全文获取类型
收费全文 | 214663篇 |
免费 | 9071篇 |
国内免费 | 162篇 |
出版年
2020年 | 2925篇 |
2019年 | 3603篇 |
2018年 | 4221篇 |
2017年 | 4550篇 |
2016年 | 5174篇 |
2015年 | 4069篇 |
2014年 | 4964篇 |
2013年 | 24168篇 |
2012年 | 6109篇 |
2011年 | 5677篇 |
2010年 | 4712篇 |
2009年 | 5223篇 |
2008年 | 5658篇 |
2007年 | 5205篇 |
2006年 | 5402篇 |
2005年 | 5204篇 |
2004年 | 4717篇 |
2003年 | 4317篇 |
2002年 | 4091篇 |
2001年 | 5229篇 |
2000年 | 4961篇 |
1999年 | 4331篇 |
1998年 | 3083篇 |
1997年 | 2864篇 |
1996年 | 2759篇 |
1995年 | 2580篇 |
1994年 | 2545篇 |
1993年 | 2481篇 |
1992年 | 3566篇 |
1991年 | 3370篇 |
1990年 | 3261篇 |
1989年 | 3054篇 |
1988年 | 3017篇 |
1987年 | 2954篇 |
1986年 | 2971篇 |
1985年 | 3253篇 |
1984年 | 3069篇 |
1983年 | 2756篇 |
1982年 | 2557篇 |
1981年 | 2524篇 |
1980年 | 2364篇 |
1979年 | 2848篇 |
1978年 | 2540篇 |
1977年 | 2421篇 |
1976年 | 2264篇 |
1975年 | 2565篇 |
1974年 | 2716篇 |
1973年 | 2671篇 |
1972年 | 2168篇 |
1971年 | 2034篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
861.
Day and Bellezza (1983) rejected a dual coding imagery explanation for the superior recall of concrete words because unrelated concrete pairs were rated lower in composite imagery but were still remembered better than related abstract pairs. We show that dual coding theory explains their results and our new findings using the same paradigm. In Experiment 1, 120 subjects rated imagery or relatedness for 108 pairs that varied in concreteness, pair relatedness, and associative strength. Incidental cued recall followed. Relatedness and strength affected imagery ratings, as did concreteness, and very low relatedness partly accounted for the low composite imagery ratings for unrelated concrete pairs. Concreteness and relatedness also affected recall, and suporior recall for unrelated concrete pairs occurred consistently under imagery but not under relatedness instructions. In Experiment 2, 40 subjects rated imagery value and recalled 24 pairs. Subsequent questioning indicated that composite images were retrieved better given stimuli from unrelated concrete than from related abstract pairs. These findings and Day and Bellezza’s original results are explained in terms of (1) imaginal and verbal associative processes, which jointly influence composite imagery ratings and recall, and (2) the critical role of stimulus concreteness during image retrieval and recall (i.e., the conceptual peg hypothesis). 相似文献
862.
Cyd C. Strauss Cynthia A. Lease Cynthia G. Last Greta Francis 《Journal of abnormal child psychology》1988,16(4):433-443
Differences between a clinical sample of younger (ages 5 to 11) and older (ages 12 to 19) children meeting DSM-III criteria for overanxious disorder (OAD) were examined. Younger and older children were compared in terms of (1) the rates of OAD diagnoses occurring in the two age groups, (2) sociodemographic characteristics, (3) symptom expression, (4) association with other forms of maladjustment, and (5) self-reported anxiety and depression. The prevalence of OAD diagnoses and sociodemographic characteristics did not differ. Although younger and older OAD children showed similar rates of most specific DSM-III OAD symptoms, older children presented with a higher total number of overanxious symptoms than younger children. Older children more frequently exhibited a concurrent major depression or simple phobia, whereas younger OAD children more commonly had coexisting separation anxiety or attention deficit disorders. Older OAD children reported significantly higher levels of anxiety and depression on self-report measures. Findings indicated that the expression of OAD varies by developmental level. 相似文献
863.
Three experiments tested the hypothesis that people can execute focused searches of semantic cases when answering questions about complex facts, such as “the teacher watered the peas, the corn, and the lettuce with the hose.” In Experiment 1, answer time varied mainly with the number of concepts in the relevant or focused case, supporting the hypothesis. Experiment 2 indicated that the irrelevant case undergoes some processing. Experiment 3 confirmed that search in Experiments 1 and 2 focused on semantic cases rather than on taxonomic categories. It is proposed that focused memory search has a high probability of retrieving the relevant case and a low probability of retrieving the irrelevant case. In the latter event, the irrelevant concepts receive full processing. 相似文献
864.
Catherine Z. Elgin 《Synthese》1988,74(3):297-311
I show that it follows from both externalist and internalist theories that stupid people may be in a better position to know than smart ones. This untoward consequence results from taking our epistemic goal to be accepting as many truths as possible and rejecting as many falsehoods as possible, combined with a recognition that the standard for acceptability cannot be set too high, else scepticism will prevail. After showing how causal, reliabilist, and coherentist theories devalue intelligence, I suggest that knowledge, as contemporary theories construe it, is not a particularly valuable cognitive achievement, and that we would do well to reopen epistemology to the study of cognitive excellences of all sorts.I am grateful to Warren Goldfarb for sharing his knowledge of wines with me, and to Kenneth Winkler for sharing his knowledge of birds. 相似文献
865.
Short-term memory for Chinese characters and radicals 总被引:1,自引:0,他引:1
Short-term memory for Chinese radicals and characters, varying in orthographic complexity, frequency, and—for radicals—intercharacter frequency (the number of compound characters that contain the radical), was studied using an immediate free-recall task. When radicals or characters are relatively frequent, so that their pronunciations are well known by literate Chinese, they seem to be maintained in verbal form in short-term memory. For these stimuli, intercharacter frequency and complexity have relatively small influences on memory span. Stimuli low in frequency, with pronunciations that are not apt to be known, seem to be maintained in visual form in short-term memory. Memory span is much smaller for these stimuli and is influenced by both intercharacter frequency and complexity. Furthermore, short-term memory for relatively high-frequency characters is interfered with more by a verbal than by a visual intervening task, whereas the opposite is true for low-frequency characters. 相似文献
866.
Sentences containing idioms used either literally or figuratively were presented repeatedly for 100 msec per presentation. Half of the sentences were preceded by a paragraph. The number of presentations required to read the sentences and cued recall of the sentences were recorded. The serial brief presentations method provided predictable and meaningful results. Sentences containing idioms used literally required more presentations than those containing idioms used figuratively. Cued recall was better for idioms used literally than for those used figuratively. These results are interpreted as support for the Idiomatic Processing Model of idiom comprehension, which suggests that the figurative meaning is processed first; only if that one is inappropriate is the literal meaning processed. 相似文献
867.
D Livesey 《Behavioral and neural biology》1988,50(2):153-163
The finding that there are maturational differences between the ability to learn and to perform a task requiring young Wistar rats to inhibit a response was examined. Using an operant task, different from that employed in the previous studies, it was established that the finding was not task specific. The relative contribution of different periods in the early training stage to later savings in learning was also examined. It was confirmed that there is an early performance deficit by weanling rats on tasks requiring them to inhibit a previously learned response in the presence of a discriminative cue. Rats given early training on the task during this period of performance deficit nevertheless showed significant savings in later learning of the task, indicating that they had learned as much in that stage as they would have if given the same training at an age when performance is at the adult level. It was revealed that despite age-related differences in performance it was not so much the age at which early training took place as the amount of training given that affected later savings. The results are discussed in light of evidence of similar differences between the learning and performance of discrimination tasks exhibited by young children. 相似文献
868.
The modulation of attacks, genital sniffs, and mounts in male SJL/J mice by ovarian-dependent urogenital substances in the urine voided by estrous females was examined. Urogenital substances were applied onto the external urogenital areas of ovariectomized mice. When compared with urine voided by estrous females, which stimulated genital sniffing, mounting, and reduced aggression, bladder urine was ineffective. Genital sniffing and mounting was stimulated by estradiol-17 beta, vaginal fluids, and preputial extract. Aggression was reduced by estradiol-17 beta, urethral catheterized urine, and vaginal fluids. Preputialectomy reduced, but did not eliminate, urinary stimulation of genital sniffing and mounting. Preputial extract stimulated aggression. Urogenital substances from ovariectomized females were ineffective in reducing attacks and stimulating genital sniffs and mounts. It was concluded that the ovarian-dependent chemosignals in the urine voided by estrous females are contributed by the urethra, vagina, and preputial gland, perhaps in part through the excretion of unconjugated estrogens. 相似文献
869.
Wistar rats of three age groups were tested in an automated tunnel-maze system of variable geometry to investigate whether changes in spontaneous locomotor activity and in learning and memory develop differentially or in a correlated fashion as a function of age. Senescent (30 months) as well as mature-adult (17 months) rats showed an age-correlated decline of locomotor activity as compared to the mature-young (5 months) group. Both working-memory (measured as within-trial arm discrimination performance) and reference-memory (measured as avoidance of "blind alley" visits) were severely affected in the senescent group, whereas the middle-aged animals suffered only from a working-memory deficit. The findings provide evidence that locomotor deficits do not necessarily interfere in the assessment of age-related changes in cognitive performance. Furthermore the results support the hypothesis that working and reference memory have different underlying physiological correlates and that these neuronal systems are differentially affected by the aging process. 相似文献
870.
J L Díaz 《Behavioral and neural biology》1988,50(2):164-183
Fifty 8-week-old Balb/c mice were individually identified and housed together in a large and enriched environment for 5 months. Maze and open field exploration, response to an aversive noise, swimming, and induced grooming tests were applied to each mouse in an initial search for possible relationships between brain morphology and spontaneous behavior in isogenic individuals living in a complex social and physical environment. The tasks generated 39 quantitative behavioral indices which include locomotion, rearing, still, and grooming bout frequencies, latencies, total, and mean bout durations. At the end of the tests, the 7-month-old mice were sacrificed and the fresh weights of their whole brain, cerebellum, brain stem, diencephalon, telencephalon, and prosencephalon were rapidly obtained. Behavioral data have wide variations and do not adjust to normal population distributions. Means of the same parameter differ between tests. A Spearman correlation matrix of all data yielded many significant correlations between indices of the same task which can be interpreted in terms of time budget and sequence probability. Significant correlations between indices of different tests suggest diverse emotionalities, exploratory strategies, and motor skills. The correlations between body and brain weights and among separate brain regions were not significant. There were several low but significant correlations between brain weights and behavioral indices. Such correlations, the resulting factors, and significant behavioral differences between mice with large and small brains suggest that mice displaying low motor activity in novel environments have larger brains and forebrain/hindbrain ratios than mice with high activity, and that animals with high scores of some specific behaviors have larger brain areas physiologically related to such behaviors.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献