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121.
Christiane Brack Annett Mikolasch Rüdiger Pukall Peter Schumann Marion Köster Frieder Schauer 《Marine Biology》2013,160(10):2699-2709
The present study examines antagonistic relationships between different microorganisms inhabiting brackish water and includes a systematic screening for bacteriolytic prokaryotes in the brackish waters of the Southern Baltic Sea (Nordruegenscher Bodden) sampled in July/August 2009. Ten of the 35 marine bacteriolytic isolates belong to the genus Bacillus. Five isolates (B. pumilus, B. subtilis, B. megaterium, B. licheniformis) lysed living microbial cells such as the bacteria Arthrobacter citreus, Arthrobacter protophormiae, Micrococcus luteus, Pseudomonas putida and the yeast Trichosporon mucoides. These and other bacteria (Aeromonas sp., Bacillus subtilis, Chromobacterium violaceum, Citrobacter freundii, Enterobacter aerogenes, Proteus mirabilis, Pseudomonas aeruginosa and Serratia marcescens) were also lysed as autoclaved and pasteurized cells on agar plates. One isolate of Bacillus pumilus showed a distinct bacteriolysis activity against pasteurized cells of A. citreus in liquid culture. Our results suggest that Bacillus species may play a role as opportunistic predators in the marine microbial food web. 相似文献
122.
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124.
The intertidal midge Clunio, which reproduces on exposed rocky seashores, becomes enclosed in an irregularly shaped air bubble during short submersion
by incoming waves. This water-repellent property of Clunio’s cuticle is caused by a complete cover of hydrophobic microtrichia offering an effective surf tolerance. These microtrichia
not only trap a thin air layer above the cuticle but also maintain a larger air bubble between the insect’s ventral side and
legs. The effectiveness of the water repellence was quantitatively characterised on the basis of a known model (Crisp and
Thorpe, Discuss Faraday Soc 3:210–220, 1948). The parameters of the model are the contact angle θ (>90°) at the contact line of air/water/microtrichia and the distance between individual microtrichia and their radius. When
the microtrichia are 1.1 μm apart and have a radius of 0.1 μm and an estimated contact angle θ of 140°, the air layer is stable against hydrostatic pressures of up to 3 m water column. As shown by a modified version
of the model, considerably larger air bubbles can be trapped by the microtrichia cover of the legs up to distances of 0.5 mm
from the body. The widely spaced (about 8 μm apart) and longer setae of Clunio are not involved in the formation of air layers and air bubble. 相似文献
125.
Maximilian Berthold Ulf Karsten Mario von Weber Alexander Bachor Rhena Schumann 《Ambio》2018,47(1):146-158
The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities. 相似文献
126.
Regional Environmental Change - Lake Baikal is the largest near-surface global freshwater source and of high interest for water quality alterations, as deterioration of water quality is a main... 相似文献
127.
To assess habitat suitability (HS) has become an increasingly important component of species/ecosystem management. HS assessment is usually based on presence/absence data related to environmental variables. An exception is Ecological Niche Factor Analysis (ENFA), which uses only presence data and which does not require absence data. Most HS modelling is based on input of all environmental parameters (EnvPs) without environmental categorization, and does not take into account species interaction and human intervention for an assessment of HS. In this study, the EnvPs are arranged into four features: geographical features, consumable features, human-factor features, and species–human interaction features. These features affect species with respect to movement, behavior and activity. The research presented here has used an already existing dataset of wildlife species and human activities/visitations, which was compiled during 2004–2006 in Phu-Khieo Wildlife Sanctuary (PKWS). Data from 2004 to 2005 were used to produce HS maps, while the data of 2006 were used for evaluating these maps. Sambar Deer (SD) was chosen to predict its own HS. Six HS maps of SD were analyzed using ENFA in the following manner: (1) inputting all EnvPs together, (2) inputting each feature, separately and (3) integrating the four resulting HS maps by model averaging. It was found that model averaging was capable of predicting the HS of SD more reliably than the model with all EnvPs put in together. Multiple linear regressions were computed between the HS map with all EnvPs and the HS maps with each feature. The results show that the HS map with only geographical features has the highest coefficient value (0.516) while the coefficient values of other HS maps with the above features are 0.296, 0.53 and −0.006, respectively. This indicates that the geographical features have an influence on the other features and that the predicting power is lower when all EnvPs are computed in the ENFA model. Therefore, in order to generate HS, each feature should at first be put into the model separately. Following that, the average of all features will be combined. 相似文献
128.
Adapting cropping systems to climate change in Nepal: a cross-regional study of farmers’ perception and practices 总被引:4,自引:1,他引:3
Sujata Manandhar Dietrich Schmidt Vogt Sylvain R. Perret Futaba Kazama 《Regional Environmental Change》2011,11(2):335-348
Climate change is a global challenge that has a particularly strong effect on developing countries such as Nepal, where adaptive
capacity is low and where agriculture, which is highly dependent on climatic factors, is the main source of income for the
majority of people. The nature and extent of the effects of climate change on rural livelihoods varies across Nepal in accordance
with its highly diverse environmental conditions. In order to capture some of this variability, a comparative study was performed
in two different ecological regions: Terai (lowland) and Mountain (upland) in the western development region of Nepal. The
study focuses on perceptions of, and on adaptations to climate change by farmers. Information was collected from both primary
and secondary data sources. Climate data were analyzed through trend analysis. Results show that most farmers perceive climate
change acutely and respond to it, based on their own indigenous knowledge and experiences, through both agricultural and non-agricultural
adaptations at an individual level. The study also shows that there is a need to go beyond the individual level, and to plan
and provide support for appropriate technologies and strategies in order to cope with the expected increasing impacts of climate
change. 相似文献
129.
Measuring contaminant flow rates at control cross sections is the most accurate method to evaluate natural attenuation processes in the saturated subsurface. In most instances, point scale measurement is the method of choice due to practical reasons and cost factors. However, at many field sites, the monitoring network is too sparse for a reliable estimation of contaminant and groundwater flow rates. Therefore, integral pumping tests have been developed as an alternative. In this study, we compare mass flow rates obtained by integral pumping test results and point scale data. We compare results of both methods with regard to uncertainties due to estimation errors and mass flow estimations based on two different point scale networks. The differences between benzene and groundwater flow rate estimates resulting from point scale samples and integral pumping tests were 6.44% and 6.97%, respectively, demonstrating the applicability of both methods at the site. Point scale-based data, especially with use of cost efficient Direct-Push technique, can be applied to show the contaminant distribution at a site and may be followed by a denser point scale network or an integral method. Nevertheless, a combination of both methods decreases uncertainties. 相似文献
130.
This paper analyzes livelihood change and livelihood sustainability of households in the upland part of the Lembang subwatershed,
West Sumatra, in response to changes in the natural resource management context during the last decade. Using the sustainable
livelihood framework (SLF), we measured livelihood changes at two separate points in time, 1996 and 2006, and assessed their
environmental, economic, social, and institutional sustainability. We found that people with a low income had less access
to capital assets than people from middle- and high-income groups. Our analysis revealed, however, that access to capital
assets increased over time, and that poor households experienced economic improvement, indicating an overall increase in economic
sustainability. Environmental sustainability, however, is threatened by intensive agricultural practices such as high agrochemical
input and intensive soil tillage on steep slopes, leading to pollution and soil erosion. Social sustainability is also a matter
of concern: while social exclusion has been reduced, income inequity has increased. Institutional sustainability is likely
to remain uncertain, as local institutions for natural resource management are still weak, despite the fact that decentralization
has been implemented during the last 8 years. External facilitation is needed to improve the livelihood of upland people while,
at the same time, enhancing the sustainability of watershed management. Strengthening local institutions, conserving natural
resources, and promoting environmentally sound agricultural practices are the three most important policies to be promoted
within the watershed. 相似文献