Two classes of metabolites fromTheonella swinhoei are localized in distinct populations of bacterial symbionts

The marine spongeTheonella swinhoei (lithistid Family Theonellidae, Order Astrophorida) has yielded many important, bioactive natural products, most of which share structural features with bacterial natural products. The presence of microbial symbionts inT. swinhoei has been reported, and it was originally suggested that the cytotoxic macrolide swinholide A and many of the bioactive cyclic peptides fromT. swinhoei were all produced by symbiotic cyanobacteria. By transmission electron microscopy, we found four distinct cell populations to be consistently present inT. swinhoei: eukaryotic sponge cells, unicellular heterotrophic bacteria, unicellular cyanobacteria and filamentous heterotrophic bacteria. Purification and chemical analyses of each cell type showed the macrolide swinholide A to be limited to the mixed population of unicellular heterotrophic bacteria, and an anti-fungal cyclic peptide occurred only in the filamentous heterotrophic bacteria. Contrary to prior speculation, no major metabolites were located in the cyanobacteria or sponge cells.     

Induction of autotomy in the American bird grasshopperSchistocerca americana (Drury) by the ecdysone agonist RH-5849 and investigation of its mode of action

The non-steroidal ecdysone agonist RH-5849 (1,2-dibenzoyl-l-tert-butylhydrazine) was found to be an effective neurotoxicant on injection into the American bird grasshopper,Schistocerca americana (Drury). Treated grasshoppers became immediately hyperactive, followed by loss of coordination, paralysis and eventually death. We also discovered that this compound induced bilateral autotomy of the metathoracic legs during the early stages of intoxication. However, no evidence of ecdysonergic or morphogenetic activities was observed. Synergism studies with neurotoxins of known mode of action suggested that RH-5849 has a mechanism of action similar to that of 4-amino pyridine, which blocks potassium channels.     

用子波变换分析方法实时监测视觉诱发电位的潜伏期

诱发电位的实时监测在临床中有重要意义。本文提出利用多分辨率子波分析技术来实时监测视觉诱发电位的潜伏期。为克服随机噪声的影响，我们引入相邻响应的相关系数来修正所检测得的潜伏期的偏移，并应用前一次响应的波峰位置来决定当前的搜寻范围。实验表明，本方法能实时监测视觉诱发电位的潜伏期。     

非线性离散竞争系统的全局稳定性

考虑一类非线性离散的Lotka-Volterra竞争系统,通过构造适当的Lyapunov函数,得到了保证该系统全局渐近稳定的充分性条件,并给出该结果在一类二维竞争系统中的应用.     

螺旋压缩机：数学模型和性能计算

本书是施普林格出版社2005年出版的一本关于螺旋压缩机的新著。螺旋式压缩机是一种最常见的用于压缩气体的机器，由于其构造简单、工作效率高而受到人们的关注。本书系统阐述了螺旋压缩机的种类、几何参数转子的设计工作原理和螺旋压缩机的计算。     

浅谈电子信息资源的合法利用

网络时代，电子信息资源已成为人们进行科学研究、商业活动和共享信息的重要手段，与此同时，网上侵权行为也时有发生。指出了电子信息资源的侵权形式，探讨了在版权法允许的范围内合法利用电子信息资源的有关问题。     

智能住宅中消防给水系统设计探讨

根据智能住宅火灾形成的特点，简述了消火栓给水系统与自动喷水灭火系统的设置方式与特点，并结合实例对消防给水方式的选择等问题进行了探讨。     

指纹识别系统的分析与研究

介绍了一种新型的指纹识别装置(晶体传感器的指纹识别装置)，并借此分析和研究了指纹识别系统的识别原理和设计方法，这些原理和方法对指导和优化指纹识别系统的设计提供了依据。     

浅议中小企业的财务管理

财务管理在企业经营管理决策中起着重要的作用，分析了目前中小企业财务管理中存在的问题，从投资模式、管理控制和人员素质等3方面提出了解决这些问题的对策。