全文获取类型
收费全文 | 32790篇 |
免费 | 1336篇 |
国内免费 | 8篇 |
出版年
2019年 | 429篇 |
2018年 | 562篇 |
2017年 | 589篇 |
2016年 | 587篇 |
2015年 | 422篇 |
2014年 | 529篇 |
2013年 | 2376篇 |
2012年 | 974篇 |
2011年 | 1042篇 |
2010年 | 611篇 |
2009年 | 607篇 |
2008年 | 898篇 |
2007年 | 881篇 |
2006年 | 830篇 |
2005年 | 747篇 |
2004年 | 731篇 |
2003年 | 661篇 |
2002年 | 692篇 |
2001年 | 1019篇 |
2000年 | 932篇 |
1999年 | 710篇 |
1998年 | 381篇 |
1997年 | 309篇 |
1996年 | 308篇 |
1992年 | 551篇 |
1991年 | 541篇 |
1990年 | 528篇 |
1989年 | 539篇 |
1988年 | 535篇 |
1987年 | 495篇 |
1986年 | 525篇 |
1985年 | 576篇 |
1984年 | 454篇 |
1983年 | 433篇 |
1982年 | 355篇 |
1981年 | 337篇 |
1979年 | 523篇 |
1978年 | 378篇 |
1977年 | 311篇 |
1976年 | 359篇 |
1975年 | 432篇 |
1974年 | 487篇 |
1973年 | 508篇 |
1972年 | 407篇 |
1971年 | 382篇 |
1970年 | 382篇 |
1969年 | 411篇 |
1968年 | 490篇 |
1967年 | 422篇 |
1966年 | 425篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
281.
282.
Smoking, body weight, and their effects on smoking behavior: a comprehensive review of the literature 总被引:19,自引:0,他引:19
This article provides a comprehensive review of the research on smoking and body weight. The relationships between smoking and body weight are evaluated in 70 cross-sectional and longitudinal investigations. The mechanisms responsible for differences in body weight are discussed, the weight-related issues that promote smoking behavior are reviewed, methods for reducing postcessation weight gain are summarized, and future research directions are proposed. A proposed working research model for studying the relationship between smoking, energy balance, and weight gain is offered. It is concluded that smoking and body weight relationships are closely related and pose significant challenges for smoking researchers. 相似文献
283.
Previous studies have shown that females tell stories that change from negative experiences (deprivation) to positive experiences (enhancement) and males tell stories that change in the opposite direction. The current study examines this phenomenon in children using a different story-telling procedure. Results were not consistent with those of previous studies. 相似文献
284.
E Kafka 《The Psychoanalytic quarterly》1989,58(4):571-591
My experience of clinical work is consistent with the conclusion that both practice and theory are improved by applying the contributions of Heinz Hartmann. His work provides an important conceptual bridge to understanding the adaptive and pathologic changes that appear in the course of human development. The specific details of those changes are just as much an issue demanding the analyst's attention as is the tracing of patterns of childhood instinctual life. In this paper, I will point to some areas of controversy where renewed attention to Hartmann's ideas might be useful, and I will attempt to illustrate the clinical utility of his theoretical contributions. 相似文献
285.
The explanation of apparent misalignment in the Poggendorff figure, based on underestimation of the intertransversal distance, was investigated in two experiments. In Experiment 1, subjects judged the intertransversal distance in the traditional Poggendorff figure and two of its variants. The size of the acute angle and the intertransversal distance were manipulated. Half of the subjects made the judgments with the method used by Wilson and Pressey (1976) and the other half made their judgments with the method used by Greist-Bousquet and Schiffman (1981). The results indicated that perceived intertransversal distance was greater with the former method. In Experiment 2, subjects adjusted the transversals to apparent collinearity in the same displays as were used in Experiment 1. The collinearity judgments were transformed to allow comparison with the results of Experiment 1. Comparison of the collinearity judgments with the distance judgments indicated that they did not follow similar trends. For each Poggendorff variant, proportional distance judgments increased as the size of the acute angle increased, and decreased as the intertransversal distance increased. Collinearity judgments did not vary as a function of intertransversal distance. As the size of the acute angle increased, collinearity judgments increased for two of the Poggendorff variants but decreased for the third. It was concluded that the findings did not support the explanation of apparent misalignment based on underestimation of the intertransversal distance. 相似文献
286.
Despite importance for theories of perception, controversy exists as to whether information is available to the perceptual system about involuntary as well as voluntary eye movements. We measured the perceived direction of targets flashed briefly in an otherwise dark field during the primary phase of optokinetic afternystagmus (OKAN), an involuntary eye movement that persists in darkness following optokinetic stimulation. Perceived direction was measured by unseen pointing in one experiment and by pointing made under visual control in a second experiment. Pointing was essentially veridical in both experiments, indicating that accurate extra-retinal information about eye position (presumably, as efference copy) exists for OKAN. Illusory motion of visual targets, which can occur during involuntary oculomotor responses, therefore cannot be attributed to a lack of efference-copy signals for such eye movements. 相似文献
287.
288.
J Allik E N Dzhafarov A J Houtsma J Ross N J Versfeld 《Perception & psychophysics》1989,46(6):513-527
Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported. 相似文献
289.
Internal consistency reliability of the fractionated and whole University of Pennsylvania Smell Identification Test 总被引:10,自引:0,他引:10
The internal consistency reliability (ICR) of the 40-item University of Pennsylvania Smell Identification Test (UPSIT) and its 10-, 20-, and 30-item fractions was explored, as well as the relationships between the fractions and the entire 40-item test. Pearson correlation coefficients (rs) were computed among all independent combinations and permutations of the four 10-item UPSIT booklets using data from 774 subjects. The median r values of the 10- and 20-item combinations were used to establish the ICRs of the 10- and 20-item tests. The ICRs of the 30- and 40-item tests were estimated using the Spearman-Brown formula and the median rs of the 20-item combinations. Additional ICR estimates of the 40-item UPSIT were obtained from nonsymmetrical fractions using the Horst formula. The ICRs for the UPSIT and its 10-, 20-, and 30-item fractions were 0.922, 0.752, 0.855 and 0.898, respectively. No major sex differences emerged. Estimates of correlations between (1) single booklets and two-booklet combinations and (2) the 40-item UPSIT using Guilford's (1953) correction for nonindependence ranged from 0.812 to 0.871. Overall, these results indicate that (1) the UPSIT and its 10-, 20-, and 30-item fragments have very high ICRs and (2) individual UPSIT booklets or their combinations can be used to assess smell function in a reliable manner where extreme time constraints are present (e.g., in surveys and in brief neuropsychological test batteries). 相似文献
290.
Obstacle perception by congenitally blind children 总被引:1,自引:0,他引:1
The ability to perceive objects from a distance and navigate without vision depends principally on auditory information. Two experiments were conducted in order to assess this ability in congenitally blind children aged 4 to 12 years who had negligible amounts of visual experience or formal mobility training. In Experiment 1, children walked along a sidewalk toward a target location to get some candy. A box was placed along the path on some trials, and the children were instructed to avoid the box if it was present. The children spent more time in the region just in front of the box than in the region just behind it, indicating that they perceived the box and acted so as to navigate around it. In Experiment 2, children attempted to discriminate whether a nearby disk was on their left or on their right. The children performed at above-chance levels, again indicating distal perception of objects. The results of both experiments suggest that blind children with little or no visual experience or formal training utilize nonvisual information, presumably auditory, to perceive objects. The specific nature of this auditory information requires further investigation, but these findings imply that the underlying perceptual ability does not require experience in spatial vision or deliberate training and intervention. 相似文献