蚯蚓回避反应在生态毒理研究中的应用进展

从回避反应的原理和试验装置、回避试验应用现状、影响回避反应的因素即化学物质的生物可利用性、土壤类型、蚯蚓种类、实验蚯蚓污染暴露史三方面进行综述,指出蚯蚓回避反应存在的问题、提出完善蚯蚓回避试验标准方法及利用回避试验监测生物修复是今后的重要发展方向。     

考虑弯曲刚度的斜拉索内共振分析

根据Hamilton原理,推导了考虑弯曲刚度的斜拉索三维非线性动力学方程,利用边界条件约化为二维系统,然后运用多尺度法分析了斜拉索可能的内共振模式,并运用数值方法研究了弯曲刚度对内共振的影响.结果表明:弯曲刚度使斜拉索固有频率变大,从而使斜拉索发生内共振的条件向左偏移,导致了斜拉索内共振的幅值和拍频都变大.     

地震波作用下高层框剪结构的非线性动力响应

In this paper, a method is presented for analysing the nonlinear dynamic response of R/C frame-wall structure under a strong earthguake ground motion. Based on the assumption that the bending stiffness of injured member is in a parabolic distribution, a n     

Reversal by L-dopa of impaired learning due to destruction of the dopaminergic nigro-neostriatal projection

Rats receiving bilateral stereotaxic injections of 6-hydroxydopamine into the zona compacta of the substantia nigra failed to learn a one-way active avoidance response. Small doses of L-dopa (1.5 milligrams per kilogram of body weight) in combination with a peripheral decarboxylase inhibitor reversed this impairment. Animals with lesions which acquired the avoidance response during L-dopa administration retained this response when drug treatment was discontinued. These experiments suggest that the dopaminergic nigro-neostriatal projection serves a critical function in the acquisition of learned instrumental responses.     

Observation learning in cats

In two experiments cats acquired a stimulus-controlled approach or avoidance response by observational or conventional shaping procedures. Observer cats acquired the avoidance response (hurdle jumping in response to a buzzer stimulus) significantly faster and made fewer errors than cats that were conventionally trained. Observer cats acquired the approach response (lever pressing for food in response to a light stimulus) with significantly fewer errors than cats that were conventionally trained. In some cases, observer cats committed one or no errors while reaching criterion.     

Arabidopsis NPL1: a phototropin homolog controlling the chloroplast high-light avoidance response

Chloroplasts relocate their positions in a cell in response to the intensity of incident light, moving to the side wall of the cell to avoid strong light, but gathering at the front face under weak light to maximize light interception. Here, Arabidopsis thaliana mutants defective in the avoidance response were isolated, and the mutated gene was identified as NPL1 (NPH-like 1), a homolog of NPH1 (nonphototropic hypocotyl 1), a blue light receptor used in phototropism. Hence, NPL1 is likely a blue light receptor regulating the avoidance response under strong light.     

Characterization of step-edge barriers in organic thin-film growth

Detailed understanding of growth mechanisms in organic thin-film deposition is crucial for tailoring growth morphologies, which in turn determine the physical properties of the resulting films. For growth of the rodlike molecule para-sexiphenyl, the evolution of terraced mounds is observed by atomic force microscopy. Using methods established in inorganic epitaxy, we demonstrate the existence of an additional barrier (0.67 electron volt) for step-edge crossing-the Ehrlich-Schwoebel barrier. This result was confirmed by transition state theory, which revealed a bending of the molecule at the step edge. A gradual reduction of this barrier in the first layers led to an almost layer-by-layer growth during early deposition stage. The reported phenomena are a direct consequence of the complexity of the molecular building blocks versus atomic systems.     

Initiation of behavior by single neurons: the role of behavioral context

Flying crickets avoid sources of ultrasound, possibly echolocating bats, by making rapid steering movements that turn them away from the stimulus. Electrical stimulation of a single, identified sensory interneuron (Int-1) elicits avoidance steering; depressing its response to ultrasound abolishes avoidance steering. Int-1 is necessary and sufficient for this behavior but only while the cricket is in flight. Thus, the sufficiency of Int-1 for eliciting this behavior is contingent on behavioral context.     

Patterns of corticosteroid and pepsinogen change related to emotional stress in the monkey

In association with conditioned avoidance sessions of 72 hours' duration, monkeys showed a response pattern characterized by increased levels of 17-hydroxy-corticosteroids and decreased levels of pepsinogen during the stress period, with a marked and prolonged elevation of pepsinogen levels occurring during the recovery period.     

Activity and responsivity in rats after magnesium pemoline injections

Rats injected intraperitoneally with magnesium pemoline avoided a buzzing sound (conditioned stimulus) associated with an electric shock to the feet (unconditioned stimulus) more frequently than controls. Drug-injected rats did not avoid the foot shock more frequently than controls, although the experi mental rats did have shorter response latencies fn the active avoidance task. In sub sequent experiments which measured activity changes and response to the buzzing sound alone, it was found that magnesium pemoline caused a lesser decrease in activity level and a more sustained responsivity to the buzzer's. sound than did control injections of tragacanth. This may account for the latency differences observed in the avoidance task.     

蒸汽爆破改性处理对麦秸板性能的影响

通过蒸汽爆破技术对麦秸原料进行处理,去除了麦秸表面的蜡质和硅等胶合阻碍成分,解决了农作物秸秆共有的胶合难的问题.研究结果表明,蒸汽爆破处理对于麦秸板的内结合强度、静曲强度、弹性模量和吸水厚度膨胀率都有显著改善.用在190℃、3 min蒸汽爆破条件下处理的麦秸制成的板材,其内结合强度约是未处理板材的10倍.在190℃、2...     

羊草克隆后代对刈割处理的响应

【背景】 母体放牧历史可以改变羊草（Leymus chinensis）克隆后代的形态及光合生理性状,也可以改变其对干旱环境的响应,但是母体放牧历史是否影响了羊草克隆后代对家畜啃食的响应尚不清楚。【目的】 研究母体放牧历史是否增强了羊草克隆后代对模拟家畜啃食（刈割）的适应性。【方法】 利用不同放牧历史的羊草克隆后代（1983年围封 VS 长期自由放牧）进行室内盆栽试验,从个体性状、子株数、生物量及生物量分配等角度对比了其对模拟放牧处理（刈割）的响应。【结果】 （1）母体放牧历史与刈割处理对羊草单株株高、单株生物量交互作用极显著,放牧羊草克隆后代（GZ）单株株高、单株生物量对刈割处理的抵抗力较围封羊草克隆后代（NG）强;但是,母体放牧历史并没有明显改变羊草克隆后代子株数对刈割处理的响应。（2）母体放牧历史与刈割处理对羊草根茎生物量交互作用显著,对地上、根系及总生物量交互作用不显著,但是NG地上、根系及总生物量在刈割处理下的表型可塑性指数及绝对减少量均明显大于GZ。因此,母体放牧经历增强了羊草克隆后代对刈割处理的适应性。（3）NG在刈割处理下被刈割掉的地上部分生物量显著小于GZ,但是NG的被刈割程度（被刈割生物量/总生物量）显著高于GZ。（4）GZ生物量分配对刈割处理响应不显著,但是刈割处理显著降低了NG的根茎生物量分配。【结论】 羊草母体经历放牧干扰后,其克隆后代对家畜啃食的适应性增强;母体放牧历史并不通过改变生物量分配增强羊草克隆后代的适牧性,叶片光合生理的响应及避牧性可能是母体放牧历史增强羊草克隆后代的途径。本研究通过控制试验排除土壤等环境因子的干扰,从植物自身角度出发,研究其克隆后代表型性状对放牧的响应,这对充分认识草原生态系统放牧退化过程及退化修复过程提供了新的视角。     

Deficits in passive avoidance and fear conditioning in mice with septal lesions

By means of a simple activity measure, mice with lesions of the septal forebrain were tested for passive avoidance (response inhibition) and fear conditioning. In two separate experiments animals with septal lesions showed little or no conditioning, as evidenced by lack of suppression of activity during and following activitycontingent foot shock. Results support and extend thehypothesis that these deficits in passive avoidance derive from the removal of normal inhibitory influences mediated by the septal area.     

Simultaneous generalization gradients for appetitive and aversive behavior

In the presence of a bright light five monkeys were trained to press a lever to avoid shock and to pull a chain for food reward. When tested with a series of lights dimmer than the conditioning stimulus, the monkeys showed a sharp gradient of effect for the rewarded response, in contrast to a very flat gradient for the avoidance response.     

蚯蚓对多菌灵污染土壤回避行为的研究

[目的]为判定和评价土壤的环境质量,并做出早期的污染预警指示。[方法]采用蚯蚓回避试验法,通过两室型蚯蚓回避反应装置,研究了蚯蚓对多菌灵污染土壤的回避行为。[结果]当土壤中多菌灵浓度≥0.8 mg/kg时,蚯蚓开始表现出对污染土壤明显的回避行为,而当土壤中多菌灵浓度≤0.2 mg/kg时,蚯蚓没有表现出对污染土壤的回避行为。[结论]蚯蚓可以作为多菌灵污染土壤的早期预警指示动物。     

Alarm Response of Diadema antillarum

Diadema antillarum possesses a sensitive escape response to juices of crushed conspecific sea urchins. Stimulation usually results in urchins moving rapidly downcurrent. Strong species specificity of the response suggests that it is an adaptation to reduce predation. Diadema antillarum also responds with a running response to contact with Cassis tuberosa, a known predator.     

Retrograde amnesia: effects of handling and microwave radiation

Rats that were irradiated with microwaves immediately after the training trial in a one-trial shock-avoidance learning task retained the conditioned avoidance response 24 hours later. However, rats that were handled a few minutes each day for 3 days before the experiment did not retain the response, although they were capable of learning in a later test.     

荔枝蝽卵平腹小峰对寄主卵的功能反应研究──对经典Holling功能反应原理的改良

一种全新设计的用于测定Ａｎａｓｔａｔｕｓｓｐ．寄生蜂对寄主卵的功能反应．在同一实验空间中，各种密度的卵卡数量不相同，但每一种密度所拥有的总卵粒数都一样．研究结果表明．寄生蜂在这种实验空间中不能表现出经典的Ｈｏｌｌｉｎｇ功能反应结果．     

Extinction in goldfish: facilitation by intracranial injection of RNA from brains of extinguished donors

Extracts rich in RNA were prepared from the brains of goldfish that had acquired and then extinguished a light-signaled avoidance to shock in an aquatic shuttle-box. Recipient fish injected intracranially with such extracts extinguished the response significantly faster than those injected with extracts prepared from brains of naive donors.     

Reinforcement magnitude as a determinant of performance decrement after electroconvulsive shock

The intensity of a foot shock may be a determinant of the rate at which an avoidance response becomes resistant to disruption by electroconvulsive shock. Mice were trained, one trial a day, in a passive avoidance learning task, with one of three foot-shock intensities. Electroconvulsive shock was administered at various intervals after each trial. At all foot-shock intensities, electroconvulsive shock given 10 seconds after each training trial was eflective in disrupting learning. Where electroconvulsive shock was given at longer intervals after each trial, those animals learning at low intensities of foot shock showed greater impairment of performance than those learning at high intensities.