全文获取类型
收费全文 | 139篇 |
免费 | 4篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 1篇 |
环保管理 | 15篇 |
综合类 | 30篇 |
基础理论 | 48篇 |
污染及防治 | 38篇 |
评价与监测 | 5篇 |
社会与环境 | 3篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 15篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2003年 | 4篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1940年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有143条查询结果,搜索用时 921 毫秒
31.
On the small North Sea island Helgoland (54°11' N, 07°55' E) we studied the stopover ecology of two subspecies of northern wheatear, Oenanthe oenanthe, during spring migration. Birds heading for Scandinavia (O. o. oenanthe) face only short flights across an ecological barrier (50-500 km) whereas those originating from Greenland and Iceland (O. o. leucorhoa) have to cover between 1,000 and 2,500 km in the impending flight. Colour-ringed individuals showed that 90% of Scandinavian birds left on the day of ringing while 40% (males) and 30% (females) of Greenland/Icelandic birds stayed at least 1 night. The birds who remained were thus mostly O. o. leucorhoa. They often established desirable feeding territories on the beach and had a high rate of body mass increase (1.7 g/day). However, subspecies did not differ in habitat choice and in foraging effort, but O. o. leucorhoa had a higher success rate in pecking. Departure decisions were analysed by comparing (a) conditions on the day of ringing between departing and staying birds and (b) for birds staying between the day of departure and the preceding day. The factors that were probably important in the decision to depart differed between subspecies. In O. o. leucorhoa, few birds departed with bad or deteriorating weather conditions (tailwind component, cloud cover), whereas departures of O. o. oenanthe seemed to be little affected by those factors. A few O. o. oenanthe stayed early in the spring migration season and/or had low fat reserves. Interference during foraging seemed to play a role because both subspecies tended to leave when the densities of northern wheatears were high. Other factors related to refuelling conditions (food supply, foraging effort, predation risk) failed to show differences between staying and departing individuals. In summary, almost all Scandinavian birds departed quickly and irrespective of refuelling and weather conditions, whereas many (but not all) Greenland/Icelandic birds seemed to prepare for a long-distance flight and carefully adjusted departure to weather conditions. The observed differences in stopover behaviour and departure decisions in the two subspecies of northern wheatear indicate that the distance to the next stopover site or to the goal area has to be considered when applying optimal migration models. 相似文献
32.
33.
Verdonck FA Boeije G Vandenberghe V Comber M de Wolf W Feijtel T Holt M Koch V Lecloux A Siebel-Sauer A Vanrolleghem PA 《Chemosphere》2005,58(9):1169-1176
Within the context and scope of the forthcoming European Union chemical regulations (REACH), there is a need to be able to prioritise the chemicals for evaluation. Therefore, a simple, pragmatic and adequately conservative approach for the identification of substances of very low or no immediate concern at an early stage is presented. The fundamental principles and basic concepts are derived from the EU Technical Guidance Document and EUSES, and are translated into an easy-to-use rule-based system. For this development, the effect on risk characterisation ratios (RCRs) of the key environmental parameters in EUSES was quantified (taking into account several standardised chemical release scenarios). Using statistical analysis, ranges were identified for each key parameter, within which the end result of the assessment was not significantly affected. This information was then translated into a lookup table from which environmental risk characterisation ratios can be directly read as a function of a few parameters. 相似文献
34.
Volker W. J. H. Kirchhoff 《Environmental science and pollution research international》1996,3(4):210-212
Increasing carbon monoxide and ozone concentrations have been observed in the lower troposphere of the Brazilian Amazon region in recent years (1989–1995). Carbon monoxide and ozone have been measured in the region continuously; from observations at a single site and many sporadic field missions, there is a clear indication that the chemical activity in the troposphere is growing, with increasing concentrations especially during the dry season. On the other hand, the most recent deforestation assessment by the Brazilian Government, performed by the Instituto Nacional de Pesquisas Espaciais (INPE) using Landsat data, shows yearly rates rising from the 11,130 km2 year?1 minimum of the 1990/91 survey, to 13,786 km2 year?1 for the 1991/92 period, and 14,896 km2 year?1 for the period 1992/94. It is argued that the increase in deforestation/biomass burning activities in “Amazonia” have produced larger carbon monoxide and ozone concentrations in the lower atmosphere. 相似文献
35.
Road development, housing growth, and landscape fragmentation in northern Wisconsin: 1937-1999. 总被引:4,自引:0,他引:4
Todd J Hawbaker Volker C Radeloff Murray K Clayton Roger B Hammer Charlotte E Gonzalez-Abraham 《Ecological applications》2006,16(3):1222-1237
Roads remove habitat, alter adjacent areas, and interrupt and redirect ecological flows. They subdivide wildlife populations, foster invasive species spread, change the hydrologic network, and increase human use of adjacent areas. At broad scales, these impacts cumulate and define landscape patterns. The goal of this study was to improve our understanding of the dynamics of road networks over time, and their effects on landscape patterns, and identify significant relationships between road changes and other land-use changes. We mapped roads from aerial photographs from five dates between 1937 and 1999 in 17 townships in predominantly forested landscapes in northern Wisconsin, U.S.A. Patch-level landscape metrics were calculated on terrestrial area outside of a 15-m road-effect zone. We used generalized least-squares regression models to relate changes in road density and landscape pattern to concurrent changes in housing density. Rates of change and relationships were compared among three ecological regions. Our results showed substantial increases in both road density and landscape fragmentation during the study period. Road density more than doubled, and median, mean, and largest patch size were reduced by a factor of four, while patch shape became more regular. Increases in road density varied significantly among ecological subsections and were positively related to increases in housing density. Fragmentation was largely driven by increases in road density, but housing density had a significantly positive relationship with largest patch area and patch shape. Without protection of roadless areas, our results suggest road development is likely to continue in the future, even in areas where road construction is constrained by the physical environment. Recognizing the dynamic nature of road networks is important for understanding and predicting their ecological impacts over time and understanding where other types of development are likely to occur in the future. Historical perspectives of development can provide guidance in prioritizing management efforts to defragment landscapes and mitigate the ecological impacts of past road development. 相似文献
36.
Otto Lüderitz Chris Galanos Volker Lehmann Hubert Mayer Ernst Th. Rietschel Jürgen Weckesser 《Die Naturwissenschaften》1978,65(11):578-585
The endotoxic principle of lipopolysaccharides (LPS) is localized in their lipid A component. Biological effects of LPS on, for instance, body temperature, blood pressure, and blood picture, are also induced by free lipid A. In contrast to the great variability of the 0-specific chains, the chemical structure of lipid A is much more constant. It is common for Salmonella and similar for other genera of the Enterobacteriaceae. Recently, a number of lipid A's have been recognized that exhibited distinct structural features compared with Enterobacteriaceae. These lipid A's were found to be also distinct with regard to some of their biological properties. 相似文献
37.
Volker Vossius 《Die Naturwissenschaften》1984,71(11):552-559
Inventions are patentable according to the German Patent Law (and the European Patent Convention), if they are new, involve an inventive step and are susceptible to industrial application. Living matter and processes performed therewith are likewise patentable. 相似文献
38.
39.
Sabine Bauer Volker Witte Melanie Böhm Susanne Foitzik 《Behavioral ecology and sociobiology》2009,64(1):45-56
Ant social parasites use chemical warfare to facilitate host colony takeover, which is a critical but recurring step in their
life cycle. Many slave-making ants use the secretion of the Dufour gland to manipulate host behaviour during parasitic nest
foundation and slave raids. Harpagoxenus sublaevis applies this chemical weapon onto defending Leptothorax host workers, which elicits deadly fights amongst them. Host species are expected to evolve counter-adaptations against this
behavioural manipulation and in this study we investigated the geographic structure of this co-evolving trait. We compared
the effectiveness of the parasitic gland secretion from different H. sublaevis populations in host colonies from various sites and analysed the occurrence of local adaptation. The two host species L. muscorum and L. acervorum generally showed different responses to the parasites’ chemical weapon: L. acervorum attacked nestmates treated with Dufour gland secretion, while L. muscorum workers fled. Flight, instead of intraspecific fights, is an adaptive host reaction as it results in fewer host fatalities
during raids. Beside interspecific host differences, we found a geographic mosaic of host resistance: parasites from a German
population strongly manipulated the behaviour of both sympatric Leptothorax populations. Russian or Italian hosts instead did not react with intracolonial aggression, but fled when confronted with
the gland secretion of their sympatric parasite. Not only variation in host resistance explains differences in the effectiveness
of the parasitic gland secretion but also interpopulational differences in its chemical composition, which were revealed by
gas chromatography and mass spectrometry. 相似文献
40.
Roger B. Hammer Susan I. Stewart Todd J. Hawbaker Volker C. Radeloff 《Journal of environmental management》2009
Rural, forested areas throughout the United States are experiencing strong housing growth with potentially detrimental impacts on the environment. In this paper, we quantify housing growth in Northern Wisconsin over the last sixty years to determine if growth rates were higher near public lands, which may represent an important recreational amenity. We used data from the U.S. Census to produce decadal housing density estimates, “backcasts,” from 1940 to 2000 for northern Wisconsin to examine “rural sprawl” in northern Wisconsin and its relationship to forested areas and public lands. We integrated housing density estimates with the 1992/1993 National Land Cover Dataset to examine the relationship between rural sprawl and land cover, especially forests. Between 1940 and 2000, private land with <2 housing units/km2 decreased from 47% to 21% of the total landscape. Most importantly, housing growth was concentrated along the boundaries of public lands. In 14 of the 19 counties that we studied, housing growth rates within 1 km of a public land boundary exceeded growth rates in the remainder of the county, and three of the five counties that did not exhibit this pattern, were the ones with the least amount of public land. Future growth can be expected in areas with abundant natural amenities, highlighting the critical need for additional research and effective natural resource management and regional planning to address these challenges. 相似文献