全文获取类型
收费全文 | 2324篇 |
免费 | 20篇 |
国内免费 | 18篇 |
专业分类
教育 | 1163篇 |
科学研究 | 361篇 |
各国文化 | 12篇 |
体育 | 488篇 |
综合类 | 37篇 |
文化理论 | 7篇 |
信息传播 | 294篇 |
出版年
2024年 | 10篇 |
2023年 | 8篇 |
2022年 | 11篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 23篇 |
2012年 | 137篇 |
2011年 | 241篇 |
2010年 | 66篇 |
2009年 | 16篇 |
2008年 | 130篇 |
2007年 | 177篇 |
2006年 | 143篇 |
2005年 | 130篇 |
2004年 | 101篇 |
2003年 | 99篇 |
2002年 | 111篇 |
2001年 | 71篇 |
2000年 | 65篇 |
1999年 | 50篇 |
1998年 | 26篇 |
1997年 | 29篇 |
1996年 | 19篇 |
1995年 | 32篇 |
1994年 | 22篇 |
1993年 | 33篇 |
1992年 | 26篇 |
1991年 | 18篇 |
1990年 | 41篇 |
1989年 | 42篇 |
1988年 | 26篇 |
1987年 | 36篇 |
1986年 | 29篇 |
1985年 | 45篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 9篇 |
1977年 | 6篇 |
1960年 | 9篇 |
1959年 | 14篇 |
1958年 | 9篇 |
1957年 | 11篇 |
1956年 | 15篇 |
1955年 | 14篇 |
1954年 | 12篇 |
1953年 | 11篇 |
排序方式: 共有2362条查询结果,搜索用时 0 毫秒
61.
Stability in cardiac indicators before birth and their utility in predicting variation in postnatal development were examined. Fetal heart rate and variability were measured longitudinally from 20 through 38 weeks gestation (n = 137) and again at age 2 (n = 79). Significant within-individual stability during the prenatal period and into childhood was demonstrated. Fetal heart rate variability at or after 28 weeks gestation and steeper developmental trajectories were significantly associated with mental and psychomotor development at 2 years (n = 82) and language ability at 2.5 years (n = 61). These data suggest that the foundations of individual differences in autonomic control originate during gestation and the developmental momentum of the fetal period continues after birth. 相似文献
62.
Vaughan Van Hecke A Mundy PC Acra CF Block JJ Delgado CE Parlade MV Meyer JA Neal AR Pomares YB 《Child development》2007,78(1):53-69
Infant joint attention has been observed to be related to social-emotional outcomes in at-risk children. To address whether this relation is also evident in typically developing children, 52 children were tested at 12, 15, 24, and 30 months to examine associations between infant joint attention and social outcomes. Twelve-month initiating and responding to joint attention were related to 30-month social competence and externalizing behavior, even when accounting for 15-month temperament ratings, 24-month cognition and language, and demographic variables. These results suggest that, in addition to associations with language and cognition, infant joint attention reflects robust aspects of development that are related to individual differences in the emergence of social and behavioral competence in childhood. 相似文献
63.
The objective of the study was to better understand the perceptions and needs of multigenerational Deaf adults related to mental health services. A survey sampled participants who were between 20 and 85 years old and Deaf. Questions were developed to identify the perspectives of Deaf adults related to the availability of mental health services, preferences for these services, and current utilization of services. Participants were grouped into age (years) categories: young adult (18-34), middle adult (35-54), older adult (55-65), and oldest (66-). Category response trends were examined using chi-square analysis. The analysis showed significant differences in the preferences and utilization of mental health care. These data also suggested preferences for service delivery. These data indicate areas of importance related to the development of programs and services for Deaf adults and to indicate where funding for services would be best utilized. 相似文献
64.
Improbable or impossible? How children reason about the possibility of extraordinary events 总被引:1,自引:1,他引:0
The present study investigated the development of possibility-judgment strategies between the ages of 4 and 8. In Experiment 1, 48 children and 16 adults were asked whether a variety of extraordinary events could or could not occur in real life. Although children of all ages denied the possibility of events that adults also judged impossible, children frequently denied the possibility of events that adults judged improbable but not impossible. Three additional experiments varied the manner in which possibility judgments were elicited and confirmed the robustness of preschoolers' tendency to judge improbable events impossible. Overall, it is argued that children initially mistake their inability to imagine circumstances that would allow an event to occur for evidence that no such circumstances exist. 相似文献
65.
This article examines how 31 triads of 6- to 10-year-old children from 3 cultural backgrounds organized their interactions while folding Origami figures. Triads of children whose families had immigrated to the United States from indigenous heritage regions of México (and whose mothers averaged only 7 grades of schooling) coordinated more often as an ensemble, whereas triads of European heritage U.S. children whose mothers had extensive schooling more often engaged dyadically or individually. When the European heritage children did engage as an ensemble, this often involved chatting rather than nonverbal conversation regarding folding, which was more common among the Mexican heritage children. Mexican heritage U.S. triads whose mothers had extensive schooling showed an intermediate pattern or resembled the European heritage children. 相似文献
66.
Ortiz R Jiménez JE García Miranda E Guzmán Rosquete R Hernández-Valle I Rodrigo M Estévez A Díaz A Hernández Expósito S 《Journal of learning disabilities》2007,40(1):80-92
The aims of this study were (a) to determine whether Spanish children with reading disabilities (RD) show a speech perception deficit and (b) to explore the locus and nature of this perceptive deficit. A group of 29 children with RD, 41 chronological age-matched controls, and 27 reading ability-matched younger controls were tested on tasks of speech perception. The effect of linguistic unit (word vs. syllable) and type of phonetic contrast (voicing, place and manner of articulation) were analyzed in terms of the number of errors and the response time. The results revealed a speech perception deficit in Spanish children with RD that was independent of the type of phonetic contrast and of linguistic unit. 相似文献
67.
Boisnoir A Decker L Reine B Natta F 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(2):215-223
Biomechanical analyses using synchronized tools [electromyography (EMG), motion capture, force sensors, force platform, and digital camera] are classically performed in a laboratory environment that could influence the performance. We present a system for studying the running sprint start that synchronizes motion capture, EMG, and ground reaction force data. To maximize motion capture (Vicon 612 with six cameras), a special dim environment was created in the stadium. "Classical" tools were combined with "purpose-built" tools intended to analyse the different aspects of movement. For example, a synchronization system was built to create a common time-base for all data recordings and a portable EMG system was synchronized by a cable that was "disconnected" by the athlete's movement out of the blocks. This disconnection represented an independent event recorded by different tools. A "gap" was measured for some sprint start events between kinetic and kinematic (motion capture) data. Calibration results, measurements of time "gap", and duration of the independent event were used to validate the accuracy of motion capture and the synchronization system. The results validate the entire experimental set-up and suggest adjustment values for motion capture data. This environment can be used to study other movements and can easily be applied to several sports. 相似文献
68.
Comparison of two Actigraph models for assessing free-living physical activity in Indian adolescents
Corder K Brage S Ramachandran A Snehalatha C Wareham N Ekelund U 《Journal of sports sciences》2007,25(14):1607-1611
This aim of this study was to compare the new Actigraph (GT1M) with the widely used Model 7164. Seven days of free-living physical activity were measured simultaneously using both the Model 7164 and GT1M in 30 Indian adolescents (mean age 15.8 years, s = 0.6). The GT1M was on average 9% lower per epoch than model 7164, thus a correction factor of 0.91 is suggested for comparison between the two monitors. The differences between monitors increased in magnitude with intensity of activity (P < 0.001) but remained randomly distributed (r = 0.01, P = 0.96). No significant difference was observed between monitors for time spent in moderate (P = 0.31) and vigorous (P = 0.34) physical activity when using the same epoch length. The Model 7164 classified less time as sedentary (P < 0.001) and more time as light-intensity activity (P < 0.001) than the GT1M. In conclusion, data from the GT1M can be compared with historical data using average counts per minute with a correction factor, and the two models might be comparable for assessing time spent in moderate to vigorous physical activity in children when using the same epoch length. 相似文献
69.
In this study, we investigated the adjustments to posture, kinematic and temporal characteristics of performance made by lower limb amputees during the last few strides in preparation for long jump take-off. Six male unilateral trans-femoral and seven male unilateral trans-tibial amputees competing in a World Championships final were filmed in the sagittal plane using a 100-Hz digital video camera positioned so that the last three strides to take-off were visible. After digitizing using a nine-segment model, a range of kinematic variables were computed to define technique characteristics. Both the trans-femoral and trans-tibial athletes appeared to achieve their reduction in centre of mass during the flight phase between strides, and did so mainly by extending the flight time by increasing stride length, achieved by a greater flexion of the hip joint of the touch-down leg. The trans-tibial athletes appeared to adopt a technique similar to that previously reported for able-bodied athletes. They lowered their centre of mass most on their second last stride (-1.6% of body height compared with -1.4% on the last stride) and used a flexed knee at take-off on the last stride, but they were less able to control their downward velocity at touch-down (-0.4 m x s(-1)). Both this and their restricted approach speed (8.9 m x s(-1) at touch-down), rather than technique limitations, influenced their jump performance. The trans-femoral athletes lowered their centre of mass most on the last stride (-2.3% of body height compared with -1.6% on the second last stride) and, as they were unable to flex their prosthetic knee sufficiently, achieved this by abducting their prosthetic leg during the support phase, which led to a large downward velocity at touch-down (-0.6 m x s(-1)). This, combined with their slower approach velocity (7.1 m x s(-1) at touch-down), restricted their performance. 相似文献
70.
Luliang Huang Shufeng Li Weiye Huang Helanlin Xiang Jianhua Jin Alexei A.Oskolski 《国家科学评论(英文版)》2023,(4):13-15
<正>The Pleistocene was a time of repeated glaciations that severely affected the land biota over large areas of Eurasia and North America. Drastic climatic fluctuations during the Pleistocene drove largescale extinctions, migrations and diversification in plant and animal populations.These dramatic processes had a strong impact on the distribution of modern flora and fauna. 相似文献