全文获取类型
收费全文 | 8129篇 |
免费 | 569篇 |
国内免费 | 237篇 |
专业分类
8935篇 |
出版年
2024年 | 11篇 |
2023年 | 85篇 |
2022年 | 77篇 |
2021年 | 107篇 |
2020年 | 190篇 |
2019年 | 182篇 |
2018年 | 207篇 |
2017年 | 194篇 |
2016年 | 188篇 |
2015年 | 118篇 |
2014年 | 144篇 |
2013年 | 426篇 |
2012年 | 120篇 |
2011年 | 104篇 |
2010年 | 78篇 |
2009年 | 110篇 |
2008年 | 115篇 |
2007年 | 135篇 |
2006年 | 124篇 |
2005年 | 112篇 |
2004年 | 83篇 |
2003年 | 77篇 |
2002年 | 61篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 50篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 38篇 |
1995年 | 24篇 |
1994年 | 14篇 |
1993年 | 18篇 |
1992年 | 25篇 |
1991年 | 10篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1987年 | 9篇 |
1985年 | 455篇 |
1984年 | 517篇 |
1983年 | 423篇 |
1982年 | 524篇 |
1981年 | 496篇 |
1980年 | 515篇 |
1979年 | 461篇 |
1978年 | 493篇 |
1977年 | 368篇 |
1976年 | 369篇 |
1975年 | 310篇 |
1974年 | 308篇 |
1973年 | 254篇 |
排序方式: 共有8935条查询结果,搜索用时 7 毫秒
71.
72.
The purpose of this study was to determine the extent to which stutters manipulate vowel duration to achieve fluency after participating in Precision Fluency Shaping. Nine stutterers who read an all-voiced sentence fluently before and after therapy were selected for study. Wide-band spectrograms were made of the initial phrase of the sentences, and vowel durations were computed. Results indicated that extended vowel durations were characteristic of the fluency of stutterers posttherapy. The subject that had the highest rate of disfluency after therapy also had the shortest vowel durations. Clinical implications concerning the importance of speech rate during carryover practice are made. 相似文献
73.
74.
Three samples of different levels of mental ability, but each of average or above- average intelligence, were administered a battery of reaction time test which measure the speed with which persons can execute various elementary cognitive processes. Discriminant analyses revealed significant differences between the groups in reaction times and intraindividual standard deviations, and univariate analyses indicated that higher ability groups tended to obtain significantly faster mean reaction times and to show significantly less intraindividual variability than lower ability groups. Groups which differed the most in mental ability differed to the greatest extent on the more complex reaction time tests but this pattern was reversed for groups which were relatively close in mean IQ. Generally, the results support the hypothesis that speed- of-processing is an important factor unferlying intelligence, but a number of puzzling findings indicate the need for continued research in this area. 相似文献
75.
W V Dube W J McIlvane H A Mackay L T Stoddard 《Journal of the experimental analysis of behavior》1987,47(2):159-175
In an arbitrary matching-to-sample procedure, two mentally retarded subjects learned conditional discriminations with two sets of stimuli. Each set included a spoken name (N1 or N2), an object (O1 or O2), and a printed symbol (S1 or S2). One subject selected conditionally (a) O1 upon N1, and O2 upon N2, and (b) S1 upon O1, and S2 upon O2. The other subject selected conditionally (a) S1 upon N1, and S2 upon N2, and (b) O1 upon S1, and O2 upon S2. For both subjects, selections of O1 and S1 produced one type of food, F1; selections of O2 and S2 produced a different type of food, F2. Both subjects also learned identity-matching performances, selecting O1, O2, S1, S2, F1, and F2 conditionally upon those stimuli as samples; F1 followed selections of O1, S1, and F1; F2 followed selections of O2, S2, and F2. Matching performances consistent with stimulus class formation involving the names, objects, symbols, and foods were demonstrated on probe trials, even though these performances had not been taught explicitly. Next, new objects, X1 and X2, were presented on identity-matching trials, producing F1 and F2, respectively. Without further training, X1 was selected conditionally upon N1, S1, and O1, and X2 was selected upon N2, S2, and O2. When the contingencies were changed so that selections of X1 and X2 were now followed by F2 and F1, respectively, X2 was selected conditionally upon N1, S1, and O1, and X1 was selected upon N2, S2, and O2. Class membership of X1 and X2 had apparently changed. This study provides evidence that reinforcers may become members of stimulus classes, and that new stimuli may become class members through relations with reinforcers. 相似文献
76.
The interaction of stimulus and reinforcer control in complex temporal discrimination. 总被引:2,自引:2,他引:0
Six pigeons were trained in a discrete-trials signal-detection procedure to discriminate between a fixed-duration stimulus (5 s or 20 s) and a set of variable durations ranging from 2.5 s to 57.5 s in steps of 5 s. For each fixed-duration stimulus, the ratio of reinforcer frequencies contingent upon reporting the fixed versus the variable stimulus was systematically manipulated. Detection performance was well controlled by both the stimulus value and the reinforcer ratio. Both the discriminability between the fixed duration and the set of variable durations, and the discriminability between the fixed duration and each of the variable durations, were independent of the reinforcer-frequency ratio when discriminability was measured as log d. The sensitivity of response bias to reinforcement-ratio changes was independent of the value of the fixed duration, but was not independent of the discriminability of the variable durations from the fixed durations. Under current models, discriminability measures in complex temporal discrimination may be independent of biasing manipulations, but bias measures are not independent of stimulus values. 相似文献
77.
Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent-chains procedure. In Experiment 1, the alternatives were terminal-link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing, reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay-reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement. 相似文献
78.
DOES EFFORT PLAY A ROLE IN THE EFFECT OF RESPONSE REQUIREMENTS ON DELAYED MATCHING TO SAMPLE? 总被引:2,自引:2,他引:0 下载免费PDF全文
The possible role of "effort" in the accuracy of pigeons' performance on a delayed matching-to-sample procedure was investigated by examining the effects of response requirements that accompanied a trial-initiating stimulus and that accompanied a sample stimulus. In the first experiment, the effect of varying the size of a fixed-ratio requirement for responses during an initiating stimulus was compared to that of varying a similar requirement for responses during the sample stimulus. Accuracy increased reliably with increases in the ratio scheduled during the sample stimulus, but was not significantly affected by increases in the ratio scheduled on the key during the initiating stimulus. In another phase of Experiment 1, sample duration was held constant while the ratio requirement was varied during the initiating stimulus. Again, accuracy of matching to sample was not significantly affected by the size of the ratio scheduled during the initiating stimulus. Experiment 2 provided a systematic replication of these results in another group of pigeons and included a more detailed analysis of responding. These results support the view that increases in sample-response requirement facilitate accuracy of delayed matching by increasing the durations of exposure to the sample stimuli, and do not support a role of effort in the sample-response effect. In Experiment 3, the facilitative effect of responses on the sample but not of those on the initiating stimulus was replicated using a simultaneous matching-to-sample procedure. This finding provides further evidence against an interpretation of response-requirement effects that appeals to effort; the finding also suggests that sample exposure might affect initial discrimination of the sample rather than remembering the sample. 相似文献
79.
Frits E. Zegers 《Psychometrika》1986,51(4):559-562
A chance-corrected version of the family of association coefficients for metric scales proposed by Zegers and ten Berge is
presented. It is shown that a matrix with chance-corrected coefficients between a number of variables is Gramian. The members
of the chance-corrected family are shown to be partially ordered.
The author is obliged to Jos ten Berge for helpful comments. 相似文献
80.
Ronaldo Iachan 《Journal of Vocational Behavior》1984,24(2):133-141
A measure of agreement for partially ordered data is suggested that makes use of the k categories with the highest ranks, the ranks of the remaining categories being disregarded. The proposed measure is applied to the Self-Directed Search in order to evaluate its agreement with occupational preference. Other forms of agreement in the Holland classification system can also be assessed by the proposed measure. Examples are congruence and husband-wife and counselor-client agreement. 相似文献