全文获取类型
收费全文 | 16055篇 |
免费 | 200篇 |
国内免费 | 9篇 |
专业分类
教育 | 10898篇 |
科学研究 | 1940篇 |
各国文化 | 392篇 |
体育 | 1145篇 |
综合类 | 6篇 |
文化理论 | 110篇 |
信息传播 | 1773篇 |
出版年
2021年 | 147篇 |
2020年 | 198篇 |
2019年 | 299篇 |
2018年 | 391篇 |
2017年 | 390篇 |
2016年 | 359篇 |
2015年 | 238篇 |
2014年 | 302篇 |
2013年 | 2881篇 |
2012年 | 322篇 |
2011年 | 324篇 |
2010年 | 291篇 |
2009年 | 277篇 |
2008年 | 343篇 |
2007年 | 312篇 |
2006年 | 284篇 |
2005年 | 261篇 |
2004年 | 295篇 |
2003年 | 203篇 |
2002年 | 200篇 |
2001年 | 263篇 |
2000年 | 284篇 |
1999年 | 251篇 |
1998年 | 155篇 |
1997年 | 150篇 |
1996年 | 150篇 |
1995年 | 123篇 |
1994年 | 119篇 |
1993年 | 165篇 |
1992年 | 234篇 |
1991年 | 252篇 |
1990年 | 251篇 |
1989年 | 239篇 |
1988年 | 204篇 |
1987年 | 215篇 |
1986年 | 202篇 |
1985年 | 248篇 |
1984年 | 206篇 |
1983年 | 205篇 |
1982年 | 190篇 |
1981年 | 150篇 |
1980年 | 160篇 |
1979年 | 232篇 |
1978年 | 174篇 |
1977年 | 165篇 |
1976年 | 148篇 |
1975年 | 126篇 |
1974年 | 149篇 |
1973年 | 139篇 |
1971年 | 129篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
ABSTRACT This article offers a textual analysis and semiotic reading of the Rich Kids of Tehran's (RKOT’s) Instagram page. Contributing to scholarship on Iranian youth media practices, this article interrogates how the RKOT navigate urban and rural space to engage in everyday processes of resistance against global and local systemic oppression. Grounding their visual representations on Instagram in historical and cultural context, the author questions how and when quotidian actions are transformed into political transgressions when posted on social media. This article emphasizes the RKOT's agency in shaping their brand by analyzing representations of gender performance, intertextuality, and national identity on Instagram. 相似文献
3.
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
4.
In the IR field it is clear that the value of a system depends on the cost and benefit profiles of its users. It would seem obvious that different users would prefer different systems. In the TREC-9 filtering track, systems are evaluated by a utility measure specifying a given cost and benefit. However, in the study of decision systems it is known that, in some cases, one system may be unconditionally better than another. In this paper we employ a decision theoretic approach to find conditions under which an Information Filtering (IF) system is unconditionally superior to another for all users regardless of their cost and benefit profiles.It is well known that if two IF systems have equal precision the system with better recall will be preferred by all users. Similarly, with equal recall, better precision is universally preferred. We confirm these known results and discover an unexpected dominance relation in which a system with lower recall will be universally preferred provided its precision is sufficiently higher. 相似文献
5.
6.
7.
8.
F. Kohlrausch 《Journal of The Franklin Institute》1871,91(5):349-355
9.
Sports Engineering - A Monark cycle ergometer is a device globally used in physiological studies to measure the work and energy levels of exercising humans. In this paper a rope-braked cycle... 相似文献
10.
Development of maximal oxygen uptake in young elite male cross-country skiers: a longitudinal study.
F Ingjer 《Journal of sports sciences》1992,10(1):49-63
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