Free amino acid composition of the intestinal contents,intestinal cells and hemolymph ofPhilosamia cynthia larvae

Summary Free amino acid composition of the intestinal contents, intestinal cells and hemolymph has been determined in larvae of the mothPhilosamia cynthia. From the hemolymph/lumen concentration ratio, an active transport could be inferred for neutral and basic amino acids. The values of cell/lumen and hemolymph/cell ratios suggested that the active step in the transport mechanism could be localized at the luminal pole of the enterocyte for neutral amino acids (except aromatic amino acids) and at the basolateral pole of the enterocyte for basic amino acids (except arginine).This work was supported by grants from Italian Consiglio Nazionale delle Ricerche and from Ministero della Pubblica Istruzione, Rome. The authors are indebted to Prof. V. Capraro for helpful discussion.     

宽浅河段航道整治线宽度确定方法

为解决航道整治线宽度理论公式求解过程中假定工程前后参数不变产生的计算误差,提出一种确定整治线宽度的新方法。该方法从河流水流运动、泥沙运动以及河床形态机理出发,通过理论研究,推导了持续冲刷状态下和输沙平衡状态下航道整治线宽度的计算公式,并利用整治效果良好的实际工程进行验证。结果表明:新方法可以规避工程前后相关参数的取值问题;与已有大多数方法相比较,新方法确定的整治线宽度与实际工程应用值最为接近,验证了该方法的可行性。     

基于时间依赖网络的危险品运输路径选择研究

为合理选择危险品运输路径,降低危险品运输事故的发生概率,以危险品运输路径选择问题为研究对象,对运输网络的时变特性进行分析,提出了动态路阻运输路径的思想。考虑到危险品运输不一定满足时间依赖网络FIFO特性,因此本文建立了包括时间阻抗、费用阻抗和风险阻抗在内的综合阻抗最小的危险品运输路线模型,采用综合阻抗最小化与时间依赖非FIFO网络最短路径综合算法对模型优化求解。给出的算例表明,不同时间段内的最优路径会发生变化,验证了该模型方法的可行性。     

流媒体实时传输技术在网络教学中的应用

本文对目前主流的流媒体实时传输技术进行了介绍和分析,为其在实时远程教学中的应用提供了一些新的思路.     

Petri网在传输协议中的应用

传输层(也称运输层)，只存在于端开放系统中，是介于第三层通信子网系统和高三层之间的很重要的一层。传输层协议在网络协议中处于非常重要的地位，对于不同的状态给出相应的网模型来进行进一步的研究具有很重要的意义。     

NEUMANN SERIES SOLUTION TO A NEUTRON TRANSPORT EQUATION OF SLAB GEOMETRY

This paper deals with the solution to an energy, dependent stationary neutrontransport equation of slab geometry. In L~p space, the equation is converted into an equiva-lent integral equation. By the study of the corresponding integral operator and its spectralradius, results of Neumann series solution are obtained, and an easy-verified condition thatthe transport equation has a nonnegative solution is given.     

Development of City Transport System and Two-wheel Vehicles

Based on the study on the city transport systems of some typical cities worldwide, this paper put forward that each city transport system has its own development mode, which is influenced by the city development plan, economic development level, traveling vehicle composition etc.. When some problems occur, such as the congestions caused by contradiction between the road capacity and vehicle composition, the city transport system may come into temporary maturity period. If the improvement for road system is limited meanwhile, optimized structure of vehicle composition should be an effective solution in this case. With the development of economy-internationalization, the development speed of city transport modernization is rapid. When traveling easiness is conflicting with efficiency, the advantages of public transport system become more obvious. Correspondingly, the superiority of two-wheel vehicles will reappear. Though the important function of two-wheel vehicles for alleviating city traffic problems i     

碳纳米管复合材料的有效热导率

考虑到碳纳米管的空间取向分布特征,建立了碳纳米管复合材料的有效热导率模型。根据Maxwell理论,推导出了计算碳纳米管复合材料有效热导率的简单公式。应用实例表明,该模型能够很好地解释在碳纳米管纳米流体中观察到的热导率异常增加现象,还可以用来分析纳米管复合材料的渗流性质,而且理论计算结果与实验结果吻合较好。     

IPv6的IP封装安全性的有效负载

对下一代互联网络协议-IPv6的IP封装的安全性的有效负载（ESP）进行了全面深入的分析,对其分组格式及实现过程进行了详细的讨论,研究了ESP在传送模式和隧道模式下的典型实现方案,并结合AH机制给出了一个典型的安全网络方案,该方案对于在IPv6网络环境下构建一个安全的网络应用具有一定的应用价值.     

Co/Al2O3/FeNi隧道结的中间层厚度对其输运特性的影响

制备了不同Al2O3厚度的Co／Al2O3／FeNi隧道结，并在77K温度下测量了其输运特性。发现随着厚度的增加，TMR下降。但是当Al2O3厚度降为2nm时，磁电阻不再出现典型的双峰曲线，而是呈现高阻和低阻两个状态。测量了隧道结的TMR随外加电压的变化、伏安特性曲线、电阻随温度的变化曲线，综合所有因素，在文中制备条件下，Al2O3厚度为4nm时，隧道结性能最好。