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1.
合成了9种多取代嘧啶环的α-氯乙酰脲,其中8种为新化合物,结构经IR,1HNMR,MS和元素分析测试而确证,初步生物活性测试结果表明:标题化合物具有优良的生物活性,且嘧啶环上取代基的性质对此类化合物影响很大,含4-羟基取代嘧啶环的标题化合物具有较好除草活性,而含4-氯取代嘧啶环的化合物一般具有一定的植调活性。  相似文献   

2.
2—氨基—4—氯—6—甲氧基嘧啶的合成   总被引:2,自引:0,他引:2  
以硝酸胍和丙二酸二乙酯为起始原料,经环合,氯化,水解,甲氧基化,合成了2-氨基-4-氯-6-甲氧基嘧啶。其收率达到70%,其结构经IR测试确定。目标化合物2-氨基-4-氯-6-甲氧基嘧啶可以用来制备抗肿瘤药物的重要中间体硝酸嘧啶氮芥化合物。  相似文献   

3.
合成了9种含多取代嘧啶环的α-氯乙酰脲,其中8种为新化合物.结构经IR,1H NMR,MS和元素分析测试而确证,初步生物活性测试结果表明:标题化合物具有优良的生物活性,且嘧啶环上取代基的性质对此类化合物影响很大,含4羟基取代嘧啶环的标题化合物具有较好除草活性,而含4氯取代嘧啶环的化合物一般具有一定的植调活性.  相似文献   

4.
报导了一种合成5-烷基-2-(对氰基苯基)嘧啶化合物的新方法。缩合形成嘧啶环的两个前体化合物分别是a-烷基-B-烷氧基丙烯醛和4-乙氧酰基苯甲脒盐酸盐。经多步反应合成了前体化合物,缩合成嘧啶环并实现了嘧啶衍生物之间的官能团转换。所合成的化合物有较好的光、热和化学稳定性,是一种性能较好的介晶材料。  相似文献   

5.
4种苯并含氮杂环化合物分别与氯乙酰氯反应,得到相应的N-氯乙酰取代的衍生物,在相转移催化剂四丁基碘化铵(TBAI)的作用下,经亲核取代反应,4种N-氯乙酰取代的苯并含氮杂环化合物通过醚键的形成被引入嘧啶结构,合成了7个新嘧啶类化合物,并经过MS,IR,^1H,^13CNMR和元素分析得到确认。  相似文献   

6.
取代苯氧乙酰硫脲类嘧啶衍生物的合成及生物活性研?…   总被引:7,自引:0,他引:7  
取代苯氧乙酸经酰化,异硫氰酸酯化,与取代-2-氨基嘧啶加成3步反应合成了10种未见文献报道的取代苯氧乙酰悄类嘧啶衍生物,结构经IR^1HNMR和元素分析等测试方法而确证,用平皿法初步测定了目标化合物的生物活性,结果表明,4-硝基苯氧乙酰硫脲类嘧啶衍生物在低浓度时促进单子叶植物的生长,高浓度时抑制了双子叶植物的生长,2,4-二氯苯氧乙酰硫脲在嘧啶衍生物,对单子叶和双子叶植物的生长均具有超高抑制活性。  相似文献   

7.
4,6—二甲氧基—2—嘧啶氨基甲酸甲酯的合成   总被引:1,自引:1,他引:0  
报道一种非光气法合成4,6-二甲氧基-2-嘧啶氨基甲酸甲酯(简称嘧啶氨基甲酸酯)的新方法,以2-氨基-4,6-二甲氧基嘧啶(简称氨基嘧啶)和碳酸二甲酯为超始原料,在甲醇钠存在下的溶剂中反应制得,收率-85%。产品经元素分析,IR,^1H NMR等证实。  相似文献   

8.
文中针对用S-B1工艺路线生产维生素B1工艺过程中的关键问题——乙酰嘧啶中间产物收率过低(60%左右),研究了原料配比、水用量和乙酰嘧啶在水中的溶解度对总收率的影响,以及工艺操作条件对生成乙酰嘧啶的反应特性的影响。并用统计方法对实验数据进行了处理,研究了操作过程对总收率的影响。结果表明,相对于1mol缩醛,甲醇钠、盐酸乙脒的最佳使用量为2.76mol和3.1mol。而且在55~65℃区间的升温时间应控制在最佳。这样,总收率依缩醛计可以提高5%~10%。  相似文献   

9.
由2,4-二氯苯氧乙酸经酰化后得酰氯,再与2-氨基-4,6-二取代嘧啶反应制得9个未见文献报道的N-(4,6-二取代嘧啶-2-基)-2,4-二氯苯氧乙酰胺.目标化合物结构经元素分析,IR和^1H NMR确证.进行了除草活性筛选,其中2个目标化合物对单子叶和双子叶的供试杂草均显示高效的除草活性.  相似文献   

10.
通过微波促进的一锅法反应合成了一系列C-5′羟基取代的嘧啶基核苷类衍生物,化合物结构经NMR和HRMS等表征.利用MTT法研究了合成化合物的抗肿瘤活性,二甲氨基修饰的嘧啶基5-甲基尿苷衍生物3a和肌苷衍生物4a显示了好的活性,IC50值分别为10.73和10.99μmol/L.而合成的其他核苷类衍生物在测试的细胞株中没有活性,说明环状氨基修饰的嘧啶基显著降低合成的核苷类衍生物的活性.  相似文献   

11.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

12.
13.
Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications (up to 574.8 km/ h test speeds or 380 km/h commercial speeds) in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.  相似文献   

14.
Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to  相似文献   

15.
Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.  相似文献   

16.
为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。  相似文献   

17.
Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.  相似文献   

18.
The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.  相似文献   

19.
介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。  相似文献   

20.
正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme  相似文献   

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