A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flo...A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression （SMR） and partial least square （PLS） methods, a model with the correlation coefficient （R1） of 0.987 and the standard deviation （SD1） of 1.377 could be obtained. Then through multiple linear regression （MLR）, another model with the correlation coefficient （R2） of 0.989 and standard deviation （SD2） of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique （SMR）, 8 vectors were selected to build up another model with its correlation coefficient （R3） and standard deviation （SD3） of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out （LOO） procedure, and the correlation coefficients （QCV） were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.展开更多
青藏高原物种丰富且属于气候变化敏感区,研究气候变化对青藏高原物种的潜在分布影响,对于该区域物种多样性保护具有重要意义。该研究以一级濒危藏药植物全缘叶绿绒蒿为研究对象,利用加权平均算法(weighted average algorithm, WAA)构建...青藏高原物种丰富且属于气候变化敏感区,研究气候变化对青藏高原物种的潜在分布影响,对于该区域物种多样性保护具有重要意义。该研究以一级濒危藏药植物全缘叶绿绒蒿为研究对象,利用加权平均算法(weighted average algorithm, WAA)构建随机森林(RF)、灵活判别分析(FDA)及人工神经网络(ANN)的集成模型,同时对比分析了WAA模型和不同生态位模型的预测精度。最后利用WAA模型预测了全缘叶绿绒蒿在当前(1970~2000年平均)和未来(2041~2060年平均)气候情景下的潜在分布,其中未来气候考虑了2种“共享社会经济路径”(SSP2-45和SSP5-85)。结果显示:(1) WAA模型的预测表明,基于RF、FDA和ANN的集成模型的AUC值为0.926,在AUC值最高RF模型的基础上提高了3%,在FDA和ANN模型的AUC值的基础上均提高了5%。(2) WAA模型确定,全缘叶绿绒蒿的潜在分布对年降水量和最暖季降水量最为敏感,其次是最热月份最高气温,同时对最湿月份降水量以及等温性表现出较低的敏感性。(3)当前全缘叶绿绒蒿潜在分布区主要分布在甘肃西南部、青海东部至南部、四川西部和西北部、云南西北部和东北部、西藏东部。(4)未来气候变化下青藏高原全缘叶绿绒蒿潜在分布预测表明,在2050年SSP2-45情景下,全缘叶绿绒蒿的潜在分布区大小与当前潜在分布区大小基本相同,但整体向西北方向高海拔高纬度地区迁移;在SSP5-85情景下,全缘叶绿绒蒿的潜在分布区明显收缩,且向西北高纬度高海拔地区延伸的趋势更加明显。展开更多
基金supported by the Foundation of Education Bureau, Sichuan Province (09ZB036)Technology Bureau, Sichuan Province (2006j13-141)
文摘A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression （SMR） and partial least square （PLS） methods, a model with the correlation coefficient （R1） of 0.987 and the standard deviation （SD1） of 1.377 could be obtained. Then through multiple linear regression （MLR）, another model with the correlation coefficient （R2） of 0.989 and standard deviation （SD2） of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique （SMR）, 8 vectors were selected to build up another model with its correlation coefficient （R3） and standard deviation （SD3） of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out （LOO） procedure, and the correlation coefficients （QCV） were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.
