全文获取类型
收费全文 | 10649篇 |
免费 | 393篇 |
专业分类
11042篇 |
出版年
2020年 | 142篇 |
2019年 | 188篇 |
2018年 | 234篇 |
2017年 | 274篇 |
2016年 | 311篇 |
2015年 | 226篇 |
2014年 | 220篇 |
2013年 | 2972篇 |
2012年 | 309篇 |
2011年 | 309篇 |
2010年 | 325篇 |
2009年 | 336篇 |
2008年 | 335篇 |
2007年 | 295篇 |
2006年 | 257篇 |
2005年 | 147篇 |
2004年 | 140篇 |
2003年 | 136篇 |
2002年 | 141篇 |
2001年 | 188篇 |
2000年 | 135篇 |
1999年 | 144篇 |
1998年 | 97篇 |
1997年 | 81篇 |
1996年 | 110篇 |
1995年 | 110篇 |
1994年 | 104篇 |
1993年 | 118篇 |
1992年 | 96篇 |
1991年 | 87篇 |
1990年 | 75篇 |
1989年 | 97篇 |
1988年 | 89篇 |
1987年 | 97篇 |
1986年 | 96篇 |
1985年 | 109篇 |
1984年 | 108篇 |
1983年 | 138篇 |
1982年 | 108篇 |
1981年 | 108篇 |
1980年 | 105篇 |
1979年 | 100篇 |
1978年 | 111篇 |
1977年 | 100篇 |
1976年 | 115篇 |
1975年 | 88篇 |
1974年 | 77篇 |
1973年 | 78篇 |
1972年 | 82篇 |
1970年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
Albert A. Dahlberg 《Journal of archaeological science》1983,10(6):552-553
4.
5.
6.
J.M.P. Cabral M.A. Gouveia A.M. Alarcão J. Alarcao 《Journal of archaeological science》1983,10(1):61-70
The concentrations of two major elements and thirteen trace elements in 73 selected sherds of fine grey ware from the Iron Age and Roman period, excavated at Conimbriga, Santa Olaia and Tavarede, Portugal, were determined by instrumental neutron activation analysis. These concentrations were used to calculate distance matrices which were then subjected to cluster analysis employing SAHN and k-means methods, as well as to principal components analysis, to group the sherds according to the overall similarity of their compositional characteristics. The results showed that equivalent groupings appeared regardless of the taxonomic method used. Two major clusters were recognized corresponding to two different sites, namely Conimbriga and Santa Olaia, suggesting that the ceramics from these sites were made locally. No significant differences in compositional patterns were observed between iron age and roman sherds from Conimbriga. 相似文献
7.
8.
9.
10.
Rosemary D.F. Bromley 《Journal of Historical Geography》1979,5(3):281-295
An investigation of three Andean towns in their regional setting forms the basis for an assessment of urban-rural demographic differences. The towns are found to have been ethnically distinct, with a larger proportion of whites than the mainly Indian rural areas. The urban populations also had a larger surplus of women, lower average marriage ages for women but lower proportions married, a higher illegitimacy rate and a slightly older age structure. Trends in urban districts differed from those in rural areas. The towns suffered major population losses, and their share of the regional population fell from nearly 10% in 1778 to around 5% in 1841. The factors affecting population trends are examined in order to identify those which had a differential urban-rural impact. Earthquake and warfare were of key significance. In a regional context of economic depression and population stagnation, these two catastrophes instigated a major urban recession. The three towns shared in the urban decline experienced in many parts of Latin America, but their recession was particularly pronounced owing to the impact of catastrophes. 相似文献