全文获取类型
收费全文 | 3439篇 |
免费 | 1016篇 |
国内免费 | 35篇 |
专业分类
4490篇 |
出版年
2017年 | 44篇 |
2016年 | 42篇 |
2014年 | 38篇 |
2013年 | 278篇 |
2012年 | 89篇 |
2011年 | 99篇 |
2010年 | 140篇 |
2009年 | 208篇 |
2008年 | 118篇 |
2007年 | 144篇 |
2006年 | 88篇 |
2005年 | 102篇 |
2004年 | 112篇 |
2003年 | 117篇 |
2002年 | 108篇 |
2001年 | 139篇 |
2000年 | 62篇 |
1999年 | 103篇 |
1998年 | 91篇 |
1997年 | 62篇 |
1996年 | 107篇 |
1995年 | 82篇 |
1994年 | 95篇 |
1993年 | 91篇 |
1992年 | 104篇 |
1991年 | 104篇 |
1990年 | 89篇 |
1989年 | 93篇 |
1988年 | 79篇 |
1987年 | 70篇 |
1986年 | 62篇 |
1985年 | 53篇 |
1984年 | 55篇 |
1982年 | 48篇 |
1981年 | 38篇 |
1980年 | 41篇 |
1979年 | 42篇 |
1977年 | 40篇 |
1973年 | 41篇 |
1972年 | 62篇 |
1971年 | 54篇 |
1969年 | 43篇 |
1968年 | 66篇 |
1967年 | 50篇 |
1966年 | 59篇 |
1965年 | 47篇 |
1964年 | 81篇 |
1963年 | 74篇 |
1962年 | 50篇 |
1961年 | 39篇 |
排序方式: 共有4490条查询结果,搜索用时 0 毫秒
81.
Fixation positions were measured for a variety of simple patterns. Generally, the spontaneous fixation tendencies hovered near the “center-of-gravity” of the pattern, providing that the overall dimensions of the figure were less than about 5 deg. “Open” figures such as angles were found to be roughly equivalent to their “enclosed” counterparts, such as triangles. The constraints imposed by the pattern upon the fixation tendencies occur at a level where the binocular inputs are processed. Of further importance was the fact that the fixation points approximate the foci observed in the same patterns when they are seen against a background of visual noise. It is suggested that the two results may be functionally related.. 相似文献
82.
The effects of incidental stimuli, defined as visual stimuli not under verbal control, upon a selection task were observed as a function of feedback contingency. Ss judged letter pairs to be valid or invalid completions of preceding letter parts. During the presentation of the letter parts, the response pair or an alternative pair of letters was intermittently presented at a threshold value individually determined for each S. One group of Ss received a light feedback of performance contingent upon responding to the incidental stimuli; whereas a second group received a random noncontingent feedback. The results indicated: (a) both groups responded to the incidental stimuli; (b) feedback contingency had no effect on frequency of responding to the incidental stimuli; (c) frequency of responding to the incidental stimuli remained constant over 32 trials. 相似文献
83.
84.
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
85.
Four pigeons were exposed to a two-key DRL procedure. At the start of a trial, key A was illuminated. A response to the lighted key turned it off and simultaneously illuminated key B. Reinforcement was available for responses on key B which followed the initial key A response by more than 2 sec. In the course of exposure to these conditions, all birds acquired superstitious response chains on key A. The distribution of the number of responses on key A preceding a key B response and the distribution of intervals elapsing from the initial key A response to the key B response were of the same form. The suggestion is made that the superstitious responding on key A served to mediate the required delay interval. However, when intervals between successive key A responses were recorded for one subject, they were found to be regularly spaced in time. Thus, the problem remains of how this behavior is itself timed. 相似文献
86.
The effects of unavoidable shocks on a multiple schedule having an avoidance component 总被引:1,自引:1,他引:0 下载免费PDF全文
Marcus B. Waller Patricia F. Waller 《Journal of the experimental analysis of behavior》1963,6(1):29-37
Two dogs were maintained on a multiple schedule having both a food reinforced and an avoidance component (Mult VI 1′ SΔ AvoidSS20 RS20 SΔ). The effects of superimposing an Estes-Skinner procedure for delivering unavoidable shocks on all components of the multiple schedule were observed. The buzzer-shock pairing of the Estes-Skinner procedure produced an increased rate of responding on the avoidance component of the schedule and also on the SΔ components. No persistent change in rate was observed on the food component during the pre-shock stimulus. Control performances on all components could be regained by either extinguishing or eliminating the buzzer-shock pairing. Extinction of the avoidance responding had little effect on the increased rates of responding produced by the Estes-Skinner procedure on the SΔ and avoidance extinction components and did not lead to a conditioned suppression of the food reinforced responding. Rate of responding during the pre-shock stimulus was observed to be relatively independent of changes in the maintaining schedules. Responding during the pre-shock stimulus could be conditioned and maintained after an extensive history of avoidance extinction. 相似文献
87.
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
88.
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
89.
90.
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