基于L2TP的VPDN技术研究与应用

介绍了L2TP协议和VPDN技术的基本原理,分析了L2TP协议实现VPDN时存在的安全问题,提出了研究VPDN技术的必要性,在对L2TP隧道协议进行分析的基础上,最后给出了VPDN技术的应用实例。     

Demand and innovation in services: The case of mobile communications

This paper aims to analyse the pricing strategies of mobile communications operators and examine the role of demand characteristics in the development of new tariff plans. In so doing, we depart from a traditional industrial organization approach to price discrimination and interpret new tariff plans as innovations. In the spirit of Schumpeter, we look at competition in this sector as depending upon this form of innovation, and we argue that, given the specific features of the industry, the development of new tariff plans is strongly related to the users’ characteristics and behaviour. Our main point is that in a context of uncertainty, demand affects firms’ innovative strategies in two ways: first, by providing information on user behaviour and by increasing the capability of market segmentation; and second, by providing the incentives to innovate. This argument is supported by an empirical analysis carried out on the basis of an original dataset which includes all the tariff plans on offer in the history of the Italian market between 1992 and 2005. We find that both a firm's installed customer base and the level of market saturation play a role in shaping firms’ innovative pricing strategies, in terms of the number and characteristics of the new tariff plans.     

马齿苋的化学成分和药理活性研究进展

介绍了马齿苋的化学成分、药理活性等方面的最新研究进展,分析了马齿苋研究方面存在的问题,提出了今后研究的方向。     

庚子百年祭——记辽宁地区的义和团运动

:百年以前 ,在中国爆发的义和团反帝爱国斗争是中华民族空前危机的产物。辽宁地区是义和团在东北三省中最为活跃的地区。以沙俄为打击重点是辽宁地区义和团运动的重要特点     

家蚕作为生物反应器新用途的开发研究

针对当今人类神经的需求,蚕业的可持续发展,高新技术的突飞猛进,蚕业的教学与科研以家蚕的性状等情况,在分析了家蚕作为生物反应器新用途开发研究的必要性和可行性的基础上,全面论述了家蚕作为生物反应器在生产白僵蚕（蛹）、高价格物质、抗菌蛋白及珍贵药材等方面的开发研究概况,并对其发展前景作了展望,这对推动该领域的研究进程具有积极意义。     

蒙脱石—氯化铁红外光谱分析

通过吡啶吸附红外光谱分析了蒙脱石(EC_1)、蒙脱石—氯化铁(EC_4(Ⅱ)、EC_4(Ⅲ)、EC_7、EC_9)特征吸收峰的相对强度。在EC_4(Ⅱ)、EC_4(Ⅲ)、EC_7、EC_9中,B酸1540cm~(-1)吸收增强,而L酸在1440cm(-1)吸收所占总酸量的比例下降。对于苯与氯化苄的反应,L酸1440cm(-1)附近吸收所占总酸量的比例越小,催化剂的催化性能越强。