关于Tchebycheff—Fourier级数的（H,λ）平均的逼近

我们定义了（Ｈ，λ）求和法，它含有（Ｎ，ｐｎ），（Ｒ＾ｒｎ）和（Ｖｍｎ）求和法。讨论了函数ｆ（ｘ）∈Ｃ＾ｒ［－１，１］（ｒ∈Ｎ０）以及ｆ（ｘ）∈Ｗ＾ｒＨ＾ａ（ｒ∈Ｎ０，０＜ａ＜１）的切比晓夫－富里埃级数的逼近阶。     

MnBiDy(Sm)永磁膜的结构和磁性

报道了采用真空蒸镀的方法制备的MnBiDy(Sm)永磁膜的结构和磁性.Mn:Bi:Dy(Sm)的投料比为2:1:0.10.薄膜经过退出处理(350—425℃,保温4h)后,具有NiAs型hcp结构,C轴垂直膜面,剩余磁感应强度B=3.4-6.5kG,内禀矫顽力_MH_c≈3-8kOe,最大磁能积(BH)_(max)=13.39MG·Oe.实验发现,薄膜厚度对MnBiDy(Sm)永磁膜的结构和磁性具有很大的影响. 关键词：     

Adsorption, desorption and activities of acid phosphatase on various colloidal particles from an Ultisol

Adsorption, desorption and activity of acid phosphatase on various soil colloidal particles and pure clay minerals were studied. Higher adsorption amounts and low percentage of desorption of acid phosphatase were found on fine soil clays (<0.2 μm). Electrostatic force and ligand exchange are the major driving forces that are involved in the adsorption of enzymes on soil clays. More enzyme molecules were adsorbed on soil clays in the presence of organic components. However, enzymes on organic clays were more easily released. One-third of the enzyme on goethite was adsorbed via ligand exchange process. Some other interactions, such as van der Waals force, hydrophobic force and hydrogen bonding may be more important in the adsorption of enzyme on kaolinite and the enzyme in this system cannot be easily removed. Coarse clays (0.2–2 μm) and inorganic soil clays had higher affinities for enzyme molecules than fine clays and organic clays, respectively. The activity of enzyme bound on soil clays was inhibited and the thermal stability was increased in the presence of organic matter. Data obtained in this study are helpful for a better understanding of the interactions of enzymes with inorganic and organic constituents in soil and associated environments.     

Coriatone and corianlactone, two novel sesquiterpenes from Coriaria nepalensis

Both coriatone (1). a novel highly oxygenated picrotoxane-type sesquiterpene, and corianlactone (2). with an unprecedented sesquiterpene basic skeleton, named coriane, were isolated from Coriaria nepalensis Wall. The structures of 1 and 2 were determined by analysis of their two-dimensional NMR data, and the structure of 2 was confirmed by X-ray analysis. Compounds 1 and 2 showed no remarkable inhibitory activity toward K(562) cells. They are cytotoxic with IC(50) > 50 microg/mL (cis-platinim: IC(50) = 0.49 microg/mL).     

Regio- and Stereocontrolled Nucleophilic Addition Reactions of An Unsymmetrically Disbustituted Butadiene η4-Molybdenum Cationic Complex

The reactions of a new cationic complex, [Cp(CO)₂Mo(η⁴-2-methyl-3-SPh-C₄H₄)]⁺ PF^?₆ (3), with carbon, hydride, and nitrogen nucleophiles were found to give only the C-1 addition products in good yield. The X-ray crystal structures of two of the addition products 4a and 4e confirm the regio- and stereochemistry of the nucleophilic additions.     

Shock waves and turbulence in a hypersonic inlet

A numerical investigation for an axisymmetric hypersonic turbulent inlet flow field of a perfect gas is presented for a three-shock configuration consisting of a biconic and a cowl. An upwind parabolized Navier-Stokes solver based on Roe's scheme is used to compute an oncoming flow Mach numberM =8, temperatureT =216 K, and pressureP =5.5293×10³ N/m². In order to assess the flow quantities, the interaction between shock and turbulence, and the inlet efficiency, three different flow calculations — laminar, turbulent with incompressible and compressible two-equationk- turbulence models — have been performed in this work.Computational results show that turbulence is markedly enhanced across an oblique shock with step-like increases in turbulence kinetic energy and dissipation rate. This enhancement is at the expense of the mean kinetic energy of the flow. Therefore, the velocity behind the shock is smaller in turbulent flow and hence the shock becomes stronger. The entropy increase through a shock is caused not only by the amplification of random molecular motion, but also by the enhancement of the chaotic turbulent flow motion. However, only the compressiblek- turbulence model can properly predict a decrease in turbulence length scale across a shock. Our numerical simulation reveals that the incompressiblek- turbulence model exaggerates the interaction between shock and turbulence with turbulence kinetic energy and dissipation rate remaining high and almost undissipated far beyond the shock region. It is shown that proper modeling of turbulence is essential for a realistic prediction of hypersonic inlet flowfield. The performed study shows that the viscous effect is not restricted in the boundary layer but extends into the main flow behind a shock wave. The loss of the available energy in the inlet performance therefore needs to be determined from the shock-turbulence interaction. The present study predicts that the inlet efficiency becomes relatively lower when turbulence is taken into account.