaline earth cations from an external alkaline aqueous source phase through an organic membrane containing a crown ether carboxylic acid and into the internal acidic aqueous phase of the emulsion droplet. The influence of varying the crown ether carboxylic acid structure upon the selectivity and efficiency of competitive metal ion transport is examined. 相似文献
995.
B. Z. Gunesin D. N. Schulz J. W. Kang A. R. Cain G. R. Hamed 《Journal of polymer science. Part A, Polymer chemistry》1984,22(2):353-363
A new convenient route to metal containing polymers is described. This method involves emulsion co(ter) polymerization of a polar hydrocarbon soluble monomer, N-isobutoxymethylacrylamide (IBMA), with styrene or styrene/butadiene, followed by addition of metals. Metal incorporation is effected by latex or solution techniques. Preparative, atomic adsorption, spectroscopic, film observation, and dilute solution data are presented in support of metal complexation. Structures for the complexes are proposed. 相似文献
996.
997.
本文描述农用薄膜中Al、Fe、Mg、Ca、Si、Cu、Ti杂质元素的发射光谱分析法,该方法直接压样于石墨电极中,简便,快速,取得了满意的结果。 相似文献
998.
T. J. Kim S. W. Lee B. K. Kang D. S. Kim A. S. Kim K. H. Shin M. K. Park Y. K. Sin 《Optical and Quantum Electronics》1995,27(5):465-471
High-quality and uniform bulk layers of (Al
x
Ga1–x
)0.5In0.5P (x=0–0.7) and AlGalnP/GainP quantum wells (QWs) are grown on 2°-off (100) GaAs substrates by low-pressure metal organic vapour phase epitaxy at a low growth rate of 0.3 nm s-1. The amount of lattice mismatch and the variation of PL peak energy of (Al0.5Ga0.5)0.5In0.5P on the 50-mm substrate are less than 6×10-4 and 2 meV, respectively. (Al0.5Ga0.5)0.5In0.5P/Ga0.5In0.5P SQWs show narrow PL spectra even from a 0.6 nm well measured at 20 K. The variation of PL peak energy from (Al0.5Ga0.5)0.5In0.5P/Ga0.5In0.5P MQWs is less than 10 meV. Also, as-cleaved AlGalnP/GalnP lasers fabricated by a three-step MOVPE show a pulsed threshold current of 82 mA at room temperature, output power of 12 mW, and the lasing wavelength at 668.2 nm. 相似文献
999.
It is shown that Lorentz harmonics provide a natural basis for the expansion and infrared regularization of a massless scalar field in two dimensions. The negative metric operators separate out simply. Each Lorentz component of the field is partially local. 相似文献
1000.