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1.
利用量子化学程序计算了12个氯喹酸酯化合物的量子化学参数,如最高占据轨道能级、最低空轨道能级、生成热、偶极矩、活性部位原子静电荷等,并对玉米根抑制活性进行了定量结构-活性相关(QSARs)分析,其中最低空轨道能级、前线轨道能级差、偶极矩、原子静电荷4类参数共同构建的模型准确性最高(R=0.887),说明该类化合物活性大小主要与电性参数相关.  相似文献   

2.
利用量子化学程序计算了12个氯喹酸酯化合物的量子化学参数,如最高占据轨道能级、最低空轨道能级、生成热、偶极矩、活性部位原子静电荷等,并对玉米根抑制活性进行了定量结构-活性相关(QSARs)分析,其中最低空轨道能级、前线轨道能级差、偶极矩、原子静电荷4类参数共同构建的模型准确性最高(R=0.887),说明该类化合物活性大小主要与电性参数相关.  相似文献   

3.
利用量子化学程序计算了12个氯喹酸酯化合物的量子化学参数(如:最高占据轨道能级、最低空轨道能级、生成热、偶极矩、活性部位原子静电荷等),并对玉米根抑制活性进行了定量结构-活性相关(QSARs)分析,其中最低空轨道能级、羰基氧原子静电荷参数共同构建的多元高阶模型准确性最高(R=0.905,R2=0.819,F=7.913,S=0.148),与之前的多元一阶模型相比(R=0.887,R2=0.786,F=2.098,S=0.213),准确性有了很大的提高.利用上述模型对化合物活性进行了预测,结果表明该模型能很好地预测化合物除草活性,预测值与实验值误差小.  相似文献   

4.
乙酰苯胺类化合物的QSAR研究   总被引:2,自引:0,他引:2  
利用量子化学程序计算了17个乙酰苯胺化合物的量子化学参数(如最高占据轨道能级、最低空轨道能级、极化率、杂原子静电荷、偶极矩等),并对化合物的最小阻滞浓度(MBC)进行了定量结构-活性相关(QSARs)分析,其中最高占据轨道能级、极化率、N(3)原子静电荷3个参数共同构建的模型准确性最高(R=0.907,F-20.064).该模型说明化合物毒性与脂溶性关系不大,而是可能通过与受体间提供电子发挥效应,且N(3)原子为作用位点.同时利用该模型对MBC进行了理论预测,结果表明该模型能很好地预测化合物的MBC,预测值与实验值误差较小.  相似文献   

5.
采用定性和定量方法分析了松油-4-醇及其14种衍生物对家蝇熏蒸和毒杀活性的构效关系.以Hyperchem软件的PM3模块对供试化合物进行量子化学计算,分别获得构效参数、轨道能级参数和单点净电荷参数.分析化合物各参数与其生物活性间的关系,并以偏最小二乘法(PLS)建立了一条电荷值—熏蒸活性模型(y=-0.159 989...  相似文献   

6.
本文计算了结构类似的21个三嗪类除草剂化合物的生成热、最高占据、最低空轨道轨道能量、偶极矩、静电势、极化度以及5个具有代表性N原子所带的电荷这些量子化学参数,结合分配系数、表面积等物理参数,进行了定量结构一活性关系(QSAR)研究,建立了相应的QSAR方程,R^2=0.863,F=1.576.利用该方程对西玛津的毒性活性进行了预测验证.预测值与理论值很接近,误差在允许的范围之内.证实了该QSAR方程可靠.  相似文献   

7.
利用量子化学密度泛函理论(DFT)中的杂化泛函B3LYP对三个系列60个喹啉环取代的喜树碱衍生物(CPTs)进行了构型优化,在6-311+G(d,p)基组下计算出相应的电子结构参数;采用逐步多元回归方法对各组化合物建立了几个新的分子描述符与抗癌活性之间的定量结构-活性关系(QSAR)模型,探讨了影响化合物抗癌活性的主要结构因素及其作用机理.结果表明,所得QSAR模型具有良好的预测能力,影响药物活性的主要因素有分子极化率和原子净电荷以及及最高占据分子轨道能量.根据所建最佳QSAR可以较准确地预测喜树碱类衍生物的抗癌活性,这有助于未来设计合成新型高效抗癌喜树碱类似物以及改进和完善其作用机理.  相似文献   

8.
取代芳烃化合物电子结构与其对发光菌毒性关系的研究   总被引:3,自引:0,他引:3  
应用量子化学半经验的MNDO方法计算了40个取代芳烃化合物的电子结构,探讨了化合物电子结构与其对发光菌毒性的关系.结果表明:(1)当化合物的分子极化度P、分子体积V、疏水参数logP较大时具有较大的水溶性和脂溶性,因而化合物的毒性较大;(2)当最高占据轨道(HOMO)能级和最低空轨道(LUMO)能级较低时,化合物容易接受电子具有较大的氧化性,取代芳烃的毒性也随之增大;(3)取代基的吸电子能力越强,吸电子基个数越多,苯环的正电性越大,化合物的毒性越大.得到的QSAR方程为:-logEC50=-2.230 O.202P-0.366EHOMO,据此可预测取代芳烃化合物对发光细菌的毒性.  相似文献   

9.
采用Gaussian98程序量子化学从头算方法对吡唑甲醛缩N^4-取代苯基氨(硫)脲化合物进行了量子化学计算.计算结果表明:此类化合物的抗溃疡作用和毒性作用与前线及近前线分子轨道能级及轨道构成有较好的线性关系.表明此类化合物在发挥生物活性时以给电子为主,吡唑环以及缩氨(硫)脲为此类化合物的生物活性区.  相似文献   

10.
采用AM1和Ab Initio DFT方法,对3-(吡啶-2)-4-(喹啉-4)-吡唑(PQP)进行了量子化学计算,给出了分子的几何构型、前沿分子轨道组成与能级、前沿轨道电子密度、原子的净电荷、键级等参数,结果表明PQP分子的稳定构型呈蝴蝶状,分子中的所有N原子和C18、C21等原子很可能是它与T β R-I作用时的活性位点。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

16.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

17.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

18.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

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