Abstract Using the method of stepwise multivariate linear regression (SMLR), the quantitative structure activity relationships (QSAR) of two isomeric series of taxol and its derivatives have been studied. It was foun...Abstract Using the method of stepwise multivariate linear regression (SMLR), the quantitative structure activity relationships (QSAR) of two isomeric series of taxol and its derivatives have been studied. It was found that the molar refractivity of the C3′substituent of the C13 side chain has significant correlation with its activity. We deduce that structural changes in the C3′substituents may be critical to the anticancer function. It would be useful to the design and synthesis of taxol like compounds with improved activities.展开更多
高光谱遥感能同时获取地物空间影像和连续且精细的光谱信息,以图谱合一的形式更为精确地描述地物,然而高光谱影像普遍存在同物异谱和同谱异物现象,给准确地物分类带来挑战;激光雷达(light detection and ranging,LiDAR)能够获取地物拓...高光谱遥感能同时获取地物空间影像和连续且精细的光谱信息,以图谱合一的形式更为精确地描述地物,然而高光谱影像普遍存在同物异谱和同谱异物现象,给准确地物分类带来挑战;激光雷达(light detection and ranging,LiDAR)能够获取地物拓扑信息,可用于构建地表三维模型,但单纯采用LiDAR数据无法准确识别地物。基于以上2点,开展高光谱影像和LiDAR数据的融合研究,采用形态学属性剖面进行特征提取,借助稀疏多项式逻辑回归分类器分类,探讨在不同特征组合下的融合与分类效果;并以黑河中游张掖绿洲农业区精细作物分类为目标,采用航空高光谱影像和LiDAR DSM数据对本文方法进行了应用验证。研究表明,该方法可获得精度更高和稳定性更好的分类结果,高光谱与LiDAR融合的方法分类精度最高可达94. 50%。展开更多
针对采用传统土地利用回归（land use regression,LUR）模型进行大气污染物浓度模拟时预测变量信息损失的缺陷,将主成分分析（principle component analysis,PCA）与逐步多元线性回归（stepwise multiple line regression,SMLR）相结合...针对采用传统土地利用回归（land use regression,LUR）模型进行大气污染物浓度模拟时预测变量信息损失的缺陷,将主成分分析（principle component analysis,PCA）与逐步多元线性回归（stepwise multiple line regression,SMLR）相结合,提出了一种改进的LUR（PCA+SMLR）模型模拟大区域PM2.5浓度空间分布的方法。首先采用相关分析筛选与PM2.5显著相关的预测变量,然后对筛选出的预测变量进行主成分变换（PCA）,最后保留所有主成分变量进行SMLR建立回归模型模拟PM2.5浓度。并以京津冀为研究区域进行实验验证,对PCR、SMLR、PCA+SMLR这3种模型的实验结果进行对比分析,结果表明,PCA+SMLR模型可提高预测变量对回归模型的贡献度,调整后R2达0.883,并且其精度检验指标及制图效果皆优于传统的LUR模型,证明了该模型可有效提高PM2.5浓度的模拟精度,对PM2.5区域联防联控具有指导意义。展开更多
The syntheses of three mixed ligand chelate copper（II） complexes of the type [Cu（L）（acac）（H2O）]BPh4 where acac=acetyleacetonate; L=N,N-dimethyl,N′-benzylethane-1,2-diamine （L1）, N,N-dimethyl, N′-2-methylbe...The syntheses of three mixed ligand chelate copper（II） complexes of the type [Cu（L）（acac）（H2O）]BPh4 where acac=acetyleacetonate; L=N,N-dimethyl,N′-benzylethane-1,2-diamine （L1）, N,N-dimethyl, N′-2-methylbenzylethane-1,2-diamine （L2） or N,N-dimethyl,N′-2-chlorobenzylethane-1,2-diamine （L3） are reported and characterized by elemental analyses, spectroscopic and molar conductance measurements. The X-ray structure of complex 1 shows that the central copper atom is placed in a distorted square pyramidal geometry made by acac and diamine chelate in the base and a H2O molecule on the apex. The prepared complexes are fairly soluble in a large number of organic solvents and show positive solvatochromism. Calculations of SMLR （stepwise multiple linear regression） method was utilized to find the best model explaining the observed solvatochromic behavior and showed that among different solvent parameters, donor number （DN） is a dominant factor responsible for the shift in the d-d absorption band of the complexes to the lower wavenumber with increasing its values. The importance of substituent effect in diamine ligand on the spectral and SMLR measurements is also discussed.展开更多
文摘Abstract Using the method of stepwise multivariate linear regression (SMLR), the quantitative structure activity relationships (QSAR) of two isomeric series of taxol and its derivatives have been studied. It was found that the molar refractivity of the C3′substituent of the C13 side chain has significant correlation with its activity. We deduce that structural changes in the C3′substituents may be critical to the anticancer function. It would be useful to the design and synthesis of taxol like compounds with improved activities.
基金The Key Project of International Cooperation of the Natural Science Foundation of China(No.40730632)the Special Fund of Ministry fo Science & Technology,China(No.2006DFA21890)the Knowledge Innovation Key Project of the Chinese Academy of Sciences(No.KZCX2-YW-126)
文摘针对采用传统土地利用回归（land use regression,LUR）模型进行大气污染物浓度模拟时预测变量信息损失的缺陷,将主成分分析（principle component analysis,PCA）与逐步多元线性回归（stepwise multiple line regression,SMLR）相结合,提出了一种改进的LUR（PCA+SMLR）模型模拟大区域PM2.5浓度空间分布的方法。首先采用相关分析筛选与PM2.5显著相关的预测变量,然后对筛选出的预测变量进行主成分变换（PCA）,最后保留所有主成分变量进行SMLR建立回归模型模拟PM2.5浓度。并以京津冀为研究区域进行实验验证,对PCR、SMLR、PCA+SMLR这3种模型的实验结果进行对比分析,结果表明,PCA+SMLR模型可提高预测变量对回归模型的贡献度,调整后R2达0.883,并且其精度检验指标及制图效果皆优于传统的LUR模型,证明了该模型可有效提高PM2.5浓度的模拟精度,对PM2.5区域联防联控具有指导意义。
文摘The syntheses of three mixed ligand chelate copper（II） complexes of the type [Cu（L）（acac）（H2O）]BPh4 where acac=acetyleacetonate; L=N,N-dimethyl,N′-benzylethane-1,2-diamine （L1）, N,N-dimethyl, N′-2-methylbenzylethane-1,2-diamine （L2） or N,N-dimethyl,N′-2-chlorobenzylethane-1,2-diamine （L3） are reported and characterized by elemental analyses, spectroscopic and molar conductance measurements. The X-ray structure of complex 1 shows that the central copper atom is placed in a distorted square pyramidal geometry made by acac and diamine chelate in the base and a H2O molecule on the apex. The prepared complexes are fairly soluble in a large number of organic solvents and show positive solvatochromism. Calculations of SMLR （stepwise multiple linear regression） method was utilized to find the best model explaining the observed solvatochromic behavior and showed that among different solvent parameters, donor number （DN） is a dominant factor responsible for the shift in the d-d absorption band of the complexes to the lower wavenumber with increasing its values. The importance of substituent effect in diamine ligand on the spectral and SMLR measurements is also discussed.
