排序方式: 共有105条查询结果,搜索用时 15 毫秒
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研究了在超临界乙醇中、氢气存在下,一系列金属-酸双功能催化剂的酸性、孔径大小、负载的金属对热解木质素加氢裂解过程的影响.制备并采用N2等温吸附和BET比表面、X射线衍射、NH3-程序升温脱附技术对催化剂进行表征.实验结果表明催化剂酸性增强可促进热解木质素的缩聚反应,从而产生大量的焦炭和水,导致其液化效率降低.微孔催化剂比介孔催化剂孔径小,与强酸共同作用会导致热解木质素裂解生成更多的小分子气体.在催化剂上负载金属Ru可有效地抑制热解木质素的缩聚反应,促进其裂解液化. 相似文献
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A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the e±cient intramolecular photoinduced electron transfer (PET). However, after addition of the transition metal ions, the chemosensor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn2+ and Cd2+. The fluorescent chemosensors with different polyamine as receptors show diverse a±nity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission. 相似文献
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The performance of the newly developed G3B3 and CBS-QB3 methods in calculating absolute bond dissociation energy (BDE) was assessed. It was found that these two methods could predict the BDE with an accuracy of about 8.4 kJ/mol and therefore, they exlfibited similar performance as the standard G3 and CBS-Q methods. On the other hand, it was demonstrated that the B3LYP method significantly underestimated the absolute BDE by 16.7—20.9 kJ/mol. This finding was valuable and timely because many researchers could use this relatively cheap method in studying radical reactions. Finally, 38 compounds were showed for which the theoretical BDE seriously deviated from the experimental data. 相似文献
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近年来随着生物医学技术的发展,人们需要越来越细致地在分子水平上研究各种生命过程。为了能够实现实时原位地观察活细胞或组织中的生命化学过程,需要使用以物理方法来选择性激活的分子探针。以共聚焦激光技术为基础的光敏开关能很好地解决这一问题。迄今,发展和用于光敏开关的光敏剂已成为化学生物学研究的重要方向。本文重点总结了各种可应用于共聚焦激光系统的单、双光子光敏基团(单光子的光敏基团主要有:硝基苯类、香豆素类等;双光子光敏基团主要有:香豆素类、喹啉类及吲哚衍生物类)以及这几类光敏基团在化学生物学中的应用。 相似文献
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生物油中有机化合物的分析与表征 总被引:1,自引:0,他引:1
综述了目前国内外生物油成分分析的状况,重点介绍了红外光谱、核磁共振、质谱、气相色谱、高效液相色谱技术以及波谱-色谱联用技术在生物油有机小分子化合物结构表征方面的应用,评价了这些技术在生物油结构表征方面的作用和价值,并分析了生物油的理化特性及化学结构对检测分析产生的影响。此外,对生物油中的低聚糖和热解木质素等低聚物的分析检测研究也进行了介绍。最后,总结了波谱和色谱技术在生物油检测分析方面存在的主要问题,并对生物油中有机物检测与分析的发展趋势进行了展望。 相似文献
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