全文获取类型
收费全文 | 134篇 |
免费 | 12篇 |
出版年
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 13篇 |
2009年 | 17篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有146条查询结果,搜索用时 500 毫秒
51.
ANDREW LOTHIAN 《Geographical Research》2008,46(2):196-207
A survey of the visual effects of wind farms was undertaken in South Australia, with the aim of quantifying the impact of wind farms on the perceived scenic quality of landscapes. In the study a total of 311 participants assessed the scenic quality of a photographed landscape in 68 coastal and inland locations where wind farms could be located, both without wind farms and with wind farms digitally added to the scene. A key finding of the study was that wind farms generally had a negative effect on landscapes of higher scenic quality but a positive effect on landscapes of lower scenic quality. The negative visual effects of a wind farm did not reduce appreciably with distance. White, blue or grey coloured turbines were preferred over tan or rainbow hues, but this finding was based on a small number of scenes. Limitations of the study included using static views of wind farms and having an insufficient number of scenes to assess the influence of the number of turbines on scenic quality ratings. The study concluded that wind farms should avoid areas of higher perceived scenic quality, particularly on the coast, and be located in areas of lower scenic quality. The study adds to the growing body of international research on community attitudes to wind farms, and contributes useful knowledge for future planning of wind farms in Australia. These research results should assist communities, government agencies and the wind energy industry and improve the planning and design of wind farms by taking community perceptions into account. 相似文献
52.
Nutrient dynamics in lake systems are influenced by the loading of sediment-associated phosphorus (P) from both internal and external sources. Despite efforts to control lake productivity through reductions in external P loading, water quality problems persist in some lakes due to high internal loading of P from bottom sediment. The present study examines the spatial distribution of chemically defined P forms (NH4Cl-RP, BD-RP, NaOH-RP, HCI-RP, and NaOH(S5)-RP) in bottom sediments of two noncalcareous Canadian Shield Lakes. Sediment P data are related to some of the physical and chemical variables that control internal P loading in lakes. The BD-RP and NaOH-RP forms are related to water depth and nonresidual iron and aluminum content of sediment. Approximately 80% of the total extractable P in the Muldrew Lakes sediment was bioavailable P (NH4Co-RP + BD - RP + NaOH - RP), which is about twice that reported in the literature for calcareous lakes. In order to model P cycling in the Muldrew Lakes, further research is required to determine the internal supply of P from the lakes' sediments and potential anthropogenic inputs ofP from private sewage disposal systems. La dynamique des nutriments dans un lac est influenceé par I'apport en phosphore (P) provenant de sources internes et externes. Malgré les efforts déployés pour contrôler le taux de P par réduction de I'apport externe, la qualityé de I'eau demeure un problème dans certains lacs à cause de la contribution interne provenant de la sédimentation de fond. Cette étude examine la distribution spatiale de formes chimiquement définies de P (NH4CI-RP, BD-RP, NaOH-RP, HCI-RP, and NaOH(85)-RP) présentes dans les sédiments de fonds de deux lacs non-calcaires du Bouclier Canadien. Les contenus en P des sediments sont reliés à certaines variables physiques et chimiques qui contrôlent I'apport interne des lacs. Le Bd-RP et le NaOH-RP sont reliés à la profondeur de I'eau ainsi qu'aux contenus non-résiduels de fer et d'aluminium du sédiment. Environ 80% du P pouvant être extrait du sédiment des lacs Muldrew éait du P (NH4Cl-RP + BD-RP + NaOH-RP) biodisponible. Ceci représente le double de ce qui est rapporté dans la littéature pour des lacs calcaires. Afin de construire un modèle du cycle du P dans les lacs Muldrew, il est important de déterminer I'apport interne de P provenant de la sédimentation et les sources anthropiques potentielles provenant des systèmes d'égouts privés. 相似文献
53.
54.
55.
56.
French Warships in the Age of Sail, 1626–1786: design,construction, careers and fates RIF WINFIELD and STEPHEN N. ROBERTS 446 pp,large format,over 200 b&w illustrations,Seaforth Publishing, 2017, £60.00 (hbk), ISBN 978‐1473893511 下载免费PDF全文
ANDREW LAMBERT 《International Journal of Nautical Archaeology》2018,47(2):493-494
57.
58.
59.
60.