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991.
992.
993.
Hong Li Sahas Rathi Elizabeth S. Sterner Hui Zhao Shaw Ling Hsu Patrick Theato Yongming Zhang E. Bryan Coughlin 《Journal of polymer science. Part A, Polymer chemistry》2013,51(20):4309-4316
The synthesis and characterization of a photocleavable block copolymer containing an ortho‐nitrobenzyl (ONB) linker between poly(methyl methacrylate) and poly(d ‐lactide) blocks is presented here. The block copolymers were synthesized via atom transfer radical polymerization (ATRP) of MMA followed by ring‐opening polymerization (ROP) of d ‐Lactide and ROP of d ‐lactide followed by ATRP of MMA from a difunctional photoresponsive ONB initiator, respectively. The challenges and limitations during synthesis of the photocleavable block copolymers using the difunctional photoresponsive ONB initiator are discussed. The photocleavage of the copolymers occurs under mild conditions by simple irradiation with 302 nm wavelength UV light (Relative intensity at 7.6 cm: 1500 μW/cm2) for several hours. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4309–4316 相似文献
994.
M. Q. Ling A. Yili H. A. Aisa Z. Bo O. N. Veshkurova Sh. I. Salikhov 《Chemistry of Natural Compounds》2011,46(6):932-934
A new peptide that had anti-oxidant activity and molecular weight 5,000.5 Da according to PAAG data and mass spectrometry
was isolated from celery seed using chromatographic methods. 相似文献
995.
The formation and co-existence of crystallographically modulated and non-modulated regions in (Ba,Sr)2TiSi2O8 fresnoites is reviewed, particularly the dependence on local composition. It is shown that perturbations of the average fresnoite structure, determined from appreciable single crystals, are in some cases better described as nanometric domain intergrowths where departures from ideal stoichiometry are characteristics of incommensuration, while modulation is absent from volumes that are less perturbed chemically. Evidence for this differentiation is obtained from selected area electron diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) images. The domains are readily distinguished by their unique contrast in bright field electron micrographs. Fourier reconstructions of HRTEM images collected from areas with darker contrast show that modulation can change within relatively small volumes. Nearby areas with lighter contrast were found by SAED to be free of structural disorder and incommensurate reflections. 相似文献
996.
Ziyuan Li Ling Ma Changhua Tang Jinyi XuXiaoming Wu Hequan Yao 《Tetrahedron letters》2011,52(43):5643-5647
Oxidative Heck coupling of thiazole-4-carboxylates via palladium(II)-catalyzed C-H bond activation has been achieved in moderate to good yields. No ligand, and no acidic additive were used in the reaction. The results showed that this protocol tolerated a series of substitutions on the thiazole ring. A preliminary attempt of direct arylation with p-xylene via Pd(II)-catalyzed C-H bond activation has also been done. 相似文献
997.
The global responses characteristics of a rotor/stator rubbing system with dry friction effects 总被引:2,自引:0,他引:2
Rotor/stator rubbing systems may undertake a number of quite different responses. Recent experiments on rotor/stator rubbing have revealed that two or three different responses may coexist. In this paper the global response characteristics of a general rotor/stator rubbing system, which takes into account the dominant factors in the process of rotor/stator rubbing, especially, the dry friction effect that is mostly neglected in the previous works and is the main factor for the self-excited dry friction backward whirl, are studied. The different solutions of the piecewise nonlinear system are derived and their stability are analyzed to get the existence boundaries of the different responses. An overall picture of the global response characteristics of this model is then obtained by drawing the existence boundaries in a same parameter space. The present results provide good understanding on the coexistence of different rubbing responses observed in tests. Moreover, deeper insight into the types of coexistence of different rubbing responses and their relationship with the system parameters is gained. 相似文献
998.
In this article, we consider a stochastic hydrodynamical equation in Heisenberg paramagnet driven by additive noise. We prove
the existence and uniqueness of smooth solutions to this equation with difference method. 相似文献
999.
1000.
Influence of non-gelling methylcellulose(MC)on gelation behavior of wheat gliadins in 13 wt%alkaline propanol/water(50:50, v/v)solution was investigated using dynamic rheological time sweep test.Increasing MC concentration(C_(MC))up to C_(MC)=1wt% caused a significant reduction in gelation time(t_(gel))of the solution and an increase in loss tangent(tanδ)value of the resultant gel at T<30℃. 相似文献