全文获取类型
收费全文 | 23653篇 |
免费 | 196篇 |
国内免费 | 131篇 |
专业分类
教育 | 15342篇 |
科学研究 | 3608篇 |
各国文化 | 166篇 |
体育 | 2419篇 |
综合类 | 23篇 |
文化理论 | 232篇 |
信息传播 | 2190篇 |
出版年
2021年 | 169篇 |
2020年 | 280篇 |
2019年 | 397篇 |
2018年 | 1142篇 |
2017年 | 1122篇 |
2016年 | 877篇 |
2015年 | 366篇 |
2014年 | 421篇 |
2013年 | 3391篇 |
2012年 | 482篇 |
2011年 | 693篇 |
2010年 | 612篇 |
2009年 | 502篇 |
2008年 | 523篇 |
2007年 | 629篇 |
2006年 | 329篇 |
2005年 | 376篇 |
2004年 | 621篇 |
2003年 | 544篇 |
2002年 | 478篇 |
2001年 | 557篇 |
2000年 | 397篇 |
1999年 | 297篇 |
1998年 | 184篇 |
1997年 | 190篇 |
1996年 | 195篇 |
1995年 | 179篇 |
1994年 | 190篇 |
1993年 | 162篇 |
1992年 | 271篇 |
1991年 | 250篇 |
1990年 | 269篇 |
1989年 | 297篇 |
1988年 | 221篇 |
1987年 | 237篇 |
1986年 | 271篇 |
1985年 | 271篇 |
1984年 | 237篇 |
1983年 | 242篇 |
1982年 | 206篇 |
1981年 | 169篇 |
1980年 | 190篇 |
1979年 | 261篇 |
1978年 | 201篇 |
1977年 | 170篇 |
1976年 | 188篇 |
1975年 | 139篇 |
1974年 | 176篇 |
1973年 | 156篇 |
1971年 | 166篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
The present study examined three hypotheses regarding the consequences of early brain damage for academic achievement: First, early brain insults will have a negative impact on achievement, even in children with normal intelligence. Second, underachievement in these children will be at least partially independent of IQ (i.e., not fully accounted for by a lowering of IQ within the average range). Third, normally intelligent children with histories of brain insult will also manifest selective cognitive dysfunctions. To test these hypotheses, we compared two groups of children who had recovered from Haemophilus influenzae type b meningitis. The "complicated" group consisted of children who, as a consequence of having sustained neurologic complications during their illness, were more likely to have had brain insults. Children in the "uncomplicated" group did not have complications with their illness and were regarded as having escaped significant central nervous system (CNS) pathology. Only children with normal hearing and a prorated Full Scale IQ of at least 80 (WISC-R) were considered. Group differences on the Wide Range Achievement Test-Revised were consistent with the first two hypotheses. Although the two groups had similar Verbal IQs, the complicated group also had a lower mean Performance IQ and performed less well on perceptually demanding neuropsychological tasks. Findings suggest that learning disabilities may have selective, brain-related cognitive antecedents; but they challenge the practice of using IQ criteria for clinical diagnosis. 相似文献
53.
54.
55.
56.
57.
This study examined two levels of media agenda effects on aggregatepublic opinion from different news sources. The effects wereinvestigated immediately and cumulatively. Content analysisdata from the 2000 U.S. presidential election coverage by fournational news organizations were related to the Gallup pre-electionpoll standings of each candidate. Regression analyses foundthat both the salience of a candidate and the salience of theattributes of a candidate cumulatively, but not immediately,influenced his standing in the polls. An analysis of news sourcessupported the finding that the two levels of agenda-settingeffects seemed mostly cumulative rather than immediate. Newsfrom different sources, however, tended to have effects of differentdegrees and sometimes different directions on candidate pollstandings. Cumulative effects of candidate salience on aggregateopinion change were found for non-partisan and neutral newssourcesreporters, poll reporting and public documentswhereasthe effects of candidate attribute salience mostly came frompartisan sourcesthe candidate himself and members ofthe competing political party. Possible political implicationsof these findings are discussed. 相似文献
58.
Question classification systems play an important role in question answering systems and can be used in a wide range of other domains. The goal of question classification is to accurately assign labels to questions based on expected answer type. Most approaches in the past have relied on matching questions against hand-crafted rules. However, rules require laborious effort to create and often suffer from being too specific. Statistical question classification methods overcome these issues by employing machine learning techniques. We empirically show that a statistical approach is robust and achieves good performance on three diverse data sets with little or no hand tuning. Furthermore, we examine the role different syntactic and semantic features have on performance. We find that semantic features tend to increase performance more than purely syntactic features. Finally, we analyze common causes of misclassification error and provide insight into ways they may be overcome. 相似文献
59.
ABSTRACTLighting a cultural heritage artifact requires balancing visual perception with preventive conservation, by providing the best lighting (in terms of spectral distribution and quantity) to enable the viewer to appreciate details and color, while limiting photo-induced degradation. The paper outlines the methodology applied by a multi-disciplinary team while lighting the Shroud of Turin at its last public exhibition in 2015. The methodology considered the special requirements of the Shroud, including exposure to ultraviolet light, while providing appropriate display conditions that would meet audience expectations. The desired appearance (readability of the body image and color) was defined with the help of Shroud researchers and confirmed by subjective tests, while appropriate light levels for preservation were set in agreement with standard requirements and using knowledge of the degradation of linen in visible and UV light. The installation provided a controlled environment and a managed visitor route to the Shroud, assuring excellent perception of both details and color, with the lowest illuminance level about 15?lx. 相似文献
60.
Steve H. Ching 《The Journal of Academic Librarianship》2018,44(2):196-206
The digital shift has provided easy access to academic library users, and yet, the usage of archival collections continues to be low. At the same time, the need for innovation in library services for cultural heritage scholarship and its advancement is emerging. This paper outlines a library-led service-learning program that connects students with lighthouse artifacts, archival collections, scholars in global academia, and wider communities. Student engagement cases are provided to illustrate the way in which the librarian utilizes the Framework of Information Literacy for Higher Education by ACRL to work closely with students. These cases also demonstrate how students can contribute to knowledge creation and preservation efforts for a specific cultural heritage topic that is not static, but which keeps receiving new contributions or additions to the depository. Thus, this paper is an answer to the ACRL's call for pilot projects to be assessed and shared with the wider community of academic librarians and support staff. It also builds on emerging roles for academic libraries like engaged learning. Librarians must move beyond simply seeing themselves as partners. Instead, librarians should see themselves as prime facilitators that co-create and co-develop cultural heritage research and historical projects by connecting actors and resources more effectively than any single actor can do alone. 相似文献