首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4944篇
  免费   2944篇
  国内免费   162篇
  8050篇
  2024年   11篇
  2023年   46篇
  2022年   22篇
  2021年   183篇
  2020年   250篇
  2019年   657篇
  2018年   536篇
  2017年   651篇
  2016年   616篇
  2015年   524篇
  2014年   459篇
  2013年   636篇
  2012年   323篇
  2011年   309篇
  2010年   235篇
  2009年   209篇
  2008年   169篇
  2007年   186篇
  2006年   175篇
  2005年   143篇
  2004年   134篇
  2003年   130篇
  2002年   126篇
  2001年   117篇
  2000年   99篇
  1999年   80篇
  1998年   57篇
  1997年   45篇
  1996年   57篇
  1995年   47篇
  1994年   51篇
  1993年   55篇
  1992年   40篇
  1991年   41篇
  1990年   41篇
  1989年   32篇
  1988年   37篇
  1987年   51篇
  1986年   28篇
  1985年   34篇
  1984年   37篇
  1983年   39篇
  1982年   39篇
  1981年   35篇
  1980年   43篇
  1979年   42篇
  1978年   45篇
  1977年   49篇
  1976年   53篇
  1975年   25篇
排序方式: 共有8050条查询结果,搜索用时 15 毫秒
21.
Alcohol-related expectancies have been recently proposed as potentially important determinants of drinking behavior. This study describes the development of a New Zealand measure of such beliefs, the Drinking Expectancy Questionnaire (DEQ). Items selected through interviews, literature review, and the modification of other relevant questionnaires were piloted on 333 drinkers in a community sample and 275 college students. Factor analyses of both samples revealed nine alcohol reinforcement domains relating to assertiveness, affective change, sexual enhancement, social enhancement, relaxation, cognitive impairment, dependence, carelessness, and aggression. The potential clinical and research possibilities using this revised expectancy measure are briefly discussed, along with the scale's strength and weaknesses.The financial assistance of the Alcoholic Liquor Advisory Council of New Zealand in conducting this study is gratefully acknowledged.  相似文献   
22.
Six pigeons were trained with a chain variable-interval variable-interval schedule on the left key and with reinforcers available on the right key on a single variable-interval schedule arranged concurrently with both links of the chain. All three schedules were separately and systematically varied over a wide range of mean intervals. During these manipulations, the obtained reinforcer rates on constant arranged schedules also frequently changed systematically. Increasing reinforcer rates in Link 2 of the chain increased response rates in both links and decreased response rates in the variable-interval schedule concurrently available with Link 2. Increasing Link-1 reinforcer rates increased Link-1 response rates and decreased Link-2 response rates. Increasing reinforcer rates on the right-key schedule decreased response rates in Link 1 of the chain but did not affect the rate in Link 2. The results extend and amplify previous analyses of chain-schedule performance and help define the effects that a quantitative model must describe. However, the complexity of the results, and the fact that constant arranged reinforcer schedules did not necessarily lead to constant obtained reinforcer rates, precluded a quantitative analysis.  相似文献   
23.
In two experiments, rats were trained to deposit ball bearings down a hole in the floor, using an algorithmic version of shaping. The experimenter coded responses expected to be precursors of the target response, ball bearing deposit; a computer program reinforced these responses, or not, according to an algorithm that mimicked the processes thought to occur in conventional shaping. In the first experiment, 8 of 10 rats were successfully shaped; in the second, 5 of 5 were successfully shaped, and the median number of sessions required was the same as for a control group trained using conventional shaping. In both experiments, “misbehavior,” that is, excessive handling and chewing of the ball bearings, was observed, and when the algorithmic shaping procedure was used, misbehavior could be shown to occur in spite of reduced reinforcement for the responses involved.  相似文献   
24.
25.
We compared the effects of sensory and edible reinforcers on resistance to satiation in three autistic children while learning visual discrimination tasks. Within-subject designs were used to compare a single sensory reinforcer with a single edible reinforcer and to compare multiple sensory reinforcers with multiple edibles. Results indicated that multiple sensory reinforcers maintained responding over more trials than did multiple edible reinforcers; however, the use of single sensory reinforcers and single edibles resulted in about equal numbers of trials to satiation. Both multiple and single sensory reinforcers produced higher percentages of correct responses than edible reinforcers. The findings are discussed in terms of the advantages of sensory reinforcers in teaching autistic children.  相似文献   
26.
We evaluated a procedure for identifying potential reinforcers with profoundly retarded individuals. In Experiment 1, six persons were repeatedly exposed to 16 stimuli, and approach behaviors to each stimulus were used to identify preferred and nonpreferred stimuli. In Experiment 2, we examined the reinforcing properties of preferred and nonpreferred stimuli by delivering them contingently on the occurrence of arbitrarily selected responses. Results revealed that the preferred stimulus conditions typically produced higher rates of responding than did either the baseline or the nonpreferred stimulus conditions, suggesting that the procedure can be used to assess reinforcer value for individuals with limited behavioral repertoires.  相似文献   
27.
In Experiment 1, Japanese monkeys were trained on three conditional position-discrimination problems with colors as the conditional cues. Within each session, each problem was presented for two blocks of ten reinforcements; correct responses were reinforced under continuous-reinforcement, fixed-ratio 5, and variable-ratio 5 schedules, each assigned to one of the three problems. The assignment of schedules to problems was rotated a total of three times (15 sessions per assignment) after 30 sessions of acquisition training. Accuracy of discrimination increased to a moderate level with fewer trials under CRF than under ratio schedules. In contrast, the two ratio schedules, fixed and variable, were more effective in maintaining accurate discrimination than was CRF. With further training, as asymptotes were reached, accuracy was less affected by the schedule differences. These results demonstrated an interaction between the effects of reinforcement schedules and the level of acquisition. In Experiment 2, ratio sizes were gradually increased to 30. Discrimination accuracy was maintained until the ratio reached 20; ratio 30 strained the performance. Under FR conditions, accuracy increased as correct choice responses cumulated after reinforcement.  相似文献   
28.
Handling time and choice in pigeons   总被引:2,自引:1,他引:1       下载免费PDF全文
According to optimal foraging theory, animals should prefer food items with the highest ratios of energy intake to handling time. When single items have negligible handling times, one large item should be preferred to a collection of small ones of equivalent total weight. However, when pigeons were offered such a choice on equal concurrent variable-interval schedules in a shuttlebox, they preferred the side offering many small items per reinforcement to that offering one or a few relatively large items. This preference was still evident on concurrent fixed-cumulative-duration schedules in which choosing the alternative with longer handling time substantially lowered the rate of food intake.  相似文献   
29.
Distributions of reinforcers between two components of multiple variable-interval schedules were varied over a number of conditions. Sensitivity to reinforcement, measured by the exponent of the power function relating ratios of responses in the two components to ratios of reinforcers obtained in the components, did not differ between conditions with 15-s or 60-s component durations. The failure to demonstrate the “short-component effect,” where sensitivity is high for short components, was consistent with reanalysis of previous data. With 60-s components, sensitivity to reinforcement decreased systematically with time since component alternation, and was higher in the first 15-s subinterval of the 60-s component than for the component whose total duration was 15 s. Varying component duration and sampling behavior at different times since component transition may not be equivalent ways of examining the effects of average temporal distance between components.  相似文献   
30.
A reinforced practice procedure was used to facilitate cooperative behavior in five children, aged 3 to 6 years, during dental treatment. In a multiple baseline design across subjects, the children were rewarded with escape, inexpensive stickers, and praise for cooperative behavior in the presence of the sights, sounds, and some sensations of the dental instruments prior to actual dental treatment. Direct observations of disruptive behavior via a 15-s interval recording system indicated baseline levels as high as 90% were reduced to less than 15% by the final treatment visit. In addition, the procedure was effective in reducing overall heart rate and blood pressure reactivity to dental treatment. All children were rated by the involved dental professionals as more cooperative and relaxed following exposure to reinforced practice.  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