首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 132 毫秒
1.
Long-term analgesic effects of inescapable shock and learned helplessness   总被引:1,自引:0,他引:1  
Although exposure to inescapable shocks induced analgesia in rats, the analgesia was not manifest 24 hours later. A brief reexposure to shock, however, restored the analgesia. This reexposure to shock had an analgesic effect only if the rats had been shocked 24 hours previously. Further, long-term analgesic effects depended on the controllability of the original shocks and not on shock exposure per se. Implications of these results for learned helplessness and stress-induced analgesia are discussed.  相似文献   

2.
Responding elicited in the squirrel monkey by electric shocks presented every 60 seconds was gradually altered in temporal patterning, especially when the shock was also produced by responses under a 30-second fixed-interval schedule. The initially elicited pattern of maximal responding just after each shock was altered by the recurrent shock and by the added fixed-interval schedule to a pattern of maximal responding just before each shock. Most shocks were produced by responses and the response pattern was maintained for several months, but little responding occurred when shocks were omitted.  相似文献   

3.
After stabilization of response rates engendered by a free-operant avoidance contingency, the lever-pressing of two squirrel monkeys was maintained for several months by a fixed-interval schedule of electric shock presentation. Initially, response-contingent shocks produced substantial increases in response rates. Continued exposure to the schedule resulted in a reduced overall rate accompanied by a change in the temporal patterning of responses. There was a pause in responding after most shock deliveries; the rate of responding then increased during the interval to reach a terminal value preceding shock presentation. Omission of shocks for part of the daily session led to higher rates of responding; the reintroduction of response-contingent shocks produced a lower overall rate and reinstated the temporal patterning of responding characteristic of the fixed-interval schedule.  相似文献   

4.
Three albino rats, trained to avoid electric shock, were stomach-loaded with from 1 to 5 ml of 32-percent aqueous solution of ethyl alcohol prior to the experimental session. Small doses produced some increases in responserates and a consistent decline in shocks received. Larger doses produced progressive uncoordination, accompanied by lower response rates and an increase in shocks received.  相似文献   

5.
运用B-N(Beveridge-Nelson)数据分解法对我国进出口贸易中不确定性事件所带来的随机冲击进行分解,并运用脉冲响应函数分析随机项给经济增长带来的冲击效应,结果表明:在国内和国外不确定性事件的发生所带来的随机冲击中,国外事件特别是金融危机等经济事件对我国进出口贸易造成了较为严重的负面影响;当前国际金融危机自2009年1月开始对我国国际贸易产生了较大的冲击,其季度冲击值平均为-0.089,占进出口贸易总额-0.87%,目前已造成进出口总额至少925.5亿元的损失;随机冲击项在对我国国际贸易带来负面影响的同时,也进一步冲击了我国的经济增长,引发了17%的经济波动,冲击周期大约为4个季度。  相似文献   

6.
探明中国西部地区农户遭受的贫困冲击状况,为制定精准扶贫政策提供参考,采用问卷方式对云南省武定县和会泽县、贵州省盘县和正安县、陕西省洛南县和镇安县1 368户农户的家庭、住房、资产、农业、收入和消费等情况进行实地调查,并根据当地农户遭受各种冲击的调查统计结果分析其对家庭生活的影响。结果表明:在调查的1 368户农户中,西部贫困地区农户的家庭人口普遍较多,抚养比较高,劳动力缺乏,收入消费水平较低,遭受过不同冲击的农户达79%。在3大类冲击因素中,灾害冲击占比最大,为61.7%;社会冲击其次,为40.4%;经济冲击第3,为26%。农户因病致贫返贫现象较严重,各种冲击对农户种植业、养殖业及家庭生产生活的影响较大,有50%的农户在面对各种冲击时仍没有应对措施。提出了农户面对3大类冲击应采取的措施。  相似文献   

7.
A behavioral method is described in which increasing intensities of electric shocks were applied to the gasserian ganglia of alert monkeys. The animals were trained to press a lever to regulate the shock level. "Pain thresholds" were thereby obtained, and these thresholds were modified by varying the shock duration and by administration of morphine.  相似文献   

8.
One year after exposure to intense electric shock, rats were punished with shocks of lesser intensity. The previous exposure increased the suppressive effects of the punishment during both the initial encounter with punishment and over the course of a 7-day test period. Rats that had not been previously exposed to shock recovered during continued shock punishment.  相似文献   

9.
Translation of unspliced transcripts after heat shock   总被引:19,自引:0,他引:19  
  相似文献   

10.
An understanding of interstellar shock waves is crucial in determining the structure of the interstellar medium. By causing the gas to radiate, interstellar shocks provide astronomers with valuable diagnostics on both the physical conditions in the interstellar medium and the energy source that produced the shock. The complexity of the interstellar plasma-its degree of ionization, its molecular content, the presence of small dust grains and cosmic rays, and the magnetic field-leads to a rich variety of structures for interstellar shocks, which are being actively investigated both observationally and theoretically.  相似文献   

11.
During the 10 February 1990 flyby of Venus, the Galileo spacecraft skimmed the downstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed.  相似文献   

12.
α-甘露聚糖肽对鲫鱼免疫应答强度的影响研究   总被引:2,自引:0,他引:2       下载免费PDF全文
为研究α-甘露聚糖肽(M annatide)对鲫鱼免疫应答强度的影响,将α-甘露聚糖肽按每天每千克体重1.5 m g的剂量拌饵投喂鲫鱼,分别于7,14,21和28 d时检测各组鲫鱼吞噬细胞的杀菌活性、白细胞的吞噬活性、SOD酶活性和血清凝集抗体效价。结果表明,不同投喂周期均可增强鲫鱼的免疫应答强度;用药饵投喂7 d的试验组,7 d后免疫应答强度很快与对照组趋于一致;21 d和28 d投喂组的免疫应答强度差异不明显,但均显著(P<0.05)高于14 d组。因此,投喂21 d左右即可达到使非特异性免疫功能增强持续30 d以上的效果。  相似文献   

13.
The objective of the paper was to detect HSP72 expression and HSP72 gene sequence in heat shocked mouse preimplantation embryos and the effects of different thermo conditions on hatching rates of embryos. The mouse blastocysts cultured in vitro were heat treated at 40℃ and 38℃ for 1 h, 2 h and 3 h and then recovered at 370C for 3 h, 2 h and 1 h, respectively, to detect their HSP72 gene expression by using RT-PCR after the total R.NA extraction. The hatching rate of the blastocysts for different treated groups was recorded and the expression of liSP72 in the blastocysts was determined by Western blot. The results showed that all the groups of blastocysts, including the control, had the expression of HSP72 gene. The expression of HSP72 protein had the highest level in the embryos stressed at 38℃ for 2 h, and it was significantly higher than that in the control group. The expression of HSP72 in the groups of blastocysts treated at 40℃ was not significantly different from that in the control group. The embryos with induction of mild heat shock at 38℃ for 2 h, then subjected to heat shock at 40℃ for 2 h, had a significant higher (P〈0.05) hatching rate of 54.74% compared to 47.85% in the embryos treated directly at 40℃ for 2 h. The above results indicated that the mouse blastocysts were sensitive to heat shock and a mild heat shock induced HSP72 gene expression. Induction of HSP72 expression with mild heat shock helped embryos to tolerate more severe heat shocks.  相似文献   

14.
Galaxy clusters form through a sequence of mergers of smaller galaxy clusters and groups. Models of diffusive shock acceleration suggest that in shocks that occur during cluster mergers, particles are accelerated to relativistic energies, similar to conditions within supernova remnants. In the presence of magnetic fields, these particles emit synchrotron radiation and may form so-called radio relics. We detected a radio relic that displays highly aligned magnetic fields, a strong spectral index gradient, and a narrow relic width, giving a measure of the magnetic field in an unexplored site of the universe. Our observations show that diffusive shock acceleration also operates on scales much larger than in supernova remnants and that shocks in galaxy clusters are capable of producing extremely energetic cosmic rays.  相似文献   

15.
Mice were shocked with 0.1, 0.3, or 0.5 ma of current at 2 to 3, 8 to 9, or 15 to 16 days. Handled, nonshocked and nonhandled controls were also used. In adulthood each group was split into thirds and taught an avoidance response under shock of 0.3, 0.5, or 0.7 ma. The amount of shock given during infancy and adulthood, and the age at which shock occurred, were all found to have significant effects upon learning.  相似文献   

16.
A significant fall in tail blood pressure occurs in paired rats after shock-induced aggression. Pressure returns to baseline levels within 4 hours after fighting. Conversely, single rats subjected to jump threshold measurements or to shocks identical to those used in the aggression paradigm show significant elevations in tail blood pressure. The size of the pressure increase in rats shocked alone appears dependent on the intensity of the shocks, while the pressure fall in rats shocked in pairs occurs over a broad range of shock intensities.  相似文献   

17.
Hungry goldfish learned to press a lever for worms on a 2-minute variable-interval schedule of reinforcement. Lever pressing was suppressed in the presence of a flashing light by (i) pairing the light with a brief electric shock ("anxiety") and (ii) punishing the lever-pressing behavior with electric shocks.  相似文献   

18.
玉米中霉菌毒素对仔猪疫苗免疫应答的影响(摘要)   总被引:1,自引:0,他引:1  
[目的]研究霉变的玉米中的毒素对仔猪免疫应答的影响。[方法]使用ELISA方法测定了霉变玉米中黄曲霉毒素B1和赭曲霉毒素A的含量;将霉变玉米饲喂仔猪,并测定仔猪血清中相应的抗体效价。[结果]试验组抗体水平明显低于对照组,免疫器官的组织切片也表明霉菌毒素可以明显抑制仔猪的免疫应答反应。[结论]玉米霉菌毒素对仔猪内脏器官和免疫应答具有重要影响。  相似文献   

19.
马飞  刘文强  刘桂芹  秦绪岭 《安徽农业科学》2010,38(35):20097-20099
[目的]研究霉变玉米中的毒素对仔猪免疫应答的影响。[方法]使用ELISA方法测定了霉变玉米中黄曲霉毒素B1和赭曲霉毒素A的含量;将霉变玉米饲喂仔猪,并测定仔猪血清中相应的抗体效价。[结果]试验组抗体水平明显低于对照组,免疫器官的组织切片也表明霉菌毒素可以明显抑制仔猪的免疫应答反应。[结论]玉米霉菌毒素对仔猪内脏器官和免疫应答具有重要影响。  相似文献   

20.
 【目的】研究不同免疫状态对肉仔鸡血液生化指标和细胞免疫应答的影响。【方法】选用健康情况良好1日龄AA肉公鸡180只,随机分为4组,每组5个重复,每重复9只。设定不同免疫应激模型,为无免疫组即对照组(no vaccine,NV),常规免疫组(conventional vaccine,CV),以及在常规免疫基础上注射细菌脂多糖的免疫亢进组(LPS)和环磷酰胺的免疫抑制组(CYP)。采用 CD3/CD4/CD8 三色流式细胞术、MTT法检测肉鸡免疫状态和非免疫状态下外周血中 T 淋巴细胞及其亚群的变化。【结果】与NV组相比,肉仔鸡的体增重和采食量均显著降低LPS组和CYP组(P<0.05),各处理料重比无显著差异(P>0.05),NV组与CV 组生产性能指标无显著差异(P>0.05),各日龄处理间血清TP、GLU和CHLO含量均无显著差异(P>0.05)。第21和35天,LPS组和CYP组血清ALB含量显著低于CV组和NV组(P<0.05);第21 天,LPS组血清α-AGP和 BUN含量显著低于NV组(P<0.05),CPY和LPS均抑制T、B淋巴细胞增殖,LPS组CD4+/CD8+T细胞百分比显著低于NV组(P<0.05)。【结论】未进行免疫肉鸡可维持机体正常的生长性能和细胞免疫稳态,LPS和CYP的刺激可降低肉鸡采食量和体增重;随日龄增加肉鸡对CYP刺激的耐受性有所上升,LPS刺激可增强肉鸡细胞免疫应答反应。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号