优缺点

In this paper the author overviews mass magnesia concrete dam thchnical origin, the present status here and abroad, and available primal problems; descripts theexpansive character of magnesia concrete, fundamental force performances and long-term lasting quality, derivates all the equations of temperature field and temperature stress field, analysises the existing canonic calculating autogenous volume deformation model of the micro-expansive concrete, at last select the expansion model of dynamics for calculating.

本文综述了大体积混凝土氧化镁筑坝技术的由来、国内外研究现状、优势及存在的主要问题；叙述了掺氧化镁微膨胀混凝土的膨胀特点、基本力学性能及长期耐久性能；推导了计算温度场及温度应力场的全部公式。对现有计算氧化镁混凝土自生体积变形的几个典型模型进行了深入的研究和分析，阐述了它们各自的优缺点，最终选定动力学模型作为计算氧化镁混凝土自生体积变形的数学模型。

These antennas can cover GSM900/DCS/PCS/UMTS operation. In the chapter 2, the antenna is designed based on the concept of monopole antenna. Furthermore, the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching. In addition, to raise distance between radiation plane and ground will avoid capacitative effect effectually. In the chapter 3, the antenna is designed based on the concept of planar inverted-F antenna. Furthermore, that the antenna structure have two radiant paths and coupled each other at tail end to do impedance matching is similar to chapter 2. But there is a difference in them. We can choose the short position to change input impedance at this structure. In the chapter 4, the antenna is designed based on the concept of planar inverted-F antenna which takes coupled-fed. It will produce the first mode and high-order mode near the frequency, 900MHz. The feature of this type is to reduce the volume effectually. This antenna can not only cover GSM900/DCS/PCS/UMTS operation but maintain good radiation efficiency. Finally, we will compare three antennas, and develop procedure with industrial view, and propose the prospect of the GSM/GPRS antenna in PND, as a conclusion.

在第二章中，我们使用单极天线设计概念，使用双路径架构并於末端耦合来对天线阻抗做匹配，产生涵盖GSM900/DCS/PCS/UMTS四频操作频带，并提高与接地面的辐射高度，以避免电容效应，使天线具有良好的辐射特性；在第三章中，使用倒F形天线设计概念，使用双路径架构於末端耦合，并於辐射臂上采取适当接地点电感效应作输入阻抗匹配，达成涵盖GSM900/DCS/PCS/UMTS系统的四个操作频带；在第四章中，采用倒F形架构并使用耦合馈入方式，使得长辐射金属臂在低频900 MHz附近产生共振，产生低频基频模态及高阶模态，以达成宽频及频宽涵盖GSM900/DCS/PCS/UMTS频带操作，并有效缩减使用体积；最后，分别比较此三种架构的优缺点，再加以业界角度来思考，研发产品天线的流程及思考方向，以及天线应用於可携式导航装置中未来的展望作为本论文的总结。

This paper reviews the development of synthetic technology of carbon nanotube by catalytic py-rolysis of carbonous compound and compares the advantages and disadvantages of moving support method and floating catalysis method.

介绍了催化热分解含碳化合物合成碳纳米管的技术，比较了基板法和流动催化法的优缺点以及它们的发展前景，并简单地介绍了碳纳米管的应用领域。

The method of directly oxidizing the hydroxymethyl to carboxylic group is named one-step process.

并分别讨论了几种方法的优缺点、催化剂的选择及其适用的反应条件。

Based on the recent progress, relative merits of those methods were analyzed. The application of Fe3O4 nano-particles in magnetic fluid, magnetic recording materials, catalytical and microwave materials and medicine were introduced.

根据最新的研究成果，比较了以上各种方法的优缺点，并介绍了磁性纳米四氧化三铁在磁性液体、磁记录材料、催化、生物医学、微波吸收材料等方面的具体应用。

Implantation of inferior vana caval filter is safe and effective in the prevention of PE. Perma-nent or temporary filter has its advantages and disadvantages.

下腔静脉滤器植入术是一种安全、有效预防肺动脉栓塞发生的临床措施，临时性和永久性滤器各有优缺点。

Energy centrobaric, ratio, zoom FFT, phase difference and spectrum simulation correcting methods are used in LDA signal processing.

将能量重心法、比值法、相位差法、频谱细化、频谱拟合等5种离散频谱校正方法应用于LDA信号处理中，通过仿真计算比较各种方法的优缺点，并选取比值法用于实时测量，取得了明显的效果。

School of Environmental Science and Engineering, Shandong University, Shandong Jinan, 250062Abstract: The preparation methods of nanometer ceric oxide at home and abroad were reviewed, their advantages and disadvantages were discussed, and its application fields were introduced too.

山东大学环境科学与工程学院，山东济南，250062摘要：综述了国内外纳米二氧化铈的制备方法，比较了各方法的优缺点，并介绍了纳米二氧化铈的应用领域。

The advantages and disadvantages, the catalyst choice and its application conditions were discussed in the chalcone synthesis.

分析了近年来查尔酮几种合成方法的优缺点，催化剂的选择及其适用的条件。

This paper introduced the working principle and kinematic regulation of intermittent sheet transfer mechanism available,expounded their advantages and disadvantages,and provided out that the tendency of this mechanism is the finer dynamic performance,higher precise and compacter.

介绍了现有间歇递纸机构的工作原理和运动特性，阐明了各自的优缺点；指出间歇递纸机构的发展趋势是对动力学性能好、传递精度高、结构紧凑的新型组合机构的研发；提出专用曲线槽轮-不完全齿轮递纸机构，通过与现有机构的分析对比，证明了新机构的优点，为间歇递纸机构的改进设计提供了新的思路。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。