992 resultados para 48-405
Resumo:
介绍了一套用于硅多条阵列探测器中的高密度多通道电荷灵敏放大器的研制和阵列探测器电子学的发展现状和工作原理,提出了设计原则和设计思路,特别介绍了一个新开发的用于硅多条探测器中的48路电荷灵敏前置放大器的设计和实际测量结果。它具有低成本、高密度的特点,好于1%的能量分辨和良好的长期稳定性。
Resumo:
Nanocrystalline Pb(Zr0.52Ti0.48)O-3 was prepared from lead acetate, zirconium oxynitrate and titanium tetra-n-butoxide by a sol-gel method. It is found that both the crystallization temperature of precursor PZT and PZT product size were increased with increase of V(C3H8O2)/V(H2O) ratio in solution used. At V(C3H8O2)/V(H2O) = 4.47 the gel was formed moderately quick, and the nanocrystalline PZT with uniform granularity and low crystallizing temperature could be obtained. The diameter of the final nanocrystalline was ranged 60similar to70 nm as measured by atomic force microscopy (AFM). The crystallizing temperature of the precursor PZT was 443degreesC and the crystallization reaction was completed at 500degreesC by DTA and TG. The sol-gel reaction process was monitored by FT-IR and XRD.
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一种制备巯基官能化MCM-48介孔分子筛的方法是将巯丙基三甲氧基硅烷溶解于甲苯中,再加入经过焙烧的MCM-48分子筛,回流12~24小时;产物经离心分离后,用甲苯洗涤直至无未反应的巯丙基三甲氧基硅烷存在,于100℃-120℃下烘干,得到巯基官能化的MCM-48分子筛;具有巯基官能化的产品具有三维孔道结构,不易堵塞,对汞离子的吸附效果好的优点。
Resumo:
本发明公开了一种MCM-48介孔分子筛的制备方法,按原料组成质量百分比将3.1~16.8%的十六烷基三甲基溴化铵和0.75~1.63%的氢氧化钠溶解在66.4~87.1%的去离子水中,在强烈搅拌下缓慢加入正硅酸乙酯,继续搅拌反应30分钟后,转移至密闭反应器中在80~150℃晶化1~3天后,加入HCl调节pH值到6~9,再在80~150℃继续晶化2天;将晶化产物经过滤、洗涤、晾干后,在550℃下焙烧6小时,得到MCM-48分子筛。分子筛的产率高达97%,BET比表面积达到1137m↑[2]/g,孔径为2.6纳米左右,该制备方法简单、易操作。
Resumo:
We report on the preparation of luminescent silica mesoporous molecular sieves (MCM-48) activated by the europium complex Eu(DBM)(3) . 2H(2)O (where DBM = dibenzoylmethane), using a simple wet impregnation method. Different concentrations of Eu(DBM)(3) . 2H(2)O were introduced into the MCM-48 cubic structure, and the resulting samples were washed with ethanol for different times. UV-Vis absorption measurements and thermogravimetric analysis were used to estimate the amount of Eu complex that has been incorporated within the pores of the MCM-48 host. The various samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy, diffuse reflectance (DR) and fluorescence measurements. The results reveal that Eu complexes have been successfully introduced into the pores of MCM-48 without disrupting the structure. All the impregnated MCM-48 materials show the typical red luminescence of Eu3+ when excited with a UV lamp. Shifts of the absorption maxima were observed in the DR and fluorescence excitation spectra and will be discussed in relation with guest-host interactions between the organic complex and the silica matrix. The decay profiles of the europium luminescence in the different samples were also measured and discussed.
Resumo:
中国科学院山西煤炭化学研究所
Efficient synthesis of high-quality MCM-48 silicas through mixed surfactants and pH adjustment route
Resumo:
This work is intended to provide a method for the preparation of maleic anhydride grafted syndiotactic polystyrene (sPS-g-MA). In particular, a novel solid reaction method by a radical grafting approach is investigated. The grafting reaction is performed at a solid state, where the syndiotactic polystyrene (sPS) is swollen in solvent at relatively low temperature compared to the conventional melt modification method. The formation of sPS-g-MA is directly confirmed by Fourier transform infrared spectroscopy and by the morphology observation of sPS/polyamide-6 (Nylon6) blends, when sPS-g-MA is used as a reactive compatibilizer.
Resumo:
以醋酸铅 ,硝酸氧锆 ,钛酸四丁酯为原料用溶胶 -凝胶法制备了纳米 Pb( Zr0 .52 Ti0 .48) O3 ( PZT)。结果表明 ,随溶剂中乙二醇单甲醚与水的比例的增大 ,PZT粉体的晶化温度增高 ,晶粒的粒径尺寸也增大 ,当V( C3 H8O2 ) / V( H2 O) =4 .4 7时 ,不仅凝胶完成时间短 ,且可得到粒度分布集中、晶化温度低的 PZT粉体。用原子力显微镜测定 PZT的粒径为 6 0~ 70 nm,用 TG-DTA分析确定在 4 43℃即可发生晶化反应 ,在 5 0 0℃下结晶完善。通过对不同温度下热处理的粉体的红外光谱和 X射线衍射的分析 ,对溶胶 -凝胶法制备 PZT粉体形成钙钛矿结构的过程进行了研究。
Resumo:
Problema do monitoramento. Sistema em funcionamento. Proposta de extensão para o PIF. Considerações finais e recomendações.