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论植物群落的水平距取样
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作者 王孟本 《山西师范大学学报(自然科学版)》 1993年第S2期122-126,共5页
在植物群落调查中,以水平距计算样方面积或点距的取样方法称之为水平距取样。水平距取样是由群落特征所决定。非水平距取样可能导致显著误差。而除了坡度为零的特殊情况外,我们事先一般并不能排除这种可能性。为了使获得的定量数据准确... 在植物群落调查中,以水平距计算样方面积或点距的取样方法称之为水平距取样。水平距取样是由群落特征所决定。非水平距取样可能导致显著误差。而除了坡度为零的特殊情况外,我们事先一般并不能排除这种可能性。为了使获得的定量数据准确可靠和便于研究结果的交流比较。在群落调查中以采取水平距取样为宜。 展开更多
关键词 植物群落 水平距取样
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Performance and Optimization of 10 Gb/s Electroabsorption Modulator in Short Transmission
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作者 WANG An bin, WU Jian, LIN Jin tong (Optical Communication Center,Beijing University of Posts and Telecommunication,Beijing 100876,CHN) 《Semiconductor Photonics and Technology》 CAS 2003年第3期162-165,共4页
Transmission performance of electroabsorption modulator in 10 Gb/s transmission systems has been simulated and analyzed under the condition of taking into account the chirp,extinction ratio, transmissivity and rise/fa... Transmission performance of electroabsorption modulator in 10 Gb/s transmission systems has been simulated and analyzed under the condition of taking into account the chirp,extinction ratio, transmissivity and rise/fall time.Results show that short transmission distance without EDFA after EAM can be used in future metropolitan area network,but the transmissivity must be carefully considered. The sampling time range and decision level can be optimized to reduce the bit error ratio. 展开更多
关键词 Electroabsorption modulator TRANSMISSIVITY Sampling time Decision level
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