全文获取类型
收费全文 | 37317篇 |
免费 | 1450篇 |
国内免费 | 22篇 |
出版年
2020年 | 398篇 |
2019年 | 471篇 |
2018年 | 658篇 |
2017年 | 678篇 |
2016年 | 712篇 |
2015年 | 506篇 |
2014年 | 649篇 |
2013年 | 3184篇 |
2012年 | 1147篇 |
2011年 | 1220篇 |
2010年 | 790篇 |
2009年 | 766篇 |
2008年 | 1133篇 |
2007年 | 1074篇 |
2006年 | 1057篇 |
2005年 | 937篇 |
2004年 | 898篇 |
2003年 | 916篇 |
2002年 | 925篇 |
2001年 | 864篇 |
2000年 | 845篇 |
1999年 | 709篇 |
1998年 | 440篇 |
1997年 | 462篇 |
1996年 | 447篇 |
1995年 | 411篇 |
1992年 | 618篇 |
1991年 | 589篇 |
1990年 | 569篇 |
1989年 | 533篇 |
1988年 | 514篇 |
1987年 | 509篇 |
1986年 | 570篇 |
1985年 | 574篇 |
1984年 | 525篇 |
1983年 | 461篇 |
1981年 | 399篇 |
1979年 | 500篇 |
1978年 | 429篇 |
1977年 | 378篇 |
1976年 | 389篇 |
1975年 | 427篇 |
1974年 | 522篇 |
1973年 | 542篇 |
1972年 | 391篇 |
1971年 | 408篇 |
1969年 | 399篇 |
1968年 | 459篇 |
1967年 | 424篇 |
1966年 | 439篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
821.
822.
Certain doses of pentobarbital consistently increased the rate of pecking engendered by a fixed-ratio schedule of 30 responses in a group of 13 pigeons, and still higher doses produced decrements in rate of responding. For individual subjects, the dose-effect functions were qualitatively similar, but differed with respect to the doses producing the maximum increase and subsequent decrease in rate. In general, the maximum occurred at lower doses and the decrement was greater at the highest dose in the birds with the highest control rates. It was also possible to distinguish between the effects of pentobarbital and several other drugs on the behavior maintained by FR 30. The results indicate that changes in rate of responding on FR 30 after drug administration are dose-dependent, drug-specific effects. 相似文献
823.
Superstitions were demonstrated with human subjects when presses on one button were reinforced on a VI 30-sec schedule while presses on a second were never reinforced. Superstitious responding, on the second button, was often maintained because presses on that button were frequently followed by reinforcement for a subsequent press on the first button. The introduction of a changeover delay (COD), which separated in time presses on the second button and subsequent reinforced presses on the first button, reduced or eliminated the superstitious responding of these subjects. Some complex superstitions were also demonstrated with other subjects for which the COD was in effect from the beginning of the session. 相似文献
824.
Daily food intake in rats was temporarily reduced by the introduction of an activity wheel and temporarily increased by the subsequent removal of the wheel. When this outcome is coupled with the positive relation between food deprivation and running—and food deprivation is seen as a loss of eating rather than as a physiological state—there is the suggestion that the total behavior output of the organism may be regulated as such. Specifically, when the rat is deprived of a behavior that recurrently comprises a large part of its total daily activity, an increase may occur in some other behavior. 相似文献
825.
Generalization of auditory intensity as a function of small amounts of discrimination training 下载免费PDF全文
Rosemary Pierrel J. Gilmour Sherman Marian W. Fischman 《Journal of the experimental analysis of behavior》1963,6(4):545-548
Rats were trained on a two-valued auditory-intensity discrimination for 5, 2, 1 or 0 days. Then, the bar-press response rate was sampled in the presence of seven added discrimination stimuli (generalization) for seven days. Daily training sessions were 4 hr in length throughout the experiment. Only the five-day group exhibited a marked superiority on the multi-valued discrimination when contrasted with the group having had no prior simple discrimination training. 相似文献
826.
Of 23 pigeons, 11 received continuous reinforcement for key pecking, and 12 received an FR 10 schedule of reinforcement. The birds were then tested without food, but with potential conditioned reinforcers presented either on the same schedule as in training, on the other schedule, or not at all. Each bird in the subgroup trained on CRF and tested with Sr's at FR 10 not only gave more responses in testing than did each bird in both subgroups receiving no Sr's, but also gave more responses than did each bird in the Sr subgroup receiving CRF training and Sr's at CRF. Cumulative records are presented to show the effects of different schedules of conditioned reinforcers. 相似文献
827.
In the simulation of human behavior on a digital computer, one first attempts to discover the manner in which subjects (Ss) internally represent the environment and the rules that they employ for acting upon this representation. The interaction between the rules and the environmental representation over a period of time constitutes a set of processes. Processes can be expressed as flow charts which, in turn, are stated formally in terms of a computer program. The program serves as a theory which is tested by executing the program on a computer and comparing the machine's performance with S's behavior. 相似文献
828.
Schedules using noxious stimuli. II: low intensity electric shock as a discriminative stimulus 下载免费PDF全文
The presence or absence of pulses of low intensity electric shock was used as a discriminative stimulus to control responding under fixed ratio reinforcement in the squirrel monkey. Initially brief periods of nonreinforcement were lengthened only when discriminative control was evident. Discriminative control was studied by (1) varying the duration of nonreinforcement periods; (2) reversing the stimulus conditions correlated with reinforcement and nonreinforcement periods; and (3) determining the minimum shock intensity necessary to maintain discriminative control. Stimulus control was not reliably affected by d-amphetamine, chlorpromazine, or morphine. The discriminative control by pulses of low intensity electric shock was similar to that by other discriminative stimuli, except that the control developed slowly and was better when the pulsing shock was correlated with reinforcement than when correlated with nonreinforcement. 相似文献
829.
830.