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991.
We report the first formation of arrays of GaN nanorods inside the nanoscale channels of mesoporous silica SBA-15. GaCl3 dissolved in toluene was incorporated into the methyl group-functionalized SBA-15 powder. The pore surfaces functionalized with methyl groups should facilitate the impregnation with GaCl3. Formation of GaN nanorod arrays within SBA-15 was carried out by heating the powder to 700 degrees C for 3 h under nitrogen atmosphere, followed by ammonolysis at 900 degrees C for 5 h. epsilon-Ga2O3, an unusual phase for Ga2O3, formed after the first thermal process and was converted into wurtzite GaN during ammonolysis. The final products have been characterized by FT-IR spectra, powder XRD patterns, TEM images and SAED patterns, EDS analysis, and nitrogen adsorption-desorption isotherm measurements to confirm the presence of GaN nanostructures. The nanorods are 6-7.5 nm in diameter, and can be a few hundreds of a nanometer in length to exhibit nanowire structure. Free-standing GaN nanorod arrays were revealed upon removal of the silica framework with HF solution. Optical characterization of the isolated GaN nanorod arrays shows a strong and sharp near band-edge emission at 375 nm, and two phonon-assisted donor-acceptor peaks at 395 and 415 nm. A broad but weak emission in the region of 335-360 nm due to the quantum confinement effect of short nanorods was observed. 相似文献
992.
A sensitive and rapid high-performance liquid chromatographic assay is developed and validated for the determination of buformin in plasma. After addition of metformin as the internal standard, the analytes were deproteinated with acetonitrile, washed with dichloromethane, and the resulting supernatant injected. Chromatography was performed at ambient temperature by pumping a mobile phase of 0.03 m diammonium hydrogen phosphate buffer (pH 7, 250 mL) in methanol (750 mL) at a fl ow rate of 1 mL/min through a silica column. Buformin and metformin were detected at 236 nm, and eluted 9.8 and 15.4 min, respectively. No endogenous substances were found to interfere. Calibration curves were linear over the concentration range of 20-2000 ng/mL. The limit of quantitation was 20 ng/mL. The intra- and inter-day relative standard deviation (RSD) was 8.3%, or less, and the accuracy was within 10.1% of the relative error (RE). The method is suitable in pharmacokinetic investigation of buformin. 相似文献
993.
994.
交联助剂对PPC/NBR弹性体结构和性能的影响 总被引:2,自引:1,他引:2
研究了马来酸酐(MA)及异氰脲酸三烯丙酯(TAIC)对聚丙撑碳酸酯/丁腈橡胶共混弹性体结构和性能的影响,发出加入MA或TAIC能有效地改善交联网络;加入适量MA能显著改善共混弹性体热氧老化稳定性;加入TAIC使共混弹性体具有优良的高弹特性和力学性能。 相似文献
995.
996.
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998.
A novel and efficient ionic liquid supported synthesis of oligosaccharides with a general protocol of coupling and purification is described. The method represents an attractive alternative to the classical solid- and fluorous-phase synthesis strategies and combines the advantage of performing homogeneous chemistry on a relatively large scale while avoiding large excesses of reagents. 相似文献
999.
制备了聚苯乙炔(PPA)LB多层膜,将其作为电荷产生层首次应用于机能分离型光电导体领域.从π A曲线发现,PPA单分子膜具有表面压力的各向异性和松弛特性.TEM照片显示,PPA分子链在LB膜中有序排列.转移比和XPS的研究表明,复合膜沉积均匀.与PPA涂膜相比,以PPA LB多层膜作为电荷产生层的光电导体表面充电电位V0=1345V,光照1s后的光衰百分比ΔV1s=6505%,半衰时间t1/2=058s,具有更优异的光电导性能. 相似文献
1000.