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   9455篇
  免费   133篇
  国内免费   4篇
教育   6414篇
科学研究   1088篇
各国文化   123篇
体育   740篇
综合类   3篇
文化理论   65篇
信息传播   1159篇
  2021年   96篇
  2020年   138篇
  2019年   254篇
  2018年   311篇
  2017年   290篇
  2016年   246篇
  2015年   167篇
  2014年   217篇
  2013年   1781篇
  2012年   209篇
  2011年   205篇
  2010年   189篇
  2009年   176篇
  2008年   200篇
  2007年   171篇
  2006年   169篇
  2005年   148篇
  2004年   162篇
  2003年   131篇
  2002年   122篇
  2001年   152篇
  2000年   142篇
  1999年   127篇
  1998年   101篇
  1997年   89篇
  1996年   93篇
  1995年   79篇
  1994年   70篇
  1993年   103篇
  1992年   120篇
  1991年   122篇
  1990年   128篇
  1989年   111篇
  1988年   91篇
  1987年   111篇
  1986年   97篇
  1985年   108篇
  1984年   98篇
  1983年   106篇
  1982年   98篇
  1981年   82篇
  1980年   83篇
  1979年   102篇
  1978年   92篇
  1977年   89篇
  1976年   76篇
  1974年   73篇
  1973年   65篇
  1972年   57篇
  1971年   59篇
排序方式: 共有9592条查询结果,搜索用时 15 毫秒
1.
A significant number of archaeological finds of the 13th–16th century from the Tuscan sites of Germagnana and Gambassi in Valdelsa—FI, was studied by different physico-chemical investigations (SEM–EDS, ICP, Mössbauer spectroscopy, XRD, XRF, TG-DTA) in order to contribute to clarify the production methodology and the pre-industrial glass manufacture technology. The studied samples are mainly non-vitreous finds as production waste, refractory materials, crucibles and raw materials; also vitreous finds as frits, skims, glasses (glass masses, glass working waste and finished products) have been taken into consideration. The obtained petrographic and physico-chemical data strongly suggest that both Gambassi and Germagnana glass manufactures were strictly connected with the sources of vitrifiable materials, situated in Tuscan sand quarries. In particular a comparison between sands from the neighbouring quarries and appropriate finds of the two archaeological sites evidences that the employed vitrifiable materials possibly belong to La Casina La Cava resort. The archaeological classification, based on macroscopic observation and stratigraphic position, was compared and verified with the scientific classification of the examined finds of Germagnana and Gambassi sites based on their composition, morphology and physico-chemical properties.  相似文献   
2.
3.
4.
5.
The aim of this study was to investigate the effects of extensive endurance training (15-25 h per week) on the development of maximal oxygen uptake (VO2 max) in boys from puberty. Maximal oxygen uptake was measured a number of times each year from the age of puberty and for the next 6-9 years in seven young male elite cross-country skiers. Mean VO2 max was measured as 76.3 and 80.1 ml kg-1 min-1 at the ages of 14 and 15 years respectively. Despite the fast rate of growth during puberty, maximal aerobic power showed seasonal variations from the age of 14, reaching a plateau at the age of 15, whereas VO2 max (ml kg-2/3 min-1) increased continuously. It is concluded that, during puberty, boys probably attain significant increases in VO2 max when appropriate amounts of endurance training are undertaken.  相似文献   
6.
As a part of efforts to evaluate and monitor the increasing public investment in early childhood education, teachers are being asked to assess children's school readiness. In this study, preschool teachers and kindergarten teachers rated children's skills in three areas (kindergarten readiness, academic skills, and communication skills), and these ratings were compared with direct assessments of the children's skills. Ratings by both groups of teachers tended to be more highly related to basic skills, such as counting and number naming, than to abilities such as solving applied problems and using expressive and receptive vocabulary. Preschool teachers' ratings had a lower association with children's observed skills and abilities than kindergarten teachers' ratings. Ratings of children attending Head Start were systematically inflated, but this relationship was mediated to a significant extent by the teachers' levels of education. More educated teachers rated children in a manner consistent with the children's directly assessed skills. Implications of these findings for informing future efforts to assess school readiness by using teacher ratings are discussed.  相似文献   
7.
8.
Objective: To determine whether information retrieval might be enhanced by making each component of a structured abstract a separately searchable field. Design: Parallel searches on records arranged so that each abstract could either be searched in its entirety or as a collection of structured fields. Subjects: Records about cardiovascular disease downloaded from MEDLINE and tested against clinical questions derived from a concurrent survey of CD-ROM use in three health science libraries. Intervention: The investigators identified terms used to structure abstracts on MEDLINE and imported the abstracts into an Idealist database prior to searching using keywords from clinical questions. Measurements and main results: recall and precision rates are given for each question in the ‘structured’ and the ‘unstructured’ set of records. Conclusions: Use of structured, rather than unstructured, abstracts improves precision at the ex-pense of recall and places heavier demands upon the searcher’s skill in choosing the correct fields within the abstract to search. Further investigation requires more accurate simulation of MEDLINE software that utilizes features such as MeSH terms, explode, facilities and delimiters.  相似文献   
9.
Three factors tied with secondary student success in content‐area reading are demonstrated: (a) validated teacher‐focused and student‐focused interventions, (b) integrated and comprehensive service delivery systems, and (c) well‐designed, data‐based professional developmental programs. Difficult challenges face secondary students with LD and their teachers with regard to these students’ participation and success in required general education classes. Recently, instructional methods and materials have been developed and validated for promoting these students’ success. Some of them focus on how general education teachers plan and teach their content‐area courses; others focus on giving students the strategies they need to respond independently to the demands of their courses. This article describes these instructional methods, a service‐delivery model for implementing these interventions in secondary schools, and professional‐development mechanisms and administrative support that must be in place for the model to be maintained effectively.  相似文献   
10.
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