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1.
本文介绍 Windows环境下网络编程的多种通信 API及 MFC(微软基础类库)对它们的封装类,重点阐述封装 WinSock API的 MFC类 CASyncSocket和Csocket的编程模型。  相似文献   

2.
含磷类血管紧张素转化酶抑制剂的3D—QSAR研究   总被引:1,自引:0,他引:1  
文章利用限制性构象搜寻(Constraints Search),确定了血管紧张素转化酶(ACE)掏剂的药效团模型(活性构象或重叠规则)。用比较分子场分析法(Comparative MolecularFidld Analysis,CoMFA)建立了含磷类ACE掏剂的3D-QSAR模型。较高的交叉验证回归系数(q^2=0. 721)及此模型对不同类型抑制剂活性的预测结果,说明了其可靠性和较好的活性预测能  相似文献   

3.
本文介绍了采用FOXPRO2.5forDos编程直接提取AutoCAD图形软件生成的几何图形实体信息,并在FOXPRO2.5forDos环境下显示AutoCAD几何图形的原理和方法,这些方法在建立工程图文数据库和CAD/CAM方面有十分重要的价值。  相似文献   

4.
AutoCADgn FOXPRO2.5 for DOS的接口   总被引:1,自引:0,他引:1  
本文介绍了采用FOXPRO2.5for Dos编程直接提取AutoCAD图形软件生成的几何图形实体信息,并在FOXPRO2.5 for Dos环境下显示AutoCAD几何图形的原理和方法,这些方法在建立工程图文数据库和CAD/CAM方面有十分重要的价值。  相似文献   

5.
Mo-算法的数值效率王大麒,李乔祥(中山大学数学系)THENUMERICALVALUEEFFICIENCYOFMo-ALGORITHM¥WangDa-qi;LiQiao-xiang(DepartmentofMathematics,ZhongshanU...  相似文献   

6.
嘧啶硫苯甲酸类的三维构效关系研究   总被引:1,自引:1,他引:0  
利用比较分子场分析(CoMFA)对16嘧啶硫苯甲酸类化合物进行了三维定量构效关系研究,得到了具有较强预测能力的QSAR模型。研究结果表明袖章效应是影响构效关系的主要因素,为更好地解释结构与活性的关系,设计新型嘧啶苯甲酸类除草剂提供了有益的指导。  相似文献   

7.
CAD/CAPP/CAM集成系统的IDEF方法建模技术   总被引:3,自引:0,他引:3  
本文讨论了采用IDEF方法建立了CIMS环境下的CAD/CAPP/CAM集成系统的功能模型与信息模型的相关技术。针对CAD/CAPP/CAM系统集成的特点,结合实例,给出了相应的建模步骤,建模思路以及有效的建模过程管理方法。  相似文献   

8.
在CAD系统中,产品模型的构造是一个基本任务。本文首先给出了使用不精确知识库管理系统来记录和处理产品构造过程的新型环境FCADE。在FCADE中,产品模型的构造过程被考虑为使用模型操作实现的模型状态的变化过程,这一过程使用模型操作之间的相关性进行记录。然后详细讨论了在FCADE中用于支持模型构造活动的两个基本功能:取消(undo),模型维护(MM)。在本文的最后,给出了FCADE的应用示例和所得出的结论。  相似文献   

9.
WebForceMediaServer与CosmoMediaBase使视频服务器更精彩CosmoMediaBase是在SGI服务器硬件平台上运行的软件,它可提供实时、交互的视频流式传输及视象内容管理,WebForceMediaServer与Cos-m...  相似文献   

10.
曾建军 《电脑》2000,(3):8-9
新的世纪,新的挑战。2000年IT业风起云涌,新的技术、新的产品层出不穷“长江后浪推前浪、一浪比一浪高。”IntelCoppermine与 AMD Athlon的较量, Socket370 Joshua的介入,CPU市场再次形成“三角力量”; Rambus、VCMRAM、FCRAM内存拉力赛也开始揭开帷幕;图形芯片的竞争更是刻不容缓,大有“兵来将挡,水来土淹”使出浑身解术,一代换一代,一代比一代强之势。“问今日之天下,谁主沉浮?一个‘芯’字了得”。这次我主要给大家综合介绍目前市场主流图形芯片的综合性…  相似文献   

11.
研究了甾族化合物的结构与抗炎活性相关的三维构效关系,采用比较分子力场分析法寻找结构与活性的关系,建立了一个可靠的构效关系模型,为活性分子的进一步修和改造提供了信息。  相似文献   

12.
13.
As a basis for predicting structural features that may lead to the design of more potent and selective inhibitors of choline acetyltransferase (ChAT), the three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were carried out on a series of trans-1-methyl-4-(1-naphthylvinyl)pyridinium (MNVP+) analogs, which are known ChAT inhibitors. 3D-QSAR studies were carried out using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods. Since these inhibitors have extremely shallow potential energy minimum energy wells and low barriers to rotation, two dihedral angles unique to these inhibitors were systematically modified to reflect the energetically preferred conformations as determined by force field calculations. An optimum alignment rule was devised based on the conformations obtained from the molecular mechanics studies, using a common substructure alignment method. The studies involve a set of 21 compounds and experimentally determined molar IC50 values were used as the dependent variable in the analysis. The 3D-QSAR models have conventional r2-values of 0.953 and 0.954 for CoMFA and CoMSIA, respectively; similarly, cross-validated coefficient q2-values of 0.755 and 0.834 for CoMFA and CoMSIA, respectively, were obtained. On the basis of these predictive r2-values the model was tested using previously determined IC50 values. CoMSIA 3D-QSAR yielded better results than CoMFA.  相似文献   

14.
In this project, several docking conditions, scoring functions and corresponding protein-aligned molecular field analysis (CoMFA) models were evaluated for a diverse set of neuraminidase (NA) inhibitors. To this end, a group of inhibitors were docked into the active site of NA. The docked structures were utilized to construct a corresponding protein-aligned CoMFA models by employing probe-based (H+, OH, CH3) energy grids and genetic partial least squares (G/PLS) statistical analysis. A total of 16 different docking configurations were evaluated, of which some succeeded in producing self-consistent and predictive CoMFA models. However, the best model coincided with docking the ionized ligands into the hydrated form of the binding site via PLP1 scoring function (r2LOO=0.735, r2PRESS against 24 test compounds=0.828). The highest-ranking CoMFA models were employed to probe NA-ligand interactions. Further validation by comparison with a co-crystallized ligand-NA crystallographic structure was performed. This combination of docking/scoring/CoMFA modeling provided interesting insights into the binding of different NA inhibitors.  相似文献   

15.
目的:应用比较分子力场法(COMFA)研究一系列喹诺酮类对HIV-1逆转录酶抑制活性的三维定量构效关系,为进一步抗HIV药物设计提供理论依据。方法和结果:在研究的29个化合物中,用比较分子力场法得到一个CoMFA模型,交叉验证系数为q~2=0.556,具有较高的预测能力及合理性,非交叉验证模型相关系数分别为r~2=0.998,标准偏差SE=0.044,F= 401.038;结论:此模型对设计和预测高活性的喹诺酮类HIV-1逆转录酶抑制活性的化合物有一定可靠性。  相似文献   

16.
17.
两类促肾上腺皮质释放因子(CRF)抑制剂的CoMFA研究   总被引:2,自引:2,他引:0  
Fipronil and related analogs, a set of new noncompetitive GABAA receptor antagonists, were investigated using comparative molecular field analysis (CoMFA) to explore their three-dimensional quantitative structure-activity relationships (3D-QSAR).Considering the structural complexity of molecules of fipronil and related analogs, three different alignments were performed in this paper. CoMFA model for housefly receptor yield the leave-one-out and cross-validated correlation coefficient q2 value of 0.511 and the conventional correlation coefficient r2 value of 0.997. The new compounds with higher activity would be designed from this model.CoMFA model for rat receptor was not successful using all these three alignments, the reason of which maybe that some molecules adopt different conformations for rat receptor.  相似文献   

18.
Fipronil and related analogs, a set of new noncompetitive GABAA receptor antagonists, were investigated using comparative molecular field analysis (CoMFA) to explore their three-dimensional quantitative structure-activity relationships (3D-QSAR). Considering the structural complexity of molecules of fipronil and related analogs, three different alignments were performed in this paper. CoMFA model for housefly receptor yield the leave-one-out and cross-validated correlation coefficient q^2 value of 0.511 and the conventional correlation coefficient r^2 value of 0.997. The new compounds with higher activity would be designed from this model. CoMFA model for rat receptor was not successful using all these three alignments, the reason of which maybe that some molecules adopt different conformations for rat receptor.  相似文献   

19.
The present study was design to examine the effect of tautomerism upon the CoMFA results. Three selected data sets involving protropic tautomerism, which are 21 p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors, 35 inhibitors of puromycin-sensitive aminopeptidase (PSA), and 67 anxiolytic agents, were used for this purpose. Atom-by-atom alignment technique was adopted to superimpose the molecules in the data sets onto a template. The structural alignments using different tautomeric forms had no significant difference except the atoms involved in tautomerism, which ensures, to a great extent, that the differences of the CoMFA results result primarily from the tautomerism. All-orientation and all-placement search (AOS-APS) based CoMFA models, in addition to the conventional ones, were derived for each system and proved to be capable of yielding much improved statistical results. In the cases of the data sets of HPPD inhibitors and PSA inhibitors, excellent AOS-APS CoMFA models (q2>0.8 with four components for the former and q2>0.7 with seven components for the latter) were obtained, and almost no significant difference in statistical quality was observed when using different tautomeric forms to derive the models. However, it was not the case when treating the data set of anxiolytic agents. The keto tautomer, which was the active form of the PBI type inhibitors, produced measurably better results (q2=0.54 with eight components) than that the enol one (q2=0.37 with five components), indicating the importance of selecting proper tautomer in the CoMFA studies. Furthermore, there existed some substantial differences of the electrostatic field contours between the two different tautomeric forms for all of the three systems considered, whereas the differences in the steric field contour maps were limited. This implies that the resulting new potent ligands may be quite different if one utilizes the CoMFA models of different tautomeric forms for guiding further structural refinements.  相似文献   

20.
采用比较分子场分析(comparative molecular field analysis,CoMFA)方法研究了两组促肾上腺皮质激素释放因子(cortico- tropin releasing factor,CRF)受体抑制剂的结构与活性关系。所得的CoMFA模型具有较好的稳定性和预报能力,q~2和r~2值分别为0.515和0.970。通过分析分子场等势图,可以直观地观察到分子周围的立体和静电特征对化合物特性的影响,为设计高活性CRF抑制剂提供了理论依据。  相似文献   

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