吡啶

In the first part, the prototropic hydroxy-oxo tautomerisms of 2 (1H)- pyridones/2-hydorxypyridines, one of the most important model systems in molecular biology, have been investigated with self-consistent reaction field method based on continuum model. The influence of the nature and position of substituent groups, the existence of intramolecular hydrogen bonding and tautomeric competition between 2-hydroxy and 4-hydroxy on the tautomeric equilibria have also been examined.

第一部分，首先从溶剂敏感的异构化性质入手，用基于连续介质的自洽反应场理论方法对一类重要的生化模型体系—2（1H）-吡啶酮／2-羟基吡啶互变异构体系进行了研究，系统地考察了取代基性质、取代基位置、分子内氢键的形成以及互变异构竞争的存在对异构化平衡的影响。

A novel BB'2-type aromatic triamine containing pyridine ring was successfully synthesized by catalytic reduction of the trinitro compound obtained by a modified Chichibabin reaction in acidic medium with hydrazine hydrate.

采用商品化的原料，在酸性介质中经改进的Chichibabin反应先合成含吡啶环的三硝基化合物，再用水合肼催化还原得到一种新型的含吡啶环BB'2型芳香三胺单体。

The results are following:(1)We investigated the influence of the positional isomeric effect on structures.Due to the less space-crowding,it is easier for 3-pytpy to behave as bridging ligand than 2-pytpy under the same reaction conditions,while,it is easier for 2-pytpy to function as tridentate chelating ligand to construct supramolecular structures.

研究结果如下：(1)研究了两个吡啶取代三联吡啶配体的位置异构效应对配合物结构的影响。3-pytpy配体比2-pytpy具有更小的空间位阻，在相同的合成条件下容易以单-三齿桥联方式配位；而2-pytpy更易以三齿螯合形式配位，通过π…π堆积作用形成超分子结构。

Four cephalosporin derivatives taking substituted or unsubstituted pyridiniomethyl group at 3-side were synthesized.

c、C-3位含氮甲基的头孢菌素衍生物：合成了4个含吡啶及取代吡啶头孢菌素衍生物。

A high performance liquid chromatographic method was studied for the simultaneous determination of pesticide imidacloprid and its two intermediates (2-chloro-5-methyl pyridine and 2-chloro-5-chloromethyl pyridin).

研究了用高效液相色谱法同时分离测定农药吡虫啉原粉和中间体2-氯-5-甲基吡啶及2-氯-5-氯甲基吡啶含量的方法。

A one-step method for the synthesis of aromatic indolizine derivatives byintramolecular 1,5-dipolar cyclization reaction of 2-(2-arylethenyl)pyridinium N-ylidesin the presence of an oxidant has been studied for the first time. In the presence ofelectron-deficient olefins, however, 2-(2-phenylethenyl)pyridinium N-ylides underwent1,3-dipolar cycloadditions and then aromatized in situ by TPCD to produce indolizinederivatives, indicating 1,3-dipolar cycloaddition proceed more readily than 1 ,5-dipolarcyclization in these conditions. Pyridinium disubstituted N-ylides, readily obtainedfrom corresponding pridinium and β-chlorovinyl ketone, underwent thermalintramolecular 1,5-dipolar cyclization to give indolizine derivatives easily.Indolizinecarbaldehyde derivatives were synthesized starting from 2-pyridinecarbaldehyde in four-steps involving 1,3-dipolar cycloaddition reaction.

本文首次研究了2-(2-芳基乙烯基)吡啶N-叶立德在氧化剂存在下的分子内1，5-偶极环化反应，采用一锅法合成了中氮茚衍生物；研究了这些N-叶立德的1，5-偶极环化和1，3-偶极环加成反应的选择性，发现当有缺电子烯烃存在时，优先进行1，3-偶极环加成反应，而不再发生分子内1，5-偶极环化反应；由β-氯乙烯酮方便地得到了烯丙基N-叶立德，他们在加热时进行分子内1，5-偶极环化反应而得到中氮茚衍生物；由2-吡啶甲醛为起始原料，通过1，3-偶极环加成反应等四步反应，得到了重要的中氮茚甲醛衍生物，这些反应都具有条件温和和操作简便的特点，是合成中氮茚衍生物的新方法。

Methods: fudr was esterified with acetic anhydride in the presence of pyridine and 4 dimethylaminopyridine.

在吡啶和4 二甲氨基吡啶存在时，fudr与乙酸酐反应，制备氟尿苷二乙酸酯，并测定其核磁共振氢谱。rp hplc测定其在正辛醇和磷酸盐缓冲液中的分配系数及不同ph缓冲液和组织匀浆中的稳定性。

The determination and degradation of clopyralid in soil and oilseed were studied. The soil samples were macerated with aqueous sodium hydrogen. The slurry was tumbled and centrifuged.

本文采用反相高效液相色谱分析测定二氯吡啶酸在油菜田土壤中和植株上的残留动态及收获期土壤和油菜籽粒中二氯吡啶酸的残留量，并对二氯毗啶酸在土壤-水中的吸附解吸特性进行了研究。

The similar nicotinoyltrifluoroacetones are synthesized from acetylpyridine and ethyl trifluoroacetate through Claisen reaction.The influnences of alcoholic natrium,reaction temperature and solvent on reaction yield is studied.The subliming method is improved.

本文以乙酰吡啶和三氟乙酸乙酯为主要原料，利用克莱森酯缩合反应，合成了三种相似结构的吡啶甲酰三氟丙酮化合物，考察了碱性试剂醇钠、反应温度和溶剂等因素对反应产率的影响，改进了纯化产物的方法。

The amount of Na(superscript +), NH4(superscript +), K(superscript +), Mg(superscript 2+), Ca(superscript 2+), Zn(superscript 2+) in fruits and juice (sports water, green tea , pear juice, carrot juice and carrot and orange juice) were respectively separated and detected by non-suppressed ion chromatography. And pyridine-2, 6-dicarbexylic was used as mobile phase to separated monovalent cations and pyridine-2, 6-dicarbexylic-ethylenedi-amine-oxalic acid was used as mobile phase to separated divalent cations.

采用非抑制型离子色谱法测定了水果以及饮料（运动型饮料、绿茶、水蜜桃汁、胡萝卜汁和胡萝卜橙汁）中Na、NH4、K、Mg(上标 2+)、Ca(上标 2+)、Zn(上标 2+)的含量，其中一价阳离子以吡啶－2，6-二羧酸为淋洗液测定，二价阳离子以吡啶－2，6-二羧酸+乙二胺+草酸为淋洗液测定。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了