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101.
Implication of two in-stream processes in the fate of nutrients discharged by sewage system into a temporary river 总被引:2,自引:0,他引:2
David A Perrin JL Rosain D Rodier C Picot B Tournoud MG 《Environmental monitoring and assessment》2011,181(1-4):491-507
The aim of this study was to better understand the fate of nutrients discharged by sewage treatment plants into an intermittent Mediterranean river, during a low-flow period. Many pollutants stored in the riverbed during the low-flow period can be transferred to the downstream environments during flood events. The study focused on two processes that affect the fate and the transport of nutrients, a physical process (retention in the riverbed sediments) and a biological process (denitrification). A spatial campaign was carried out during a low-flow period to characterize the nutrient contents of both water and sediments in the Vène River. The results showed high nutrient concentrations in the water column downstream of the treated wastewater disposal (up to 13,315 μg N/L for ammonium and 2,901 μg P/L for total phosphorus). Nutrient concentrations decreased rapidly downstream of the disposal whereas nutrient contents in the sediments increased (up to 1,898 and 784 μg/g for total phosphorus and Kjeldahl nitrogen, respectively). According to an in situ experiment using sediment boxes placed in the riverbed for 85 days, we estimated that the proportion of nutrients trapped in the sediments represents 25% (respectively 10%) of phosphorus (respectively nitrogen) loads lost from the water column. In parallel, laboratory tests indicated that denitrification occurred in the Vène River, and we estimated that denitrification likely coupled to nitrification processes during the 85 days of the experiment was significantly involved in the removal of nitrogen loads (up to 38%) from the water column and was greater than accumulation processes. 相似文献
102.
Several Torres Strait communities have significant infrastructure and sacred sites located only a few metres above sea level. As a consequence, these areas are vulnerable to erosion due to the projected increase in storm surge intensity caused by climate change. Common sense suggests that Islanders would welcome new scientific research about how climate change might affect them, in order to understand the significance of these impacts and the timeframes involved. However, one leader has taken a seemingly counterintuitive stance, and has refused to let new climate research occur. We explore why this position was taken, and the implications of this decision for ongoing scientific research. In order to carry out this analysis, we provide a contextual background by assessing Islanders' recent experience with scientific researchers, and the response of policy-makers to it. We find that despite a clearly documented problem with “top-down” decision-making, this process remains. In this instance, we find that there is a systemic lack of collaboration with Islanders to allow them to prioritise their concerns, and a lack of adequate resources to allow them to build their resilience to climate impacts. We conclude that only through a genuine collaborative approach to climate adaptation can activities be properly developed, prioritised and undertaken. 相似文献
103.
Hungshu Wang PhD. Judith L. Bellinger Kathleen Brierley Laura E. Dawson Claire L. Goldsmith Alasdair G. W. Hunter 《黑龙江环境通报》1994,14(9):868-872
Single copies of tiny chromosome fragments, appearing either as single or as double minutes, were observed in a high frequency in amniotic fluid cultures of five mothers who underwent prenatal testing because of advanced age. In four cases, the minutes had arisen de novo. The minutes were later confirmed in fetal skin following termination of pregnancy in one case; in another, in cord blood following the birth of a normal boy; and in the third, in peripheral blood of a normal 3-year-old girl. In the fourth case, the minutes were not confirmed in cord blood following the birth of a normal boy. A follow-up chromosome study of the baby boy in the fifth case was not possible but the minutes were maternally transmitted. 相似文献
104.
Claire Freeman 《Journal of Environmental Planning and Management》1996,39(1):65-78
Local Agenda 21, with its major emphasis on local accountability and democratization, challenges perceptions of local governance and offers a long overdue opportunity, for local authorities in particular, to develop broad-based, effective, participatory structures. This paper examines initial responses to this opportunity. It models the newly emerging participatory structures and processes in selected English local authority areas, and demonstrates that there may be no one path that local authorities should follow. A number of alternative approaches to community participation can and are being adopted, contingent upon local circumstances. 相似文献
105.
106.
Living in groups raises important issues concerning waste management and related sanitary risks. Social insects such as ants live at high densities with genetically related individuals within confined and humid nests, all these factors being highly favorable for the spread of pathogens. Therefore, in addition to individual immunity, a social prophylaxis takes place, namely, by the removal of risky items such as corpses and their rejection at a distance from the ant nest. In this study, we investigate how Myrmica rubra workers manage to reduce encounters between potentially hazardous corpses and nestmates. Using both field and laboratory experiments, we describe how the spatial distribution and the removal distance of waste items vary as a function of their associated sanitary risks (inert item vs. corpse). In the field, corpse-carrying ants walked in a rather linear way away from the nest entrance and had an equal probability of choosing any direction. Therefore, they did not aggregate corpses in dedicated areas but scattered them in the environment. In both field and laboratory experiments, ants carrying corpses dropped their load in more remote—and less frequented—areas than workers carrying inert items. However, for equidistant areas, ants did not avoid dropping corpses at a location where they perceived area marking as a cue of high occupancy level by nestmates. Our results suggest that ants use distance to the nest rather than other occupancy cues to limit sanitary risks associated with dead nestmates. 相似文献
107.
Studying evolutionary mechanisms in natural populations often requires testing multifactorial scenarios of causality involving direct and indirect relationships among individual and environmental variables. It is also essential to account for the imperfect detection of individuals to provide unbiased demographic parameter estimates. To cope with these issues, we developed a new approach combining structural equation models with capture-recapture models (CR-SEM) that allows the investigation of competing hypotheses about individual and environmental variability observed in demographic parameters. We employ Markov chain Monte Carlo sampling in a Bayesian framework to (1) estimate model parameters, (2) implement a model selection procedure to evaluate competing hypotheses about causal mechanisms, and (3) assess the fit of models to data using posterior predictive checks. We illustrate the value of our approach using two case studies on wild bird populations. We first show that CR-SEM can be useful to quantify the action of selection on a set of phenotypic traits with an analysis of selection gradients on morphological traits in Common Blackbirds (Turdus merula). In a second case study on Blue Tits (Cyanistes caeruleus), we illustrate the use of CR-SEM to study evolutionary trade-offs in the wild, while accounting for varying environmental conditions. 相似文献
108.
Human activity causes abrupt changes in resource availability across the landscape. In order to persist in human-altered landscapes organisms need to shift their habitat use accordingly. Little is known about the mechanisms by which whole communities persist in human-altered landscapes, including the role of complementary habitat use. We define complementary habitat use as the use of different habitats at different times by the same group of species during the course of their activity period. We hypothesize that complementary habitat use is a mechanism through which native bee species persist in human-altered landscapes. To test this idea, we studied wild bee communities in agro-natural landscapes and explored their community-level patterns of habitat and resource use over space and time. The study was conducted in six agro-natural landscapes in the eastern United States, each containing three main bee habitat types (natural habitat, agricultural fields, and old fields). Each of the three habitats exhibited a unique seasonal pattern in amount, diversity, and composition of floral resources, and together they created phenological complementarity in foraging resources for bees. Individual bee species as well as the bee community responded to these spatiotemporal patterns in floral availability and exhibited a parallel pattern of complementary habitat use. The majority of wild bee species, including all the main crop visitors, used fallow areas within crops early in the season, shifted to crops in mid-season, and used old-field habitats later in the season. The natural-forest habitat supported very limited number of bees, mostly visitors of non-crop plants. Old fields are thus an important feature in these arable landscapes for maintaining crop pollination services. Our study provides a detailed examination of how shifts in habitat and resource use may enable bees to persist in highly dynamic agro-natural landscapes, and points to the need for a broad cross-habitat perspective in managing these landscapes. 相似文献
109.
Alice Rémy Arnaud Grégoire Philippe Perret Claire Doutrelant 《Behavioral ecology and sociobiology》2010,64(11):1839-1847
Badges of status, usually color patches, are hypothesized to serve as important signals within natural populations by communicating
an individual’s fighting ability or aggressiveness before an interaction ever takes place. These signals, which may evolve
via sexual and/or social selection, mediate intra-specific competition by influencing the outcome or escalation of contests
between individuals. The last 10 years saw the rise of interest in the role of ultraviolet (UV)-based coloration in intra-sexual
communication. However, the rare experimental studies that tested this hypothesis found opposite results, which may originate
from the different methodological procedures used to assess the badge of status theory. We present here the results of an
experiment testing whether male blue tits (Cyanistes caeruleus) respond differently to unfamiliar conspecifics presenting contrasted UV crest coloration. In an aviary, we simultaneously
presented two caged blue tits with enhanced (UV+) or reduced (UV−) crest coloration to a focal bird. We found that focal males
acted more aggressively towards the UV− males than UV+ males. In addition, focal males fed more often close to males that
were similar in brightness or duller than themselves. We conclude that, in blue tits, UV blue crest coloration affects both
social and aggressive responses towards unfamiliar individuals, and thus it has some properties of a badge of status. 相似文献
110.
Claire Brussol Matthew Duane Patrick Carlier Dimitrios Kotzias 《Environmental science and pollution research international》1999,6(3):138-140
The photo-induced degradation of naphthalene, 1,4-naphthoquinone, 1-naphthol and 1-NO2 naphthalene, adsorbed on silica gel, and with the addition of nitrogenous air pollutants e.g. NO2 (as KNO2) was investigated. Results indicate that compounds adsorbed onto a solid carrier are degraded when irradiated with UV light
(λ > 290 nm) in the presence of nitrites. The key species initiating the naphthalene degradation is the OH-radical which is
generated through the photolysis of NO2. Reaction products identified were 2-formyl-cinnamaldehyde, 1,4-naphthoquinone, nitronaphthol, o-phthaldialdehyde, phthalide
and nitronaphthalene. A mass balance between 40–50% was achieved. Under the same irradiation conditions, 1-NO2 naphthalene is mainly degraded by direct photolysis while degradation of 1-naphthol and 1,4-naphthoquinone proceeds via the
reaction with OH-radicals. Identified products were hydroxy-nitro-nitroso- and quinones compounds. 相似文献