全文获取类型
| 收费全文 | 40448篇 |
| 免费 | 602篇 |
| 国内免费 | 67篇 |
专业分类
| 教育 | 29317篇 |
| 科学研究 | 3432篇 |
| 各国文化 | 388篇 |
| 体育 | 2996篇 |
| 综合类 | 52篇 |
| 文化理论 | 351篇 |
| 信息传播 | 4581篇 |
出版年
| 2022年 | 254篇 |
| 2021年 | 422篇 |
| 2020年 | 597篇 |
| 2019年 | 942篇 |
| 2018年 | 1811篇 |
| 2017年 | 1808篇 |
| 2016年 | 1539篇 |
| 2015年 | 782篇 |
| 2014年 | 1074篇 |
| 2013年 | 7544篇 |
| 2012年 | 1103篇 |
| 2011年 | 1297篇 |
| 2010年 | 1067篇 |
| 2009年 | 955篇 |
| 2008年 | 1056篇 |
| 2007年 | 1091篇 |
| 2006年 | 803篇 |
| 2005年 | 802篇 |
| 2004年 | 708篇 |
| 2003年 | 643篇 |
| 2002年 | 551篇 |
| 2001年 | 772篇 |
| 2000年 | 643篇 |
| 1999年 | 552篇 |
| 1998年 | 344篇 |
| 1997年 | 355篇 |
| 1996年 | 385篇 |
| 1995年 | 363篇 |
| 1994年 | 315篇 |
| 1993年 | 317篇 |
| 1992年 | 494篇 |
| 1991年 | 465篇 |
| 1990年 | 490篇 |
| 1989年 | 479篇 |
| 1988年 | 392篇 |
| 1987年 | 449篇 |
| 1986年 | 422篇 |
| 1985年 | 450篇 |
| 1984年 | 391篇 |
| 1983年 | 357篇 |
| 1982年 | 314篇 |
| 1981年 | 279篇 |
| 1980年 | 269篇 |
| 1979年 | 417篇 |
| 1978年 | 327篇 |
| 1977年 | 270篇 |
| 1976年 | 264篇 |
| 1975年 | 229篇 |
| 1974年 | 237篇 |
| 1971年 | 245篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
11.
12.
U. Casellato F. Fenzi P. Guerriero S. Sitran P. A. Vigato U. Russo M. Galgani M. Mendera A. Manasse 《Journal of Cultural Heritage》2003,4(4):337-353
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
13.
Continuous observation of the physical activity of 56 preadolescent children was conducted in four regions of England from October 1988 to July 1989. Observations were undertaken during school break times, lunch times, and physical education lessons, as well as during the children's free time. Of total time observed, the children spent 32.4% of it engaged in moderate to vigorous physical activity (MVPA). Children were shown to be most active during school breaks and least active during free time at home. However, it is thought that cardiorespiratory benefits are best achieved by participation in sustained periods of MVPA. Only 8 (14%) of the 56 children were observed to participate in MVPA for sustained periods of 20 min or longer. A random sample of 55 physical education lessons was observed. Only 6 children engaged in MVPA for sustained periods of 5 min or more, and no children participated in MVPA for 10 min or longer. The implications of these results are that, although the children engaged in a reasonable amount of MVPA, it may not have been sustained for periods of sufficient length to produce a cardiovascular training response. Consideration is given to ways of promoting lifelong involvement in physical activity. 相似文献
14.
15.
16.
17.
18.
19.
20.