全文获取类型
收费全文 | 965篇 |
免费 | 6篇 |
专业分类
971篇 |
出版年
2021年 | 6篇 |
2020年 | 29篇 |
2019年 | 45篇 |
2018年 | 36篇 |
2017年 | 45篇 |
2016年 | 36篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 242篇 |
2012年 | 21篇 |
2011年 | 24篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 22篇 |
2007年 | 26篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 17篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1970年 | 5篇 |
1969年 | 5篇 |
排序方式: 共有971条查询结果,搜索用时 15 毫秒
81.
82.
83.
Modern technology lends itself to holistic exploration and widely accessible outreach. New technology allows scientists studying
our planet either from space or deep under the seas, to explore and reveal both natural and cultural resources that have previously
escaped our scrutiny. However, the use of these new technologies is expensive and often the exclusive tool of industrial research.
Yet, these new technologies can lead the way to greater collaboration, better science and more public access. In 2003 and
2004, a landmark project, combining government agencies, industrial technology and outreach set new standards in collaborative
scientific exploration. The project focused on six shipwrecks at depth in the Gulf of Mexico. The questions posed by the project
illuminate how science and industry can collaborate to produce remarkable results. The papers presented in this issue form
a model for deepwater exploration. 相似文献
84.
85.
86.
A wooden Roman anchor was discovered at the retreating shore of the Dead Sea, north of Ein Gedi. The anchor's wood material was coated by a thick veneer of aragonite and gypsum crusts. The wood was dated by radiocarbon to the early Roman time in the Levant. Lead isotope analyses carried out on the Pb–Fe–Cu anchor material (remains of the anchor's metal parts) yielded ratios that indicate origin of the metal in Italian ores (maybe Tuscan). For the wooden part of the anchor a local tree was used. 相似文献
87.
88.
During recent reinvestigations in the Great Cave of Niah in Borneo, the ‘Hell Trench’ sedimentary sequence seen by earlier excavators was re-exposed. Early excavations here yielded the earliest anatomically-modern human remains in island Southeast Asia. Calibrated radiocarbon dates, pollen, algal microfossils, palynofacies, granulometry and geochemistry of the ‘Hell Trench’ sequence provide information about environmental and vegetational changes, elements of geomorphic history and information about human activity. The ‘Hell’ sediments were laid down episodically in an ephemeral stream or pool. The pollen suggests cyclically changing vegetation with forest habitats alternating with more open environments; indicating that phases with both temperatures and precipitation reduced compared with the present. These events can be correlated with global climate change sequences to produce a provisional dating framework. During some forest phases, high counts of Justicia, a plant which today colonises recently burnt forest areas, point to fire in the landscape. This may be evidence for biomass burning by humans, presumably to maintain forest-edge habitats. There is evidence from palynofacies for fire on the cave floor in the ‘Hell’ area. Since the area sampled is beyond the limit of plant growth, this is evidence for human activity. The first such evidence is during an episode with significant grassland indicators, suggesting that people may have reached the site during a climatic phase characterised by relatively open habitats ∼50 ka. Thereafter, people were able to maintain a relatively consistent presence at Niah. The human use of the ‘Hell’ area seems to have intensified through time, probably because changes in the local hydrological regime made the area dryer and more suitable for human use. 相似文献
89.
David d’Avray 《History of European Ideas》2013,39(8):1003-1018
A distinction between hard-to-shake but rational convictions, on the one hand, and the rationality that calculates causal and logical consequences, on the other hand, can generate questions for the history of ethics. Most moral thinkers draw some such distinction but the contours of the line differ greatly, and, in drawing the line, past moral thinkers tend to be influenced by their own deeply held principles, which in turn tend to reflect their social world. Questions about where the line between values and instrumental calculation are drawn and about the effect on this of the moral thinkers own social world are applied by way of illustration to Thomas Aquinas and Kant. The paper attempts to use Weberian social theory to elucidate a theme in the history of ethics, making every effort to keep the two kinds of theory distinct. 相似文献
90.