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螺吡喃光控转变的半经验动力学研究
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作者 雷依波 吴少美 +2 位作者 韩慧仙 豆育升 文振翼 《陕西师范大学学报(自然科学版)》 CAS CSCD 北大核心 2013年第2期44-48,共5页
采用半经典的电子-辐射-离子动力学模拟(SERID)研究了螺吡喃分子开环反应的非绝热动力学过程.采用简化模型的螺吡喃(mSP)简化计算.开环过程中mSP分子首先经过一个圆锥相交点后变为顺式-反式-顺式-模型部花青(CTC-mMC)继而又变为顺式-反... 采用半经典的电子-辐射-离子动力学模拟(SERID)研究了螺吡喃分子开环反应的非绝热动力学过程.采用简化模型的螺吡喃(mSP)简化计算.开环过程中mSP分子首先经过一个圆锥相交点后变为顺式-反式-顺式-模型部花青(CTC-mMC)继而又变为顺式-反式-反式-模型部花青(CTT-mMC).这与实验中螺吡喃分子开环后由于第一个异构体顺式-顺式-顺式-模型部花青(CCC-mMC)不稳定而在很短时间内转变为CTC-mMC基本一致.模拟过程中亦发现CTC-mMC不如CTT-mMC稳定,体系经CTT-mMC后回到能量较低的CTT-mMC构型.mSP的3个C—C—C—C二面角随时间扭转的实时动力学过程验证了以前理论推测的反应机理,模拟得到的激发态寿命与实验值基本一致. 展开更多
关键词 激光诱导光化学反应 半经典电子-辐射-离子动力学模拟 螺吡喃开环反应
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Evaluation of Desertification Processes in SeridóRegion (NE Brazil)
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作者 Reinaldo Antonio Petta Leila Vespoli de Carvalho +1 位作者 Stefan Erasmi Charles Jones 《International Journal of Geosciences》 2013年第5期12-17,共6页
This paper outlines procedures to analyze the desertification processes in the semi-arid Seridó Region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental in... This paper outlines procedures to analyze the desertification processes in the semi-arid Seridó Region (NE Brazil). Using the Geosystem theory, the detection of desertification areas was based on environmental indices, digital image processing in multispectral analysis and Geographic Information System (GIS).The first step was to treat the rainfall data and NDVI satellite Modis, aiming at identifying areas which do not present vegetation cover, even during the rainy seasons.The second step was to work on a regional scale using Landsat ETM + images (2000-2005) and data collected in the field, as the evaluations of exposed surfaces, that together with MDT/SRTM-NASA and thematic maps, allowed to classify the altitude and slope of the relief, soils type, different morphologies and geology, and correlate them with the areas susceptible to desertification process. The integration of the georeferenced data, related to these indicators, allowed the identification of five different levels of susceptibility to desertification (very high, high, moderate, low and very low), and the geographic domain of each class. Based on the analysis of the dynamics of the vegetation cover, we can establish that the main results refer that there is a decrease of the biomass at the region, associated with the dense caatinga vegetation areas, but more important, with the scrub and degraded areas. 展开更多
关键词 DESERTIFICATION CAATINGA MODIS LANDSAT NDVI seridó Brazil
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一种新型柴油机的热功参数分布式检测系统的设计
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作者 毛新勇 高世伦 蒋方毅 《柴油机设计与制造》 2001年第3期31-33,共3页
介绍了以8051单片机为基础,586为主机的多功能柴油机热功参数分布式检测系统的设计思想和工作流程,分析了系统的模拟电路和数字接口电路,并给出了接口硬件电路和实例。
关键词 分布式系统 串行通讯 AD转换器 LED显示 计算机 柴油机 热功参数 VB 检测
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