毒死蜱·阿维菌素复配剂对棉铃虫表皮穿透能力研究

本文报道用高效液相色谱法来测定复配剂及各复配单剂对棉铃虫幼虫的表皮穿透能力。研究发现毒死蜱与阿维菌素复配后能相互促进对方对害虫表皮的穿透,并且毒死蜱对阿维菌素的促进作用要大于阿维菌素对毒死蜱的促进作用;复配剂的表皮穿透速率明显提高,处理后10h实际表皮穿透率（94.5％）已相当于其处理后24h理论表皮穿透率（94.0％）.     

25%毒死蜱·阿维菌素乳油防治白菜小菜蛾试验研究

利用25%毒死蜱·阿维菌素乳油复配剂3个不同剂量与其单剂1.8%阿维菌素乳油、48%毒死蜱乳油对白菜小菜蛾进行防治试验,试验结果表明,25%毒死蜱·阿维菌素乳油复配剂弥补了单剂阿维菌素乳油在施药前期防效较低的劣势,既具备了化学农药的特性,也具备了生物农药的特点,在300～400 g/hm2(有效成分)的情况下对白菜小菜蛾的防治效果在90%以上,且对白菜生长安全.     

阿维菌素及其复配剂防治棉铃虫的效果

进行了阿维菌素及其复配剂防治棉铃虫的田间药效试验。结果表明:阿维菌素与毒死蜱和三唑磷复配后,对棉花棉铃虫的速效性和持效性较阿维菌素均有所提高,建议在田间防治棉花棉铃虫时,使用阿维菌素与毒死蜱或三唑磷复配制剂,既可延长农药的使用寿命,又可减少农药的使用量。     

杀虫剂18种单剂和10种复配剂对褐飞虱和灰飞虱的活性差异

室内采用稻茎浸渍法测定了褐飞虱和灰飞虱对18种杀虫剂的敏感性,同时测定了10种稻田后期常用复配剂在2种飞虱间的增效作用及毒力差异.结果表明氟虫腈、毒死蜱、阿维菌素、烯啶虫胺、噻虫嗪杀虫剂对2种飞虱的毒力较高,LC50值为 0.11～1.51 mg/L;供试的吡虫啉和噻嗪酮系列复配剂对褐飞虱都有增效或相加作用,但相同配比下吡虫啉与仲丁威、噻嗪酮与毒死蜱、噻嗪酮与混灭威、噻嗪酮与甲萘威、噻嗪酮与速灭威复配,对灰飞虱表现为拮抗作用;10个复配组合对灰飞虱的毒力均低于或显著低于褐飞虱.研究结果为科学合理地使用化学农药防治褐飞虱和灰飞虱提供了依据.     

阿维菌素与毒死蜱混用对小菜蛾的增效作用

为延缓小菜蛾对阿维菌素和毒死蜱的抗性、提高药剂混用对小菜蛾的防治效果,采用浸叶法测定1.8%阿维菌素乳油、30%毒死蜱水乳剂以及二者不同配比对小菜蛾3龄幼虫的室内毒力,确定这2种药剂混用的最佳配比。结果表明,2种药剂单独使用时,阿维菌素的毒力明显高于毒死蜱,LC50分别为0.120 9,154.125 9 mg/L;2种药剂以1∶1,1∶2,2∶1,1∶5,5∶1复配,共毒系数分别为255.13,300.53,257.86,312.17,191.12,均大于120,表现出明显的增效作用,以阿维菌素与毒死蜱1∶5复配时增效作用最明显。     

阿维菌素与橡胶籽油复配对朱砂叶螨的联合作用

室内测定了阿维菌素和橡胶籽油对朱砂叶螨的毒力及其复配剂的联合作用。结果表明,阿维菌素和橡胶籽油对朱砂叶螨雌成螨的LC50分别为0.01μg/ml和1311.81μg/ml;阿维菌素与橡胶籽油复配对朱砂叶螨成螨增效作用显著,共毒系数最高为293.90;阿维菌素及其与橡胶籽油最优复配剂对经药剂处理螨卵孵化的若螨具有显著的杀灭活性,且相同浓度下复配剂显著优于阿维菌素单剂,但两药剂对螨卵的直接毒杀活性均很低。阿维菌素与橡胶籽油复配剂这一高效、安全生物农药在害螨防治中极具应用前景。     

温度对10%甲氰菊酯·阿维菌素杀螨活性的影响

在室内通过测定不同温度下复配剂10%甲氰菊酯.阿维菌素对朱砂叶螨的毒力效应,确定温度与复配剂毒力和增效作用的变化关系。结果表明:复配剂10%甲氰菊酯.阿维菌素及单剂对朱砂叶螨T.cinnabarinus的毒力在22~30℃的5个温度梯度下均随温度的升高而增强,在22~26℃范围内毒力变化较大,在26~30℃范围内变化相对平缓;不同温度下3种复配剂都表现较好的增效作用,甲氰菊酯和阿维菌素按有效成分96∶4的比例复配在5个温度梯度下均表现出最好的增效作用,按有效成分97∶3比例复配次之,按有效成分98∶2比例复配相对较差。试验表明,温度对复配剂的毒力及增效作用有明显影响。     

阿维菌素·丙溴磷复配剂防治稻纵卷叶螟的研究

对阿维菌素.丙溴磷复配剂防治稻纵卷叶螟进行了研究。结果表明,阿维菌素和丙溴磷质量比例在1：60～1：160的范围里,复配剂都对稻纵卷叶螟有增效作用,其中最大增效比例为1：60。复配剂对稻纵卷叶螟有更高的防治效果,可替代部分高毒、高价位农药,并减少用药量。     

毒死蜱和甲胺基阿维菌素苯甲酸盐在甘蓝及玻片上的消解动态与复合效应研究

研究毒死蜱、甲胺基阿维菌素苯甲酸盐(以下简称甲维盐)单剂以及两者的混剂在田间甘蓝中的消解动态和室内玻片上的光解情况.田间试验表明,单剂与混剂中的毒死蜱在甘蓝中的消解半衰期差异不显著,甲维盐在甘蓝中的消解半衰期差异显著.光解试验表明,甲维盐与毒死蜱的剂量比为10∶1时,甲维盐对毒死蜱的光解产生显著的促进作用,其作用效应与剂量比成正相关;毒死蜱与甲维盐剂量比为3∶1时,毒死蜱对甲维盐的光解产生显著的促进作用,剂量比为5∶1时达到饱和.结合田间试验毒死蜱与甲维盐在甘蓝中的初始剂量比为168∶1,表明过量的毒死蜱加快了甲维盐在甘蓝中的消解,而低剂量的甲维盐对毒死蜱在甘蓝中的消解影响不显著.     

15%阿维菌素·毒死蜱EC防治菜蛾的效果

与 48 %毒死蜱EC、0 .9%阿维菌素EC相比 ,15 %阿维菌素·毒死蜱EC对菜蛾的防效好 ,田间使用推荐 3 75ml/hm2 的剂量。     

Transformation of a star into a planet in a millisecond pulsar binary

Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.     

Action at a distance along a DNA

A number of ways are known by which an event at one location on a DNA molecule can affect an event at a distant location on the same molecule. Three classes of mechanisms are described for such distal actions: tracking or translocation of a protein along a DNA, the association of two proteins bound at separate sites to form a DNA loop in between, and distal interactions that are affected by the topology of the DNA. The basic characteristics of each type of mechanism are discussed in terms of the known physicochemical properties of DNA. The various modes of action at a distance are often interrelated. Examples include the formation of positively and negatively supercoiled DNA loops by tracking and the strong effects of DNA topology on looping.     

Development of a receptor on a foreign nerve fiber in a Pacinian corpuscle

When the sensory fiber of a Pacinian corpuscle (in cat mesentery) is transected (at the inferior mesenteric nerve) transduction fails within 30 hours: the nerve ending produces no generator potentials in response to mechanical stimulation. Electrically elicited nerve impulse conduction continues for at least another 18 hours. A transducer mechanism develops on a regenerating nerve fiber when this fiber enters the denervated corpuscle. Such transducer development takes place on myelinated fibers from the inferior mesenteric nerve, which normally supplies corpuscles, as well as on myelinated hypogastric nerve fibers, which normally do not go to corpuscles, including fibers larger than the original corpuscle afferents.     

Conversion of a peroxiredoxin into a disulfide reductase by a triplet repeat expansion

Pathways for the reduction of protein disulfide bonds are found in all organisms and are required for the reductive recycling of certain enzymes including the essential protein ribonucleotide reductase. An Escherichia coli strain that lacks both thioredoxin reductase and glutathione reductase grows extremely poorly. Here, we show that a mutation occurring at high frequencies in the gene ahpC, encoding a peroxiredoxin, restores normal growth to this strain. This mutation is the result of a reversible expansion of a triplet nucleotide repeat sequence, leading to the addition of one amino acid that converts the AhpC protein from a peroxidase to a disulfide reductase. The ready mutational interconversion between the two activities could provide an evolutionary advantage to E. coli.     

离散型三维竞争系统中某群体竞争获胜的条件

研究了离散型三维竞争系统的模型结构与稳定性,得到了这类竞争系统中各类平衡点的坐标及其性质,获得了系统在某些边界上的平衡点渐近稳定的充分条件和不稳定的充分条件,并由此得到了系统中的某群体在竞争过程中竞争获胜淘汰所有对手的条件和参与竞争的各个群体永不和谐的充分条件.