全文获取类型
收费全文 | 519篇 |
免费 | 4篇 |
国内免费 | 13篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 19篇 |
环保管理 | 65篇 |
综合类 | 144篇 |
基础理论 | 88篇 |
污染及防治 | 143篇 |
评价与监测 | 31篇 |
社会与环境 | 31篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 24篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 49篇 |
2012年 | 19篇 |
2011年 | 35篇 |
2010年 | 31篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 24篇 |
2006年 | 22篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1980年 | 6篇 |
1975年 | 3篇 |
1969年 | 4篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1963年 | 4篇 |
1962年 | 9篇 |
1961年 | 3篇 |
1960年 | 5篇 |
1959年 | 6篇 |
1958年 | 4篇 |
1957年 | 8篇 |
1956年 | 4篇 |
1955年 | 3篇 |
1933年 | 2篇 |
1932年 | 3篇 |
1923年 | 2篇 |
排序方式: 共有536条查询结果,搜索用时 15 毫秒
1.
2.
Herbert H. Koepf 《Agriculture, ecosystems & environment》1984,11(3):268-270
3.
4.
5.
Neill A. Herbert Jon E. Skjæraasen Trygve Nilsen Anne G. V. Salvanes John F. Steffensen 《Marine Biology》2011,158(4):737-746
The frequency of low O2 (hypoxia) has increased in coastal marine areas but how fish avoid deleterious water masses is not yet clear. To assess whether
the presence and oxygen pressure (PO2) level of an O2 refuge affects the hypoxia avoidance behaviour of fish, individual Atlantic cod (Gadus morhua L.) were exposed to a range of O2 choices in a 2-way choice chamber at 11.4°C over two different experiments. Cod in the first experiment were allowed access
to a fixed O2 refuge (fully air-saturated seawater) whilst oxygen pressure (PO2) on the other side was reduced in steps to a critically low level, i.e. 4.3 kPa—a point where cod can no longer regulate
O2 consumption. Under these conditions, cod did not avoid any level of hypoxia and fish swimming speed also remained unchanged.
In contrast, strong avoidance reactions were exhibited in a second experiment when fish were again exposed to 4.3 kPa but
the safety, i.e. PO2, of the refuge was reduced. Fish not only spent less time at 4.3 kPa as a result of fewer sampling visits but they also swam
at considerably slower speeds. The presence of an avoidance response was thus strongly related to refuge PO2 and it is unlikely that cod, and possibly other fish species, would enter low O2 to feed in the wild if a sufficiently safe O2 refuge was not available. It is therefore hypothesized that the feeding range of fish may be heavily compressed if hypoxia
expands and intensifies in future years. 相似文献
6.
Maria Clara P. Amorim José Miguel Simões Vitor C. Almada Paulo J. Fonseca 《Behavioral ecology and sociobiology》2011,65(4):707-716
Signal attributes should show different degrees of variability depending on the information to be conveyed. Species identity
is usually associated with stereotyped features of a signal, whereas other types of information such as individual quality
and motivation are associated with signal plasticity. Lusitanian toadfish males form aggregations during the breeding season
and emit a tonal advertisement call (the boatwhistle) to attract mates to their nests. We test the hypothesis that the boatwhistle
can convey information both on individual identity and motivation by checking how signal parameters vary with time. We study
how the physical (tide level) and social (calling alone or in a chorus) environments and male calling rate affect this advertisement
signal and how all these external and internal factors (environment, social and male motivation) blend to modulate the Lusitanian
toadfish’s advertisement call. Boatwhistles of each male were very stereotyped in short periods of time (minutes), but intra-male
signal variability greatly increased in a longer time scale (days). Nevertheless, significant differences among males could
still be found even in a long time scale. Pulse period was the acoustic feature that most contributed to discriminate among
males. Tide level and male calling rate modulated boatwhistle characteristics, and there was a differential effect of tide
on call attributes depending on male calling rate. Social acoustic environment only affected calling rate. These results suggest
that inter-individual differences in call characteristics and call plasticity may mediate both male–male assessment and mate
choice. 相似文献
7.
The European Union introduced several policy instruments based in the extended producer responsibility (EPR) in order to improve the environmental performance of products and services through their life cycles. In this context, the Portuguese government decided to apply the EPR concept to tyres, and producers were obliged to constitute an end-of-life management system to promote the collection, recycling and reuse of end-of-life (EOL) tyres. This required producers, distributors, recyclers and retreaders to be identified and characterized, and local processing infrastructures to be analyzed. The information was used to design an economically optimised EOL tyre management system while promoting the activity of all EOL operators in order for the imposed collecting and recovery targets to be fulfilled. This paper discusses the interaction between the different governmental, private and academic institutions for the creation of the integrated management system for EOL tyres, the approach taken, the technical, political and legal aspects underneath them, as well as the environmental consequences induced by the creation of the management system. The results obtained during the first years of operation are reported and show an increase in the collection and recycling of EOL tyres and the consolidation of the collection and processing infrastructures. 相似文献
8.
João Paulo Silva Author Vitae Mário Santos Author Vitae Author Vitae Domingos Leitão Author Vitae Author Vitae Márcia Pinto Author Vitae Author Vitae João Alexandre Cabral Author Vitae 《Ecological modelling》2010,221(16):1954-1963
Collision with conductors and earth cables is a known impact generated by transmission power lines, however there is virtually no information on how these infrastructures might affect bird distribution in a landscape context. With this work we specifically hypothesise that transmission power lines may affect the occurrence of a threatened bird, the little bustard (Tetrax tetrax). To test this hypothesis we used a Stochastic Dynamic Methodology (StDM), analysing the effects of power lines in a landscape perspective and simulating population trends as a response to power line installation and habitat changes induced by agricultural shifts in southern Portugal. The data used in the dynamic model construction included relevant gradients of environmental conditions and was sampled during the breeding seasons of 2003-2006. Transmission power lines were significantly avoided by the little bustard and the developed StDM model showed that the distance to these utility structures is the most important factor determining breeding densities in sites with suitable habitat for the species, which possibly leads to displacement of populations and habitat fragmentation. The model simulations also provided the base to analyse the cumulative effects caused by the habitat degradation that can ultimately lead to the extinction of local populations. Within priority conservation sites, the dismantling of existing transmission lines should be considered whenever possible, in order to ensure adequate breeding habitat. The model is considered useful as an auxiliary tool to be used in environmental impact assessments, management and conservation studies. 相似文献
9.
Atlantic herring, Clupea harengus, increase their swimming speed during low O2 (hypoxia) and it has been hypothesised that the behavioural response is modulated by the degree of “respiratory distress” (i.e. a rise in anaerobic metabolism and severe physiological stress). To test directly whether a deviation in physiological homeostasis is associated with any change in behavioural activity, we exposed C. harengus in a school to a progressive stepwise decline in water oxygen pressure
and measured fish swimming speed and valid indicators of primary and secondary stress (i.e. blood cortisol, lactate, glucose and osmolality). Herring in hypoxia increased their swimming speed by 11–39% but only when
was <8.5 kPa and in an unsteady (i.e. declining) state. In parallel with the shift in behaviour, plasma cortisol also exhibited an increase with
plasma osmolality was subject to a transient rise at 8.5 kPa and plasma glucose was generally reduced at
However, without any rise in anaerobically derived lactate levels, there was no evidence of respiratory distress at any set
We show that a shift in physiological homeostasis is indeed linked with an increase in the swimming speed of herring but the physiological response reflects a hypoxia-induced shift in metabolic fuel-use rather than respiratory distress per se. The significance of this behavioural–physiological reaction is discussed in terms of behavioural-energetic trade-offs, schooling dynamics and the hypoxia tolerance of herring. 相似文献
10.