神经网络对硫代磷酰胺酯类化合物的QSAR研究

本文开始是应用神经网络函数连接网络FLN进行高活性除草剂硫代磷酰胺酯类化合物OSAR分析的,如图1所示.FLN原始输入模式各分量x_i经系列函数变换f_j(x_i)形成扩展分量x_j~E,组成增强输入模式,不经隐蔽层而直接与输出层神经元加权互连,网络输出为     

N—取代三氯乙酰胺合成取代脲类除草剂的研究

在碱性条件下，以Ｎ－取代三氯乙酰胺与２种胺反应，合成了８种取代脲类除草剂。     

世界农业转基因作物的发展与展望

“转基因”是指利用分子生物学手段将外源性基因转移到某种特定生物体中，使其生物形态或机能发生部分改变。“转基因技术”就是将体外操作的重组基因(DNA)转入生物体内，产生新性状的技术。“转基因作物”是指为达到特定目的而将DNA进行人为改造的作物。以转基因生物体直接作为食品或以其为     

化学除草技术水稻直播田

近几年来，水稻直播面积逐年增加，但由于直播水稻的露田多，露田时间长，造成直播田的杂草发生量大，种群复杂，恶性杂草多。防除直播田杂草已成为当前农民迫切需要解决的技术难题。根据多年实践，笔者总结了一套行之有效的防治措施。     

百合田杂草的化学防治

通过对百合及百合田杂草生长习性的研究探讨，选用化学除草剂对防除百合田杂草的效果及安全性进行了多点实验．结果表明：24％乙氧氟草醚和33％除草通防效好，安全性高．     

大田化学除草实用技术要点

无论是水田还是旱田在使用化学除草剂之前,均需了解掌握用药地块的杂草种类以及由优势种形成的杂草群落,然后才能有针对性地选择恰当的除草剂,在使用除草剂之前,必须认真阅读标签和说明书,首次使用的除草剂,应在当地植保部门指导下,经过试验后再大面积推广应用.     

温湿度对3种酰胺类除草剂毒力的影响

通过室内盆栽试验测量作物株高的方法，分别对甲草胺、乙草胺、异丙甲草胺在不同温度及不同湿度条件下对油菜和玉米的毒力的影响进行了比较．实验结果表明；3种药剂作用在玉米和油菜上，毒力随着湿度的增加而升高，产生药害越明显；毒力随着温度的升高或降低都会升高，并且在低温条件下药害对作物的影响最严重．     

碳酸盐岩流体包裹体(NaCl-H2O)的合成及捕获机理分析

对碳酸盐岩原生、次生流体包裹体的形成机理进行了分析,并分别在压力为100 Mpa、温度为400～300℃和350℃条件下,利用高温高压釜合成了碳酸盐岩原生、次生流体包裹体(NaCl-H2O),模拟了包裹体的形成过程,并利用激光拉曼光谱及显微测温技术对合成包裹体的成分、均一温度、盐度等参数进行了定量分析.结果表明,合成的原生、次生包裹体气相与空气成分相符,其均一温度分别为372.8℃和321.02℃,盐度分别为23.22%和19.54%.与实验前设定的条件相符,从而验证了合成包裹体的准确性,并为进一步分析包裹体相态奠定了基础.     

Study on structure-activity relationship of mutation-dependent herbicide resistance acetohydroxyacid synthase through 3D-QSAR and mutation

Seventy-four sulfonylureas were synthesized and tested for their inhibitory activity against the whole enzyme of E. coli acetohydroxyacid synthase (AHAS, EC 2.2.1.6) isoenzyme II, and 3D-QSAR analyses were performed based on these inhibitory activities. The binding conformation of chlorimuron-ethyl, a commercial herbicide of AHAS, in the crystal structure of AHAS complex was extracted and used as template to build the initial three-dimensional structure of other sulfonylureas, and then all structures were fully geometry optimized. After systematic optimization of the alignment rule, molecular orienta- tion, grid space and attenuation factor, two satisfactory models with excellent performances (CoMFA: q2 = 0.735, r2 = 0.954, n = 7, r 2 pred = 0.832; CoMSIA: q2 = 0.721, r2 = 0.913, n = 8, r 2pred = 0.844) were estab- lished. By mapping the 3D contour maps of CoMFA and CoMSIA models into the possible inhibitory active site in the crystal structure of catalytic subunit of yeast AHAS, a plausible binding model for AHAS, with best fit QSAR in the literature so far, was proposed. Moreover, the results of 3D-QSAR were further utilized to interpret resistance of site-directed mutants. A relative activity index (RAI) for AHAS enzyme mutant was defined for the first time to relate the 3D-QSAR and resistance of mutants. This study, for the first time, demonstrated that combination of 3D-QSAR and enzyme mutation can be used to decipher the molecular basis of ligand-receptor interaction mechanism. This study refined our understanding of the ligand-receptor interaction and resistance mechanism in AHAS-sulfonylurea system, and provided basis for designing new potent herbicides to combat the herbicide resistance.     

超高效绿色除草剂

由南开大学农药国家工程研究中心承担的“超高效除草剂#92825大田示范推广“项目通过验收。验收会上，与会专家分别实地考察了大面积施用10％单嘧磺隆可湿粉的冬小麦除草示范田和施用44％谷草灵可湿粉(单嘧磺隆混剂)的谷田除草示范田的除草效果，并给予了高度评价，认为该药完全符合大田除草剂示范推广的要求，建议尽快办理农药临时登记，