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In this paper, we discuss non-elementary subgroups and discontinuous subgroups of PU(1,n; C), and give their geometric characterizations. 相似文献
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Emulsifier-free emulsion polymerization of styrene in the presence of β-hydroxy propyl acrylate was studied.The emulsifier-free self cross linked polystyrene latex microspheres was obtained.Monomer conversion is higher than 90% when [St],[β-HPA],[KPS] is 2.66,0.228,and 5.8×10^-3mol/L respectively under 80℃ for 5h.The mono-dispersed latex particle diameter and colloidal particle concentration were given as D=0.23um,N=3.13×10^13/cm^3 by TEM analyse,The factors of influencing latex stability were discussed.Thecopolymer was characterized by IR and dissolution experiment.The apparent activation energy of polymerization and polymerization rate constant were obtained to be 78.7KJ/mol and 514.4/mol.s respectively. 相似文献
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Shu-ning Li Xin-lin Yang Wen-qiang Huang 《高分子科学》2007,(6):555-563
Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine)(poly(EGDMA-co-4-VPy))microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate(EGDMA)and 4-vinylpyridine (4-VPy)with 2,2'-azobisisobutyronitrile(AIBN)as initiator in neat acetonitrile.The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm,which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles.The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction. 相似文献
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这就是希尔伯特第 3 问题.希尔伯特第3问题,正是指向了数千年来数学家们一直努力求解的体积理论基础的谜团. 相似文献
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61.IntroductionLetX~{X,(w),t20}beastandardd-dimensionalBrownianmotioninR'(d22).ThefirsthittingtimeofXforaBorelsetBinRdisdefinedtobeThefirsthittingplaceisX(TB).InthispapergwemainlyconsiderthesphereZ'--,(0,r)~{x:xERd,lxl~r}andthesphericalshellZ'--,(0,a)UZ'--,(0,b)~{x.xER',lxl=aorlxl~b},wherer>0,a>0,b>0anda相似文献
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DongJunWANG QunLUO DanDanJIA XiaoDongLI XinQiouWANG YongHuang ZhenZHEN XinHouLIU 《中国化学快报》2003,14(12):1306-1308
The hydrolysis of tetraethoxysilane (TEOS) occurred on the surface of poly(methyl methacrylate) (PMMA) microshperes immediately after these microshperes were prepared in TEOS. Micron-sized hollow SiO2 spheres were obtained by calcination of the coated PMMA microshperes. It was found that the final hollow spheres were constituted by small SiO2 particles. 相似文献
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Preparation,Characterization,and in vitro Release of Biodegradable Erythromycin-gelatin Microspheres
Blank and erythromycin-loaded gelatin microspheres were successfully fabricated via emulsion chemical- crosslinking technique. The surface morphology of the microspheres was characterized by scanning electron microscope(SEM) and optical microscope. The results show that the microspheres were spherical and smooth. The particle average size of erythromycin-loaded microspheres was found to be 20.6 μm, with a high purity of more than 90% and with a good dispersibility. The microspheres could be obtained in a high yield. Erythromycin released from the microspheres was monitored in buffer and artificial body fluid at 37 ℃. Average drug content was 27.2%, and erythromycin-loaded gelatin microspheres showed good release profiles with a nearly constant release during 4-8 h in artificial body fluid in vitro degradation studies. These gelatin microspheres are useful for studying and developing various drug-delivery systems. 相似文献