全文获取类型
收费全文 | 35篇 |
免费 | 7篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 13篇 |
地质学 | 16篇 |
海洋学 | 3篇 |
天文学 | 8篇 |
自然地理 | 1篇 |
出版年
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1943年 | 2篇 |
1940年 | 1篇 |
排序方式: 共有42条查询结果,搜索用时 0 毫秒
41.
Jonathan A. Sandor Jay B. Norton Jeffrey A. Homburg Deborah A. Muenchrath Carleton S. White Stephen E. Williams Celeste I. Havener Peter D. Stahl 《Geoarchaeology》2007,22(3):359-386
Research on soil fertility is presented in the context of runoff agriculture, a venerable farming system that has been used for millennia in arid to semiarid regions, where water is a major limiting resource for crop production. The agroecology of runoff farming was studied with the Zuni to evaluate nutrient and hydrologic processes, management, maize productivity, and soil quality in some of the oldest recognized fields in the United States. This ancient Southwest agriculture has functioned without conventional irrigation or fertilization by tapping into biogeochemical processes in natural watersheds connected to fields. Carefully placed fields are managed on alluvial fans and other valley margin landforms to intercept runoff and associated sediment and organic debris transported from adjoining forested uplands. We report on research to evaluate and link nitrogen and phosphorus, two key nutrients for crop production, in watershed, soil, and crop components of this agroecosystem. Nutrient data have been collected by observational and experimental methods for each component and the transport of nutrients from watershed to field to maize. The condition of Zuni agricultural soils suggests that their knowledge and management of soils contributed to effective conservation. This study and others indicate the need for further long‐term monitoring and experimental research on watersheds, runoff processes, field soils, and crops across a range of arid to semiarid ecosystems. © 2007 Wiley Periodicals, Inc. 相似文献
42.
Zooarchaeology can contribute to issues that lie beyond the traditional boundaries of archaeology and paleobiology. The techniques and methods of zooarchaeology are essential to an historical ecology that has emerged as a powerful perspective for understanding indigenous peoples and landscapes of the neotropics, both in the present and the past. In order to realize fully its potential contributions to historical ecology, zooarchaeology must reject the arbitrary dichotomization of culture and nature and a viewpoint that considers indigenous peoples as passive reactors to environments rather than as active creators of human landscapes. Zooarchaeology must avoid the seduction of neo-Malthusian assumptions that underlie many cherished models, and should do more than simply list extinctions at the hands of prehistoric humans. Instead, zooarchaeologists should focus on the study of past human landscapes, explore dynamic disturbances and the human maintenance of habitat mosaics, record the infrastructure of intensive agriculture, and understand the indigenous logic of past biodiversity management. When archaeologists study the landscapes of previous human populations, they are engaged in the practice of historical ecology. 相似文献