全文获取类型
收费全文 | 143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 | 37篇 |
基础理论 | 47篇 |
污染及防治 | 36篇 |
评价与监测 | 5篇 |
社会与环境 | 3篇 |
出版年
2022年 | 2篇 |
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 | 3篇 |
1999年 | 5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 | 2篇 |
1964年 | 4篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1958年 | 2篇 |
1957年 | 1篇 |
1940年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 31 毫秒
51.
Urs Gimmi Shelley L. Schmidt Todd J. Hawbaker Camilo Alcántara Ulf Gafvert Volker C. Radeloff 《Journal of environmental management》2011
Protected areas are cornerstones of biodiversity conservation, but they are in danger of becoming islands in a sea of human dominated landscapes. Our question was if protected areas may even foster development in their surroundings because they provide amenities that attract development, thus causing the isolation of the ecosystems they were designed to protect. Our study analyzed historic aerial photographs and topographical maps to reconstruct road development and building growth within and around Indiana Dunes and Pictured Rocks National Lakeshores in the U.S. Great Lakes region from 1938 to 2005, and to estimate the effects of park creation in 1966 on changes in landscape patterns. Historic U.S. census housing density data were used as a baseline to compare observed changes to. Our results showed that park establishment was effective in reducing and stopping the fragmenting impact of development within park boundaries. However, increased amenity levels following park establishment led to enhanced development in the surroundings of both parks. In the extreme case of Indiana Dunes, building density outside the park increased from 45 to 200 buildings/km2 and road density almost doubled from 3.6 to 6.6 km/km2 from 1938 to 2005. Development rates of change were much higher than in the broader landscape, particularly after park establishment. The potential amenity effect was up to 9500 new buildings in the 3.2-km zone around Indiana Dunes between 1966 and 2005. For Pictured Rocks the absolute effect was smaller but up to 70% of the observed building growth was potentially due to amenity effects. Our findings highlight the need for conservation planning at broader scales, incorporating areas beyond the boundaries of protected areas. 相似文献
52.
Lars Hendrik Simon Volker Wilkens Thomas Fedtke Michael Beyer 《Journal of Loss Prevention in the Process Industries》2013,26(6):1583-1589
This paper shows the results of our investigations on the ignition source ultrasound in dust-air atmospheres. Ultrasound is, on the one hand, considered to be an ignition source according to international safety standards (EN 1127–1 (2011)). On the other hand, though, ultrasound is used for various applications in gases and air, such as level and flow measurement, or in the process industry, but no explosion accidents have yet been reported. Our research now shows that it is indeed possible to ignite dust-air mixtures in ultrasound fields under certain conditions. We conducted our experiments in an ultrasound standing wave field and used maize starch, calcium stearate and sulfur dust. For ignitions, an absorbing target was needed to convert the acoustic energy into heat. From theoretical estimations and experiments critical conditions that provoke ultrasonically triggered explosions are identified. 相似文献
53.
Volker Witte Leif Abrell Athula B. Attygalle Xiaogang Wu Jerrold Meinwald 《Chemoecology》2007,17(1):63-69
Summary. Dufour glands of Paratrechina longicornis were analyzed chemically using GC-MS techniques. The glands contained twelve alkanes between C9 and C20 chain length with undecane and tridecane as the main components, six alkenes (1- and 4-undecene, 1-, 4-, and 6- tridecene,
and heptadecadiene), two alkyl formates (C11 and C13), and saturated and polyunsaturated acids. Many of the alkanes and alkenes were behaviorally active causing a short lasting
attraction of ants with different intensity. Detection of the major gland compound undecane in recruitment trails by in vivo
SPME sampling provided evidence for its use as a recruitment pheromone. Both poison gland (formic acid) and Dufour gland (undecane)
contents were detected on SPME fibers which had been attacked by the ants. 相似文献
54.
Ants belong to the most important groups of arthropods, inhabiting and commonly dominating most terrestrial habitats, especially
tropical rainforests. Their highly collective behavior enables exploitation of various resources and is viewed as a key factor
for their evolutionary success. Accordingly, a great variety of life strategies evolved in this group of arthropods, including
seed harvesters, gardeners, and planters, fungus growers, nomadic hunters, life stock keepers, and slave makers. This study
reports the discovery of a new lifestyle in ants. In a Southeast Asian rainforest habitat, Euprenolepis procera is specialized in harvesting a broad spectrum of naturally growing mushrooms, a nutritionally challenging and spatiotemporally
unpredictable food source. While unfavorable to the vast majority of animals, E. procera has developed exceptional adaptations such as a shift to a fully nomadic lifestyle and special food processing capabilities,
which allow it to rely entirely on mushrooms. As a consequence, E. procera is the most efficient and predominant consumer of epigeic mushrooms in the studied habitat and this has broad implications
for the tropical rainforest ecosystem. 相似文献
55.
The evolution of bird migration—a synthesis 总被引:1,自引:1,他引:0
We approach the problem of the evolution of bird migration by asking whether migration evolves towards new breeding areas
or towards survival areas in the non-breeding season. Thus, we avoid the ambiguity of the usually discussed “southern-home-theory”
or “northern-home-theory”. We argue that migration evolved in birds that spread to seasonal habitats through gradual dispersal
to enhance survival during the non-breeding season; this in contrast to the alternative idea suggesting that migration evolved
towards new breeding areas to increase reproductive success. Our synthesis is based on the threshold model explaining how
migratory traits can change rapidly through microevolutionary processes. Our model brings former theories together and explains
how bird migration, with the appropriate direction and time program, evolves through selection after genetically non-directed
events such as dispersal and colonization. The model does not need the former untested assumptions such as competition as
a reason for migration and for the disappearance of sedentary populations or higher reproductive success in temperate breeding
areas. Our theory offers answers to questions such as how birds with a southern origin may gradually reach northern latitudes,
why migration routes may follow historical expansion routes and why birds leave an area for the non-breeding season and move
back instead of breeding on their wintering grounds. The theory proposes gradual change through selection and not sudden changes
such as long distance dispersal or mutations and can be applied to migration at all latitudes and in all directions. The scenario
provides a reasonable concept to understand most of the existing migratory phenomena on the basis of the ecology and genetics
of migratory behaviour. 相似文献
56.
57.
Realistic meteorological fields are a prerequisite for the determination of pollutant concentrations and depositions by means
of a chemistry transport model. Different configurations of the 5th generation NCAR/Penn State University mesoscale meteorological
model MM5 were tested to determine the optimum set up for long term hindcasts that cover several months up to years. Four
dimensional data assimilation (FDDA) significantly enhances the spatio temporal representation of temperature, humidity and
wind. Best agreement with radiosonde observations could be achieved when temperature, humidity and wind were grid nudged every
6 h. The quality of the resulting meteorological fields showed no significant systematic temporal or spatial variation over
Europe in a model run of the year 2000. It was found that the hydrological cycle was not correctly reproduced by the model
when no nudging was applied. The relevant model run showed too high relative humidity and too high rainfall when compared
to observations. This led to considerably lower aerosol concentrations close to ground and a shift in the deposition patterns
of particle bound pollutants like the carcinogenic benzo(a)pyrene (B(a)P).
Guest Editor: Dr. S. T. Rao. 相似文献
58.
How simple can a model be that still captures essential aspects of wildfire ecosystems at large spatial and temporal scales? The Drossel-Schwabl model (DSM) is a metaphorical forest-fire model developed to reproduce only one pattern of real systems: a frequency distribution of fire sizes resembling a power law. Consequently, and because it appears oversimplified, it remains unclear what bearings the DSM has in reality. Here, we test whether the DSM is capable of reproducing a pattern that was not considered in its design, the hump-shaped relation between the diversity of succession stages and average annual area burnt. We found that the model, once reformulated to represent succession, produces realistic landscape diversity patterns. We investigated four succession scenarios of forest-fire ecosystems in the USA and Canada. In all scenarios, landscape diversity is highest at an intermediate average annual area burnt as predicted by the intermediate disturbance hypothesis. These results show that a model based solely on the dynamics of the fuel mosaic has surprisingly high predictive power with regard to observed statistical properties of wildfire systems at large spatial scales. Parsimonious models, such as the DSM can be used as starting points for systematic development of more structurally realistic but tractable wildfire models. Due to their simplicity they allow analytical approaches that further our understanding under increasing complexity. 相似文献
59.
Reaching the economic, environmental and sustainability objectives of all societies requires overcoming several major energy challenges; it necessitates rapid progress in multiple areas. The scenario pathways presented in this paper describe transformative changes toward these goals, taking a broad view of the four main energy challenges faced by society in the 21st century: providing universal access to modern energy for all; reducing the impacts of energy production on human health and the environment; avoiding dangerous climate change; and enhancing energy security. The overarching objective of the paper is to provide policy guidance on how to facilitate the transformation of the energy system to achieve these multiple energy objectives. Particular focus is given to the required pace of the transformation at both the global and regional levels, and to the types of financial and policy measures that will be needed to ensure a successful transition. Synergies and trade‐offs between the objectives are identified, and co‐benefits quantified. The paper makes an important contribution to the scenario literature by approaching the global transition toward sustainable development in a more integrated, holistic manner than is common in other studies. 相似文献
60.
Persistence of the fluoroquinolone antibiotic difloxacin in soil and lacking effects on nitrogen turnover 总被引:1,自引:0,他引:1
Rosendahl I Siemens J Kindler R Groeneweg J Zimmermann J Czerwinski S Lamshöft M Laabs V Wilke BM Vereecken H Amelung W 《Journal of environmental quality》2012,41(4):1275-1283
The environmental risks caused by the use of fluoroquinolone antibiotics in human therapeutics and animal husbandry are associated with their persistence and (bio)accessibility in soil. To assess these aspects, we administered difloxacin to pigs and applied the contaminated manure to soil. We then evaluated the dissipation and sequestration of difloxacin in soil in the absence and presence of plants within a laboratory trial, a mesocosm trial, and a field trial. A sequential extraction yielded antibiotic fractions of differing binding strength. We also assessed the antibiotic's effects on nitrogen turnover in soil (potential nitrification and denitrification). Difloxacin was hardly (bio)accessible and was very persistent under all conditions studied (dissipation half-life in bulk soil, >217 d), rapidly forming nonextractable residues. Although varying environmental conditions did not affect persistence, dissipation was accelerated in soil surrounding plant roots. Effects on nitrogen turnover were limited due to the compound's strong binding and small (bio)accessibility despite its persistence. 相似文献