全文获取类型
收费全文 | 96766篇 |
免费 | 3981篇 |
国内免费 | 46篇 |
出版年
2020年 | 1122篇 |
2019年 | 1373篇 |
2018年 | 1950篇 |
2017年 | 1972篇 |
2016年 | 2058篇 |
2015年 | 1434篇 |
2014年 | 1744篇 |
2013年 | 8351篇 |
2012年 | 3186篇 |
2011年 | 3300篇 |
2010年 | 1997篇 |
2009年 | 2037篇 |
2008年 | 2956篇 |
2007年 | 2926篇 |
2006年 | 2600篇 |
2005年 | 2287篇 |
2004年 | 2316篇 |
2003年 | 2137篇 |
2002年 | 2118篇 |
2001年 | 3108篇 |
2000年 | 2965篇 |
1999年 | 2277篇 |
1998年 | 1165篇 |
1997年 | 998篇 |
1996年 | 1008篇 |
1995年 | 963篇 |
1994年 | 929篇 |
1993年 | 952篇 |
1992年 | 1827篇 |
1991年 | 1712篇 |
1990年 | 1704篇 |
1989年 | 1572篇 |
1988年 | 1542篇 |
1987年 | 1450篇 |
1986年 | 1469篇 |
1985年 | 1570篇 |
1984年 | 1271篇 |
1983年 | 1095篇 |
1982年 | 864篇 |
1979年 | 1299篇 |
1978年 | 967篇 |
1976年 | 848篇 |
1975年 | 1093篇 |
1974年 | 1215篇 |
1973年 | 1211篇 |
1972年 | 1056篇 |
1971年 | 945篇 |
1968年 | 1054篇 |
1967年 | 983篇 |
1966年 | 899篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
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
962.
The Sentencing Reform Act of 1984, which created the U.S. Sentencing Commission, required that the commisson consider prison capacity in drafting sentencing guidelines. As part of the commission's efforts to meet this requirement, we developed a computer simulation capable of projecting the impact of the commission's guidelines on future sentences and prison populations. According to our projections, “straight” probation sentences will be reduced significantly under the guidelines. However, reducing the use of probation will generate only modest demands on the prisons, and then mostly for community corrections phased in over the course of 5 years. We also project that, while average time served for violent offenses will increase substantially, average time served for most property crimes will remain largely the same. Finally, while we forecast that federal prison populations will grow markedly by the end of this century, this is more a result of the Anti-Drug Abuse Act of 1986 and the career offender provision of the Comprehensive Crime Control Act of 1984 than a result of the guidelines. 相似文献
963.
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
964.
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
965.
966.
KATHLEEN McNAMARA KATHRYN M. RICKARD 《Journal of counseling and development : JCD》1989,68(2):184-189
This article discusses the implications of the Downing and Roush (1985) model of feminist identity development for feminist therapy with women. Following a summary of the model, the potential pitfalls of feminist therapy with the passive-acceptant client are described, as well as potential issues at subsequent stages of the client's identity development. Suggestions are made regarding how to facilitate clients' movement to higher levels of development. Finally, a research agenda is proposed that suggests hypotheses to be tested that arise from applying this model to conducting therapy with women. 相似文献
967.
J M Stern S K Johnson 《Journal of comparative psychology (Washington, D.C. : 1983)》1989,103(3):269-280
Prior to assuming the upright crouching posture over their pups during nursing bouts, lactating rats typically engage in several oral behaviors, including nuzzling, licking and rearranging pups. By acutely depriving dams of various aspects of perioral stimulation from pups (with anesthesia of the mystacial pads or of the tongue, with mouth suturing, or with muzzling), we found the following: (1) Distal stimulation from pups maintains proximity-seeking behavior, but is insufficient to stimulate nursing behavior. (2) Lack of tongue feedback decreases pup licking and hastens the onset of crouching. (3) Snout, but not tongue, contact with pups is required for hovering over them. (4) The position of the dam while hovering over her litter enables the pups to gain access to her ventrum, thereby provoking her upright, crouching posture. (5) Older pups are capable of bypassing the dam's perioral attentions and stimulating crouching directly by burrowing under the dam's ventrum. 相似文献
968.
969.
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
970.
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