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湖南省果园捕食性瓢虫的研究 总被引:1,自引:0,他引:1
萧健民 《湖南农业大学学报(自然科学版)》1996,22(2):156-163
1984~1990年对湖南省39个县(市)果园捕食性瓢虫资源进行了调查,共获49种,分属鞘翅目瓢虫科的6个亚科,30个属。列出了名录,并研究了异色瓢虫和龟纹瓢虫两个优势种的主要生物学特性及低浓度化学农药对这两种瓢虫的影响。 相似文献
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丁硫克百威在韭菜和土壤中的残留动态研究 总被引:9,自引:0,他引:9
通过大田试验及气相色谱分析,研究了丁硫克百威在韭菜和土壤中的残留动态。结果表明,丁硫克百威在韭菜中的残留半衰期为1.5d,在土壤中,未能检测出丁硫克百威残留。按推荐剂量750mL·hm-2和2倍剂量1500mL·hm-2施用丁硫克百威20%乳油,使用3次,采样距最后一次施药间隔期14d时,丁硫克百威及其代谢物在韭菜和土壤中的残留量分别为0.026mg·kg-1、未检出和0.097mg·kg-1、未检出。 相似文献
54.
新杀虫剂HNPC-A9908对蛋白核小球藻生理生化特性的影响 总被引:4,自引:0,他引:4
以蛋白核小球藻为材料,采用室内植物生长箱培养方法,研究了HNPC—A9908[O-(3一苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]对小球藻细胞的致毒机理。结果表明,低浓度时HNPC—A9908对蛋白核小球藻蛋白质含量具有刺激增加的作用;随着浓度的加大,藻细胞蛋白质含量逐渐降低。同时藻细胞超氧化物歧化酶(SOD)和过氧化物酶(POD)活性也表现出类似的趋势,说明SOD和POD活性的降低打破了小球藻细胞内活性氧产生与清除之间的正常平衡状态,是HNPC—A9908造成藻细胞活性氧过量产生和积累,进而引起藻细胞膜脂过氧化伤害的主要原因之一 相似文献
55.
试验选用15只3月龄新西兰雄兔,随机分为Ⅰ、Ⅱ、Ⅲ组,灌胃尿素量分别占日采食量3%、6%和9%(即每只兔灌胃4 5g、9 0g和13 5g尿素)。灌入尿素后,Ⅰ、Ⅱ组兔子未表现中毒症状,Ⅲ组则表现出明显中毒症状,且有兔子死亡。血液生化指标分析结果显示,兔被灌入尿素后,血清中的氨态氮和尿素态氮迅速升高,达峰值后逐渐下降,中毒死亡时血清氨态氮和尿素态氮的值分别为21 40mg/L和1082 21mg/L,血清中GOT和GPT的活性也升高,死亡兔的值分别为28 18和70 05卡门氏单位。结果表明:兔对尿素有很强的耐受能力。 相似文献
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Most administrators and ecologists agree that reducing the levels of hazardous fuels on forests is essential to restore healthy watersheds and protect adjacent human communities. The current debate over the appropriateness, technique, and timing of treatments utilized to restore vegetation structure and composition is currently on-going at local, state, and national levels. To provide information for these forums, the efficacy of seven traditional silvicultural systems and two types of reserves used in the Sierra Nevada mixed conifer forests is evaluated in terms of vegetation structure, fuel bed characteristics, modeled fire behavior, and potential wildfire related mortality. The systems include old-growth reserve, young-growth reserve, thinning from below, individual tree selection, overstory removal, and four types of plantations. These are the most commonly used silvicultural systems and reserves on federal, state, and private lands in the western United States. Each silvicultural system or reserve had three replicates and varied in size from 15 to 25 ha; a systematic design of plots was used to collect tree and fuel information. The majority of the traditional silvicultural systems examined in this work (all plantation treatments, overstory removal, individual tree selection) did not effectively reduce potential fire behavior and effects, especially wildfire induced tree mortality at high and extreme fire weather conditions. Overall, thinning from below, and old-growth and young-growth reserves were more effective at reducing predicted tree mortality. 相似文献
59.
Seedlings of alfalfa, rape, spinach, and wheat, potted on sandy soil, were irrigated with an aqueous extract of pea shoot (PE, 9.84 g dry weight l–1) or a solution of Ca, K, Mg, P, and NO3‐N salts (SS) in a concentration similar to that in PE, for 31–48 days. In comparison to water‐irrigated controls, both SS and PE treated plants showed nearly equal increases in shoot dry weight (29–40 %), whereas PE‐treated plants had higher fresh weights (38–84 %) due to increased succulence. Treatment with SS did not enhance, but sometimes even reduce, the concentrations of Ca, K, Mg, and several trace elements in shoot tissues. In contrast, PE‐treated plants had higher Ca, K, Mg, and organic N, but lower As and Ni contents and were thus of higher nutritive value. Reduced contents of metals in plant tissue correlated with their reduced solubility in the soil solution, which was not due to changes in pH. Fertilizer components such as K and Mg (metals of lower exchange intensity) were incorporated into the soil to release Ca, Sr, and Ba (metals of higher exchange intensity) and reduce the solubility of most trace elements and metal‐complexing humic substances. In addition, application of Ca precipitated heavy metals and humic complexes directly from the soil solution. This effect was partially overcome by PE. Its carboxylic acids could act as phytochelators of metal ions and as mobilizers of the highly diffusible humic substances which carry metals to roots. It is concluded that continuous PE application replaces the quantities of Ca, K, Mg, P, and organic N, but not of NO3‐N consumed during plant growth. Using PE does not add any relevant quantities of toxic metals to the plant‐soil system. 相似文献
60.
对金融消费者进行保护的最根本原因是金融交易中的金融机构处于信息优势地位而引发的道德风险问题损害了处于弱势地位的金融消费者的合法权益。然而,通常容易被忽视的是当金融消费者处于信息优势地位及过度的金融消费者保护而引发的道德风险问题。通过运用经济学当中的信息不对称理论、委托代理理论对金融交易中产生的双重道德风险进行分析,更好地防范双重道德风险的产生,保护金融消费者的权益。 相似文献