全文获取类型
收费全文 | 38726篇 |
免费 | 1579篇 |
国内免费 | 14篇 |
出版年
2020年 | 357篇 |
2019年 | 414篇 |
2018年 | 571篇 |
2017年 | 578篇 |
2016年 | 645篇 |
2015年 | 486篇 |
2014年 | 552篇 |
2013年 | 2589篇 |
2012年 | 1088篇 |
2011年 | 1054篇 |
2010年 | 662篇 |
2009年 | 630篇 |
2008年 | 945篇 |
2007年 | 936篇 |
2006年 | 811篇 |
2005年 | 783篇 |
2004年 | 732篇 |
2003年 | 668篇 |
2002年 | 690篇 |
2001年 | 1264篇 |
2000年 | 1221篇 |
1999年 | 887篇 |
1998年 | 395篇 |
1992年 | 862篇 |
1991年 | 800篇 |
1990年 | 819篇 |
1989年 | 715篇 |
1988年 | 711篇 |
1987年 | 683篇 |
1986年 | 714篇 |
1985年 | 787篇 |
1984年 | 588篇 |
1983年 | 544篇 |
1982年 | 368篇 |
1981年 | 357篇 |
1980年 | 343篇 |
1979年 | 686篇 |
1978年 | 424篇 |
1977年 | 415篇 |
1976年 | 412篇 |
1975年 | 583篇 |
1974年 | 668篇 |
1973年 | 714篇 |
1972年 | 617篇 |
1971年 | 578篇 |
1970年 | 573篇 |
1969年 | 562篇 |
1968年 | 751篇 |
1967年 | 664篇 |
1966年 | 595篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
801.
Rats provided with chronic, continuous access to intracranial self-stimulation (ICS) exhibit discrete episodic response patterns. Response episodes under two conditions were examined for systematic trends in the spacing of times between successive responses (interresponse times; IRTs) to better identify the motivational bases of ICS. Three trends were observed in self-initiated and experimenter-provoked episodes. First, initial responses of spontaneous episodes typically had declining interresponse times. Second, this trend was not present when responses were provoked rather than spontaneous. Third, absolute times between responses varied across conditions, with provoked behavior having significantly lower initial IRTs. The findings suggest that for spontaneously initiated responding a transient facilitatory process cumulates at the beginning of ICS episodes. For provoked responding, it is possible that a manipulation which increased the initial probability of responding over time may have done so by maximizing an initial phasic priming process. At their onset, spontaneous and provoked episodes may be characterized by quantitatively differing motivational profiles. 相似文献
802.
Recent data on post-war birth cohorts in the U.S.A. show a negative relationship between IQ and fertility, both actual and expected. Previous investigators (e.g. Bajema, the Reeds and Waller) had found a slightly positive relationship for certain pre-war birth cohorts. This secular change in the relationship between IQ and fertility is replicated here for data on the membership of the American Mensa. Members born before the war exhibit a fertility below but close to that of the equivalent cohorts in the nation as a whole. Members born during and after the war exhibit a fertility that is substantially lower than that of the equivalent national cohorts. Apparently, rising fertility, which characterized the period in which the pre-war birth cohorts bore their children, causes a convergence in birth rates across IQ classes. Declining and/or low fertility, which characterizes the period in which the post-war birth cohorts are bearing their children, has the opposite effect, i.e. a divergence in birth rates across IQ classes, with the lower birth rates in the higher-IQ classes. The membership of Mensa may not be a representative sample of the high-IQ population as a whole, as it seems to attract a disproportionate number of low procreators even for this population. However, there is no reason to believe that changes in fertility rates across cohorts within Mensa, relative to changes in the national fertility rates, do not reliably reflect changes in fertility rates across cohorts within the high-IQ population of the U.S.A. as a whole, again relative to those of the nation, though these rates may be fluctuating around different means. 相似文献
803.
Sybil B.G. Eysenck G. Easting P.R. Pearson 《Personality and individual differences》1984,5(3):315-321
A total of 1505 children (633 boys and 872 girls) completed the I6 Impulsiveness Questionnaire. Reliabilities, scale intercorrelations and means and standard deviations are given after slight modifications were made to the original scoring key on the basis of factor analyses. Age means for both sexes are also given. 相似文献
804.
R Stillman E DeRenzo O Wolkowitz H Allen R A Lehman R J Wyatt 《Brain and cognition》1984,3(3):335-342
Robust lateralization developed in right-handed adults who were asked to judge letter pairs as "same" or "different" during 4608 trials. By the end of the first two blocks (768 trials) "same" responses were favored when presented in the RVF (transmitted directly to the left hemisphere) and "different" responses were favored when presented in the LVF (transmitted direction to the right hemisphere). This gradually reversed over sessions with "same" responses becoming faster for letters presented in the LVF, and "different" responses becoming faster for stimuli presented in the RVF. The laterality acquired under these conditions was cumulative and reproducible, appeared in all 16 subjects, and was preserved between sessions a week apart. The data suggest that laterality is a flexible and reversible characteristic of the human brain even when stimulus and task remain constant. 相似文献
805.
Summary Previous investigations of the global precedence hypothesis (Navon, 1977) have utilized compound letter stimuli. In these stimuli there is no predictive relationship between the global and local levels. Pictorial stimuli, however, contain mutually predictable global and local levels. This study investigated the global precedence hypothesis with pictorial stimuli using a Stroop-like interference task similar to that used by Navon. Subjects were required to respond either to the global (e.g., beach or farm) or local (e.g., boat or tractor) level of a scene. The display size and consistency of the global and local levels were varied. Response latencies supported global precedence for small scenes (4°) but local precedence for large scenes (16°). The results are interpreted by a model in which the priority of processing is determined by a critical spatial frequency sampling bandwidth.Portions of this research were presented at the meeting of the Psychonomic Society, Minneapolis, November, 1982. The authors with to express their sincere appreciation to Tom Petros for his assistance in data analysis. Requests for reprints should be addressed to James R. Antes, Department of Psychology, University of North Dakota, Grand Forks, ND 58202. 相似文献
806.
John B Pryor Teri L Kott Gregory R Bovee 《Journal of experimental social psychology》1984,20(3):246-262
The following question is addressed: How do multiple, simultaneously present cognitive structures influence the representation and recall of social information? In an empirical study examining both free and cued recall, we found the variable information redundancy to influence both the organization and accuracy of subjects' recollections of trait-related behaviors. Redundancy was defined in terms of the degree of person/trait overlap in a social information ensemble. Some evidence indicated that this effect is attributable to an increase in the discriminability of the organizational structures during encoding. The implications of these findings for understanding the formation of integrated cognitive representations of individuals and the spontaneous use of traits in social information processing are discussed. 相似文献
807.
R.Edward Geiselman Nancy A Haight Lori G Kimata 《Journal of experimental social psychology》1984,20(5):409-424
Four experiments were conducted to study the nature of context effects on the perceived physical attractiveness of faces. In Experiment 1, photos of faces scaled on attractiveness were presented in sets of three, with target faces appearing in the middle flanked by two context faces. The target faces were of average attractiveness, with the context faces being either high, average, or low in attractiveness. The effect of the context was one of assimilation, rather than contrast, regardless of whether the persons in the photos were portrayed to be associated. This result was interpreted in terms of a “generalized halo effect” for judgments of the physical attractiveness of stimuli within a group. Presenting the persons of a set as friends enhanced the perceived attractiveness of the target face but only when the context did not contain a face of low attractiveness. In Experiment 2, the assimilation effect was observed to carry over to influence ratings of the target faces several minutes after the context faces had been removed. Experiment 3 showed the assimilation effect to be robust regardless of whether the context was composed of two faces or one, but Experiment 4 showed the assimilation effect to be evident only when the context faces were presented simultaneously with the target. 相似文献
808.
An attempt to replicate and extend the successful results of Foxx and Brown's (1979) nicotine-fading, self-monitoring procedure for smoking abstinence or controlled smoking was undertaken using a combination of their procedure and cognitive-behavioural interventions. The latter consisted of: (1) a variation of Meichenbaum's (1977) self-instructional training and (2) a simple, direct manipulation of Bandura's (1977) concept of self-efficacy. Evidence was found to support Foxx and Brown's (1979) procedure with respect to reduced smoking rate and nicotine/tar intake. Combinations of treatments did not result in an enhancement of these effects. However, with respect to smoking abstinence, comparable results were only found in groups receiving specific training in self-efficacy. It was suggested that the variability of findings in this study as well as those in the literature subsequent and relating to Foxx and Brown's (1979) procedure might be accounted for using Bandura's (1977) self-efficacy concept. 相似文献
809.
A consecutive series of 30 school refusers received behavioural treatment (BTA). Their outcome is compared with that of 16 school refusers who were hospitalized and 20 who received psychotherapy and home tuition. The BTA group showed superior outcome compared to the other two groups. The Home-tuition group did very badly. There was no evidence of symptom substitution in the 28 cases treated successfully by behaviour therapy. 相似文献
810.