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功能化离子液体[bmim]OTs催化乙酰化反应 总被引:2,自引:0,他引:2
以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)为溶剂,对甲基苯磺酸根(OTs-)为阴离子的功能化离子液体[bmim]OTs为催化剂进行苯甲醇的乙酰化反应.结果表明,该体系循环使用10次后仍能保持良好的催化活性和稳定性,并对各种(伯、仲、叔)醇类、酚类和胺类化合物的乙酰化反应表现出良好的普适性.核磁共振波谱(13C NMR)分析结果表明,具有亲核性的[bmim]OTs和酰化试剂乙酸酐(Ac2O)形成的活性中间体AcOTs,是催化反应的活性物种. 相似文献
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Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing. 相似文献
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Vascular Doppler optical coherence tomography(DOCT) images with weak boundaries are usually difficult for most algorithms to segment. We propose a modified random walk(MRW) algorithm with a novel regularization for the segmentation of DOCT vessel images. Based on MRW, we perform automatic boundary detection of the vascular wall from intensity images and boundary extraction of the blood flowing region from Doppler phase images. Dice, sensitivity, and specificity coefficients were adopted to verify the segmentation performance. The experimental study on DOCT images of the mouse femoral artery showed the effectiveness of our proposed method, yielding three-dimensional visualization and quantitative evaluation of the vessel. 相似文献
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A pair of enatiomerically pure ligands,(R-)/(S-)2-(4-carboxyphenyl)-4,5-dihydrothiazole-4-carboxylic acid(H2L^R & H2L^S), have been synthesized by the reactions of 4-cyanobenzoic acid with L-and D-cysteine, respectively. Four coordination polymers have been prepared from the ligands and structurally determined by single-crystal X-ray diffraction analysis. Complexes 1 R and 1 S([NiL(Py)(H2 O)]×H2 O, for 1 R, L =(L^R)2-;for 1 S, L =(L^S)2-) exhibit chiral helical one-dimensional chains, and complexes 2 R and 2 S({[ZnL2(H2 O)3]×CH3 CN}n, for 2 R L =(L^R)2-, for 2 S L =(LS)2-) are two-dimensional sheets. Luminescent and chir-optical properties have been investigated and compared with the free ligands. The complexes have blue-shift in luminescence spectrum compared with the free ligands. 相似文献
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采用低压化学气相沉积法(LPCVD)在大面积(40 cm ×40 cm)超薄柔性玻璃和硬质玻璃衬底上分别制备了B掺杂的ZnO(BZO)透明导电薄膜及非晶硅薄膜太阳能电池,对比了两种衬底上BZO薄膜的形貌、光学和导电性能及其非晶硅薄膜电池的性能.结果表明,在相同LPCVD工艺下,超薄柔性玻璃衬底上BZO薄膜的生长速率相对减小;当生长相同厚度BZO薄膜时,超薄柔性玻璃衬底的透光率相对于硬质玻璃衬底提高约2;,同时并具有相同的导电能力.在柔性玻璃衬底上制备的非晶硅薄膜电池的初始和稳定转化效率也相对提高,分别达到9.16;和7.82;. 相似文献
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分别用固相反应和柠檬酸盐溶胶-凝胶法制备义组成为Sr2(Gd1.5Ce0.5)Cu2Oz的前驱物,再用真空烧结的方法合成了(Hg,M)-1222相铜氧化合物(Hg0.75M0.25)Sr2(Gd1.5Ce0.5)Cu2Oz(M=W,Mo,V,Cr,Ti)。溶胶-凝胶法同固相法相比混合更均匀,反应温度低,成相情况好,改进该方法后,用溶解度较高的Ce(NO3)3代替不溶于硝酸的CeO2,制得了纯1222相。研究了不同退火条件对样品电阻温度特性的影响的影响,发现高氧压退火有助于超导转变,M=W,Mo时得到超导体,Tc(onset)在13-27K之间。 相似文献
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课余时间,我从老师那里借来了2004年第4期的《化学教育》,里面有北大附中刘晟同学写的“实践出真知——记KIO3热分解实验”一文。通读全文,我不禁对他认真思索,勇于质疑的学习精神敬佩不已,同时也使我注意到在文章结尾部分作者总结的反应方程式: 相似文献