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Atoms in most organic molecules are often carbon,oxygen,nitrogen,sulfur,halogens,etc. Based on the three-dimensional structure of a molecule,a molecular structural characterization(MSC) method called improved molecular electronegativity-distance vector(I-MEDV) was developed. It was used to describe the structures of 37 compounds of styrax japonicus sieb flowers. Through multiple linear regression(MLR),a QSRR model was built up. The correlation coefficient(R1) of the model was 0.980. Then,4 vectors were selected to build another model through the method of stepwise multiple regression(SMR) ,and the correlation coefficient(R2) of the model was 0.975. Moreover,all the two models were evaluated by performing the crossvalidation with the leave-one-out(LOO) procedure and the correlation coefficients(Rcv) were 0.948 and 0.968,respectively. The results show that the I-MEDV could successfully describe the structures of organic compounds. The stability and predictability of the models were good. 相似文献
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A new molecular structural characterization(MSC)method called molecular vertexes correlative index(MVCI)was constructed in this paper.The index was used to describe the structures of 45 compounds and a quantitative structure-activity relationship(QSAR)model of toxicity(–lgEC50)was obtained through multiple linear regression(MLR)and stepwise multiple regression(SMR).The correlation coefficient(R)of the model was 0.912,and the standard deviation(SD)of the model was 0.525.The estimation stability and prediction ability of the model were strictly analyzed by both internal and external validations.The Leave-One-Out(LOO)Cross-Validation(CV)correlation coefficient(RCV)was 0.816 and the standard deviation(SDCV)was 0.739,respectively.For the external validation,the correlation coefficient(Rtest)was 0.905 and the standard deviation(SDtest)was 0.520,respectively.The results showed that the index was superior in molecular structural representation.The stability and predictability of the model were good. 相似文献
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课程目标达成评价是专业人才培养目标与毕业要求达成评价的基础,是师范类专业认证工作中的重要考查内容之一。有机化学实验是化学专业的必修实践类课程,为合理评价该课程的教学质量及教学效果,以内江师范学院化学专业的有机化学实验课程为例,介绍了该课程的基本信息、课程目标及其对毕业要求指标点的支撑。从形成性评价和终结性评价、直接评价和间接评价、综合评价等方面详细介绍了课程目标达成评价过程及评价结果的应用,研究结果为相关课程的教学改革和教学质量评价提供参考。 相似文献
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构建了基于分子三维结构计算的原子电负性距离矢量(atomic electronegative space distance vector,AESDV),用以描述各芳香醚类化合物分子中不同等价碳原子的化学微环境,并结合原子自身杂化状态指数(AHSI),建立了13C核磁共振定量结构波谱关系的多元线性回归模型,复相关系数(R)为0.964,标准误差(SD)为8.673.经留一法交互检验的复相关系数(RCV)为0.948,标准误差(SDCV)为10.362.随机抽出样本进行外部检验,得到测试集的复相关系数(Rtest1及 Rtest2)分别为0.979和0.939,标准误差(SDtest1及 SDtest2)分别为6.400和10.162.研究结果表明,使用该方法所建模型具有良好的预测能力和稳定性. 相似文献
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The molecular electronegativity interaction vector (MEIV) was used to describe the molecular structure of 30 selected esters. Two excellent QSTR models were built up by using multiple linear regression (MLR) and partial least-squares regression (PLS). The correlation coefficients (R) of the two models were 0.945 and 0.941, respectively. The models were evaluated by performing the cross validation with the leave-one-out (LOO) procedure. The cross-verification correlation coefficients (RCV) of the two models were 0.921 and 0.919, respectively. The results showed that the models constructed in this work could provide estimation stability and favorable predictive ability. 相似文献
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本文采用分子电性距离矢量( Molecular Electronegativity-distancevector,MEDV)对地下水中26个挥发性化合物进行了结构表征,并与其色谱保留时间建立定量结构-保留关系(QSRR)模型.得到的MLR模型复相关系数(R2)为0.901,留一法(LOO)交互校验(CV)预测值的复相关系数(R2cv)为0.806;PLSR模型复相关系数(R2)为0.882,留一法(LOO)交互校验(CV)预测值的复相关系数(R2cv)为0.750.结果表明分子电性距离矢量(MEDV)能较好地表征该体系化合物结构,所建模型具有良好的稳定性与预测能力. 相似文献