全文获取类型
收费全文 | 56479篇 |
免费 | 958篇 |
国内免费 | 5篇 |
专业分类
57442篇 |
出版年
2020年 | 775篇 |
2019年 | 989篇 |
2018年 | 1114篇 |
2017年 | 1125篇 |
2016年 | 1391篇 |
2015年 | 996篇 |
2014年 | 998篇 |
2013年 | 4766篇 |
2012年 | 1752篇 |
2011年 | 1917篇 |
2010年 | 1150篇 |
2009年 | 1135篇 |
2008年 | 1729篇 |
2007年 | 1688篇 |
2006年 | 1500篇 |
2005年 | 1362篇 |
2004年 | 1321篇 |
2003年 | 1217篇 |
2002年 | 1243篇 |
2001年 | 1790篇 |
2000年 | 1681篇 |
1999年 | 1295篇 |
1998年 | 694篇 |
1997年 | 590篇 |
1996年 | 548篇 |
1995年 | 540篇 |
1994年 | 510篇 |
1993年 | 531篇 |
1992年 | 1032篇 |
1991年 | 971篇 |
1990年 | 953篇 |
1989年 | 857篇 |
1988年 | 836篇 |
1987年 | 815篇 |
1986年 | 815篇 |
1985年 | 867篇 |
1984年 | 688篇 |
1983年 | 586篇 |
1982年 | 480篇 |
1979年 | 658篇 |
1978年 | 494篇 |
1976年 | 451篇 |
1975年 | 596篇 |
1974年 | 626篇 |
1973年 | 601篇 |
1972年 | 548篇 |
1971年 | 481篇 |
1968年 | 548篇 |
1967年 | 547篇 |
1966年 | 480篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
251.
252.
In this study we combined daily diary data with interview data to investigate individual differences in the impact of stressful daily events on mood. Using a sample of 96 women in an urban community, we examined perceived neighborhood quality and major life events as possibly potentiating the effects of stressful daily events, and we viewed social supports as potentially buffering this daily process. Results confirmed that the presence of chronic ecologic stress (neighborhood perceptions) exacerbated the immediate effects of stressful daily events on mood and also increased the likelihood of enduring effects of daily stressors on next day's mood. Contrary to expectations, previous exposure to major life events decreased the impact of stressful daily events. The availability of social supports, although not buffering the impact of stressful daily events on mood, did mitigate the enduring effects of these events on next day's mood. This study also presents a method for analyzing daily time-series data, while correcting for potential problems of autocorrelated error terms. As such, this study represents a significant advance over previous analytic approaches to time-series data in the study of the stress process. 相似文献
253.
Left sidedness and sleep difficulty: the alinormal syndrome 总被引:1,自引:1,他引:0
Four indexes of laterality: handedness, footedness, eyedness, and earedness, were assessed in a sample of 1274 subjects. Left- and right-sided groups were compared on two aspects of self-reported sleep difficulty: trouble falling asleep and frequent night wakenings. The incidence of sleep difficulty was found to be elevated in the left-sided groups. The results are discussed in terms of a possible complex of behavioral deviations from the statistical norm, called the alinormal syndrome. 相似文献
254.
255.
Vladimir A. Smirnov 《Studia Logica》1987,46(1):1-15
There is given the proof of strict embedding of Leniewski's elementary ontology into monadic second-order calculus of predicates providing a formalization of the class of all formulas valid in all domains (including the empty one). The elementary ontology with the axiom S (S S) is strictly embeddable into monadic second-order calculus of predicates which provides a formalization of the classes of all formulas valid in all non-empty domains. 相似文献
256.
Lori A. McElroy 《Memory & cognition》1987,15(2):148-153
The generation effect is the phenomenon in which words are remembered better when generated than when read. These experiments test the possibility that at least one consequence of generating is enhanced semantic processing. Homographs were used as targets, presented with rhymes in Experiment 1 so as not to bias meaning, and with synonyms in Experiment 2 to bias one meaning of each homograph. In beth experiments, extralist synonym cues were provided at recall. In Experiment 1 a generation effect was obtained when the retrieval cues biased the dominant meaning of the homograph (determined from free association norms), whereas in Experiment 2 a generation effect was found when the retrieval cues biased the same meaning that was biased during study. In neither experiment was a generation effect obtained with retrieval cues that biased the other meaning of each homograph. These results indicate that the generation effect is dependent upon the compatibility of the semantic processing conducted at study and test. Since it is impossible to process the meaning of a homograph when generating it from a rhyme cue, the meaning of the homograph could only have been processed after the word had been generated. The finding in Experiment 1 that a generation effect was obtained with rhymes when semantic retrieval cues were provided demonstrates that the enhancement properties associated with generation are not restricted to the information used to guide the generation process. This finding also indicates that one locus of the generation effect is in the processing that occurs after the word has been generated. 相似文献
257.
The functional development of cardiac and adrenal medullary responses to reflex activation of the sympathetic nervous system was studied in preweanling spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) normotensive rats. Pups of the two strains received injections of insulin or saline at 2, 4, 8, 12, or 16 days of age and were sacrificed 3 h later. Insulin administration produces a significant decrease in circulating levels of glucose which in turn results in a centrally mediated increase in sympathetic outflow. The induction of ornithine decarboxylase (ODC) in heart and the depletion of epinephrine from the adrenal medulla served as tissue markers of functional sympathetic neurotransmission. WKY and SHR pups had comparable levels of ODC activity in heart under basal conditions. In contrast, levels of catecholamines in the adrenals were greater in SHR pups at 2 and 4 days of age. Following insulin administration, SHR pups exhibited a greater induction of cardiac ODC activity at 2, 4, and 8 days of age compared to age-matched WKY controls. However, there were no differences between SHR and WKY pups in the magnitude of the adrenal medullary response to insulin-induced hypoglycemia. These alterations in sympathetic-target tissue development during the first postnatal week of life may contribute in part to the higher arterial pressures maintained by SHRs throughout the lifespan. 相似文献
258.
J M Henderson A Pollatsek K Rayner 《Journal of experimental psychology. Human perception and performance》1987,13(3):449-463
The results of three different experiments suggested that the relation between an object in the fovea on fixation n and an object subsequently brought into the fovea on fixation n + 1 affects the time to identify the second object. In Experiment 1 we extended previous work by demonstrating that a previously seen related priming object speeded the time to name a target object even when a saccade intervened between the two objects. In Experiment 2 we replicated this result and further showed that the benefit on naming time was due to facilitation from the related object rather than inhibition from the unrelated object. In addition, naming of the target object was much slower in both experiments when there was not a peripheral preview of the target object on fixation n. However, because the effect of the foveal priming object was greater when the target was not present than when it was present, priming did not appear to make extraction of the extrafoveal information more efficient. In Experiment 3, fixation times were recorded while subjects looked at four objects in order to identify them. Fixation time on an object was shorter when a related object was fixated immediately before it, even though the four objects did not form a scene. The size of the facilitation was roughly comparable to that in several analogous experiments where scenes were used. The results suggest that the effects of a predictive scene context on object identification may be explainable in terms of an object-to-object or "intralevel" priming mechanism. 相似文献
259.
R E Remez P E Rubin L C Nygaard W A Howell 《Journal of experimental psychology. Human perception and performance》1987,13(1):40-61
When listeners hear a sinusoidal replica of a sentence, they perceive linguistic properties despite the absence of short-time acoustic components typical of vocal signals. Is this accomplished by a postperceptual strategy that accommodates the anomalous acoustic pattern ad hoc, or is a sinusoidal sentence understood by the ordinary means of speech perception? If listeners treat sinusoidal signals as speech signals however unlike speech they may be, then perception should exhibit the commonplace sensitivity to the dimensions of the originating vocal tract. The present study, employing sinusoidal signals, raised this issue by testing the identification of target /bVt/, or b-vowel-t, syllables occurring in sentences that differed in the range of frequency variation of their component tones. Vowel quality of target syllables was influenced by this acoustic correlate of vocal-tract scale, implying that the perception of these nonvocal signals includes a process of vocal-tract scale, implying that the perception of these nonvocal signals includes a process of vocal-tract normalization. Converging evidence suggests that the perception of sinusoidal vowels depends on the relation among component tones and not on the phonetic likeness of each tone in isolation. The findings support the general claim that sinusoidal replicas of natural speech signals are perceptible phonetically because they preserve time-varying information present in natural signals. 相似文献
260.
Homicide which occurs in intimate social relationships was studied using data from three Western Canadian cities. Variables which may be related to the relationship and homicide are also examined. Unstable relationships are clearly differentiated from other relationships and are more likely to result in homicide. Implications for future research are discussed. 相似文献