试析克林顿政府对华政策的演变     

何越 《许昌学院学报》2005,24(4):116-119

克林顿执政时期对华政策是一个不断发展和变化的过程，受美国国会、利益集团、媒体、民众等诸多因素的影响，它经历了最惠国待遇与人权挂钩、“接触”与“遏制”模糊不定、全面接触替代孤立遏制、充满矛盾与冲突的全面接触等四个不同时期的演变：体现了冷战后务实的、以经贸为中心的外交新理念.  相似文献   

一种RLC参数测量新方法     

刘芬  杨继生  宋延民 《天津工程师范学院学报》2007,17(1):31-33

提出了一种基于数字正交采样测量参数电阻R、电感L、电容C的新方法,分析了该方法的测量原理,并对其进行了计算机仿真。仿真结果表明了该测量方法的正确性和有效性。  相似文献   

隔震技术在建筑结构中的应用和展望     

孙国荣 《泰州职业技术学院学报》2007,7(1):34-37

从隔震和消能减震的角度,对目前土木工程领域结构控制技术进行了综合评述,首先对国内外现有的隔震技术进行了分类探讨;其次根据阻尼器的工作原理,对其进行了分别阐述;最后从我国实际情况出发,对今后隔震技术的研究、应用中需重点解决的问题提出了若干建议。  相似文献   

调整工艺路线改革天然药物化学实验   总被引：2，自引：0，他引：2  

徐娟华  姚爱平  黄亦佳  卢启洪  董兆怿 《实验室研究与探索》2004,23(4):24-25,30

对粉防己生物碱的提取分离工艺路线进行调整设计,改革天然药物化学实验,使有机整体化和降低成本、毒性等;采用酸水—有机溶剂法提取生物碱,柱层析、制备层析分离汉防己甲素和汉防己乙素;柱层析分离成功率约82%,制备层析成功率100%。找到了适合学生实验室的工艺和条件,提高了学生的实验兴趣和实验效果。  相似文献   

土与结构动力相互作用隔震体系的MB计算方法     

陈辉  张丽丽 《北京工业职业技术学院学报》2012,11(1):1-5

采用刚性地基假定是目前结构控制研究的基本条件,此假定忽略了土与结构相互作用效应的影响。但由于土与结构相互作用效应对结构振动特性有一定的影响,进而影响结构控制的效果,因此有必要研究土与结构动力相互作用的简化计算方法。基于上述原因,进行了线性体系土与结构相互作用效应对隔震体系的MB计算方法的研究。  相似文献   

An Analysis of the Ballad of the Sad Café from the Perspective of Grei mas’Semiotic Square     

田杰 《海外英语》2012,(17):192-193,206

Greimas’s Semiotic Square is a new approach in analyzing literary works.Based on Sassure and Jacnson’s claim on binary opposition,Gereimas extends it to four actants and adds contradictory relationships.By assign meanings to the four actants,an analysis of the complicated relationship between the roles in a text can be made and a revelation of the theme of the text can be realized.Previous studies of this novel take it as an excellent work revealing loneliness and isolation is thought to be the basic condition of human existence.Other study covers the effects of the unrequited love.Quiet differently,this paper tries to interpret this novel by Greimas’semiotic square and thereby revealing the widely accepted theme of this novel that isolation and loneliness is the final destiny of human being in modern society.  相似文献   

电子商务系统网络安全隔离技术的研究     

林平 《闽江学院学报》2012,33(5):97-99

针对目前Internet上的黑客软件、网络病毒针对TCP/IP协议设计的特点及Windows终端与Windows终端服务器之间可以通过IPX协议建立通信连接的技术特征,提出外网Windows终端服务器选用一网卡只加载标准的TCP/IP协议与Internet相连,另一网卡只加载IPX协议仅与内网Windows终端相连的组网方案,阻隔黑客软件攻击与网络病毒传播的通信通道,研究电子商务系统内外网络安全隔离新型应用模式.  相似文献   

Absence of postzygotic isolating mechanisms: evidence from experimental hybridization between two species of tropical sea urchins     

M. Aminur Rahman  Tsuyoshi Uehara  Aziz Arshad  Fatimah Md. Yusoff  Mariana Nor Shamsudin 《Journal of Zhejiang University. Science. B》2012,13(10):797-810

Two reef margin species of tropical sea urchins, Echinometra sp. C (Ec) and Echinometra oblonga (Eo), occur sympatrically on Okinawa intertidal reefs in southern Japan. Hybridization between these species was examined through a series of cross-fertilization experiments. At limited sperm concentrations, where conspecific crosses reached near 100% fertilization, both heterospecific crosses showed high fertilization rates (81%–85%). The compatibility of the gametes demonstrated that if gamete recognition molecules are involved in fertilization of these species, they are not strongly species-specific. We found that conspecific crosses reached peak fertilization levels much faster than did heterospecific crosses, indicating the presence of a prezygotic barrier to hybridization in the gametes. Larval survival, metamorphosis, and juvenile and adult survival of hybrid groups were nearly identical to those of their parent species. Hybrids from crosses in both directions developed normally through larval stages to sexually mature adults, indicating that neither gametic incompatibility nor hybrid inviability appeared to maintain reproductive isolation between these species. In adults, Ec×Ec crosses gave the highest live weight, followed by Eo (ova)×Ec (sperm), Ec (ova)×Eo (sperm), and Eo×Eo. Other growth performance measures (viz., test size, Aristotle’s lantern length, and gonad index) of hybrid groups and their parental siblings showed the same trends. The phenotypic color patterns of the hybrids were closer to the maternal coloration, whereas spine length, tube-foot and gonad spicule characteristics, pedicellaria valve length, and gamete sizes showed intermediate features. Adult F₁ hybrids were completely fertile and displayed high fertilization success in F₁ backcrosses, eliminating the likelihood that hybrid sterility is a postzygotic mechanism of reproductive isolation. Conversely, intensive surveys failed to find hybrid individuals in the field, suggesting the lack or rarity of natural hybridization. This strongly suggests that reproductive isolation is achieved by prezygotic isolating mechanism(s). Of these mechanisms, habitat segregation, gamete competition, differences in spawning times, gametic incompatibility or other genetic and non-genetic factors appear to be important in maintaining the integrity of these species.  相似文献   

从空间组织角度看新冠肺炎疫情隔离管控中的问题及对策建议          下载免费PDF全文

孙炜  金凤君 《中国科学院院刊》2022,37(8):1108-1115

隔离管控是遏制新冠肺炎疫情传播蔓延的有效手段,但在隔离管控中暴露出来的城市管理、社会民生等方面问题值得深思。文章首先梳理了近期新冠肺炎疫情隔离管控中出现的5类问题,并在扼要回顾了国内外相关研究后提出从结合系统论思维的空间组织角度展开研究是契合的方向;进而从空间组织与系统科学的客观规律出发探究问题背后的原因,指出了从理论上缺乏对隔离管控决策的系统化考量,从实践上缺乏常态到非常态切换的准备是造成问题的根源。最后,文章从空间组织体系的优化、基础设施与能力建设、后备演练机制等3方面提出了建议。  相似文献   

Laugh so you don't cry: teachers combating isolation in schools through humour and social support     

《Ethnography and Education》2013,8(2):195-209

The structure of the teaching profession leaves teachers professionally and personally isolated from other adults. This article will discuss the results of an ethnography focused on the rare informal social interaction that occurs among teachers in a United States’ school, with a particular focus on the lunch hour. Specifically, this article explores the reciprocal nature of support provided within self-generated congregational spaces. This study demonstrates the positive use of humour in combating stress in the teaching profession, and how these relationships support Hochschild's (1983) theory of emotional labour.  相似文献