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221.
222.
Several Brønsted acidic functional ionic liquids (FILs) with an alkane sulfonic acid group were synthesized. These FILs as dual solvent-catalysts for Nipagin esterification reactions were investigated. The results indicated that [HSO3-pMIM]HSO4 has the best catalytic activity and recyclability among the various kinds of FILs investigated, and its structure was characterized by infrared and NMR. The [HSO3-pMIM]HSO4 could be easily separated from the reaction mixture and reused without noticeably decreasing the catalytic activity.
223.
We give a new proof of Kiselman's minimum principle for plurisubharmonic functions, inspired by Demailly's regularization of plurisubharmonic functions by using Ohsawa–Takegoshi's extension theorem. 相似文献
224.
A large number of macroscopic pores or graphite participates were introduced into commercially pure Al and ZA27 alloy by infiltration
process to comparatively study the influence of macroscopic defects on the damping behaviors of the materials. The mean diameter
of the bulk defects is ( 1.0 ± 0.5) mm, and the volume fractions of pores and graphite particulates are in the range of 50%–
75% and 19%–94%, separately. It is shown that addition of a number of pores or graphite particulates can significantly improve
the damping of commercially pure AI, due to the comprehensive effects of the macroscopic and microscopic defects. However,
the pores have little effect on the damping capacity of high damping ZA27 alloy, and graphite particulates make the high temperature
internal friction peak decrease. It is considered that graphite particulates may repress the intrinsic damping mechanism of
ZA27 alloy. 相似文献
225.
Readily available chiral hybrid NH2/tetrazole ligand [(S)‐TEA, 1 ] in combination with Ru‐BINAP or Ru‐DIOP complexes catalyzes the asymmetric hydrogenation of a number of simple ketones with moderate enantioselectivity (up to 72% ee). The tetrazole functionality results in reversal of the typically observed chiral‐induction for related systems and allows for hydrogenation to be uncharacteristically conducted in (non‐protic) THF solvent. The observed catalyst performance is sensitive to the reaction conditions employed and the particular compounds involved. The origins of such features are considered to derive from the added functionality provided by the tetrazole moiety in 1 , which due to its modular nature provides a good basis for further development. 相似文献
226.
色谱法辅助傅里叶变换红外光谱法用于固定源大气醛酮毒物现场监测 总被引:4,自引:0,他引:4
1 引言 1990年美国公布的新空气清洁法中列出了9种重点控制的醛酮污染物:由于FTIR光谱法具有快速、方便等特点,很适合于现场分析,所以美国国家环保局希望FTIR光谱法能成为固定污染源大气毒物现场监测方法。我们曾建立了FTIR光谱自动差减定量软件及醛酮的FTIR标准谱图库,并探讨了将其用于定量的可行性问题。本文将其用于北京第三有机化工厂乙醛车间工艺尾气的现场监测。该厂废气经吸收塔后直接放空。2 实验部分 相似文献
227.
本文利用完整描述方法研究复合索赔次数模型与混合索赔次数模型中总索赔次数的概率分布 ,得到了十余例典型索赔次数模型的相关结果 ,这些结果推广了文献 [1]、[2 ]、[6 ]的有关结论。 相似文献
228.
介绍了移动通信基站电源供电系统直流负荷分级切断的由来,以及实现这一功能的方法,指出其不尽完善之处,给出了改进意见,并对在工程中如何引入这一功能提出了自己的观点。 相似文献
229.
着重讨论BaTiO3细粉体的晶相对X7R介质瓷的电气性能的影响。通过X射线衍射谱分析该细粉体的晶相结构,结果表明:立方相的BaTiO3介电常数很低;四方相的BaTiO3介电常数高,介质的电性能也好。所以我们用四方相BaTiO3的含量来衡量X7R介质瓷的质量。BaTiO3四方相含量越高,X7R介质瓷电性能越好。 相似文献
230.
Yunhua Wang Fusheng Yang 《IEEE transactions on bio-medical engineering》1995,42(8):762-768
The dynamic extraction of evoked potential is a problem of great interest in EEG signal processing. Here, a comprehensive method is presented which integrates spatial analysis and dipole localization to make full use of the spatial-temporal information contained in the multichannel stimulation records. A realistic double boundary head model is constructed through CT scans and a two-step method devised to overcome the ill-posed nature of the forward problem of EEG caused by the low conductivity of the skull. As a result, visual evoked potentials can be effectively extracted from only two consecutive records and the dynamic information of visual evoked potential thus procured. The efficiency of the presented method has been verified by means of computer simulation and a clinical experiment 相似文献