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101.
1959—1960年作者等在江西、湖南等地区配合大面积防治森林害虫之际,开展了DDT等化学药剂对于不同越冬时期的马尾松毛虫幼虫的毒效试验。据野外观察结果,将马尾松毛虫越冬幼虫划分为5个时期。即越冬前活动期、越冬前期、越冬期、越冬后期、越冬后活动期。试验证明:不同化学药剂对越冬松毛虫幼虫的毒效随着不同时期和温度条件而变化。就一般论:DDT的效果,在比较低温(日均温10—20℃)时特别显著;666及敌百虫的效果,在比较高温时(20℃以上)为显著。其中尤以敌百虫为更甚。DDT对不同时期幼虫的毒效大小为:越冬后期>越冬前期>越冬期>越冬前活动期>越冬后活动期≥夏季(4-5龄)幼虫;其中以越冬后期幼虫抵抗力最弱。从原则上论这是施药的最适宜时期,从25% DDT乳剂4,000倍稀释液在越冬后期(2,3月间)施用,毒效可达92%以上,用6,000倍稀释液亦达82%以上。如用γ6%可湿性666,800倍稀释液在越冬前、后期使用,毒效可达70-80%以上。50%敌百虫乳剂在温度20℃以上时(越冬前、后活动期)毒效显著增高。此时如用5,000-6,000倍稀释液喷洒,毒效可达70-80%左右。由此,作者认为:在长江以北,每年发生2代以下的松毛虫地区,可用DDT和666稀释液在越冬前、后期进行防治。长江以南,每年发生2代以上的马尾松毛虫地区,不但可用DDT、666来防治越冬前、后期幼虫;而且在幼树林地内越冬期的幼虫亦可防治。在上述地区内,敌百虫乳剂仅适于在越冬前、后活动期或夏季幼虫期温度较高时使用。就一般论,在越冬前期施用药剂时,如能选定在寒流侵袭之前喷射,效果更为显著。 相似文献
103.
在离体猫丘脑脑片上观察了乙酰胆碱对外膝体中继神经元膜的低阈值T-型钙电导的影响。电流箝位和电压箝位实验结果都显示:将膜电位箝制到给药前的对照水平,排除了乙酰胆碱的去极化作用后,大多数(82%)外膝外神经元的低阈值钙电导仍然被乙酰胆碱所抑制。说明这种抑制作用独立于乙酰胆碱引起的膜电位变化,而是对低阈值T-型钙通道的直接作用。 相似文献
104.
105.
Ozone induced emissions of biogenic VOC from tobacco: relationships between ozone uptake and emission of LOX products 总被引:5,自引:0,他引:5
JONATHAN BEAUCHAMP ARMIN WISTHALER ARMIN HANSEL EINHARD KLEIST MARCO MIEBACH ÜLO NIINEMETS ULI SCHURR & JÜRGEN WILDT 《Plant, cell & environment》2005,28(10):1334-1343
Volatile organic compound (VOC) emissions from tobacco ( Nicotiana tabacum L. var. Bel W3) plants exposed to ozone (O3 ) were investigated using proton-transfer-reaction mass-spectrometry (PTR-MS) and gas chromatography mass-spectrometry (GC-MS) to find a quantitative reference for plants' responses to O3 stress. O3 exposures to illuminated plants induced post-exposure VOC emission bursts. The lag time for the onset of volatile C6 emissions produced within the octadecanoid pathway was found to be inversely proportional to O3 uptake, or more precisely, to the O3 flux density into the plants. In cases of short O3 pulses of identical duration the total amount of these emitted C6 VOC was related to the O3 flux density into the plants, and not to ozone concentrations or dose–response relationships such as AOT 40 values. Approximately one C6 product was emitted per five O3 molecules taken up by the plant. A threshold flux density of O3 inducing emissions of C6 products was found to be (1.6 ± 0.7) × 10−8 mol m−2 s−1 . 相似文献
106.
107.
Alfonso Romo De Vivar Eugene Bratoeff Eliseo Ontiveros David C. Lankin Norman S. Bhacca 《Phytochemistry》1980,19(8):1795-1797
The new germacranolide, viguilenin, was isolated from Viguiera linearis and its structure was established by chemical and spectroscopic means. 相似文献
108.
109.
Sexual competition and N supply interactively affect the dimorphism and competiveness of opposite sexes in Populus cathayana
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JUAN CHEN TINGFA DONG BAOLI DUAN HELENA KORPELAINEN ÜLO NIINEMETS CHUNYANG LI 《Plant, cell & environment》2015,38(7):1285-1298
Several important dioecious species show sexual spatial segregation (SSS) along environmental gradients that have significant ecological effect on terrestrial ecosystem. However, little attention has been paid to understanding of how males and females respond to environmental gradients and sexual competition. We compared eco‐physiological parameters of males and females of Populus cathayana under different sexual competition patterns and nitrogen (N) supply levels. We found that males and females interacting with the same or opposite sex showed significant differences in biomass partition, photosynthetic capacity, carbon (C) and N metabolism, and leaf ultrastructure, and that the sexual differences to competition were importantly driven by N supply. The intersexual competition was enhanced under high N, while the intrasexual competition among females was amplified under low N. Under high N, the intersexual competition stimulated the growth of the females and negatively affected the males. In contrast, under low N, the males exposed to intrasexual competition had the highest tolerance, whereas females exposed to intrasexual competition showed the lowest adaptation among all competition patterns. Sexual competition patterns and N supply levels significantly affected the sexual dimorphism and competitiveness, which may play an important role in spatial segregation of P. cathayana populations. 相似文献
110.
Revisiting Coptotermes (Isoptera: Rhinotermitidae): a global taxonomic road map for species validity and distribution of an economically important subterranean termite genus
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THOMAS CHOUVENC HOU‐FENG LI JAMES AUSTIN CHRISTIAN BORDEREAU THOMAS BOURGUIGNON STEPHEN L. CAMERON ELIANA M. CANCELLO REGINALDO CONSTANTINO ANA MARIA COSTA‐LEONARDO PAUL EGGLETON THEODORE A. EVANS BRIAN FORSCHLER J. KENNETH GRACE CLAUDIA HUSSENEDER JAN KŘEČEK CHOW‐YANG LEE TIMOTHY LEE NATHAN LO MATTHEW MESSENGER AARON MULLINS ALAIN ROBERT YVES ROISIN RUDOLF H. SCHEFFRAHN DAVID SILLAM‐DUSSÈS JAN ŠOBOTNÍK ALLEN SZALANSKI YOKO TAKEMATSU EDWARD L. VARGO AKINORI YAMADA TSUYOSHI YOSHIMURA NAN‐YAO SU 《Systematic Entomology》2016,41(2):299-306