全文获取类型
收费全文 | 57096篇 |
免费 | 2939篇 |
国内免费 | 48篇 |
出版年
2019年 | 738篇 |
2018年 | 975篇 |
2017年 | 1019篇 |
2016年 | 1085篇 |
2015年 | 774篇 |
2014年 | 957篇 |
2013年 | 4472篇 |
2012年 | 1702篇 |
2011年 | 1799篇 |
2010年 | 1138篇 |
2009年 | 1162篇 |
2008年 | 1526篇 |
2007年 | 1589篇 |
2006年 | 1413篇 |
2005年 | 1337篇 |
2004年 | 1302篇 |
2003年 | 1212篇 |
2002年 | 1221篇 |
2001年 | 1805篇 |
2000年 | 1607篇 |
1999年 | 1277篇 |
1998年 | 695篇 |
1997年 | 586篇 |
1996年 | 610篇 |
1994年 | 548篇 |
1992年 | 1046篇 |
1991年 | 1014篇 |
1990年 | 971篇 |
1989年 | 981篇 |
1988年 | 974篇 |
1987年 | 877篇 |
1986年 | 905篇 |
1985年 | 952篇 |
1984年 | 795篇 |
1983年 | 717篇 |
1982年 | 602篇 |
1981年 | 568篇 |
1979年 | 876篇 |
1978年 | 666篇 |
1976年 | 587篇 |
1975年 | 717篇 |
1974年 | 847篇 |
1973年 | 889篇 |
1972年 | 708篇 |
1971年 | 678篇 |
1970年 | 653篇 |
1969年 | 658篇 |
1968年 | 849篇 |
1967年 | 726篇 |
1966年 | 723篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
232.
M J Nissen J L Ross D B Willingham T B Mackenzie D L Schacter 《Brain and cognition》1988,8(1):117-134
We studied an individual with multiple personality disorder in whom each of several personalities claimed to have no direct awareness of the others and to be unable to consciously remember the experiences of other personalities. A broad selection of implicit and explicit memory tests was used to determine the extent to which one personality had access to knowledge acquired by another and the circumstances in which that knowledge would be expressed. The implicit assessment of memory was a necessary but not sufficient condition for demonstrating interpersonality access. The degree of compartmentalization of knowledge in this patient depended largely on whether the interpretation of presented information was likely to differ across personalities. 相似文献
233.
Knowledge and beliefs regarding the consequences of cigarette smoking and their relationships to smoking status in a biracial sample 总被引:3,自引:0,他引:3
R C Klesges G Somes R W Pascale L M Klesges M Murphy K Brown E Williams 《Health psychology》1988,7(5):387-401
The purpose of this investigation was to evaluate carefully smoking-related knowledge and beliefs and their relationships to smoking status in a large, heterogeneous sample of smokers and nonsmokers in two settings: (a) a large, biracial southern city and (b) a small midwestern community. Participants were 611 (198 male, 413 female) adult respondents to a random-dialing telephone survey in Fargo, North Dakota (n = 200), and Memphis, Tennessee (n = 411). Each participant was given the Smoking Attitudes Survey, which assesses generalized health beliefs as well as health-related problems associated with smoking. Participants' knowledge of smoking-associated diseases (e.g., lung cancer) and of diseases not associated with smoking (e.g., kidney stones) was assessed. Stepwise regression analysis of composite knowledge scores revealed four independent predictors of the health consequences of smoking: education, race, smoking status, and income. Smokers, compared to nonsmokers, reported less knowledge related to the health consequences of smoking, were more likely to be male, were less concerned with the health consequences of smoking, and were more concerned about the health consequences of cholesterol. The best predictor of smokers who had never attempted cessation was their greater concern over weight control when compared to smokers with a history of smoking cessation attempts. The results are discussed in terms of smoking prevention and intervention efforts. 相似文献
234.
Studies of psychosocial influences on coronary artery atherogenesis in cynomolgus monkeys 总被引:1,自引:0,他引:1
The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described. 相似文献
235.
The vocationally-indecisive individual presents a major counselling problem. The theory and research behind career indecision is discussed and a counselling approach based on identity formation is outlined. Four identity statuses — Identity Achievements, Foreclosures, Identity Diffusions, and Moratoriums — are described and counselling approaches for each are explored. 相似文献
236.
Two different types of stimulus objects, a live female quail artificially adorned with bright orange feathers and an inanimate toy dog, served as conditioned stimuli. For subjects in experimental groups, the conditioned stimuli were presented shortly before access to a sexually receptive normal female quail. For subjects in control groups, exposure to the conditioned stimuli was unpaired with copulatory opportunity. Subjects in the experimental but not in the control groups quickly came to approach the location of the conditioned stimulus objects. When an adorned female quail served as the conditioned stimulus, the conditioned approach behavior was controlled by a combination of the presence of the orange adornments and the visual cues of the head and neck of the female bird, and the approach behavior persisted as the adorned female moved to new locations. When the toy dog served as the conditioned stimulus, the conditioned approach behavior was limited to the spatial cues that surrounded the toy dog during conditioning trials. Although both types of stimulus objects evoked conditioned approach behavior, only the adorned female stimulus supported copulatory behavior. This last finding indicates that copulatory behavior can become redirected toward novel stimuli as a result of conditioning, but only under special circumstances. The results are consistent with the suggestion that appetitive components of reproductive behavior are more susceptible to conditioning than consummatory components. Possible reasons for this are discussed, together with implications of the results for the contribution of conditioning processes to sexual selection. 相似文献
237.
J E Mazur 《Journal of the experimental analysis of behavior》1988,49(1):37-47
In a series of conditions, pigeons chose between 1.5 s and 3 s of access to grain, each preceded by some delay. The delay that preceded the small reinforcer was constant throughout a condition. The delay that preceded the large reinforcer was increased or decreased a number of times each session in order to estimate an "indifference point," a delay at which the subject chose each alternative about equally often. The experiment was designed to determine whether variations in any of four features of this adjusting-delay procedure would systematically alter the estimated indifference points. The four features were the total trial duration, the number of center-key responses necessary to begin a trial, the number of choice trials that preceded each change in the adjusting delay, and step size--the size of each increment and decrement in the delay. Manipulation of the first three features had no systematic effects on the indifference points. As step size was increased from 0.5 s to 6 s, within-session variability of the adjusting delay steadily increased, and the 6-s step size produced larger indifference-point estimates for some subjects. The results suggest that, within certain limits, these procedural features can be altered without affecting the indifference-point estimates, but that the use of a large step size can distort the estimates. Some theoretical implications of the relative constancy of indifference points across these procedural variations are discussed. 相似文献
238.
Self-control in mentally retarded adolescents: choice as a function of amount and delay of reinforcement.
下载免费PDF全文
![点击此处可从《Journal of the experimental analysis of behavior》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Three severely mentally retarded adolescents were studied under discrete-trial procedures in which a choice was arranged between edible reinforcers that differed in magnitude and, in some conditions, delay. In the absence of delays the larger reinforcer was consistently chosen. Under conditions in which the smaller reinforcer was not delayed, increasing the delay to delivery of the larger reinforcer decreased the percentage of trials in which that reinforcer was chosen. All subjects directed the majority of choice responses to the smaller reinforcer when the larger reinforcer was sufficiently delayed, although the value at which this occurred differed across subjects. Under conditions in which the larger reinforcer initially was sufficiently delayed to result in preference for the smaller one, progressively increasing in 5-s increments the delay to both reinforcers increased percentage of trials with the larger reinforcer chosen. At sufficiently long delays, 2 of the subjects consistently chose the larger, but more delayed, reinforcer, and the 3rd subject chose that reinforcer on half of the trials. These results are consistent with the findings of prior studies in which adult humans responded to terminate noise and pigeons responded to produce food. 相似文献
239.
S R Hursh T G Raslear D Shurtleff R Bauman L Simmons 《Journal of the experimental analysis of behavior》1988,50(3):419-440
Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio. 相似文献
240.
Two experiments investigated the effects of successive reinforcement contexts on choice. In the first, concurrent variable-interval schedules of primary reinforcement operated during the initial links of concurrent chains. The rate of this reinforcement arranged by the concurrent schedules was decreased across conditions: When it was higher than the terminal-link rate, preference for the higher frequency initial-link schedule increased relative to baseline. (During baseline, a standard concurrent-schedule procedure was in effect). When the initial-link reinforcement rate was lower than the terminal-link rate, preference converged toward indifference. In the second experiment, a chain schedule was available on a third key while a concurrent schedule was in effect on the side keys. When the terminal link of the chain schedule was produced, the side keys became inoperative. Availability of the chain schedule did not affect choice between the concurrent schedules. These results show that only when successive reinforcement contexts are produced by choice responding do those successive contexts affect choice in concurrent schedules. 相似文献