全文获取类型
收费全文 | 5646篇 |
免费 | 259篇 |
专业分类
5905篇 |
出版年
2020年 | 121篇 |
2019年 | 107篇 |
2018年 | 202篇 |
2017年 | 203篇 |
2016年 | 223篇 |
2015年 | 145篇 |
2014年 | 146篇 |
2013年 | 1703篇 |
2012年 | 167篇 |
2011年 | 164篇 |
2010年 | 143篇 |
2009年 | 135篇 |
2008年 | 123篇 |
2007年 | 98篇 |
2006年 | 106篇 |
2005年 | 70篇 |
2004年 | 71篇 |
2003年 | 71篇 |
2002年 | 68篇 |
2001年 | 75篇 |
2000年 | 52篇 |
1999年 | 61篇 |
1998年 | 51篇 |
1997年 | 54篇 |
1996年 | 46篇 |
1995年 | 55篇 |
1994年 | 50篇 |
1993年 | 55篇 |
1992年 | 52篇 |
1991年 | 47篇 |
1990年 | 35篇 |
1989年 | 45篇 |
1988年 | 38篇 |
1987年 | 47篇 |
1986年 | 47篇 |
1985年 | 46篇 |
1984年 | 58篇 |
1983年 | 55篇 |
1982年 | 52篇 |
1981年 | 45篇 |
1980年 | 56篇 |
1979年 | 54篇 |
1978年 | 48篇 |
1977年 | 46篇 |
1976年 | 39篇 |
1975年 | 35篇 |
1973年 | 40篇 |
1972年 | 34篇 |
1971年 | 37篇 |
1969年 | 31篇 |
排序方式: 共有5905条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
66.
67.
In order to carry out strontium (Sr) isotope analysis, glass artefacts from South Asia were sampled with portable laser ablation (pLA), a relatively novel sampling technique that leaves damage invisible to the naked eye. Subsequently, thermal ionization mass spectrometry (TIMS) was used to obtain Sr isotope ratios after sample dissolution and separation. In this study, the goal was twofold: to determine whether the measurements of Sr isotope ratios were impacted by using a portable laser as a sample tool; and to assess the pertinence of using Sr isotope ratios to provenance Indian glass. Despite a deterioration in the precision of the measurement of the Sr isotope ratios for artefacts sampled with pLA compared with the traditional sampling method, the Sr isotope ratios of certain Indian glass are so different that this does not affect their separation but a comparison of data sets obtained using standard methods and pLA might be challenging. 相似文献
68.
F. Albarde J. Blichert‐Toft F. de Callataÿ G. Davis P. Debernardi L. Gentelli H. Gitler F. Kemmers S. Klein C. Malod‐Dognin J. Milot P. Tlouk M. Vaxevanopoulos K. Westner 《Archaeometry》2021,63(1):142-155
The reasons why the Western Mediterranean, especially Carthage and Rome, resisted monetization relative to the Eastern Mediterranean are still unclear. We address this question by combining lead (Pb) and silver (Ag) isotope abundances in silver coinage from the Aegean, Magna Graecia, Carthage and Roman Republic. The clear relationships observed between 109Ag/107Ag and 208Pb/206Pb reflect the mixing of silver ores or silver objects with Pb metal used for cupellation. The combined analysis of Ag and Pb isotopes reveals important information about the technology of smelting. The Greek world extracted Ag and Pb from associated ores, whereas, on the Iberian Peninsula, Carthaginians and Republican‐era Romans applied Phoenician cupellation techniques and added exotic Pb to Pb‐poor Ag ores. Massive Ag recupellation is observed in Rome during the Second Punic War. After defeating the Carthaginians and the Macedonians in the late second century bce , the Romans brought together the efficient, millennium‐old techniques of silver extraction of the Phoenicians, who considered this metal a simple commodity, with the monetization of the economy introduced by the Greeks. 相似文献
69.
Alan T. Murray 《Geographical analysis》2021,53(1):13-18
Prompted by a series of panel sessions at a recent American Association of Geographers annual meeting entitled “A Globe‐Shaped Crystal Ball: The Next Fifty Years of Geographical Analysis,” participants were asked to speculate on the future of the journal, which of course has broader implications for spatial and geographic analytics. In what follows, I provide my thoughts on the journal as a reader, contributor, referee, and former editor of Geographical Analysis. The major points touched upon include the following. First, application to address substantive concerns will come to dominate the field. Second, the spatial data deluge will continue unabated, but will lead to important advances because of better detail and less abstraction of reality. Third, analytical methods will evolve specifically for big data. Fourth, the point‐and‐click revolution will result in ever more use of spatial analytics, but also will lend itself to greater and more widespread abuse of these methods. Fifth, addressing assumptions and theoretical foundations of long utilized approaches will revolutionize a new generation of spatial analytics. Sixth, geographic uncertainty and bias will be more than an afterthought, and methods will emerge to support meaningful analysis. Finally, spatial optimization will have increased prominence in fundamental analysis, particularly associated with establishing and evaluating significance. 相似文献