全文获取类型
收费全文 | 83492篇 |
免费 | 3369篇 |
国内免费 | 42篇 |
出版年
2020年 | 863篇 |
2019年 | 1068篇 |
2018年 | 1509篇 |
2017年 | 1505篇 |
2016年 | 1629篇 |
2015年 | 1139篇 |
2014年 | 1363篇 |
2013年 | 6668篇 |
2012年 | 2523篇 |
2011年 | 2636篇 |
2010年 | 1612篇 |
2009年 | 1588篇 |
2008年 | 2403篇 |
2007年 | 2382篇 |
2006年 | 2072篇 |
2005年 | 1928篇 |
2004年 | 1859篇 |
2003年 | 1692篇 |
2002年 | 1750篇 |
2001年 | 2680篇 |
2000年 | 2526篇 |
1999年 | 1940篇 |
1998年 | 981篇 |
1997年 | 859篇 |
1996年 | 798篇 |
1993年 | 779篇 |
1992年 | 1689篇 |
1991年 | 1560篇 |
1990年 | 1579篇 |
1989年 | 1390篇 |
1988年 | 1355篇 |
1987年 | 1330篇 |
1986年 | 1372篇 |
1985年 | 1474篇 |
1984年 | 1153篇 |
1983年 | 1034篇 |
1979年 | 1199篇 |
1978年 | 850篇 |
1977年 | 770篇 |
1976年 | 804篇 |
1975年 | 1073篇 |
1974年 | 1157篇 |
1973年 | 1194篇 |
1972年 | 1064篇 |
1971年 | 965篇 |
1970年 | 921篇 |
1969年 | 901篇 |
1968年 | 1173篇 |
1967年 | 1093篇 |
1966年 | 976篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
841.
Age, exercise, and coding performance 总被引:1,自引:0,他引:1
We investigated the effects of exercise on the coding performance of young and older subjects. Hypotheses were tested that exercise either facilitates spatial localization or reduces susceptibility to distraction in older subjects. In a balanced design, we administered Digit Symbol and Symbol Digit coding tasks to exercisers and nonexercisers at two age levels under conditions of low or high within-task interference. The findings showed higher performance by the exercisers than by the nonexercisers only at the older age level and only with the Symbol Digit task. These findings support the hypothesis that exercise compensates for a loss of spatial localization skills with age. We found no evidence that susceptibility to distraction either increased with age or was affected by chronic exercise. 相似文献
842.
Frontal lobe dysfunction and memory impairment in patients with chronic progressive multiple sclerosis 总被引:2,自引:0,他引:2
Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly. 相似文献
843.
Steven R. Smith 《Behavioral sciences & the law》1989,7(2):145-180
This article reviews the history of and basis for mental health testimony. It surveys the roles of such experts in the legal system and the concomitant problems with current approaches. Finally, it suggests specific reforms that may improve the use of mental health experts in legal proceedings. 相似文献
844.
Hal R. Arkes 《Behavioral sciences & the law》1989,7(4):429-456
Principles in the judgment/decision making literature relevant to the legal community are reviewed. These principles are divided into four areas: the decision process itself, communicating a judgment to others, evaluating a decision, and possible ways of “debiasing.” Several influences on the decision process are enumerated, among them being insufficient consideration of base rates, selective memory for relevant material, the framing of the decision in either the domain of losses or the domain of gains, and consideration of the “cues to causation.” Particular attention is paid to suboptimal consideration of covariation information. In communicating the decision to others the two most prominent findings are overconfidence in expressing one's decision and the inability to describe accurately the bases of one's decision. Evaluating a decision is plagued by two biases. The first is the hindsight bias. After an event has occurred we tend to exaggerate how easily we could have predicted the event beforehand. The second is the outcome bias. We tend to base our evaluation of the decision upon the evaluation of the outcome. Among the debiasing techniques mentioned are the admonition to “consider the opposite” of the preferred option, the reduction of reliance on memory, and the use of decision aids. 相似文献
845.
M T Phelps W A Roberts 《Journal of comparative psychology (Washington, D.C. : 1983)》1989,103(4):326-338
We studied central-place foraging in rats (Rattus norvegicus) by placing food items that varied in size and weight at the ends of a 4-arm radial maze. In Experiments 1-3, rats increasingly tended to carry food to the center of the maze as the size of those items increased. Very large food items often were hoarded in the center. Rats consumed food faster on the arms than in the center, and rats traveled faster when carrying food than when not. Blocking arm entrances increased travel time between the center and the arms and decreased food carrying at every item weight except the largest. In Experiments 4-6, important conditions that influence the degree of food-carrying behavior were discovered; these were the intersection of maze arms, the presence of a conspecific, and the use of open vs. closed maze arms. 相似文献
846.
D A Nelson 《Journal of comparative psychology (Washington, D.C. : 1983)》1989,103(2):171-176
Estimate the amount of frequency variation that affected individual and species recognition by song in territorial male field sparrows with field playbacks of neighbors' songs lowered in frequency in 6 increments between 324 and 1296 Hz. Males gave strong responses to neighbors' songs that had been lowered by about 400 Hz, which is about 11% of the mean midfrequency in field sparrow song. Territorial responses were eliminated when neighbors' songs were lowered by more than about 900 Hz. Thus, there is a fairly narrow range of frequencies within which field sparrow songs can vary while functioning in communication. Ss' responses appear to be constrained by the normal range of song frequency variation within the species, but the range of variability within songs of individuals did not influence the degree of frequency shift required to render neighbors' songs unfamiliar. 相似文献
847.
848.
Dilys R. Davies 《Current Psychology》1989,8(4):267-272
The present study examined the effect of gender-typed labeling of a task on the performance of children. A total of 72 boys
and girls aged 11, 13 and 16 years took part in the study. The same measure of performance—a perceptual motor task—was used
across all conditions. Two main dimensions were investigated: first, the effect of of directly labeling the task as gender
appropriate or inappropriate; second, the effect of the instruction to role-enact a person competent at the task labeled gender
appropriate or inappropriate. The results indicate that children of all ages studied perform better at the task labeled gender
appropriate rather than inappropriate. Children also perform better when role-acting competence at a gender-typed labeled
task than under conventional testing procedures. The implications of these findings are discussed. 相似文献
849.
Relationship of racial stressors to blood pressure responses and anger expression in black college students 总被引:5,自引:0,他引:5
The physiological effects of racism, as a stressor, were examined as they related to blood pressure (BP) and anger experiences in Black college students. Current research has failed to consider the stressful effects of racism as a factor contributing to the higher incidence of essential hypertension among Blacks. Twenty-seven Black college students viewed three excerpts showing racist situations involving Blacks; anger-provoking, nonracist situations; and neutral situations. After each scene, BP was taken, and a mood checklist was administered. The Framingham Anger Scale and the Anger Expression Scale were administered. Analyses revealed that BP significantly increased during the presentation of racist stimuli but not of anger-provoking or neutral stimuli. Self-reports of state anger, as measured by the mood checklist, were significant for both the anger-provoking and racist stimuli. BP scores were significantly correlated to the two trait anger measures. Exposure to racist stimuli was associated with BP increases among Blacks. Such cumulative exposure to racism may have important implications for the etiology of essential hypertension. 相似文献
850.
The study was designed to examine the influence of significant others (mothers, fathers, and male and female peers) on continuing involvement in sport by adolescent females. Survey data were collected from 376 girls using a forced-choice, self-administered questionnaire. Maintenance of involvement was measured by the proportion of possible years in which the respondents were involved in physical activity within each of three participation contexts (intramural, interschool, and community sport). Several indicators of significant other influence were used. The degree to which involvement in physical activity is maintained is positively related to the source, amount and type of influence received from significant others, and varied by the participation context. Overall, the socializing influence of significant others was able to account for 11% of the variance in intramural activity, 20% of the variance in interschool sport, and 10% of the variance in community-based activity.This study was funded by a grant from Fitness Canada. 相似文献