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以改进的荧光非辐射能量转移法研究高分子共混物 总被引:2,自引:1,他引:1
荧光非辐射能量转移(NRET)法可灵敏地反映出在几纳米尺度上分子相互作用的信息。这一性质已广泛用于高分子共混物相容性的研究。通常的NRET方法是通过测定两种聚合物链的相互接近的程度得到有关相容性的信息。但相区的大小与形态都会影响能量转移的效率,且需对共混物中的组成聚合物分别以荧光能量给体和受体进行标记,与此不同,本 相似文献
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Polyvinyl alcohol coated magnetic particles (PVA ferrofluids) have been synthesized by chemical co-precipitationof Fe(Ⅱ)/Fe(Ⅲ) salts in 1.5 mol/L NH_4OH solution at 70℃ in the presence of PVA. The resultant colloidal particles havecore-shell structures, in which the iron oxide crystallites form the cores and PVA chains form the shells. The hydrodynamicdiameter of the colloidal particles is in the range of 108 to 155 nm, which increases with increasing PVA concentration from5 wt% to 20 wt%. The size of the magnetic cores is ca. 5~10 nm, which is relatively independent of PVA concentration.Under transmission electron microscopic (TEM) examination, the magnetic cores exhibit somewhat irregular shapes varyingfrom spherical, oval, to cubic. Magnetometry measurement revealed that the PVA coated magnetic particles aresuperparamagnetic. The saturation magnetization of 5 wt% and 20 wt% PVA ferrofluids at 300 K is 54 and 49 emu/g.respectively. All the PVA ferrofluids exhibited excellent colloidal stability in pure water and phosphate buffer saline (PBS,pH=7.4). The ferrofluids can remain stable in above solutions for more than three months at 4℃. 相似文献
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荧光法研究含长链烷基聚丙烯酰胺的疏水微区结构 总被引:2,自引:0,他引:2
荧光法研究含长链烷基聚丙烯酰胺的疏水微区结构邱星屏,张雪蓉,丁马太(厦门大学化学系,厦门,361005)关键词萘酚,聚丙烯酰胺,疏水微区聚丙烯酰胺作为增粘剂和絮凝剂,已用于石油开采、水处理等领域[1].在聚丙烯酰胺链上引进少量疏水侧基,可显著地改变其... 相似文献
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本文报道了一组取代四苯基卟啉蒽醌化合物的合成和光谱性质研究,并根据波谱数据和各化合物荧光猝灭程度的不同,讨论了化合物的结构以及取代基,卟啉和蒽醌之间的距离对分子内电子传递产生影响的内在因素。 相似文献
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Magnetic nanoparticles with average diameter in the range of 6.4-8.3 nni have been synthesized by a chemical co-precipitation of Fe(Ⅱ)and Fe(Ⅲ)salts in 1.5 M NH4OH solution.The size of the magnetic particles is dependent on both temperature and the ionic strength of the iron ion solutions.The magnetic particles formed at higher temperature or lower ionic strength were slightly larger than those formed at lower temperature or higher ionic strength respectively.In spite of the different reaction conditions,all the resultant nanoparticles are nearly spherical and have a similar crystalline structure.At 300 K,such prepared nanoparticles are superparam-agnetic.The saturation magnetizations for 7.8 and 6.4 nm particles are 71 and 63 emu/g respectively,which are only ~ 20-30% less than the saturation magnetization(90 emu/g)of bulk Fe3O4 Our results indicated that a control of the reaction conditions could be used to tailor the size of magnetic nanoparticles in free precipitation. 相似文献
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The dependence of measured viscosity on NaCl concentration (0.1 to 3.0M), pH (range of 2—13) and cadoxen composition w_(cad) (from 2% to 100%) for the lacquer polysaccharide in NaCl/cadoxen/H_2O mixture containing HCl or without were obtained. All the viscosity exponents γin the Mark-Houwink equations under three different solvent condition arc close to 0.5. The w_(cad) dependence of reduced viscosity ηsp/c confirms the single strand chain of the polysaccharide. As the γvalues close to 0.5 and values of unperturbed dimension _θ/M and [η] much smaller than those for usual linear polymers, these facts suggest that the polysaccharide chains in the aqueous solutions should be dense random coil owing to the highly branched structure. 相似文献
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Ten fractionated samples of Chinese lacquer polysaccharide in aqueous 0.1M NaC1 solution were studied by aqueous-phase gel permeation chromatography (GPC). The universal calibration, broad MWD calibration and corrected column dispersion were adopted to the analysis of GPC chromatograms of the polysaccharide. The molecular weights M_w, M_n and polydispersity index M_w/M_n obtained from GPC are in good agreement with the results of light scattering and membrane osmometry. It is verified that the universal calibration concept is applicable to the lacquer polysaccharide having a number of side chains. 相似文献
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