全文获取类型
收费全文 | 80461篇 |
免费 | 3308篇 |
国内免费 | 37篇 |
专业分类
83806篇 |
出版年
2020年 | 901篇 |
2019年 | 1102篇 |
2018年 | 1563篇 |
2017年 | 1633篇 |
2016年 | 1650篇 |
2015年 | 1201篇 |
2014年 | 1411篇 |
2013年 | 6797篇 |
2012年 | 2599篇 |
2011年 | 2692篇 |
2010年 | 1666篇 |
2009年 | 1678篇 |
2008年 | 2366篇 |
2007年 | 2274篇 |
2006年 | 2106篇 |
2005年 | 1771篇 |
2004年 | 1752篇 |
2003年 | 1726篇 |
2002年 | 1619篇 |
2001年 | 2734篇 |
2000年 | 2608篇 |
1999年 | 1929篇 |
1998年 | 919篇 |
1997年 | 767篇 |
1996年 | 841篇 |
1995年 | 761篇 |
1994年 | 763篇 |
1993年 | 743篇 |
1992年 | 1616篇 |
1991年 | 1507篇 |
1990年 | 1482篇 |
1989年 | 1399篇 |
1988年 | 1374篇 |
1987年 | 1298篇 |
1986年 | 1261篇 |
1985年 | 1361篇 |
1984年 | 1094篇 |
1983年 | 918篇 |
1979年 | 1118篇 |
1978年 | 838篇 |
1977年 | 731篇 |
1975年 | 936篇 |
1974年 | 1026篇 |
1973年 | 1095篇 |
1972年 | 910篇 |
1971年 | 816篇 |
1969年 | 739篇 |
1968年 | 929篇 |
1967年 | 798篇 |
1966年 | 831篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
D S Blough 《Journal of experimental psychology. Animal behavior processes》1985,11(2):261-280
In a three-choice discrimination task, pigeons learned to distinguish each letter of the alphabet from all the other letters and each of 16 random dot patterns from all the others. Discrimination errors were used to generate a matrix of interletter and interpattern similarities. Human estimates of letter similarity were obtained from the literature, and human subjects rated the similarity of the dot patterns. Pigeon and human performances were described and compared through correlation, multidimensional scaling, and cluster analysis. Fits of the data by simple-feature and template models were computed and compared. The correlation between pigeon and human similarity matrices was .68 for letters and .72 for dot patterns. The other analyses revealed broadly similar patterns of results from the two species but suggested also that, relative to human data, the best fits to the pigeon data required fewer dimensions, fewer features, and fuzzier templates. There was some indication that pigeon discriminations depended on relatively simple features, and several of these were tentatively identified. The different methods employed might have influenced these apparent differences between pigeons and humans, but, overall, the results suggest considerable cross-task and cross species generality in the processing of these simple forms. 相似文献
982.
S Roberts M D Holder 《Journal of experimental psychology. Animal behavior processes》1985,11(2):194-214
Six experiments with rats used a psychophysical choice procedure to study the internal clock used to discriminate duration. They investigated if the clock is sensitive to the signal value (associative strength) of a stimulus. The experiments involved two types of trials. On choice trials, a stimulus lasted a short (e.g., 3 s) or long (e.g., 12 s) duration; then the rats chose between two levers. The rewarded choice depended on the duration of the stimulus. On conditioning trials, the stimulus used on choice trials was presented, but it ended without food (extinction trials) or with food (pairing trials) regardless of what the rat did. The main stimulus minus accuracy with the long stimulus. Experiment 1 showed that extinction trials increased short bias relative to training without conditioning trials or to training with pairing trials. The rest of the experiments tested explanations of these results. The same results were found when extinction trials were the same duration as the short stimulus (Experiment 2), when extinction trials were a random duration (Experiment 5), and when the signal value of the conditioned stimulus was changed in another way (Experiment 6). The effect of conditioning trials was modality specific (Experiments 3 and 4). Of the explanations considered, the best one--the only one not contradicted at least once--is that changing the signal value of a stimulus changes how the clock times the stimulus. Reducing signal value reduces the measured duration. 相似文献
983.
J Cranney M E Cohen H S Hoffman 《Journal of experimental psychology. Animal behavior processes》1985,11(1):112-119
In laboratory rats (as in humans) a low-intensity tone that precedes a high-intensity burst of noise by approximately 100 ms can reduce the amplitude of the startle reaction elicited by the burst of noise. A series of four experiments with rats investigated the relation between the inhibitory effects of tonal frequency change and the length of the silent period (gap) preceding it. The major findings were the following: (a) A gap in an otherwise continuous pure tone inhibited startle when the gap occurred approximately 100 ms prior to the noise burst. (b) Although an increase in gap duration increased the inhibition afforded by the gap, the maximum inhibition was yielded by gaps of 100 ms and greater; this maximum was equivalent to the inhibition yielded by the presentation of a postgap tone alone. (c) A shift in tonal frequency across a 10-ms gap yielded more inhibition than did the same gap with no frequency shift; again the shift yielded equivalent inhibition to the presentation of the postgap tone alone. (d) An increase in the frequency shift increased inhibition when the shift occurred across a 10-ms gap, but not when the shift occurred across a 100-ms gap. 相似文献
984.
Deep dyslexia in childhood? 总被引:1,自引:0,他引:1
L S Siegel 《Brain and language》1985,26(1):16-27
Deep dyslexia is an acquired reading disorder in which semantic substitutions (e.g., city read as town) are made in reading single isolated words. In this paper, evidence for deep dyslexic-type errors is presented from the word-recognition responses of six children, aged 7 years and 0 month to 8 years and 9 months, with severe reading disorders. These semantic substitutions occur in the absence of phonological skills. Therefore, it appears that there exists a small subset of developmental dyslexics who at the beginning of acquisition of reading skills are able to engage in semantic processing, but who show severe impairment of phonological processing. The existence of these reading errors indicate that the use of a phonological code is not necessary to extract meaning from the printed word. 相似文献
985.
Observers detected a briefly flashed target letter embedded in word, pronounceable nonword, and unpronounceable nonword contexts. The word context facilitated perception under both holistic and analytical processing strategies; the facilitative effect was enhanced when processing was analytical. 相似文献
986.
987.
The attitudes of 674 speech-language pathologists toward stuttering, stutterers, stuttering therapy, parents of stutterers, and related issues were studied during the years 1973–1983. During that period, clinician attitudes were found to shift away from support of the John-sonian concepts, which suggest parental causality and dangers in early intervention. In addition, clinicians became less likely to perceive stutterers as possessing psychologic disorders and misperceptions of their problem and of their interpersonal relationships. However, a significant number of clinician's were found to continue to hold unsubstantiated beliefs regarding the personality of stutterers, their parents, and the efficacy of early intervention with very young stutterers. The results of the study were interpreted as suggesting the need to educate fluency specialists. 相似文献
988.
989.
In reviewing the literature on the social impact of high school, six themes were identified: (1) students perceive strong norms for conformity to school rules, (2) the emphasis on conformity and control influences the quality of student/teacher relations which tend to be role bound and inflexible, (3) paths to social status continue to emphasize athletic competence, (4) peer group identification has an impact on social relations within the larger community as well as in the school setting, (5) powerlessness is felt as a result of the authoritarian approach to decision making, and (6) the overall high school environment does not enhance students' beliefs in the Bill of Rights. It was concluded that high school students have limited opportunities for flexible self-definition. As a result of the way they are treated by authority figures and the strong pressures toward conformity, many adolescents fail to learn the extent of their rights or effective strategies for the exercise of power. 相似文献
990.
This study investigated young adults' contraceptive behaviors and attitudes through application of a comprehensive, theoretical framework. Specifically, a social-psychological approach to understanding preventive behaviors (e.g., contraceptive practices), was developed, incorporating the Health Belief Model and other factors, which offered a means for evaluating the extent to which contraceptive behaviors were influenced by individual and group characteristics. The study group consisted of 283 unmarried students at several schools who were, on average, 19 years of age. Results suggested that effective contraceptive behavior associated most strongly with respondents' perceiving relatively few barriers to their use of contraception, their maintenance of extensive interpersonal skills, and their regarding peer norms as consistent with effective contraceptive behavior. Findings also underlined a need for continuing education about sexuality and contraception. Dangerous misinformation prevailed regarding respondents' knowledge of areas that include anatomy, physiology, and appropriate use of effective contraceptive methods. Finally, results implied a need to consider broad behavioral, social, and interpersonal issues as they relate to young adults' effective contraceptive behavior. Future studies of contraceptive risk taking are encouraged to examine both individual and social factors affecting sexual and contraceptive practices if unplanned pregnancy is to be minimized, if not eliminated. 相似文献