预柱吸附-毛细管气相色谱-质谱法分析鲜花头香的化学成分

预柱吸附-毛细管气相色谱-质谱法是分析鲜花头香化学成分的快速和简便方法。本文讨论了该法的一些实验条件对分析结果的影响,为选择最佳的实验条件提供了科学依据。     

A study on the reaction of 2''''-hydroxychalcones with I_2-H_2SO_4-DMSO system

The reaction of 2'-hydroxychalcones with I_2-H_2SO_4-DMSO system has been studied. The results obtained by us are entirely different from those reported in the literature. The mechanism of this reaction has also been investigated.     

全多孔球形硅胶基质高效液相色谱填料研究进展

结合本实验室的研究工作,评述了以全多孔球形硅胶为基质的正相反相色谱填料、手性色谱填料、离子色谱填料以及核一壳型色谱填料的研究进展．     

A constitutive model of frozen soil with damage and numerical simulation for the coupled problem

Based on the microcosmic mechanics of composite materials, an elastic constitutive model for frozen soil with damage is presented. For frozen sandy soil with a range of ice contents and under a range of temperature conditions, quantitative results determined by this constitutive model agree with practically measured stress-strain curves. After numerically simulating the coupled water, temperature and stress fields of channel frozen and frozen roadbed using a self-developed finite-element routine, more accur...     

Surface Confined Ionic Liquid—A New Stationary Phase for the Separation of Ephedrines in High-performance Liquid Chromatography

In this article, a new and effective stationary phase based on ionic liquid modified silica is first reported and used for the separation of ephedrines in high-performance liquid chromatography (HPLC). The separation results indicate the high efficiency and reproducibility of the stationary phase. The electrostatic interaction, ion-exchange interaction between the solutes and the stationary phase are considered to attribute the effective separation. Moreover, the free silanols on the surface of the silica are effectively masked by the immobilized ionic liquid, a result of which is to decrease the non-specific absorption.     

Regioselective Addition of Silyl Enolates to α, β-Unsaturated Aldehyde and its Acetal Catalyzed by MgI_2 Etherate

In our previous letter1, we have reported the unique catalytic reactivity of MgI2 etherate 1 in the chemoselective Mukaiyama-type aldol reactions of aryl or vinyl aldehyde and aldehyde acetals with silyl enolates. Aryl or alkyl a, b-unsaturated aldehydes (and their acetals) are particularly reactive in this catalytic addition reaction due to possibly the effective activation of the electron-rich carbonyl by highly oxyphilic Lewis acidic species, i.e. IMg+, in non-coordinative media (i.e. CH…     

First Asymmetry Synthesis and Stereochemistry of Glutinone

Rencently, two new sesquiterpenoids, glutinone 1 and lucinone 2, were isolated from the aerial parts of traditional medicine2 Jasonia glutinosa1 by Castillo and co-workers3. However, Castillo only gave the structure of glutinone, but its absolute configuration is still unknown. Here, we wish to report our stereoselective construction of the four possible diastereoisomers (9a, 9b, 9c & 9d) of glutinone. By comparing the spectrum data with that of the natural product, we outlined the stereoc…     

聚四氟乙烯和二硫化钼填充聚酰亚胺复合材料的摩擦磨损性能研究

采用MM-200型摩擦磨损试验机考察了聚四氟乙烯(PTFE)和MoS2填充聚酰亚胺(PI)复合材料在干摩擦下与GCr15轴承钢对摩时的摩擦磨损性能，并利用扫描电子显微镜和X射线能量色散谱仪分析了PI复合材料及其偶件磨损表面形貌和元素面分布．结果表明，PTFE和MoS2均可降低PI的摩擦系数，其中PI 30％MoS2复合材料的减摩性能最佳，其摩擦系数同纯PI的相比降低了约50％．除PI 10％PTFE 20％MoS2外，其它几种复合材料的抗磨性能均明显优于纯PI，其中PI 20％PTFE 10％MoS2复合材料的抗磨性能最佳，其磨损率比纯PI的低1个数量级．PI复合材料的摩擦磨损性能同其在偶件磨损表面形成的转移膜的性质密切相关，当转移膜厚度适当且分布较均匀时，PI复合材料的减摩抗磨性能良好．     

壳聚糖希夫碱铜多相催化剂的制备及其催化苯乙烯环丙烷反应的研究

采用均相和多相两种方法合成了壳聚糖希夫碱－Cu(Ⅱ)配合物，用于催化苯乙烯的不对称环丙烷反应，考察了不同制备方法和不同铜含量对催化剂催化性能的影响以及催化剂的重复使用情况，当催化剂的铜含量为4．4％时，得到20．7％的ee值。     

Enantioselective Synthesis of （＋）-Nuciferal, （＋）-（E）-Nuciferol and （＋）- α -Curcumene by Chiral Hydrogenesterification Reaction

Using chiral hydrogenesterification reaction as the key step, the stereoselective synthesis of ( )-nuciferal 1, ( )-(E)-nuciferol 2 and ( )-α-curcumene 3 has been achieved.