全文获取类型
收费全文 | 227篇 |
免费 | 1篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 1篇 |
废物处理 | 9篇 |
环保管理 | 8篇 |
综合类 | 68篇 |
基础理论 | 41篇 |
污染及防治 | 74篇 |
评价与监测 | 11篇 |
社会与环境 | 19篇 |
灾害及防治 | 1篇 |
出版年
2022年 | 2篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 4篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1982年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1968年 | 2篇 |
1966年 | 4篇 |
1965年 | 3篇 |
1963年 | 2篇 |
1961年 | 4篇 |
1960年 | 2篇 |
1958年 | 1篇 |
1957年 | 3篇 |
1955年 | 2篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1952年 | 1篇 |
1951年 | 1篇 |
1949年 | 1篇 |
1946年 | 1篇 |
1932年 | 1篇 |
1929年 | 1篇 |
1917年 | 1篇 |
排序方式: 共有232条查询结果,搜索用时 31 毫秒
111.
Oborn I Modin-Edman AK Bengtsson H Gustafson GM Salomon E Nilsson SI Holmqvist J Jonsson S Sverdrup H 《Ambio》2005,34(4-5):301-310
A systems analysis approach was used to assess farmscale nutrient and trace element sustainability by combining full-scale field experiments with specific studies of nutrient release from mineral weathering and trace-element cycling. At the Ojebyn dairy farm in northern Sweden, a farm-scale case study including phosphorus (P), potassium (K), and zinc (Zn) was run to compare organic and conventional agricultural management practices. By combining different element-balance approaches (at farmgate, barn, and field scales) and further adapting these to the FARMFLOW model, we were able to combine mass flows and pools within the subsystems and establish links between subsystems in order to make farm-scale predictions. It was found that internal element flows on the farm are large and that there are farm internal sources (Zn) and loss terms (K). The approaches developed and tested at the Ojebyn farm are promising and considered generally adaptable to any farm. 相似文献
112.
113.
114.
Since the substantial loss of subtidal eelgrass (Zostera marina L.) in the 1930s, seagrass beds in the Wadden Sea are limited to the intertidal zone and dominated by Z. noltii Hornem. This study deals with the effect of vegetated tidal flats on quantities of mobile epifauna and proves empirically the function of seagrass canopies as a refuge for marine animals remaining in the intertidal zone at ebb tide. Drop-trap samples were taken in the Sylt-Rømø Bight, a shallow tidal basin in the northern Wadden Sea, on vegetated and unvegetated tidal flats during July and August 2002, and during the entire growth period of Z. noltii from May to September in 2003. The species composition in Z. noltii and bare sand flats showed minor differences since only two isopod species (Idotea baltica and I. chelipes) occurred on Z. noltii flats exclusively. Juvenile shore crabs (Carcinus maenas L.), brown shrimps (Crangon crangon L.) and common gobies (Pomatoschistus microps Krøyer) were also found abundantly on bare sand flats. However, the results showed significantly higher abundances and production of these dominant species on vegetated tidal flats. Additionally, the analyses of faunal size classes indicated higher percentages of small individuals in the seagrass bed during the entire sampling period. Despite drastic diurnal fluctuations of dissolved oxygen at low tide, faunal density in the residual water layer remaining in seagrass canopies at ebb tide was found to be consistently higher than that found in artificially created tide-pool units. Although species composition of mobile epifauna did not basically differ between vegetated and unvegetated tidal flats, Z. noltii beds are considered to contribute quantitatively to the function of tidal flats, as an extended juvenile habitat for some of the most important species of the Wadden Sea food web.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
115.
Harald J. Geyer Derek C. G. Muir Irene Scheunert Christian E. W. Steinberg Antonius A. W. Kettrup 《Environmental science and pollution research international》1994,1(2):75-80
According to present understanding, persistent superlipophilic chemicals — such as octachlorodibenzo-p-dioxin, octachlorodibenzofuran, Mirex etc — with log Kow > 6 and cross sections > 9.5 Å, bioconcentrate in aquatic organisms only little from ambient water. The most convincing argument against it is that in bioconcentration experiments with superlipophilic chemicals amounts applied exceeded water solubility by several orders of magnitude. This paper describes various methods for determining bioconcentration factors (BCF) of superlipophilic compounds. As exemplified with octachlorodibenzo-p-dioxin, BCF values evaluated by these methods match well with those calculated by QSARs for fish and mussels based on log Kow and water solubility. As expected, these BCF values exceed previous values by several orders of magnitude. For BCF evaluation of superlipophilic chemicals in aquatic organisms we recommend:
- flow-through systems, kinetic method (OECD guideline No. 305 E)
- ambient concentrations < water solubility
- during the uptake and especially during the elimination phase no toxic effects of the test organisms should occur.
116.
117.
118.
Karl Oliver Kagan Harald Abele Britta Yazdi Bettina Böer Klaus Pintoffl Dave Wright Markus Hoopmann 《黑龙江环境通报》2011,31(13):1229-1233
119.
In the past 35 years, various kinds of dynamic models have been used to study vegetation development during primary or secondary succession. Typically, one specific model or models with the same conceptual background were employed. It remains largely unknown to what extent such model-based findings, e.g., on the speed of succession, depend on the specific model approach.To address this issue, we estimated the time elapsing during secondary succession in subalpine conifer forests of the Swiss National Park using three models of different conceptual background: (i) a forest gap model, (ii) a Markov chain model, and (iii) a minimum spanning tree model.Starting from a 95- to 125-year-old mountain pine (Pinus montana Miller) forest, all three models predicted a similar successional development. Even though the forest gap model and the Markov chain model are based on totally different approaches and were calibrated using different data sets, they both forecasted that it would take 500–550 years to reach a late-successional forest stage. The minimum spanning tree model, which only reveals a certain number of time steps yielding a minimum time estimate, showed a development of tree density (stems/ha) that was similar to the results of the forest gap model, but a strict quantitative comparison is not feasible.Our study shows that modeling forest development using three different approaches is quite powerful to obtain a robust estimate of the speed of forest succession. In our case, this estimate is higher than what has been suggested in previous studies that investigated secondary forest succession. The use of several approaches allows for a more comprehensive analysis in terms of variables covered (e.g., relative forest cover in the Markov approach vs. stand-scale species composition in the forest gap model). We recommend that in studies focusing on the speed of succession, several models should be employed simultaneously to identify inconsistencies in our knowledge and to increase confidence in the results. 相似文献
120.
The migration of large aggregations of animals that sweep through the landscape is a phenomenon with large consequences in many ecosystems. It has been suggested that such migrations are mediated by resource depletion. Under this hypothesis it has been shown that simple foraging rules may generate density-dependent migratory waves (DDMW) in which the speed and amplitude increase with animal abundance. We tested these predictions on a 32-year data set of the spatial distribution of the two youngest age groups of a small pelagic schooling fish, the capelin (Mallotus villosus), by the end of their annual feeding migration in the Barents Sea. Our data suggest that the two age groups divided the Barents Sea by forming migratory waves that moved in opposite directions. The aggregation and spatial displacement of these waves increased with increasing age-specific abundance. However, possibly through social interactions, migratory pattern was modified by the abundance of the other age group. 相似文献