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31.
一、引言 自从Gahan及其合作者(Gahan et al.,1945)、Kenneday(1947)、Muirhead-Thomson(1947)等在实验室和田间试验中发现了DDT对蚊虫的刺激作用,并有致使接触的蚊虫飞离处理表面或处理房屋的现象以来,研究这类氯化烃物作室内滞留喷洒的作用,显然巳不能满足于一般的毒效试验,必须进一步观察处理对于夜晚侵入蚊虫各项活动的影响,尤其是对它们所引起的行为的改变。这样的观察近年来已引起了有关学者的重大注意(如 Bertram,1950;Davidson,1953;Muirhead-Thomson,1950;Wharton,1951;Reid & Wharton,1956;等等)。  相似文献   
32.
Abstract. Rapid, tropic leaf movements and photo-synthetic responses of the heliotropic plant, soybean, Glycine max cv. Cumberland, grown under two different nitrogen, three different light and two different water treatments were examined. Measurements of leaf orientation during midday periods outdoors, and tropic reorientation of leaflets in response to vertical illumination indoors, revealed a positive, linear relationship between leaf water potential and the cosine of the angle of incidence between the leaf and the direct beam of the excitation light. This relationship was altered by nitrogen availability, such that a lower cosine of incidence (lower leaf irradiance) for a given leaf water potential was measured for plants grown under low nitrogen compared to those grown under high nitrogen. Additionally, plants grown under low nitrogen and low water availability showed more rapid rates of leaf movement compared to plants receiving high levels of these resources. Light regime during growth had no effect on the relationship between the cosine of incidence and leaf water potential. Reduced water and nitrogen availabilities during growth resulted in lower photosaturated rates of photosynthesis and stomatal conductance, as well as alterations in the relationship between these parameters. Thus, higher values for the ratio of intercellular CO2/ambient CO2 were measured for low-N grown plants (higher nitrogen use efficiencies) and lower values of this ratio for water stressed plants (higher water use efficiencies). The results show that environmental growth conditions other than water availability have the potential to modify leaf orientation responses to vectorial light in heliotropic legumes such as soybean. This has implications for the potential of heliotropic movements to minimize environmental stress-induced damage to the photosynthetic apparatus, and to modulate leaf-level resource use efficiencies.  相似文献   
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The role of roots in regulating primary leaf senescence of 14-day-old soybean seedlings was investigated. Compared with intact seedlings, the senescence of primary leaves is accelerated by removal of the root system but delayed if apical bud and the first trifoliate leaf are removed. No difference in senescence was found between intact seedlings and seedlings without roots, apical bud, and first trifoliate leaf. Lateral roots seem to play a predominant role in regulating primary leaf senescence. However, neither root nodules nor primary root play any function in senescence. Results indicate that benzyladenine (BA) at optimal concentration (2 mg/1) completely replaces the roots to prevent the senescence of primary leaves, whereas gibberellic acid (GA) and abscisic acid (ABA) accelerate. The effect of indole-3-acetic acid (IAA) to replace roots in preventing senescence depends on the season the young seedlings are grown. Additional, though indirect, information of acropetal transport of ABA is provided. In conclusion, it seems that cytokinins in lateral roots play a predominant role in leaf senescence and the normal supply of root cytokinins is important in leaf metabolism.  相似文献   
35.
夜蛾趋光特性的研究——向灯飞原因的进一步分析   总被引:6,自引:0,他引:6  
高慰曾 《昆虫学报》1980,(4):369-373
在灯区内亮灯之后,棉铃虫蛾和粘虫蛾的复眼状况受照射灯光的影响。 一、灯距与复眼色素分布有以下关系: 二.在100—5米范围内,每当灯距减小一半,直射光强增强到原来的四倍时,复眼色素变化只有原来的1—2.36倍。 2.在上述范围内,直射光强的变幅要比虫眼所体现的相应变幅大200倍左右,表明虫眼对光强变化有相当大的调节和适应能力。 二、受光方向不同,能使同一个体的两眼处于不同状态。 三、上灯的棉铃虫、粘虫、小地老虎和毒蛾,同一个体的两眼状态基本一致,说明接受光照条件相同;复眼状况从形态上看介于充分光、暗适应之间,而偏近于暗适应状况。 根据光照与复眼状况的相关性,对夜娥类的扑灯原因和灯区的有效范围,进行了初步探讨。  相似文献   
36.
一.前言 黑热病是河北省常见的流行病之一。其预防措施主要在于扑灭其传染媒介——白蛉。故如欲作出切合实际的防治计划,必需对白蛉的生态习性有所了解;以便掌握其生活规律,而用最经济而有效的办法扑灭之。据吴征鉴氏(1950)综合性报告,白蛉在我国分布极广,已发现者17种,其中以中华白蛉为黑热病主要传染媒介。在长江以北各流行省份皆曾发现。据 1949年中央卫生部召开的黑热病防治会议报告所载,在河北省北京、通县、天津、定县、北戴河等地均曾发现中华白蛉;在北京、天津、通县等地曾发现有  相似文献   
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38.
Summary

The effects of myocardial ischemia and reperfusion on interstitial hydroxyl radical production, in the left ventricular myocardium of anesthetized cats, were investigated. Ringer's solution containing salicylic acid was perfused through an implanted microdialysis probe. Hydroxyl radical production was evaluated as the 2,3 and 2,5 dihydroxybenzoic acid (DHBA) concentrations in the microdialysates by an on-line high performance liquid chromatography system. Myocardial ischemia for 60 min, induced by ligation of the left anterior descending coronary artery, significantly increased both 2,3 and 2,5 DHBA levels when compared with the sham-operated cats. Naloxone (1 mg/kg, bolus, intravenous), an endogenous opioid peptide receptor antagonist, significantly suppressed the ischemia-induced production of hydroxyl radicals. Myocardial ischemia also induced cardiac arrhythmia. Naloxone reduced the severity of ischemia-induced arrhythmia, as observed by a significantly lower arrhythmia score (1.4 ± 0.2 vs. 4.6 ± 0.4 for control), and by diminished incidence of ventricular tachycardia (0/7 vs. 8/8 for control) and ventricular fibrillation (0/7 vs. 3/8 for control). Furthermore, perfusion of dynorphin (0.25 μg, 2.5 μg and 25 μg), an endogenous opioid peptide receptor agonist, increased hydroxyl radical production. Our results suggest that, in anesthetized cats, myocardial ischemia can induce production of interstitial hydroxyl radical in left ventricular myocardium, and this production may involve the actions of released endogenous opioid peptides on their receptors.  相似文献   
39.
利用ISSR和RAPD标记,对名邛台地野生油茶种质进行遗传多样性分析。从60条简单重复序列引物中筛选出16条引物,在65份样品中共扩增出213条带,其中多态位点为203个,多态位点百分率为95.31%;从30条寡居核苷酸引物中筛选出8条引物,共扩增出105条带,其中多态性位点94个,多态位点百分率为89.52%。结果表明:名邛台地野生油茶种质具有较丰富的遗传多样性,ISSR和RAPD标记可以应用于油茶种质遗传多样性分析。  相似文献   
40.
Nalpha-Acetylated microperoxidase-8 (Ac-MP-8) is a water soluble, ferric heme model for peroxidases. We report here that Ac-MP-8 catalyzes catalase-type reaction in addition to peroxidase-type and cytochrome P450-type reactions. The catalase activity of Ac-MP-8 was determined by the Clark oxygen electrode, which measures the production of oxygen in solution. The Km and kcat of the decomposition of hydrogen peroxide (H2O2) catalyzed by Ac-MP-8 are 40.9 mm and 4.1 per s, respectively. The specificity constant (kcat/Km) of Ac-MP-8 in catalase-type reaction of H2O2 is 100.2,/m/s, which is 5- to 12- and 50- to 100-fold less than those of MPs in cytochrome P450-type reaction of aniline/H2O2 and peroxidase-type reaction of o-methoxyphenol/H2O2, respectively. These results indicate that Ac-MP-8 can catalyze three different types of reactions, and the relative catalytic specificities of Ac-MP-8 with a histidyl ligand exhibit the following orders: peroxidase-type > cytochrome P450-type > catalase-type reactions. Comparisons of the enzyme activities of Ac-MP-8 suggest that the fifth ligands of hemoproteins influence the ratio of the three types of reactions.  相似文献   
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