The effect of some Frescon analogs on the aquatic snail,Lymnaea stagnalis: III. Relation of some physical and chemical properties to neurotoxicity and molluscicidal effectiveness     

B.L. Brezden  D.R. Gardner 《Pesticide biochemistry and physiology》1980,13(2):189-197

The hydrolysis rates, particle sizes in suspension, and the relative lipophilicity of Frescon and its analogs were determined and compared with their neurotoxic and molluscicidal effectiveness. The hydrolysis rates of these compounds were closely correlated to their neurotoxicity, and, with one exception, to their molluscicidal effectiveness as well. The aberrant behavior of the one analog could not be attributed to a retarded penetration rate or an excessively large particle size in suspension. There appears to be some, as yet, unidentified factor which determines the molluscicidal activity of this analog. However, it is likely that both neurotoxicity and molluscicidal action are the result of a nucleophilic displacement reaction, although at different targets. Also, differences in the relative molluscicidal effectiveness of the Frescon analogs at different concentrations were possibly due to variations in particle size, which appears to be a function of the type and amount of emulsifier used.  相似文献   

Structure-activity relationships of pyrethroids based on direct action on nerve     

Keiichiro Nishimura  Toshio Narahashi 《Pesticide biochemistry and physiology》1978,8(1):53-64

The structure-activity relationships of 30 synthetic pyrethroids have been studied by measurements of their direct action on isolated crayfish nerve cord. The concentrations of pyrethroids used to increase the frequency of spontaneous discharges to 200% of the control (NS₂₀₀), those to decrease the frequency back to the control level, and those to further decrease the frequency to 10% of the control were measured as indexes of the nerve action. These values did not necessarily run parallel with those for the lethal dose 50 or the knock-down 50. Large differences in NS₂₀₀ were found among optical isomers of tetramethrin and phenothrin, and there was a synergism with respect to the nerve stimulating action between (+) and (?) forms of tetramethrin. (+)-trans-Permethrin was unique in that it exhibited a potent insecticidal action with a very weak nerve action. It is necessary to compare the direct action on the target site for the purpose of establishing the true structure-activity relationships of synthetic pyrethroids.  相似文献   

Toxicity in the brain of organophosphate insecticides: Comparison of the toxicities of metabolites with parent compounds using an intracerebral injection method     

K.D. Rainsford 《Pesticide biochemistry and physiology》1978,8(3):302-316

The toxicity in the brain of several parathion, fenthion, and fensulfothion insecticides and their toxic metabolites was determined by a technique of directly injecting the compounds into the region of the third ventricle of conscious mice, an area rich in cholinesterase activity. The results were compared on a body weight basis to the toxicity of these compounds when given by ip and oral routes. The results show that there is a direct relationship between the relative inhibition of cholinesterase activity in the brain by the organophosphates (e.g., methyl paraoxon, Sumioxon, and some members of the fenthion series) and the toxicity of these compounds in the brain. Methyl paraoxon and Sumioxon were found to be very toxic in the brain, Sumioxon being three to four times less toxic than methyl paraoxon. This is of the same order of effect of these compounds in inhibiting cholinesterases. It is concluded that any selective effects of Sumithion compared with methyl parathion must be due to the greater rate of metabolism of Sumithion to less toxic metabolites as well as to the lower toxicity of the oxon metabolite and not due to the relative rates of penetration of the toxic oxygen metabolites as previously suggested [J. Miyamoto, Agr. Biol. Chem.28, 422 (1964)]. A gas-liquid chromatographic method was employed to assess the distribution in the brain following intracerebral injection of the parathion-type compounds. The results suggest that there may be intracerebral metabolism of thionophosphates in vivo.  相似文献   

野生地被蛇莓和甘野菊的抗旱性研究     

sun@.com 《中国农学通报》2006,22(5):322-322

（北京林业大学园林学院,北京 100083）  相似文献   

The agronomic performance and nutritional content of oat and barley varieties grown in a northern maritime environment depends on variety and growing conditions     

《Journal of Cereal Science》2017

Warmer temperatures and increasing interest in high provenance food and drink products are creating new opportunities for cereal growing in northern Europe. Nevertheless, cultivation of oats and barley in these areas for malting and milling remains a challenge, primarily because of the weather, and there are few reports of their nutritional content from this region. In this study, trials in Orkney compared agronomic characteristics and nutritional content of recommended UK oat and barley varieties with Scandinavian varieties over three years. For a subset of varieties, nutritional content was compared with samples cultivated in more southerly sites. For Orkney, barley was considered a more suitable crop than oats because varieties matured earlier. In both crops, Scandinavian varieties matured earlier than UK varieties and some produced comparable yields. The range of values for macronutrients and minerals in oats and barley in Orkney were similar to those reported previously for other locations, but there were some significant differences attributable to variety and year. Compared with grain samples from more southerly locations, oats in Orkney had a significantly lower β-glucan and higher sodium content. The lower β-glucan may have resulted from higher rainfall and lower temperatures during the months of grain filling and maturation.  相似文献   

猪圆环病毒研究进展   总被引：1，自引：0，他引：1  

高骏  胡建华  孙凤萍  李春华  王英  蒋凤英 《上海交通大学学报(农业科学版)》2005,23(1):107-110

近年来断奶仔猪多系统衰竭综合征(post-weaning muhisystemic wasting syndrome,PMWS)在全世界范围内呈不断流行和蔓延的趋势。猪圆环病毒Ⅱ型(PCV-2),目前已被世界各国学者确认为是引起PMWS的主要病原体,许多对PCV-2的研究也主要是针对PMWS的。本文就近年来对猪圆环病毒的病原及致病性、流性病学、诊断及防制等方面的研究进展作一综述。  相似文献   

All-male broods of Tilapia nilotica × T. aurea hybrids     

Yoel Pruginin  Shmuel Rothbard  Giora Wohlfarth  Amir Halevy  Rom Moav  Gideon Hulata 《Aquaculture (Amsterdam, Netherlands)》1975,6(1):11-21

The proportion of males in single pair crosses between Tilapia nilotica females and T. aurea males was found to vary between 50 and 100%. There was no apparent influence of the T. aurea males on these proportions. In a similar test nine T. vulcani females were paired with T. aurea males, and the proportion of males in their hybrid offspring ranged between 93 and 98%. Two T. nilotica mothers of all-male hybrid broods mated with unselected T. nilotica males, and all their daughters also reproduced all-male hybrid broods when crossed with T. aurea males. The reciprocal cross of T. aurea females with T. nilotica males reproduced three males to each female offspring. Growth rate tests of the all-male T. nilotica × T. aurea hybrids, and the T. vulcani × T. aurea hybrids did not reveal heterosis.  相似文献   

农业部所属国家重点实验室的现状与思考     

郑传临  朱蔚彤 《华中农业大学学报》1997,16(6):624-632

介绍了农业部所属６个国家重点实验室的基本情况，并与全国同类实验室进行了比较，同时针对存在的问题，提出了几点建议。  相似文献   

学习对提高机关干部素质与能力的分析     

赵富才  陶改生  盛清茂 《陕西林业》2006,(1)

机关是学校的“窗口”,在学校全局工作中发挥着重要作用。要圆满完成学校的工作任务,必须依靠高素质的干部队伍。同时,机关干部要始终模范地执行党的各项决定,做好本职工作,在师生员工中起到表率作用,也必须依靠学习提高自身的素质。讲学习是干部健康成长的要求,是提高干部综合素质的根本途径,是新形势下搞好机关工作的保证。  相似文献   

民国初年逊清岁费问题初探（1912—1916）     

陈肖寒 《四川畜牧兽医学院学报》2009,(4):90-94

清室逊位后,民国政府按照《清室优待条件》的规定,每年付给逊清皇室一笔费用以维持其生计。然而,一方面民国初年政府财政极其困难,逊清岁费多有拖欠,而逊清皇室开支浩繁,导致其常常入不敷出;另一方面袁世凯等人又出于维持同逊清皇室友好关系以利用其影响力的需要,竭力维持对清室的优待条件,由此导致了民国初年政府在对待逊清岁费问题上言行不一的矛盾现象。  相似文献