全文获取类型
收费全文 | 2169篇 |
免费 | 79篇 |
出版年
2020年 | 31篇 |
2019年 | 54篇 |
2018年 | 66篇 |
2017年 | 88篇 |
2016年 | 90篇 |
2015年 | 51篇 |
2014年 | 57篇 |
2013年 | 594篇 |
2012年 | 64篇 |
2011年 | 63篇 |
2010年 | 62篇 |
2009年 | 63篇 |
2008年 | 61篇 |
2007年 | 34篇 |
2006年 | 48篇 |
2005年 | 48篇 |
2004年 | 45篇 |
2003年 | 38篇 |
2002年 | 35篇 |
2001年 | 40篇 |
2000年 | 34篇 |
1999年 | 23篇 |
1998年 | 34篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 27篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 17篇 |
1984年 | 26篇 |
1983年 | 23篇 |
1982年 | 25篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 21篇 |
1978年 | 10篇 |
1977年 | 19篇 |
1976年 | 17篇 |
1975年 | 11篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1972年 | 10篇 |
1970年 | 9篇 |
排序方式: 共有2248条查询结果,搜索用时 31 毫秒
991.
992.
993.
Citizen and government co-production of data: Analyzing the challenges to government adoption of VGI
With the recent rise of open government and open data initiatives, governments are increasingly adopting new approaches of citizen participation to support a more democratic, transparent, and inclusive government system. Among other forms of citizen participation, Volunteered Geographic Information (VGI) is one approach to connecting citizens and government. Accepting VGI as a way to update government data or collect near-real-time information from citizens can create a partner-like relationship where citizens voluntarily contribute time and effort to support government actions. However, as a relatively new approach to citizen participation and data collection, VGI requires evaluation from the perspective of governments. This research investigates the challenges and opportunities that governments have found through the implementation of VGI projects. Results are drawn from interviews conducted with 19 government organizations, revealing organizational and technical challenges that limit the adoption of VGI. Organizational challenges are associated with government mindset, implementation, and project management, while technical challenges involve development of the system and quality of data. Given these challenges, we derive recommendations within the phases of project initiation, implementation, and expansion that can foster VGI adoption in government. 相似文献
994.
Peter Taber 《Anthropology today》2017,33(6):16-20
To the extent that environmental governance aspires to be based on positive knowledge of what ‘the environment’ consists of and how it functions, programmes of environmental management must find ways to study it. This article draws on scholarship on knowledge infrastructures to examine a trajectory of scientific work in Ecuador focused on biodiversity and the recent uptake of this infrastructure for the study of climate change. When combined with an appreciation for the character of power and knowledge in modern institutions, analyses of experts’ ‘infrastructure work’ elucidate how environmental problems take shape as objects of expert intervention at the level of concrete, technical practices. Incorporating scientific infrastructure within the ambit of environmental anthropology can help us to understand the shape of environmental politics to come. 相似文献
995.
996.
997.
998.
999.
Peter A. Jell 《Alcheringa: An Australasian Journal of Paleontology》2013,37(4):253-259
Plumulites richorum sp. nov. is represented by two complete sclerite assemblages from Early Devonian strata of the Humevale Formation in a small quarry northeast of Kinglake West, Victoria. The completeness of these sclerite assemblages necessitates a revision of terminology applied to machaeridians. Moreover, the sclerite assemblages make it necessary to erect a new Family Plumulitidae and allow several deductions about the animal itself, namely: 1, there was a discrete head possibly with soft anterior projections; 2, there was considerable modification of sclerites and their arrangement near the head, indicating possible sexual dimorphism; 3, sclerites were almost certainly not rigidly attached to the soft parts of the animal. The material shows that Plumulites was neither an arthropod nor an echinoderm, but rather a vagile benthic animal probably belonging to the Annelida. 相似文献
1000.
Catherine Delano-Smith Peter Barber Damien Bove Christopher Clarkson P. D. A. Harvey Nick Millea 《Imago Mundi: The International Journal for the History of Cartography》2017,69(1):1-36
Remarkably little is known about the earliest surviving separate-sheet medieval map of Britain that takes its name from its former owner, Richard Gough (1735–1809), and that has been variously dated to between 1300 and 1400, and later. It presents a sophisticated cartographical image at a time when detailed maps of individual regions were almost unknown in Europe, yet nothing is agreed about its possible origins, context (ecclesiastical or secular), or why and how it was compiled. In the belief that historical interpretation has to stem from an intimate knowledge of the map as artefact—the state of the parchment, nature of the inks, palaeography—as well as image, an informal study group of historians and scientists (the Gough Map Panel) was convened in 2012 to examine the map through high resolution digital reproduction, hyperspectral analysis, three-dimensional analysis and Raman pigment analysis. Although the study is still ongoing, much that is new has been discovered, notably about the way features were marked on the map, Gough’s application to the map of a damaging reagent to render place-names readable, and the extent to which the original map (now dated to c.1400), although never completed, was nonetheless reworked on two different occasions in the fifteenth century, effectively creating two further maps. These and other findings are summarized here to encourage the further study of the map’s features that is needed before it can be fully understood. 相似文献