首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13篇
  免费   0篇
  国内免费   1篇
化学   13篇
物理学   1篇
  2022年   1篇
  2019年   1篇
  2016年   1篇
  2014年   1篇
  2013年   1篇
  2012年   3篇
  2011年   3篇
  2008年   3篇
排序方式: 共有14条查询结果,搜索用时 218 毫秒
1.
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   
2.
廖立敏  李建凤  王碧 《结构化学》2011,30(10):1397-1402
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   
3.
以单、双乙酰基二茂铁为原料,经还原和脱水反应,高效地合成了单、双齿功能性配体--二茂铁乙基咪唑和二茂铁双乙基咪唑,其结构经1H NMR,IR,MS和元素分析表征.  相似文献   
4.
5.
李建凤  廖立敏 《化学教育》2022,43(24):56-61
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   
6.
以三苯胺为原料,通过改进的乌尔曼反应高效地合成了三-(4-吡唑基)苯基胺(1),其结构经X-射线单晶衍射仪,1H NMR,IR,MS和元素分析表征.1属于正交晶系,Pccn空间群,晶胞参数:a=23.394(7)A,b=34.021(9)A,c=11.719(3)A.分子问通过氢键和弱的π----π作用相互连接.  相似文献   
7.
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   
8.
本文以洋葱为原料,以多糖提取率为考察指标,用苯酚-硫酸法测定多糖的总糖含量。采用正交试验确定了纤维素酶、木瓜蛋白酶和果胶酶的最佳配比为18∶5∶10,进而采用中心组合设计对洋葱多糖的复合酶法提取工艺进行了优化。结果表明:在提取温度55℃、时间120min、pH为5.0、酶用量为0.4%、料液比为1∶40(m/V)时,洋葱多糖提取率为3.27%,多糖含量高达50.5%,实验重现性好。  相似文献   
9.
李建凤  廖立敏  王碧 《结构化学》2011,30(9):1225-1232
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   
10.
李建凤  张圆  邓小艳  翟好英 《分析试验室》2019,38(11):1334-1338
在HAc-NaAc缓冲溶液中,罗丹明类染料罗丹明6G(Rh6G)、罗丹明B(RhB)和丁基罗丹明(b-RhB)分别在553,582和589 nm处产生一个较强的荧光峰。加入异烟肼(INH)后,由于异烟肼分别与Rh6G,RhB和b-RhB发生作用,从而使得3种体系的荧光均发生猝灭。在最佳实验条件下,异烟肼浓度分别在0. 10~20μg/mL,0. 10~25μg/mL和0. 50~22μg/mL范围内与各体系的荧光强度改变值(!F)之间呈良好的线性关系,且3种体系的检出限分别为9. 04,21. 7和20. 4 ng/mL。据此,建立了一种荧光猝灭法测定药物中异烟肼含量的分析方法。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号