全文获取类型
收费全文 | 145篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 9篇 |
环保管理 | 16篇 |
综合类 | 11篇 |
基础理论 | 46篇 |
环境理论 | 1篇 |
污染及防治 | 40篇 |
评价与监测 | 12篇 |
社会与环境 | 7篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 2篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 17篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1956年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有146条查询结果,搜索用时 156 毫秒
111.
The deterministic models applied in economics of fisheries are extended to comprise price uncertainty and risk aversion among the fishing units. It is proved that in the open-access fishery both the total fishing effort and the number of fishing units are reduced as the variance of the price increases; that the total fishing effort may be smaller in the open-access fishery than in the optimal fishery at a high variance; that only a fixed producer price system can create a first-best optimum, and that a tax on revenue is more efficient than both fishing unit quotas or tax on catch. 相似文献
112.
Ø. Holand R. B. Weladji K. H. Røed H. Gjøstein J. Kumpula J.-M. Gaillard M. E. Smith M. Nieminen 《Behavioral ecology and sociobiology》2006,59(5):682-688
The manipulation of the sex ratio and age structure in many managed ungulate populations calls for a better understanding
of their potential consequences on females’ condition and behavior during rut. During 1996–2002, we manipulated the male age
structure and male percentage (nine treatments during 7 years) within an experimental herd of semidomestic reindeer (Rangifer tarandus) and investigated their influence on both the body mass change and the behavior of females during rut. On average, the females
lost body mass (−0.95±SE 0.18 kg) during rut, which we contend to reflect somatic costs. The females’ losses increased as
the percentage of male decreased, but this was certainly ascribed to one treatment with high male percentage (27.7%) as compared
to the others (ranging from 3.9 to 12.2%). Female losses were highest for treatments including both young and adult males
as compared to only adult or only young males, and higher for treatments including only young compared to only adult males.
This is supported by (1) the higher female harassment frequency when females are exposed to only young or a mixture of young
and adult males as compared to only adults, (2) the higher female harassment frequency by young males as compared to adults
in the mixed treatments, and (3) the reduced females’ feeding activity in treatments including both young and adult males.
We conclude that the male age structure during rut will influence the females’ behavior and mass change and may have implications
for females’ life history and for population dynamics. 相似文献
113.
Methanol extracts of freshly harvested cells of the marine diatom Phaeodactylum tricornutum were found to produce a feeding deterrent effect in the copepod Tigriopus californicus. Bioassay guided fractionation of the methanol extracts led to the isolation of four compounds possessing feeding deterrent activity. The compounds were identified as apo-10-fucoxanthinal (1), apo-12-fucoxanthinal (2), apo-12-fucoxanthinal (3), and apo-13-fucoxanthinone (4) by detailed spectroscopic analysis and comparison with authentic compounds produced semi-synthetically from fucoxanthin. Compounds 1 to 4 exhibited feeding deterrent responses in T. californicus at concentrations of less than 20 ppm. 相似文献
114.
The deposition of untreated waste is illegal after the year 2005 on account of the new Technical Instructions for Housing Refuse (Technische Anleitung (TA) Siedlungsabfall). Therefore, the thermal treatment of waste is becoming more important than in the past. The traditionally used grate firing with steam boilers has potential for improvement. The characteristics of the different types of pyrolysis processes are explained and compared using the experience of projects planned, or already realized, in the state of Bavaria. This paper takes credit of the waste pyrolysis plant in Burgau, which is in operation since 1983, and the advanced pyrolysis plants in Fürth (Schwelbrenn-process) and in Ansbach (Thermoselect-process). The conversion-process is another newly developed method of thermal waste treatment. Some information will also be given about the pyrolysis plant for plastics in Ebenhausen. A comparison of the emission of conventional grate firing, and of 2-stage pyrolysis processes with the standards of the German laws for emission (17th BImSchV) shows, that all these processes, if planned correctly, meet the legal standards of emission. It is expected that in the future different thermal processes for waste treatment will prove successful, depending on the task. 相似文献
115.
The effect of ozone on below-ground carbon allocation in wheat 总被引:15,自引:0,他引:15
Short-term (14)CO(2) pulse and chase experiments were conducted in order to investigate the effect of ozone on below-ground carbon allocation in spring wheat seedlings (Triticum aestivum L. 'ANZA'). Wheat seedlings were grown in a sand-hydroponic system and exposed to either high ozone (38-40 ppm-h) or low ozone (23-31 ppm-h) for 21 days in a series of replicated experiments. Following the ozone exposures, the plants were pulsed with (14)CO(2) and allocation of (14)C-labeled photosynthate was measured in the plant and growth media. Soluble root exudates were measured, without disturbing the plant roots, 24 h after the (14)CO(2) pulse. Shoot biomass was reduced by 17% for the high ozone and 9% for the low ozone exposures, relative to control treatments. Root biomass was reduced by 9% for the high ozone exposures, but was not significantly different than the controls for the low ozone. The amount of (14)C activity in the shoot and root tissue 24 h after the (14)CO(2) pulse, normalized to tissue weight, total (14)CO(2) uptake, or the total (14)C retention in each plant, was not affected by either high or low ozone exposures. The amount of (14)C activity measured in the growth media solution surrounding the roots increased 9% for the high ozone exposures, and after normalizing to root size or root (14)C activity, the growth media solution (14)C activity increased 29 and 40%, respectively. Total respiration of (14)CO(2) from the ozone-treated plants decreased, but the decrease was not statistically significant. Our results suggest that soluble root exudation of (14)C activity to the surrounding rhizosphere increases in response to ozone. Increased root exudation to the rhizosphere in response to ozone is contrary to reports of decreased carbon allocation below ground and suggests that rhizosphere microbial activity may be initially stimulated by plant exposure to ozone. 相似文献
116.
Monte Carlo assessment of uncertainty in the simulated hydrological response to land use change 总被引:2,自引:0,他引:2
We quantified the uncertainty in hydrological response for a set of land use change scenarios by varying plant parameters
within realistic uncertainty bounds in a Monte Carlo analysis. The results show that simulated hydrological fluxes significantly
change after the introduction of outwintering suckler cow management, despite the presence of a significant amount of output
uncertainty due to uncertainty in the plant parameterisation. The key to a proper uncertainty assessment was to consider the
uncertainty in the difference between the scenarios instead of the absolute uncertainty of each single scenario. Additionally,
a sensitivity analysis showed that changing soil properties in response to land use change does not result in significantly
different results in the scenario analysis. 相似文献
117.
Heavy metal surveys in Nordic lakes; concentrations, geographic patterns and relation to critical limits 总被引:1,自引:0,他引:1
Skjelkvåle BL Andersen T Fjeld E Mannlo J Wilander A Johansson K Jensen JP Molseenko T 《Ambio》2001,30(1):2-10
In the autumn of 1995, coordinated national lake surveys were conducted in the Nordic countries, including Russian Kola. The 11 metals (Pb, Cd, As, Zn, Cu, Ni, Co, Fe, Mn, Cr, V) investigated in nearly 3000 lakes have generally low concentrations and distinct geographical patterns. Direct and indirect influence of long-range transported air pollution is the major important factor for distribution of Pb, Cd, Zn and to a certain degree Co. Total organic carbon (TOC) concentrations in lakes are important for Fe and Mn but also to a certain degree for As, Cr and V. Bedrock geology is the major controlling factor for Cu and Ni, with the exception of areas around the smelters in the Kola peninsula, where the Cu and Ni concentrations in lakes are very high due to local airborne pollution. Bedrock and surficial geology is also an important factor for controlling the concentrations of As, Co, Cr and V. The results indicate that heavy metal pollution in lakes is a minor ecological problem on a regional scale in the Nordic countries. 相似文献
118.
Warfvinge P Falkengren-Grerup U Sverdrup H Andersen B 《Environmental pollution (Barking, Essex : 1987)》1993,80(3):209-221
A dynamic soil chemistry model was used to explain the observed decrease in soil base saturation between 1949 and 1984 at three stands in southern Sweden. The results show that acid deposition has caused soil acidification. The model, SAFE (Soil Acidification in Forest Ecosystems), includes the fundamental physical processes such as leaching and accumulation, and chemical processes such as cation exchange, mineral weathering, nutrient uptake and solute equilibrium reactions. The sources and sinks of base cations in the soil system were quantified, showing that weathering, deposition of base cations and depletion of exchangeable base cations supply cations to the soil solution in similar amounts in the upper 1 m during the acidification phase. This demonstrates that budget studies alone cannot be used to distinguish between long-term capacity to resist acidification, represented by weathering, from short-term buffering caused by cation exchange. 相似文献
119.
We estimated silicate uptake kinetics for 8 spring diatom species using a model based on time series measurements of the depletion
of dissolved silicate (DSi) and increases in biomass. Furthermore, the carbon: nitrogen: silicate stoichiometric relationships
and maximum growth rates were determined. Differences in DSi uptake kinetics and maximum growth rate were distinct among the
species. All the most common diatom species (Chaetoceros wighamii, Pauliella taeniata, Skeletonema costatum and Thalassiosira baltica) were relatively lightly silicified and had variable but relatively low half-saturation constants (K
s
), indicating that they are well adapted to low DSi concentrations. The less common Diatoma tenuis and Nitzschia frigida had higher K
s
values, suggesting that they are more vulnerable to DSi limitation. The much used nitrogen:silicate ratio of 1 for marine
diatom biomass was too low for most of the examined species, while a ratio of 2–3 seems to be more appropriate for these Baltic
Sea species. 相似文献
120.
Bacterial antibiotic resistance levels in Danish farmland as a result of treatment with pig manure slurry 总被引:17,自引:0,他引:17
Sengeløv G Agersø Y Halling-Sørensen B Baloda SB Andersen JS Jensen LB 《Environment international》2003,28(7):587-595
Resistance to tetracycline, macrolides and streptomycin was measured for a period of 8 months in soil bacteria obtained from farmland treated with pig manure slurry. This was done by spread plating bacteria on selective media (Luria Bertani (LB) medium supplemented with antibiotics). To account for seasonal variations in numbers of soil bacteria, ratios of resistant bacteria divided by total count on nonselective plates were calculated. Soil samples were collected from four different farms and from a control soil on a fifth farm. The control soil was not amended with animal manure. The occurrence of tetracycline-resistant bacteria was elevated after spread of pig manure slurry but declined throughout the sampling period to a level corresponding to the control soil. Higher load of pig manure slurry yielded higher occurrence of tetracycline resistance after spreading; however, the tetracycline resistance declined to normal occurrence defined by the tetracycline resistance occurrence in the control soil. Concentrations of tetracycline in soil and in pig manure slurry were measured using HPLC. No tetracycline exceeding the detection limit was found in soil samples. Manure slurry concentrations of tetracycline for three of the farms were 42, 81 and 698 microg/l, respectively. For streptomycin and macrolides, only minor variations in resistance levels were detected. Results obtained in this study thus indicate that tetracycline resistance levels in soil are temporarily influenced by the addition of pig manure slurry. The results indicate also that increased amount of pig manure slurry amendment may result in increased levels of tetracycline resistance in the soil. 相似文献