首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   93篇
  免费   16篇
林业   8篇
综合类   16篇
农作物   6篇
畜牧兽医   4篇
植物保护   75篇
  2023年   6篇
  2022年   3篇
  2020年   11篇
  2019年   7篇
  2018年   7篇
  2017年   4篇
  2016年   6篇
  2015年   7篇
  2014年   4篇
  2013年   11篇
  2012年   5篇
  2011年   5篇
  2010年   4篇
  2009年   5篇
  2008年   3篇
  2007年   4篇
  2006年   5篇
  2005年   4篇
  2003年   1篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1993年   1篇
  1990年   1篇
  1986年   1篇
排序方式: 共有109条查询结果,搜索用时 31 毫秒
101.
采用提取、萃取及柱层析等方法,从山蒟Piper hancei Maxim甲醇提取物的石油醚和氯仿萃取相中分离到6个脂肪链酰胺类化合物,通过核磁共振、质谱并结合相关文献比对,其结构被分别鉴定为已知化合物chingchengenamide A( C1 )、N-异丁基-反-2-反-4-癸二烯酰胺( C2 )、假荜拨酰胺A( C3 )、荜茇宁( C4 )、N-p-香豆酰酪胺( C5 )和N-反式-阿魏酰酪胺( C6 ),其中 C1 为首次从山蒟中获得。利用幼虫浸液法测试了各化合物对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus幼虫的12 h杀虫活性。结果表明:在20 mg/L下,化合物 C1 对白纹伊蚊的杀虫活性较高,其校正死亡率为100%,LC50值为5.37 mg/L;化合物 C1 、 C2 、 C3 和 C4 对致倦库蚊的杀虫活性较高,20 mg/L下的校正死亡率分别为100%、88.5%、100%和100%,LC50值分别为1.03、9.68、3.08和2.87 mg/L。  相似文献   
102.
103.
BACKGROUND: The current study investigates, for the first time, the mosquito larvicidal activities of leaf and twig essential oils from Clausena excavata Burm. f. and their individual constituents against Aedes aegypti L. and Aedes albopictus Skuse larvae. The yields of essential oils obtained from hydrodistillation were compared, and their constituents were determined by GC‐MS analyses. RESULTS: The LC50 values of leaf and twig essential oils against fourth‐instar larvae of Ae. aegypti and Ae. albopictus were 37.1–40.1 µg mL?1 and 41.1–41.2 µg mL?1 respectively. This study demonstrated that C. excavata leaf and twig essential oils possess mosquito larvicidal activity, inhibiting the growth of mosquito larvae for both species at a low concentration. In addition, results of larvicidal assays showed that the effective constituents in leaf and twig essential oils were limonene, γ‐terpinene, terpinolene, β‐myrcene, 3‐carene and p‐cymene. The LC50 values of these constituents against both mosquito larvae were below 50 µg mL?1. Among these effective constituents, limonene had the best mosquito larvicidal activity, with LC50 of 19.4 µg mL?1 and 15.0 µg mL?1 against Ae. aegypti and Ae. albopictus larvae respectively. CONCLUSION: The findings suggested that the essential oils from Clausena excavata leaf and twig and their effective constituents may be explored as a potential natural larvicide. Copyright © 2008 Society of Chemical Industry  相似文献   
104.
BACKGROUND: In Brazil, dengue vector control is hampered by the resistance of Aedes aegypti L. populations to organophosphates (OPs). Insect growth regulators (IGRs) are a promising alternative, as their mechanisms of action are different from those of conventional insecticides. The authors analysed the effect of the IGR triflumuron, a chitin synthesis inhibitor, on the Ae. aegypti insecticide-susceptible strain Rockefeller, as well as on field populations both susceptible (TemS) and resistant (TemR) to the OP temephos. RESULTS: Triflumuron arrested development and inhibited adult emergence of the Rockefeller strain in a dose-dependent way (EI(50) and EI(90) of 0.8 and 1.8 microg L(-1) respectively). A direct relationship between triflumuron concentration and the precocity of its effects was evident. TemS and TemR temephos resistance ratios (RR(90)) were 4.5 and 13.8, triflumuron RR(90) being 1.0 and 1.3 respectively. CONCLUSION: The IGR triflumuron exhibited a dose-dependent effect against the reference Ae. aegypti Rockefeller strain. It was also effective against two field populations, regardless of their OP resistance status. The present results are discussed in the context of utilization of chitin synthesis inhibitors as potential alternatives in the control of Ae. aegypti in Brazil.  相似文献   
105.
为明确蛇莓[Duchesnea indica(Andr)Focke]中杀蚊幼活性成分,以淡色库蚊(Culex pipiens pallens)和白纹伊蚊(Aedes albopictus)3龄幼虫为试虫,采用活性跟踪法,对蛇莓乙醇提取物进行活性成分分离、鉴定和活性测定。从蛇莓乙醇提取物乙酸乙酯相中得到2个具有杀蚊幼活性的化合物,鉴定为齐墩果酸和芹菜素。浸渍法测定表明,乙酸乙酯萃取相对淡色库蚊和白纹伊蚊3龄幼虫LC50值分别为459.12和438.09mg/L,正丁醇相为471.41和430.81mg/L,显示较好的杀蚊幼活性,且乙酸乙酯相和正丁醇相差异性不显著;齐墩果酸对淡色库蚊和白纹伊蚊3龄幼虫24h处理LC50值分别为25.36和22.31mg/L,芹菜素对淡色库蚊和白纹伊蚊3龄幼虫24h处理LC50值分别为31.29和27.22mg/L。  相似文献   
106.
室内条件下,研究了不同浓度毒死蜱微球和毒死蜱乳油在水中的消解动态及其对白纹伊蚊Aedes albopictus 3龄幼虫的持续毒杀作用。结果表明:毒死蜱微球在水中的消解速率比乳油慢,半 衰期比乳油的长,高浓度微球和乳油的消解半衰期均长于低浓度下的消解半衰期。有效成分为1.2、 12和24 mg/L的毒死蜱微球和毒死蜱乳油在水中的消解半衰期分别为(19.4±2.1) d、(27.8±1.6) d、(31.0±1.7) d和(12.8±1.0) d、(16.1±0.9) d、(19.7±1.1) d;毒死蜱微球对白纹伊蚊3龄幼虫的毒杀作用强于乳油且持效期长,1.2 mg/L的毒死蜱微球水解85 d后处理白纹伊蚊3龄幼虫的死亡率高达76.6%,高于相同浓度、相同条件乳油的处理(53.3%),具有良好的持效性。  相似文献   
107.
The culture supernatant of a strain of Bacillus subtilis isolated from soil samples killed larvae of the mosquito Aedes aegypti. The metabolites produced by B. subtilis were characterized using high performance liquid chromatography (HPLC). Mortality rate was dose-dependent for all larval instars of A. aegypti. Log probit analysis (95% confidence level) revealed an LC50 of 1.73 and an LC90 3.71 μg/ml. Molecular weights/masses of B. subtilis metabolites were confirmed using SDS–PAGE analysis. B. subtilis metabolites were confirmed using HPLC analysis. We demonstrate that secondary metabolites from B. subtilis have larvicidal activity against A. aegypti and may be suitable for the control of this and other mosquito vectors of human disease. The larvae to the metabolites, significant reduction in the activities of acetylcholinesterse, α-carboxylesterase, and acid phosphatases were recorded.  相似文献   
108.
结果表明:伊蚊白天产卵量大于晚上,而且喜在黑色、粗糙的容器中(靠近水面处)产卵;盛水容器离地面距离越高,白纹伊蚊产卵量越少.在福州,幼虫出现在3月中旬,成虫始见于3月下旬,7至9月为发生高峰期;10月底至翌年3月上旬不见成虫活动.  相似文献   
109.
Isomers of pyrethroids usually have different insecticidal activities. Permethrin, a non‐cyano pyrethroid, is not an exception and cis‐permethrin is much more active than the trans‐isomer against Triatoma infestans, vector of Chagas' Disease in Argentina. The large‐scale separation of cis‐ and trans‐permethrin was performed by successive recrystallizations from ethanol‐water mixtures. An aqueous suspension concentrate (flowable) formulation of pure crystalline cis‐permethrin was prepared and assayed for its insecticidal activity on wood and ceramic surfaces against nymph V of T infestans. This formulation was at least three times more effective than deltamethrin, with LC50 values on ceramic of 0.11 µg cm−2 and 0.33 µg cm−2 respectively. On wood surfaces, the LC50 value was 0.57 µg cm−2 compared with 3.20 µg cm−2 for deltamethrin. Against other insect species such as Periplaneta americana, Aedes aegypti and Culex quinquefasciatus, the suspension concentrate formulation of cis‐permethrin was, however, less effective than similar formulations of deltamethrin or β‐cypermethrin. © 2000 Society of Chemical Industry  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号