Alkaloids from the Roots of Saccopetalum prolificum

In recent years, an increased interest in the phytochemistry of the Annonaceae has beensparked by the isolation of the antileukemic Annonaceous acetogenin'. Saccopela/umprolificllm (Chun el How) Tsiang (Allnonaceae) is an evergreen tree distributed inHainan Province, P. R. China. The ethanolic extract of the plant exhibited cell growthinhibitory activity (20 ig/ml) against LIZ10 lymphocytic leukemia. A new alkaloid,prolifine (l), was isolated from the roots of S. proldicum, in addition t…     

La_(0.5)M_(0.5)MnO_3(M=Sr,Ba)的水热合成与表征

我们用水热法合成了钙钛矿锰氧化物La0.5M0.5MnO3(M=Sr,Ba)系列样品,研究了制备条件对结构、形貌和磁性的影响.     

A Novel Synthesis of Alkylamino Substituted Methylenediphosphonates Using Bis(trichloromethyl) Carbonate and RCONR1R2

An efficient, economical and easy method for the synthesis of dimethylaminomethylenediphosphonates using bis(trichloromethyl) carbonate and RCONR1R2 has been developed, which proceeded under relatively mild conditions.     

生态工业链定价策略的博弈分析

生态工业链与传统供应链不同，传统供应链中的定价策略在生态工业链中不再适用。为了解决该问题，基于单一上游企业和单一下游企业构成的生态供应链系统，应用博弈理论对上游企业生产产品时产生的副产品或者废物定价策略进行研究。分别得出了一个非合作博弈的均衡解（斯坦克尔伯格均衡）和一个合作博弈的均衡解（联合定价），并进一步对各种定价策略的效率进行了分析。最后对原料短缺时的定价情况进行了讨论。     

Beam Polarization Dependence of Diffraction Efficiency in Photorefractive LiNb03 Crystal

In weak doped photorefractive LiNbO3 crystal, the diffraction efficiency is highly relevant to the writing and reading beam polarizations. In this paper, based on dynamic coupled-wave equations, we theoretically discuss the diffraction efficiency under four writing and reading polarization conditions, then reach the proven conclusion that with o-polarized beams to write and with e-polarized beam to readout, the diffraction is the largest.     

一种计算工作时间参数新方法

为了编制和优化施工进度计划,计算构成施工项目的各项工作最早开始时间、最迟开始时间、最早完成时间、最迟完成时间、总时差和自由时差等时间参数十分重要.提出了一种计算工作时间参数新方法.该方法以工作完成时间为决策变量,通过建立和求解线性规划模型来得到各种工作时间参数.其建模思路清晰,不需绘制网络图,能用通用办公软件EXCEL求解.模拟计算表明,用该方法与用标准网络计划技术计算出的工作时间参数完全一致.     

An extremal sparsity property of the Jordan canonical form

We prove that among all the matrices that are similar to a given square complex matrix, the Jordan canonical form has the largest number of off-diagonal zero entries. We also characterize those matrices that attain this largest number.