首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23491篇
  免费   312篇
  国内免费   126篇
教育   16521篇
科学研究   2532篇
各国文化   269篇
体育   1959篇
综合类   14篇
文化理论   249篇
信息传播   2385篇
  2021年   182篇
  2020年   351篇
  2019年   513篇
  2018年   699篇
  2017年   668篇
  2016年   662篇
  2015年   452篇
  2014年   549篇
  2013年   4367篇
  2012年   513篇
  2011年   551篇
  2010年   438篇
  2009年   422篇
  2008年   521篇
  2007年   490篇
  2006年   473篇
  2005年   457篇
  2004年   399篇
  2003年   423篇
  2002年   396篇
  2001年   386篇
  2000年   383篇
  1999年   385篇
  1998年   245篇
  1997年   251篇
  1996年   297篇
  1995年   288篇
  1994年   241篇
  1993年   226篇
  1992年   321篇
  1991年   326篇
  1990年   327篇
  1989年   339篇
  1988年   286篇
  1987年   288篇
  1986年   281篇
  1985年   316篇
  1984年   278篇
  1983年   281篇
  1982年   240篇
  1981年   239篇
  1980年   233篇
  1979年   315篇
  1978年   244篇
  1977年   223篇
  1976年   198篇
  1975年   173篇
  1974年   183篇
  1973年   157篇
  1971年   147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
Social loafing refers to the tendency for individuals to reduce their own personal input when performing as part of group. This phenomenon may be problematic if it exists in educational contexts, given a current emphasis on group collaborative classroom activities. The present study investigated whether social loafing existed in a collaborative educational task, employing groups of three and eight participants. The results indicated that individuals working within the smaller groups were more productive than those working in larger groups, consistent with the social loafing hypothesis. Future research should determine whether the detrimental effects on students' collaborative performance attributable to social loafing are justifiable in terms of gains accrued in other (e.g. interpersonal) domains.  相似文献   
944.
Coopetition, i.e., cooperation between competing actors, has become a pervasive strategy for innovative firms. The primary focus of studies investigating coopetition centers on inter-firm relationships, highlighting the benefits, limits and configurational patterns of cooperative relationships between competing firms. Only a small, emerging group of studies seeks to extend the concept to the intra-firm level, stressing the existence and effects of competition and cooperation between units that are part of the same organization. This paper contributes to this latter group by investigating the effects of internal coopetition on knowledge and innovation sharing and highlighting the fundamental role of knowledge brokers in managing the resulting tensions. Based on a qualitative case study of the video game publisher Ubisoft, we stress how the tensions raised by internal coopetitive settings limit knowledge sharing between units, and we analyze the mechanisms through which the knowledge broker helps to overcome these limits. We identify three main functions of this knowledge broker that allow the promotion of knowledge and innovation transfer to occur between coopeting units: (1) protecting the unit’s competitive advantage by introducing a lagging principle in the transfer process, (2) reducing sharing costs by standardizing innovative solutions, and (3) enhancing awareness of and trust in innovative solutions by centralizing knowledge diffusion.  相似文献   
945.
While literature suggests that college students may be less reluctant to seek help in online rather than traditional courses, little is known about how online instructors give help in ways that lead to increased student help seeking and academic success. In this study, we used theories and research on learning assistance and scaffolding, teacher immediacy, social presence, and academic help seeking to explore through a cross-case study design how three online instructors differed in their use of cognitive and social supports and how those differences related to student perceptions of support, help seeking, and performance. Primary data sources included all course postings by the instructors, interviews with the instructors, observational field notes on course discussions, student interviews, and final student grades. Archived course documents and student discussion postings were secondary data sources. Data analysis revealed that while all instructors provided cognitive and social support, they varied in their level of questioning, use of direct instruction, support for task structuring, and attention to group dynamics. This variation in teaching presence related to differences across the courses in student perceptions of support, student help seeking in course discussions, and final course grades. Implications for online teaching and suggestions for further research are offered.
Joan L. WhippEmail:
  相似文献   
946.
27 children with early onset (less than 4 years) diabetes (EOD), 24 with late onset (greater than 4.0 years) diabetes (LOD), and 30 sibling controls were compared in their performance on tests of intellectual functioning and school achievement. The results indicated that children with EOD, particularly girls, scored lower than the other groups of diabetic children and siblings on tests of visuospatial but not verbal ability. Many of the children with EOD were also having difficulty at school, and a number were currently receiving special education. Diabetic children with earlier onset had more hypoglycemic convulsions than those with later onset. Regression analyses revealed that duration of illness, age of onset, and hypoglycemic convulsions significantly predicted spatial ability.  相似文献   
947.
Administrators need intense support in their early years in their jobs to master the demands of the position and to emerge as effective leaders for their schools. This article reports on a leadership coaching program offered by a university to support graduates as they transition to new school leadership roles. First year research results of the Program for New Principals indicate that all of the program participants felt that the coaching program was a positive addition to the induction experience for new administrators. New principals viewed coaching positively and emphasized that it is both a valuable and unique form of professional development. Both coaches and new principals cited personalized support as one of the coaching model's most significant assets. The results should inform the development of a model of leadership coaching for new administrators.  相似文献   
948.
A growing body of research documents the positive outcomes of research experiences for undergraduates, including increased persistence in science. Study of undergraduate lab learning experiences has demonstrated that the design of the experience influences the extent to which students report ownership of the project and that project ownership is one of the psychosocial factors involved in student retention in the sciences. To date, methods for measuring project ownership have not been suitable for the collection of larger data sets. The current study aims to rectify this by developing, presenting, and evaluating a new instrument for measuring project ownership. Eighteen scaled items were generated based on prior research and theory related to project ownership and combined with 30 items shown to measure respondents’ emotions about an experience, resulting in the Project Ownership survey (POS). The POS was analyzed to determine its dimensionality, reliability, and validity. The POS had a coefficient alpha of 0.92 and thus has high internal consistency. Known-groups validity was analyzed through the ability of the instrument to differentiate between students who studied in traditional versus research-based laboratory courses. The POS scales as differentiated between the groups and findings paralleled previous results in relation to the characteristics of project ownership.  相似文献   
949.
The purpose of this study was to determine the effects of short-term normoxic and hypoxic exercise on plasma endothelin-1 and nitric oxide levels, and the relationship of arterial compliance and pulmonary artery pressure to endothelin-1. Seven endurance-trained males completed two incremental and two steady-state exercise tests performed at ventilatory threshold in normoxia and hypoxia (fraction of inspired oxygen = 0.14). Plasma endothelin-1was measured throughout steady-state tests. Arterial compliance using applanation tonometry, plasma nitric oxide and pulmonary artery pressure using Doppler echocardiography were measured before and after exercise. Small arterial compliance and pulmonary artery pressure significantly increased following exercise. There were no main effects of condition or time for plasma endothelin-1and nitric oxide levels. There were no significant relationships between plasma endothelin-1 and arterial compliance or pulmonary artery pressure. In conclusion, mechanisms other than the endothelial system may play a role in the exercise-induced changes in small artery compliance in this study population. Moderate hypoxia and a 30-minute steady-state exercise have limited effects on plasma endothelin-1 in endurance-trained males.  相似文献   
950.
ABSTRACT

This study aimed to examine: (i) the effect of decreasing training load (TL) during taper weeks on physical match activities in professional soccer players, and (ii) to disclose the relationship between weekly TL and physical match activities. Rating of perceived exertion was collected after each training session and match to quantify the TL in 19 professional players over 17 standard and 7 taper weeks during the season. Physical match activities were quantified by a computerised match analysis system and compared between standard training and taper weeks. Compared to standard weeks, the duration and frequency of training sessions during the taper weeks decreased (?21.7% and ?18.8%, respectively; < 0.01) with no change in intensity (?4.8%; = 0.09). Consequently, the weekly TL decreased during the taper weeks (?25.5%; < 0.01). Increases in distance covered by intense running (+15.1%; < 0.05), high-intensity running (HIR) (+15.7%; < 0.01), number of sprints (+17.8%; < 0.05) and number of high-speed runs (+15.7%; < 0.05) were observed during the seven matches played after the taper weeks. High relationships were observed between TL and HIR distance covered, number of HIR and number of sprints (r = ?0.53; r = ?0.55; r = ?0.65, respectively; < 0.01). Decreasing TL during taper weeks by reducing training duration and frequency but maintaining intensity was associated with an increase in physical activities during matches. However, it needs to be determined whether tapering or other match factors led to the changes in match activity.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号