Ytterbium triflate hydrate catalyzed Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds

Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.     

0MATLAB在空间图形中的动态应用

学生空间思维的不足影响了学生对空间曲面的理解和重积分的学习。本文通过二个实例,重点讨论了用MATLAB动态生成空间图形的技巧。     

CID-ICP-AES用于高纯试样的分析性能

研究了CID-IP-AES用于测定高纯物质的分析性能。以高纯LiOH为对象，研究了低浓度范围内分析线的选择，标准曲线的特性，探讨了直接用于高纯物质分析的检测能力及可行性。     

A survey of works on the theory of toroidal shells and curved tubes

This paper gives a survey of works on the theory of toroidal shells which were done by our two universities in recent years. This paper was supported by DAAD Germany     

A MEMS micromirror driven by electrostatic force

A microelectromechanical systems (MEMS) micromirror is demonstrated in this paper. The micromirror is actuated by an electrostatic force and can achieve a large out of plane stroke by eliminating the electrostatic pull-in effect. The micromirror consists of a mirror of 400 μm by 400 μm in the center, a spring and three fixed bottom electrodes each side. Design principles and the analytical model are both developed, and they are verified by finite element analysis (FEA). The resonant frequency for the piston movement of the designed micromirror is about 2.5 kHz by FEA simulation. The micromirror prototype has been fabricated by a surface micromachining process and it is successfully tested using a microsystem analyzer. An out of plane stroke of 1.65 μm is observed at 100 V and it agrees well with the predicted result from analytical model.     

Synthesis, activity evaluation and 3D-QSAR study of some novel derivatives of 4, 5, 6, 7-tetrahydrothieno [3,2-c] pyridine

A series of novel derivatives of 4, 5, 6, 7-tetrahydrothieno [3,2-c] pyridine were synthesized and structurally characterized by 1H NMR and MS. Their in vivo anti-platelet aggregation activities were evaluated. A 3D-QSAR was performed using the CoMFA and the CoMSIA. This model provided useful guidelines for novel anti-platelet thienopyridines design.     

Asymmetric bioreduction of substituted acenaphthenequinones using plant enzymatic systems： A novel strategy for the preparation of （＋）- and （-）-mono hydroxyacenaphthenones

Regio- and enantioselective reduction of substituted acenaphthenequinones were conducted under mild reaction conditions using plant enzymatic systems. A screening of 15 plants allowed the selection of two suitable plants fulfilling enantiocomple- mentarity. The （＋）- and （-）-mono hydroxyacenaphthenones were achieved with high conversion and good enantiomeric purity using peach （Prunus persica （L.） Batsch., conversion 98%, 71% ee） and carrot （Daucus carota L., conversion 95%, 81% ee）, respectively.     

On the viscosity of magnetic fluid with low and moderate solid fraction

The design of a pressurized capillary rheometer operating at prescribed temperature is described to measure the viscosity of magnetic fluids (MFs) containing Fe3O4 magnetic nanoparticles (MNPs). The equipment constant of the rheometer was obtained using liquids with predetermined viscosities. Experimentally measured viscosities were used to evaluate different equations for suspension viscosities. Deviation of measured suspension viscosities from the Einstein equation was found to be basically due to the influence of spatial distribution and aggregation of Fe3O4 MNPs. By taking account of the coating layer on MNPs and the aggregation of MNPs in MFs, a modified Einstein equation was proposed to fit the experimental data. Moreover, the influence of external magnetic field on viscosity was also taken into account. Viscosities thus predicted are in good agreement with experimental data. Temperature effect on suspension viscosity was shown experimentally to be due to the shear-thinning behavior of the MFs.     

New Sesquiterpenoids from Hedychium yunnanense gagnep

Hedychium yunnannense Gagnep is the unique species of Zingiberaceae occurring only in Yunnan province of China and its wild resource is very abundant. Several sesquiterpenoids and diterpenoids from the petroleum ether fraction of the ethanol extract of the plant have been reported1, 2 by Zhao Qing et al. Some of them show antioxidant and cytotoxic activities. In order to use the wild plant resources efficiently, we made further systematic investigations on the chemical constituents of the rh…