从价格的演变历程浅析国内民航运输价格改革

从价格的演变历程入手,对目前民航客运价格存在的问题及成因进行初步分析,提出价格改革的思路,进而促进相关垄断行业的改革与发展.     

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau since 1.8 Ma recorded by major elements in sediments of the South China Sea

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau has been investigated in the study of global change. Core sediment samples drilled in the South China Sea during ODP Leg184 are the best materials for studying long-term variability of the East Asian monsoon. R-mode factor analysis of major elements in the fine grain-sized carbonate-free sediments (<4 μm) of the upper 185 mcd splice of ODP Site 1146 drilled during Leg184 in the South China Sea shows that Ti, TFe2O3, MgO, K2O, P, CaO, and Al2O3 are representative of a terrestrial factor. The variation in the terrestrial factor score is subject to chemical erosion in the source region and thus indicates the evolution of the East Asian summer monsoon. The terrestrial factor score has three stepwise decreases at ~1.3 Ma, ~0.9 Ma, and ~0.6 Ma, indicating the phased weakening of the East Asian summer monsoon is related to wholly stepwise, quick uplifts of the Tibetan Plateau since 1.8 Ma. The periodic fluctuation of the terrestrial factor score since ~0.6 Ma indicates that the glacial-interglacial cycles have been the main force driving the evolution of the East Asian monsoon. As in the case of Chinese loess, the long-term evolution of the East Asian monsoon recorded in sediments of the South China Sea reflects a coupled effect of the glacial-interglacial cycle and uplift of the Tibetan Plateau.     

城市道路网络演变模型

为了探寻城市道路网络的内在演变规律,基于叶脉生长模型,提出了道路网络演变模型,分析路网中节点的生成规律;根据道路网络的特点,提出生成节点与已有路网的连接规则.以上海市浦东新区为研究对象,研究节点新增比例与经济、人口等指标的关系,提出了节点新增比例模型.按照提出的演变模型,模拟研究年的道路网络,对比实际路网和模拟路网的一些复杂网络指标.结果表明,该模型能较好地模拟实际路网的变化.     

武术技击模式演进的动力机制研究

运用文献资料、访谈、问卷调查、数理统计及逻辑分析法研究了影响武术技击模式演进的主要动力因素,并对其内外因素进行界定.认为其作用机制是主导与多元相统一的动力机制,在不同时序和不同阶段武术技击模式演进受多元动力作用是不同的,在诸动力因素作用中“技术轨道”是首位权重.     

略论工程“双重双螺旋”及其演化机制

本文把工程演化过程理解为一种双重双螺旋过程,即由技术链和非技术链(经济-社会链)共同构成的双螺旋。演化过程则由技术发明-工程创新-产业扩散三个环节组成。其中,工程双重双螺旋中技术链的演化,其基本内容是技术硬件(机器)和技术软件(知识和制度)双螺旋的演化。选择与建构机制是工程演化过程中的一个重要机制。选择机制使得在技术-经济进化过程中,技术创新成果经过市场的选优汰劣,保证了工程活动和市场经济的健康演进。建构机制则体现为技术链与经济-社会链的双重双螺旋变革,形成新类型的双重双螺旋等形式。     

工程演化论的研究内容、范畴、方法与意义

工程演化论是工程哲学研究的新领域,它是探索工程演化进程机理和规律的理论。本文讨论了工程演化论研究的缘起、研究对象与内容,提出了工程演化论的基本范畴和研究方法,指出工程演化论研究具有重要的理论意义和现实意义。     

城市及其发展观的历史演变

本文把城市发展的历史与人类文明发展的四个阶段结合起来,论述了城市在农业文明中的诞生与发展,在工业文明中的革命性转变和激剧发展,以及在即将来临的生态文明中的可能转向。在此基础上,从城市的规模、性质、开放性、人口密度、空间布局与形态、文化风貌等多方面对城市发展观的历史变迁进行了反思。     

简说羽毛化石的研究

自第一枚始祖鸟化石发现以来,鸟类的起源与演化成为了古生物研究的热点之一。有关鸟类的起源问题涉及了恐龙以及早期鸟类的形态结构、飞行以及羽毛等多方面内容。在早白垩世热河生物群以及相邻地区侏罗纪地层发现的许多保存精美的带毛恐龙,中生代的鸟类化石,为鸟类的恐龙起源提供了重要证据,并且使我们对羽毛的起源和演化有了较丰富的认识。笔者主要介绍了带毛恐龙的羽毛化石的研究现状,并结合发育生物学,讨论了关于羽毛的发育和演化问题。     

Improving the thermal stability of lactate oxidase by directed evolution

Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y). The half-life of this lactate oxidase at 70 °C was about 2 times that of E160G/V198I and about 36 times that of the wild-type enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution. Received 15 September 2006; received after revision 21 October 2006; accepted 2 November 2006     

利用试探方程法求mKdV方程组的精确行波解

利用试探方程法化所求耦合mKdV方程组为初等积分形式,再利用多项式完全判别系统讨论被积函数中4阶多项式的根的情况,进而给出显示精确解.由此求得的精确解包括有理函数型解,双曲函数型解(孤子解),三角函数型周期解等.