具阶段偏食的Beddington-DeAngelis反应食物链模型分析

讨论了一类三种群Beddington-DeAngelis反应食物链模型,其中第一个种群具有两阶段结构,且第二个种群对第一个种群有阶段偏食现象,得到了系统的一致持久性,进一步证明了在适当条件下,周期解及概周期解的存在性和全局渐近稳定性.     

确定聚类数目的一个准则

Aiming to provide an appropriate number K of clusters, in this paper, we propose a new criterion function - H criterion function, whose three properties have also been proved. We validate the performance of the H criterion function on one artificial dataset and three real-world datasets, and the results are almostly consistent with a previous method. The nonparametric criterion we proposed is intuitive, simple and the computational cost is acceptable.     

A 1.107 μm Yb3+-doped Phosphate Fiber Laser Pumped by a Ti:sapphire

Lasers and amplifiers in a single fiber have been developed rapidly, especially for optical fiber communication and various sensors, in the recent years. However, remarkable progress and achievement have been made mainly in silica fiber doped with rare earth elements. In this paper, we report the progress on the development of the Yb3+-doped phosphate fiber laser.     

Straightness Measurement Using Laser Diode and CCD Camera

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Lingshuine,an Unexpected Passerini Product from the Hainan Sponge Axinyssa variabilis

Lingshuine ( 1 ), a novel sesquiterpene amide, along with three known N‐containing compounds, 2 – 4 , have been isolated from the Hainan sponge Axinyssa variabilis. The structure of 1 was elucidated by detailed analysis of the spectroscopic data and by chemical methods. Lingshuine represents the first example of a Passerini product formed during the isolation process.     

An on-line method for determining ATPase bioactivity and its application to human umbilical vein endothelial cell membrane

Based on the determination of inorganic phosphate (the product of ATP dephosphorylation by ATPase), a method for on-line determination of bioactivity of ATPase on cell membrane is presented, in which on-line sampling of cell membrane and separation of inorganic phosphate is employed in a flow injection system. The method has been successfully applied to the investigation of variation of ATPase from human umbilical vein endothelial cell membrane; the results show that ATPase activity decreases with elapsed time studied, which may supply important information for the pertinent studies on cell membrane enzymes bioactivity.     

基于STB7100的高清IPTV机顶盒设计

介绍一种基于ST芯片的高清IPTV机顶盒硬件设计方案,给出了软硬件各模块的结构和设计.该方案以STB7100为核心.能够处理H.2641AVC和MPEG-2高清和标清信号,同时支持多种格式输出.