全文获取类型
收费全文 | 272篇 |
免费 | 2篇 |
专业分类
安全科学 | 16篇 |
废物处理 | 11篇 |
环保管理 | 31篇 |
综合类 | 37篇 |
基础理论 | 66篇 |
污染及防治 | 94篇 |
评价与监测 | 9篇 |
社会与环境 | 7篇 |
灾害及防治 | 3篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 14篇 |
2012年 | 12篇 |
2011年 | 30篇 |
2010年 | 18篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 21篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 17篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有274条查询结果,搜索用时 31 毫秒
231.
Johan Höjesjö Bart Adriaenssens Torgny Bohlin Christopher Jönsson Illka Hellström Jörgen I. Johnsson 《Behavioral ecology and sociobiology》2011,65(9):1801-1810
The main aims of this study were to investigate (1) the occurrence and strength of the shyness–boldness behavioural syndrome
in brown trout fry, (2) whether this syndrome is associated with paternal migratory life history, (3) whether fry survival
and growth in the wild is associated with paternal life history and/or boldness and (4) whether offspring performance showed
maternal effects. Nine female migratory trout were each crossed with one migratory and one resident male and the offspring
were raised in hatchery tanks until first feeding. The behavioural studies showed that fry that responded bold towards a novel
object also accepted a novel food item earlier and responded more aggressively towards their own mirror image. Principal component
analysis showed that this shyness–boldness syndrome (PC1) explained 34% of the behavioural variation. Offspring boldness was
not affected by paternal migratory life history, but significant effects of the female parent suggested maternal and/or genetic
effects. Deviations from this pattern (PC2), where some individuals behaved less aggressively and performed more approaches
to food, explained an additional 17% of the variation in behaviour, and was significantly influenced by length and paternal
migratory life history. Fry growth and survival in nature was not associated with boldness (PC1) or PC2, suggesting that alternative
behavioural strategies can be successful in nature. However, female parent effects on variation in fry size persisted over
the first growth period in the wild, suggesting that these effects may influence offspring fitness during early life when
major selection occurs. 相似文献
232.
233.
Johan Gardères Laure Taupin Jasnizat Bin Sa?din Alain Dufour Ga?l Le Pennec 《Marine Biology》2012,159(8):1685-1692
Many bacteria live in close association with sponges. Within these consortia, molecules of communication such as quorum-sensing and hormone-like molecules may occur in order to regulate the partnership. Of particular interest, bacterial N-acyl-l-homoserine lactones (AHLs) were screened in supernatants from Suberites domuncula-associated bacteria using an E. coli bioluminescent reporter system. These sponge-associated bacteria were beforehand isolated on several media supplemented or not with a sponge extract to attempt to isolate sponge-specific bacteria. Out of 81 AHL-producing bacteria, three strains requiring sponge extract to grow were selected for AHL characterization. The in vitro produced AHLs, that is, in bacterial culture supernatants, were identified as N-(3-butanoyl)-l-homoserine lactone and N-(3-oxododecanoyl)-l-homoserine lactone and quantified using LC–ESI–MS/MS. The in vivo production of AHLs by sponge-associated bacteria has also been demonstrated in a healthy host for the first time: N-(3-oxododecanoyl)-l-homoserine lactone, N-(3-hexanoyl)-l-homoserine lactone, and N-(3-heptanoyl)-l-homoserine lactone. This AHL production in sponges may suggest a potential role of these molecules between sponge-associated bacteria and/or between sponge-associated bacteria and the sponge. 相似文献
234.
Wim Bonckaert Adam Tofilski Fabio S. Nascimento Johan Billen Francis L. W. Ratnieks Tom Wenseleers 《Behavioral ecology and sociobiology》2011,65(4):633-640
In insect societies, workers often try to challenge the reproductive monopoly of the queen by laying their own eggs. Successful
worker reproduction, however, is frequently prevented by queen policing or worker policing, whereby either the mother queen
or non-reproductive workers selectively kill worker-laid eggs. Recently, a third mechanism—“selfish” worker policing—has also
been described in which the workers selectively police worker-laid eggs but also lay eggs themselves. Here, we present results
from the monogynous wasp Dolichovespula norwegica, which show that all three kinds of policing—queen policing, worker policing and “selfish” worker policing—co-occur. The
net effect of these three kinds of policing collectively favoured the queen’s reproduction, as within 1 day 44% of the worker-laid
eggs versus only 8% of the queen-laid eggs were eaten. Of the worker-laid eggs that were killed by workers, approximately
two thirds were eaten by the reproductive workers even though these made up only a small proportion, 8%, of the work force.
This means that policing workers obtained both direct fitness benefits as well as indirect (inclusive) fitness. In addition,
we show that worker policing was carried out by a limited, specialised set of workers that was estimated to constitute approximately
one quarter of the whole colony and of which 66% were non-reproductive. 相似文献
235.
Reconnecting to the Biosphere 总被引:3,自引:0,他引:3
Folke C Jansson A Rockström J Olsson P Carpenter SR Chapin FS Crépin AS Daily G Danell K Ebbesson J Elmqvist T Galaz V Moberg F Nilsson M Osterblom H Ostrom E Persson A Peterson G Polasky S Steffen W Walker B Westley F 《Ambio》2011,40(7):719-738
Humanity has emerged as a major force in the operation of the biosphere, with a significant imprint on the Earth System, challenging social-ecological resilience. This new situation calls for a fundamental shift in perspectives, world views, and institutions. Human development and progress must be reconnected to the capacity of the biosphere and essential ecosystem services to be sustained. Governance challenges include a highly interconnected and faster world, cascading social-ecological interactions and planetary boundaries that create vulnerabilities but also opportunities for social-ecological change and transformation. Tipping points and thresholds highlight the importance of understanding and managing resilience. New modes of flexible governance are emerging. A central challenge is to reconnect these efforts to the changing preconditions for societal development as active stewards of the Earth System. We suggest that the Millennium Development Goals need to be reframed in such a planetary stewardship context combined with a call for a new social contract on global sustainability. The ongoing mind shift in human relations with Earth and its boundaries provides exciting opportunities for societal development in collaboration with the biosphere--a global sustainability agenda for humanity. 相似文献
236.
In this study we investigate how thermal power plants with once-through cooling could be affected by future climate change
impacts on river water temperatures and stream flow. We introduce a model of a steam turbine power plant with once-through
cooling at a river site and simulate how its production could be constrained in scenarios ranging from a one degree to a five
degree increase of river temperature and a 10–50% decrease of stream flow. We apply the model to simulate a large nuclear
power plant in Central Europe. We calculate annual average load reductions, which can be up to 11.8%, assuming unchanged stream
flow, which leads to average annual income losses of up to 80 million €. Considering simultaneous changes in stream flow will
exacerbate the problem and may increase average annual costs to 111 million € in a worst-case scenario. The model demonstrates
that power generation could be severely constrained by typical climate impacts, such as increasing river temperatures and
decreasing stream flow. 相似文献
237.
Urban dwellers depend on the generation of ecosystem services for their welfare. The city of Stockholm is growing, and a 25% increase in population is projected by 2030. The effects of urban development were estimated through the quantification of nitrogen (N) leakage to the Baltic Sea under two urban development scenarios. We found that total net N load will increase by 6% or 8%, depending on which growth scenario is applied, and population increase by itself will contribute at least 15% of the point source N leakage. Technical improvements in sewage treatment could, according to our results, decrease total N load to the Baltic Sea by 4%. Based on our results, we conclude that proactive measures such as spatial urban planning can provide a constructive tool for sustainable urban development on regional as well as national and international scales, depending on geographical context as well as the ecosystem services' scale of operation. 相似文献
238.
Evaluating the BANCS Streambank Erosion Framework on the Northern Gulf of Mexico Coastal Plain
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mitchell McMillan Johan Liebens Christopher Metcalf 《Journal of the American Water Resources Association》2017,53(6):1393-1408
The Bank Assessment of Nonpoint source Consequences of Sediment (BANCS) framework allows river scientists to predict annual sediment yield from eroding streambanks within a hydrophysiographic region. BANCS involves field data collection and the calibration of an empirical model incorporating a bank erodibility hazard index (BEHI) and near‐bank shear stress (NBS) estimate. Here we evaluate the applicability of BANCS to the northern Gulf of Mexico coastal plain, a region that has not been previously studied in this context. Erosion rates averaged over two years expressed the highest variability of any existing BANCS study. As a result, four standard BANCS models did not yield statistically significant correlations to measured erosion rates. Modifications to two widely used NBS estimates improved their correlations (r2 = 0.31 and r2 = 0.33), but further grouping of the data by BEHI weakened these correlations. The high variability in measured erosion rates is partly due to the regional hydrologic and climatic characteristics of the Gulf coastal plains, which include large, infrequent precipitation events. Other sources of variability include variations in bank vegetation and the complex hydro‐ and morphodynamics of meandering, sand bed channels. We discuss directions for future research in developing a streambank erosion model for this and similar regions. 相似文献
239.
The USDA’s Conservation Reserve Program (CRP) has predominantly used only a few species of dominant prairie grasses (CP2 practice)
to reduce soil erosion, but recently has offered a higher diversity planting practice (CP25) to increase grassland habitat
quality. We quantified plant community composition in CP25 and CP2 plantings restored for 4 or 8 years and compared belowground
properties and processes among restorations and continuously cultivated soils in southeastern Nebraska, USA. Relative to cultivated
soils, restoration increased soil microbial biomass (P = 0.033), specifically fungi (P < 0.001), and restored soils exhibited higher rates of carbon (C) mineralization (P = 0.010). High and low diversity plantings had equally diverse plant communities; however, CP25 plantings had greater frequency
of cool-season (C3) grasses (P = 0.007). Older (8 year) high diversity restorations contained lower microbial biomass (P = 0.026), arbuscular mycorrhizal fungi (AMF) biomass (P = 0.003), and C mineralization rates (P = 0.028) relative to 8 year low diversity restorations; older plantings had greater root biomass than 4 year plantings in
all restorations (P = 0.001). Low diversity 8 year plantings contained wider root C:N ratios, and higher soil microbial biomass, microbial community
richness, AMF biomass, and C mineralization rate relative to 4 year restorations (P < 0.050). Net N mineralization and nitrification rates were lower in 8 year than 4 year high diversity plantings (P = 0.005). We attributed changes in soil C and N pools and fluxes to increased AMF associated with C4 grasses in low diversity plantings. Thus, reduced recovery of AMF in high diversity plantings restricted restoration of belowground
microbial diversity and microbially-mediated soil processes over time. 相似文献
240.
Jean-Michel Roberge Hjalmar Laudon Christer Björkman Thomas Ranius Camilla Sandström Adam Felton Anna Sténs Annika Nordin Anders Granström Fredrik Widemo Johan Bergh Johan Sonesson Jan Stenlid Tomas Lundmark 《Ambio》2016,45(2):109-123
The rotation length is a key component of even-aged forest management systems. Using Fennoscandian forestry as a case, we review the socio-ecological implications of modifying rotation lengths relative to current practice by evaluating effects on a range of ecosystem services and on biodiversity conservation. The effects of shortening rotations on provisioning services are expected to be mostly negative to neutral (e.g. production of wood, bilberries, reindeer forage), while those of extending rotations would be more varied. Shortening rotations may help limit damage by some of today’s major damaging agents (e.g. root rot, cambium-feeding insects), but may also increase other damage types (e.g. regeneration pests) and impede climate mitigation. Supporting (water, soil nutrients) and cultural (aesthetics, cultural heritage) ecosystem services would generally be affected negatively by shortened rotations and positively by extended rotations, as would most biodiversity indicators. Several effect modifiers, such as changes to thinning regimes, could alter these patterns. 相似文献