全文获取类型
收费全文 | 87篇 |
免费 | 46篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 11篇 |
2008年 | 17篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
排序方式: 共有133条查询结果,搜索用时 15 毫秒
111.
G Collier D F Johnson G Borin C E Mathis 《Journal of the experimental analysis of behavior》1994,62(2):169-184
Rats in a laboratory foraging paradigm searched for sequential opportunities to drink in two water patches that differed in the bar-press price of each "sip" (20 licks) of water within a bout of drinking (Experiment 1) or the price and size (10, 20, or 40 licks) of each sip (Experiment 2). Total daily water intake was not affected by these variables. The rats responded faster at the patch where water was more costly. However, they accepted fewer opportunities to drink, and thus had fewer drinking bouts, and drinking bouts were smaller at the more costly patch than at the other patch. This resulted in the rats consuming a smaller proportion of their daily water from the more costly patch. The size of the differences in bout frequency and size between the patches appears to be based on the relative cost of water at the patches. The profitability of each patch was calculated in terms of the return (in milliliters) on either effort (bar presses) or time spent there. Although both measures were correlated with the relative total intake, bout size, and acceptance of opportunities at each patch, the time-based profitability was the better predictor of these intake measures. The rats did not minimize bar-press output; however, their choice between the patches and their bout sizes within patches varied in a way that reduced costs compared to what would have been expended drinking randomly. These data accord well with similar findings for choices among patches of food, suggesting that foraging for water and food occurs on the basis of comparable benefit-cost functions: In each case, the amount consumed is related to the time spent consuming. 相似文献
112.
C E Mathis D F Johnson G H Collier 《Journal of the experimental analysis of behavior》1995,63(3):295-311
Foraging involves the expenditure of both time and effort in the acquisition of food; animals typically modify their meal patterns so as to reduce these expenditures or costs. The contribution of time, as compared with effort, to the overall cost perceived by an animal is not known. We investigated the effect of foraging time as a cost independent of effort by measuring the meal patterns of rats living in a laboratory foraging simulation in which they earned all their daily intake. They pressed a bar once to initiate an interval (procurement interval) leading to the presentation of a large cup of food from which they could eat a meal of any size. As the length of the interval increased from 1 s to 46 hr, meal frequency decreased regularly. Meal size increased in a compensatory fashion, and total daily intake was conserved through an interval of 23 hr. The changes in meal frequency occurred because of changes in the rat's latency to bar press after each meal. The functions relating meal frequency and size to the procurement interval were of the same shape as those seen when cost is the completion of a bar-press requirement, which entails the expenditure of both effort and time. When the bar-press requirement was increased to 10, meal frequency was reduced, but time and effort did not appear to simply add together in the rat's perception of cost. These data reveal that time is preceived to be a cost by rats foraging in this laboratory environment. These results suggest that the time parameters of foraging are different from those of consumption. 相似文献
113.
Preferences of hungry pigeons among 10 grains and pellets were analyzed using a Thurstone scaling procedure. The recovered scales were positively correlated with size of the feed. The correlations improved when the Thurstonian assumption of equal-sized discriminal dispersions (Case V) was replaced with the assumption of proportional-sized dispersions (Case VI), as entailed by Weber's law. The correlations weakened when the experiments were conducted with the pigeons close to their free-feeding weights, where the probability of sampling alternative grains increased. In the final experiment, exposure to a large pellet shifted the preferences between two smaller pellets. 相似文献
114.
A I Houston 《Journal of the experimental analysis of behavior》1991,56(3):585-589
Hastjarjo, Silberberg, and Hursh (1990) have presented data on the foraging behavior of rats and discussed it in terms of risk-sensitive foraging theory. Because risk-sensitive foraging theory is comprised of several different models, it does not lead to general predictions about when an organism should prefer a foraging option with high variance to a foraging option with low variance. Any comparison of data with the predictions of the theory must be based on an appropriate model. I draw attention to various experiments that are potentially relevant to the results reported by Hastjarjo et al. and show how the time period over which the organism must survive can influence a model's predictions about risk sensitivity. 相似文献
115.
恶性肿瘤动物模型的建立 总被引:5,自引:0,他引:5
建立恶性肿瘤动物模型是医学科研工作者重要的研究手段。恶性肿瘤的自发肿瘤模型,诱发肿瘤模型和移植肿瘤模型有着各自的机体与外界施加因素之间对立平衡,对界因素逐渐同体所转化和接纳,最终导致肿瘤形成,同时机体也荷瘤。因此,任何影响动物和施加固的条件均可促进和减弱肿瘤形成的起始,进展,结局。就三种恶性肿瘤动物模型建立过程中启示呈现出来,并对不同模型特点和选择进行评述。 相似文献
116.
Despite claims to the contrary, all leading theories about operant choice may be seen as models of optimality. Although melioration is often contrasted with global maximization, both make the same core assumptions as other versions of optimality theory, including momentary maximizing, hill climbing, and the various versions of optimal foraging theory. The present experiment aimed to test melioration against more global optimality and to apply the visit-by-visit analysis suggested by foraging theory. Rats were exposed to concurrent schedules in which one alternative was always variable-ratio 10 and the other alternative was a variable-interval schedule. Although choice relations varied from rat to rat, the overall results roughly confirmed the matching law, a result often taken to support melioration. Pooling the data across sessions and across rats, however, resulted in no increment in unsystematic variance, lending support to the contention by Ziriax and Silberberg (1984) that the choice relation is partly constrained. When the data were analyzed at the level of visits, the results either disconfirmed predictions of melioration or showed regularities about which melioration is silent. Instead, performance tended toward a rough optimization, in which responding favored the variable ratio, but with relatively brief visits to the variable interval. There were no asymmetries in travel or variability that would indicate that different processes were involved in generating visits at the two different schedules. The findings point toward a more global optimality model than melioration and demonstrate the value of per-visit analysis in the study of concurrent performances. 相似文献
117.
The meal patterns of 2 cats in a laboratory habitat with variable foraging costs were examined in a foraging paradigm in which subjects could initiate meals at any time by completing a predetermined number of bar presses (the procurement price) and then could eat any amount. From meal to meal, the procurement price either was fixed or varied among a geometric series of five prices. As the fixed price or the mean of the variable prices increased, meal frequency decreased and meal size increased; daily intake was unaffected. Within variable-price schedules, meal size was not related to the just-paid procurement price. These results suggest that cats respond to the global rather than to the local cost structure of their habitat. They appear to respond to an average of the prices encountered, initiating meals of a frequency and size appropriate to that average. This was true even when the average price was high, meals were infrequent, and thus price encounters were widely separated in time. Therefore, the time window over which the consequences of behavior can affect behavior is longer than often conceived, at least in economies in which the animal controls its intake and the frequency, size, and distribution of its meals. 相似文献
118.
In three experiments using the barpress conditioned suppression task with albino rats, we studied the renewal (relapse) of conditioned fear in an ABA fear-renewal paradigm. We found that explicitly unpaired (EU) deliveries of conditioned stimuli (CSs) and unconditioned stimuli (USs) in Context B thwarted fear renewal in Context A. Evidence contraindicated a suggestion by Rauhut, Thomas, and Ayres (2001) that US habituation plays a key role in this effect. For example, renewal was thwarted only when EU CSs and USs were intermingled rather than given in succession. The possibility that EU treatments thwart renewal by creating a CS that inhibits fear in the test context also received no support. Thus, summation and retardation tests in Context A found no evidence that the EU CS became inhibitory, finding instead evidence for a residual excitation. Other possible interpretations of the results and some implications for clinical practice are noted. 相似文献
119.
Dien J 《Brain and cognition》2008,67(3):292-323
Existing models of laterality, while often successful at describing circumscribed domains, have not been successful as explanations of the overall patterns of hemispheric asymmetries. It is therefore suggested that a new approach is needed based on shared contributions to adaptive hemispheric roles rather than functional and structural intrahemispheric similarities. This paper proposes a model of laterality, the Janus model, based on evolutionary considerations of complementary hemispheric roles. It is proposed that the left hemisphere has the role of anticipating future scenarios and choosing between them while the right hemisphere has the role of integrating ongoing information into a unitary view of the past in order to immediately detect and respond to novel and unexpected events. Evidence for these complementary roles is provided in research on motor control and semantic priming. Finally, the Janus model is contrasted with efforts to cast the frequency model as a general model of laterality. 相似文献
120.
The Great Apes and the Severely Disabled: Moral Status and Thick Evaluative Concepts 总被引:1,自引:0,他引:1
Logi Gunnarsson 《Ethical Theory and Moral Practice》2008,11(3):305-326
The literature of bioethics suffers from two serious problems. (1) Most authors are unable to take seriously both the rights
of the great apes and of severely disabled human infants. Rationalism—moral status rests on rational capacities—wrongly assigns
a higher moral status to the great apes than to all severely disabled human infants with less rational capacities than the
great apes. Anthropocentrism—moral status depends on membership in the human species—falsely grants all humans a higher moral
status than the great apes. Animalism—moral status is dependent on the ability to suffer—mistakenly equates the moral status
of humans and most animals. (2) The concept person is widely used for justificatory purposes, but it seems that it cannot play such a role. It seems that it is either redundant
or unable to play any justificatory role. I argue that we can solve the second problem by understanding person as a thick evaluative concept. This then enables us to justify assigning a higher moral status to the great apes than to
simple animals: the great apes are persons. To solve the first problem, I argue that certain severely disabled infants have
a higher moral status than the great apes because they are dependent upon human relationships for their well-being. Only very
limited abilities are required for such relationships, and the question who is capable of them must be based on thick evaluative
concepts. Thus, it turns out that to make progress in bioethics we must assign thick evaluative concepts a central role.
相似文献
Logi GunnarssonEmail: |