Three-dimensional fluorescence spectral characteristics of dissolved organic carbon in cave drip waters and their responses to environment changes: Four cave systems as an example in Guizhou Province,China

Understanding the responses of fluorescence spectral characteristics of cave drip waters to modern environment and climate changes is key to the reconstructions of environmental and climatic changes using fluorescence spectral characteristics of speleothems. The fluorescence spectral characteristics of dissolved organic carbon （DOC） in four active cave systems were analyzed with a three-dimensional （3D） fluorescence spectral analysis method. We found that the fluorescence types of DOC were mainly of fulvic-like and protein-like fluorescences, both in soil waters and cave drip waters. The intensity of fulvic-like fluorescence was positively correlated with the concentrations of DOC, suggesting that the DOC of cave drip waters was derived from the overlying soil layer of a cave system. Compared with the other cave systems, the variation range of the excitation and emission wavelengths for fulvic-like fluorescence of cave drip waters in Liangfeng cave system that had forest vegetation was smaller and the excitation wavelength was longer, while its fluorescence intensity varied significantly. By contrast, the excitation and emission wavelengths and fluorescence intensity for that in Jiangjun cave system that had a scrub and tussock vegetation showed the most significant variation, while its excitation wavelength was shorter. This implies that the variation of vegetation overlying a cave appears to be a factor affecting the fluorescence spectral characteristics of cave drip waters.     

三重抗干扰晶闸管触发隔离输出电路

设计了一种抗干扰能力极强的晶闸管触发隔离电路.光耦隔离器件的电源依靠脉冲变压器供电的设计,极大的提高了触发电路的抗干扰能力.     

行程时间可靠性研究

文章结合已有研究成果,提出了行程时间可靠性的概念,分析了基于供需随机性构建的路径行程时间可靠性、OD对行程时间可靠性及系统行程时间可靠性模型,最后构建了基于最可能状态的行程时间可靠性近似算法。     

The English Corner: an Effective Way to TBLT

本文探讨了任务型教学法在中国实施的现状以及英语教学中存在的问题,并将课堂英语教学与英语角加以比较。研究表明英语角更有利于任务型教学的开展并且在发展学生口语交际技能及提高口语水平方面有其独到的优势。本文还就英语角的设计提出了一些可行的方法与建议。本论文的案例研究建立在天津财经大学英语学习俱乐部英语角活动的基础之上。     

闭管回流——分光光度法测定化学需氧量(COD)

采用闭管回流——分光光度法测定水样的化学需氧量(COD)与标准(经典)回流法测定结果一致,该方法适用于环境监测中污水水质的检测。方法的准确度和精确度符合测试要求,且试剂用量少、成本低、无需滴定、操作简便,易实现数据在线处理,尤其适合室内外批量测试。文中考察了影响测试结果的因素,确立了试剂配制方法和操作程序。     

论颜色符号系统的模糊性

颜色在我们身边无所不在,世界上的各个民族每天都在用他们的语言对颜色进行描述和分类,而无论是哪一个民族的语言的颜色词,它们在概念上和内涵上都是模糊的,这是因为语言和文化这两个符号系统都是模糊的。     

Improving the accuracy of GRACE Earth's gravitational field using the combination of different inclinations

In this paper,the GRACE Earth's gravitational field complete up to degree and order 120 is recovered based on the combination of different inclinations using the energy conservation principle.The results show that because different inclinations of satellite are sensitive to the geopotential coefficients with different degrees/and orders m.the design of GRACE exploiting 89° inclination can effectively improve the accuracy of geopotential zonal harmonic coefficients.However,it is less sensitive to the geopotential tesseral harmonic coefficients.Accordingly.the second group of GRACE exploiting lower inclination is required to determine high-accurately the geopotential tesseral harmonic coefficients and cover the shortage of the single group of GRACE exploiting 89° inclination.Two groups of GRACE individually exploiting 89° (82°-84°)inclinations are the optimal combination of the Earth'S gravitational field recovery complete up to degree and order 120.In the degree 120,the joint accuracy of cumulative geoid height based on two groups of GRACE individually exploiting 89° and 83° inclinations is averagely two times higher than the accuracy of a group of GRACE exploiting 89° inclination.     

现代汉语篇章中总结连接成分前后项的语义关系

总结连接成分是一种重要的篇章连接手段,它前后项的语义关系有并列、递进、因果、分总等关系,通过分析．我们发现,前后项的语义关系并不是简单的归纳概括关系,后项是在前项的基础上改换另一种说法,来达到帮助读者或听者掌握作者或说者意图的目的。     

大型公建选址与城市空间发展互动研究

在对城市大型公建概念界定的基础上,从影响大型公建选址的空间要素出发,对城市大型公建的选址与城市空间发展之间的互动关系进行深入研究,并以南京市奥体中心的选址进行实证分析,以期对城市大型公建的选址提供理论和实践的依据.     

神话中的"回首"原型及其意义初探——兼谈藏文化中的回首禁忌

文章在跨文化比较的基础上,通过归纳概括提出神话中"回首"原型的概念,并结合结构主义理论分析了该原型的意义和历史衍化,指出它是男性话语在文学中占主导地位的情况下对原始社会从母权制向父权制历史性过渡的一种象征性阐释。结合该原型,文章兼对藏族文学中的"回首"情节进行了研究。