全文获取类型
收费全文 | 564篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 14篇 |
环保管理 | 26篇 |
综合类 | 270篇 |
基础理论 | 108篇 |
环境理论 | 1篇 |
污染及防治 | 103篇 |
评价与监测 | 20篇 |
社会与环境 | 23篇 |
灾害及防治 | 2篇 |
出版年
2018年 | 7篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2013年 | 22篇 |
2012年 | 12篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 18篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 27篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 34篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 8篇 |
1965年 | 11篇 |
1964年 | 11篇 |
1963年 | 9篇 |
1962年 | 11篇 |
1961年 | 11篇 |
1960年 | 18篇 |
1959年 | 10篇 |
1958年 | 10篇 |
1957年 | 10篇 |
1956年 | 10篇 |
1955年 | 6篇 |
1954年 | 5篇 |
1951年 | 5篇 |
排序方式: 共有571条查询结果,搜索用时 0 毫秒
311.
Alain Jacot Hendrik Reers Wolfgang Forstmeier 《Behavioral ecology and sociobiology》2010,64(10):1515-1525
The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalizations are the most commonly
used cues in avian parent–offspring communication, and it has been shown in several species that fledglings respond specifically
to their parents' contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect
recognition errors or alternatively a strategy of fledglings to obtain food or other direct benefits from unrelated adult
birds. In a playback experiment, we tested whether zebra finch Taeniopygia guttata fledglings perceive variation in adult call signatures to recognize their parents and whether the propensity to respond to
unrelated individuals is related to the gender of adults and to signal properties of male and female calls. Male calls are
learnt and show high intra-sexual variation, which may improve the accurate recognition of the father's individual signature.
In contrast, calls of adult females are innate, show lower intra-sexual variation such that the mother's call is more likely
to be confused with another female call. We demonstrate that fledglings are able to recognize their parents. In addition,
fledglings reacted more strongly to unrelated females compared with unrelated males. Our findings suggest that responses to
unrelated adults may reflect recognition errors and indicate the importance of variation in identity signals for individual
recognition processes in parent–offspring communication. 相似文献
312.
Scenarios of global bioenergy production: The trade-offs between agricultural expansion, intensification and trade 总被引:1,自引:0,他引:1
Hermann Lotze-Campen Alexander Popp Tim Beringer Christoph Müller Alberte Bondeau Stefanie Rost Wolfgang Lucht 《Ecological modelling》2010,221(18):2188-2196
Increased future demands for food, fibre and fuels from biomass can only be met if the available land and water resources on a global scale are used and managed as efficiently as possible. The main routes for making the global agricultural system more productive are through intensification and technological change on currently used agricultural land, land expansion into currently non-agricultural areas, and international trade in agricultural commodities and processed goods. In order to analyse the trade-offs and synergies between these options, we present a global bio-economic modelling approach with a special focus on spatially explicit land and water constraints as well as technological change in agricultural production. For a global bioenergy demand scenario reaching 100 ExaJoule (EJ) until 2055 we derive a required rate of productivity increase on agricultural land between 1.2 and 1.4 percent per year under different land allocation options. A very high pressure for yield increase occurs in Sub-Saharan Africa and the Middle East, even without additional bioenergy demand. Moreover, we analyse the implicit values (shadow prices) of limited water resources. The shadow prices for bioenergy are provided as a metric for assessing the trade-offs between different land allocation options and as a link between the agricultural and energy sector. 相似文献
313.
314.
Oelmann Y Kreutziger Y Temperton VM Buchmann N Roscher C Schumacher J Schulze ED Weisser WW Wilcke W 《Journal of environmental quality》2007,36(2):396-407
Previous research has shown that plant diversity influences N and P cycles. However, the effect of plant diversity on complete ecosystem N and P budgets has not yet been assessed. For 20 plots of artificially established grassland mixtures differing in plant diversity, we determined N and P inputs by bulk and dry deposition and N and P losses by mowing (and subsequent removal of the biomass) and leaching from April 2003 to March 2004. Total deposition of N and P was 2.3 +/- 0.1 and 0.2 +/- 0.01 g m(-2) yr(-1), respectively. Mowing was the main N and P loss. The net N and P budgets were negative (-6.3 +/- 1.1 g N and -1.9 +/- 0.2 g P m(-2) yr(-1)). For N, this included a conservative estimate of atmospheric N(2) fixation. Nitrogen losses as N(2)O were expected to be small at our study site (<0.05 g m(-2) yr(-1)). Legumes increased the removal of N with the harvest and decreased leaching of NH(4)-N and dissolved organic nitrogen (DON) from the canopy. Reduced roughness of grass-containing mixtures decreased dry deposition of N and P. Total dissolved P and NO(3)-N leaching from the canopy increased in the presence of grasses attributable to the decreased N and P demand of grass-containing mixtures. Species richness did not have an effect on any of the studied fluxes. Our results demonstrate that the N and P fluxes in managed grassland are modified by the presence or absence of particular functional plant groups and are mainly driven by the management. 相似文献
315.
Henne Paul D. Bigalke Moritz Büntgen Ulf Colombaroli Daniele Conedera Marco Feller Urs Frank David Fuhrer Jürg Grosjean Martin Heiri Oliver Luterbacher Jürg Mestrot Adrien Rigling Andreas Rössler Ole Rohr Christian Rutishauser This Schwikowski Margit Stampfli Andreas Szidat Sönke Theurillat Jean-Paul Weingartner Rolf Wilcke Wolfgang Tinner Willy 《Regional Environmental Change》2018,18(1):205-221
Regional Environmental Change - Planning for the future requires a detailed understanding of how climate change affects a wide range of systems at spatial scales that are relevant to humans.... 相似文献
316.
317.
Contamination of industrial sites by wood preservatives such as chromated copper arsenate (CCA) may pose a serious threat to groundwater quality. The objective of this study was to characterise the spatial variability of As and Cr concentrations in the solid phase and in the soil water at a former wood impregnation plant and to reveal the fundamental transport processes. The soil was sampled down to a depth of 2m. The soil water was extracted in situ from the vadose zone over a period of 10 months at depths of 1 and 1.5m, using large horizontally installed suction tubes. Groundwater was sampled from a depth of 4.5m. Results showed that arsenic and chromium had accumulated in the upper region of the profile and exhibited a high spatial variability (As: 21-621 mg kg(-1); Cr: 74-2872 mg kg(-1)). Concentrations in the soil water were high (mean As 167 microg L(-1); Cr: 62 microg L(-1)) and also showed a distinct spatial variability, covering concentration ranges up to three orders of magnitude. The variability was caused by the severe water-repellency of the surface soil, induced by the concurrent application of creosote wood preservatives, which leads to strong preferential flow as evident from a dye experiment. In contrast to soil water concentrations, only low As concentrations (<12 microg L(-1)) were detected in the groundwater. High Cr concentrations in the groundwater (approx. 300 microg L(-1)), however, illustrated the pronounced mobility of chromium. Our study shows that at sites with a heterogeneous flow system in the vadose zone a disparity between flux-averaged and volume-averaged concentrations may occur, and sampling of soil water might not be adequate for assessing groundwater concentrations. In these cases long-term monitoring of the groundwater appears to be the best strategy for a groundwater risk assessment. 相似文献
318.
319.
Dirk Bunke Wolfgang Reuter Monika Kohla Andreas Ahrens 《Umweltwissenschaften und Schadstoff-Forschung》2005,17(2):114
Ziel und Hintergrund
Seit Oktober 2003 liegt der Verordnungsentwurf zur Neuordnung der europ?ischen Chemikalienpolitik vor. Aus ihm ergeben sich zahlreiche, zum Teil neuartige Aufgaben für Hersteller und Importeure von Chemikalien, Zubereitungen und Erzeugnissen, für nachgeschaltete Anwender und für den Handel. Die Landesregierung Nordrhein-Westfalen hat in einem Pilotprojekt Schlüsselelemente des REACH-Systems in der Praxis erprobt. In dieser Ver?ffentlichung werden Erfahrungen aus dem Projekt aufgezeigt, die speziell für die Textilveredlung wichtig sind. 相似文献320.