计算单向复合材料弹性模量的新公式

根据复合材料单层的实际构造，提出了串并联组合模型，采用微观力学与宏观力学相结合的方法，推导出一组计算单向复合材料弹性模量的新公式。其优点是：Ｅ１和ｖ（１２）、Ｅ２和Ｇ（１２）的计算式形式对称，结构简单，计算容易，物理意义明确。我们把由世界上许多著名学者提出的多组预测公式和本文导出式计算所得的结果与国内外已发表的硼／环氧、碳／环氧、玻璃／环氧复合材料的实验数据相比较，结果表明：导出式比其他公式精确、更有价值，可供二程设计使用。     

Rewiring cellular metabolism for heterologous biosynthesis of Taxol

Abstract

Taxol is one of the anticancer drugs synthesized naturally in the evergreen Taxus brevifolia forest tree belonging to the yew family (Taxaceae) growing on the Pacific. There are reportedly evidence for treating ovarian, breast and lung cancers through this drug given its unique structural and functional features. Extraction of this drug from yew trees bark is one of the most common ways of producing this drug, but 3000 trees are needed to obtain a kilogram of Taxol. Hence, further attention has recently been attracted to the metabolic engineering strategies, including, engineering cellular metabolism of microorganisms and their optimization. Accordingly, the present paper article was aimed to review recent advances in elevating the production and commercialization of Taxol through metabolic engineering techniques.     

The reaction of phenylarsenazo with chromium(III)

The conditions for the reaction between phenylarsenazo (PAA) (2-[(2-arsonophenyl)azoj-7-(phenylazo)-1, 8-dihydroxynaphthalene-3,6-disulphonic acid) and chromium(III) have been studied. A blue 1:1 complex is formed at pH 2.2 on heating the reactants at 100 degrees for 15 min. It has maximum absorption at 635 nm and is stable for at least 24 hr. The molar absorptivity is 3.3 x 10(4) 1.mole(-1).cm(-1). Beer's law is obeyed in the chromium concentration range 0-1.4 mug ml . The reaction has been successfully applied to determination of chromium in alloy steel.     

Relative raman line intensities for H2 and for D2. Correction factors for molecular non-rigidity

Ab initio calculations are presented for H₂ and D₂ relative Raman intensities originating from common rotational levels for both vibrational-rotational and pure rotational transitions. Factors f(J) required to correct measured intensities for molecular non-rigidity (e.g. in temperature measurements) are tabulated. The calculations are compared with literature perturbation-theory equations (significant differences at large J in vibration-rotation) and with experiment.     

Ionic conductivity in Na+, K+, and Ag+ β″-alumina

This paper presents measurements of the ionic conductivity in single crystals of β″-alumina (0.84 M₂O · 0.67 MgO · 5.2 Al₂O₃, M = Na, K, Ag). Single crystals of sodium β″-alumina were grown from a melt of Na₂O, MgO, and Al₂O₃ at 1660 to 1730°C. Selected crystals were converted to the other isomorphs by ion exchange. The conductivity of sodium β″-alumina varies from 0.18 to 0.01 (ohm · cm)^?1 at 25°C depending upon crystal growth conditions. Potassium β″-alumina has the unusually high room temperature conductivity of 0.13 (ohm · cm)^?1. Silver β″-alumina has a slightly lower conductivity, 4 × 10^?3 (ohm · cm)^?1 at 25°C. The activation energies of sodium and potassium β″-alumina decrease with increasing temperature, while that of silver β″-alumina is constant from ?80 to 450°C.     

生物技术在玉米育种中的应用

介绍了在玉米育种上得到应用并取得可喜进展、简便实用的主要生物技术。阐述了这些生物技术的操作方法，以及它们的现状和存在问题。     

simELFN:提高Ad hoc网络TCP性能

标准TCP把Adhoc网络中的移动丢包也解释为网络发生了拥塞，从而启动拥塞控制。造成TCP性能的下降。simELFN技术利用中间节点的反馈信息并结合路由协议自身的特性，能区分丢包的本质原因，并且能避免其他反馈方法所面临的多个重复确认问题。经过分析和仿真表明simELFN能够有效地提高TCP性能。     

桥梁工程控制可视化软件的基本框架

详细描述了桥梁工程控制和结构分析可视化软件的功能要求，提出了此类软件的基本框架，以Ｗｉｎｄｏｗｓ为开发平台，实现了一个用于板的有限元分析的可视化实验软件，证明了这一框架的可行性。     

气调保鲜工程的技术经济分析

果品蔬菜的贮藏，目前最先进可靠的保鲜贮藏方法是控制气体成份、温度与湿度的气调保鲜方式。气调工程的方案很多，其保鲜效果、经济效益差别很大。本文对各类型的气调库进行技术经济分析，求得在不同条件下的最佳方案，以满足国内外保鲜技术应用的需要     

系统工程的软化——第二届英—中—日系统方法论国际会议述评

本文的系统工程指的是狭义的系统工程，包括系统工程方法论及其相应的建模与计算机技术。文章围绕第二届英-中-日系统方法论国际会议，介绍了近年来系统工程的软化趋向。全文分为三个部分，第一部分会议背景．论述了系统工程领域70年代所面临的困境，80年代以来的反思与对出路的探索；第二部分会议内容，介绍了这次会议所涉及的软的系统方法论及技术；第三部分是结束语。