多圆盘上的Toeplitz算子的紧的乘积

对于多圆盘上的有界多重调和函数f,g,我们证明多圆盘Bergman空间上的Toeplitz算子的乘积TfTg是紧算子的充要条件是TfTg是零.这等价于f或g是零.换位子TfTg-TgTf是紧算子当且仅当换位子TfTg-TgTf是零.这等价于对每一个j,存在不全为零的常数αj和βj,使得αjf+βjg关于变量zj(1≤j≤n)是常数.     

新的4′-去甲表鬼臼衍生物的2D NMR研究

采用¹H-¹H COSY、NOESY、¹H-¹³C HMQC及HMBC二维NMR技术鉴定了2个新合成的4β-5- 氟尿嘧啶取代-4′-去甲表鬼臼毒衍生物, 并对它们的¹H和¹³C NMR 谱峰进行了全归属.     

基于Ohlson模型的企业权益价值自适应估计

企业价值估计是投资的基础.1995年,J.Ohlson将超额收益RI（Residual Income）用于企业价值估价,形成了企业价值估价的一个分支.然而,Ohlson模型要求正确估计收益率和未来各期的超额收益,在应用上有明显的局限性.本文以Ohlson超额收益估价模型为基础,结合Gordon增长模型,建立了一个企业权益资本价值估价新模型.对该模型的参数估计,我们采取逐步迭代的方法,逐步吸收企业成长过程中的信息,不断修正模型参数,直至得到“满意”的参数.我们证明了这个参数估计过程是收敛的,因此新模型有更好的可操作性.     

Lagrange multipliers for functions derivable along directions in a linear subspace

We prove a Lagrange multipliers theorem for a class of functions that are derivable along directions in a linear subspace of a Banach space where they are defined. Our result is available for topological linear vector spaces and is stronger than the classical one even for two-dimensional spaces, because we only require the differentiablity of functions at critical points. Applying these results we generalize the Lax-Milgram theorem. Some applications in variational inequalities and quasilinear elliptic equations are given.

     

走近物理学大师--宾尼格印象记

多年来在海外访问工作，有幸会面了不少物理学大师，他们的音容笑貌至今萦回耳畔脑际；其中印象最深的当数宾尼格（Gerd Binnig）先生．     

Microwave-assisted one-pot regioselective synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines

A protocol for regioselective one-pot synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines under controlled microwave heating has been developed. Starting from commercially available 2-aminophenols, a base-mediated regioselective O-alkylation took place with 2-bromoalkanoates to give the acyclic intermediates, which underwent spontaneously an intramolecular amidation reaction to furnish 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines in 44-82% yields. For the acyclic intermediate possessing an electron-withdrawing group, microwave heating was necessary for the annulation reaction.     

凸规划下的保序回归

本文从约束最优化的观点来研究保序回归的解的问题 ,利用MATLAB给出了保序回归问题的求解方法 ,使得求解速度大大加快。本文的方法对进一步讲座其他保序回归问题具有一般性。     

偏压电极对KT-5C装置等离子体边缘的影响

通过电极偏压来控制KT 5C装置边缘区等离子体的径向电场 ,发现在正偏压作用下 ,径向电场剖面由小的负阱状变成明显的山包结构 ,从而形成一个加强的E×B剪切层。剪切层附近的等离子体参数变陡 ,不仅等离子体极向流速度大大增加 ,而且其方向也由沿电子逆磁漂移方向改变为离子的逆磁漂移方向。这些变化导致等离子体边界横向输运被抑制、整体约束得到改善     

A new potent immunosuppressive isoflavanonol from Campylotropis hirtella

Four new flavonoids were isolated from Campylotropis hirtella and these are a chromone and a 2H-chromene, an isoflavone and an isoflavanonol. The structures of these compounds were elucidated by extensive spectroscopic measurements. All of the compounds were assessed for immunosuppressive activity. Compound 4 showed very strong T lymphocyte suppression activity (IC₅₀: 0.13 μM) and potent B lymphocyte suppression activity (IC₅₀: 0.26 μM). Due to its potent immunosuppressive activity and lower cytotoxicity, further structure–activity studies will be pursued on this compound.