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271.
Francisco J. Arjona Susana Sangiao-Alvarellos Sergio Polakof Angel García-López María P. Martín del Río Gonzalo Martínez-Rodríguez José L. Soengas Juan M. Mancera 《Marine Biology》2008,153(4):661-671
To assess the interaction between testosterone (T) treatment and acclimation to different salinities, seawater-acclimated
gilthead sea bream (Sparus auratus) were implanted with slow-release coconut oil implants alone (control) or containing T (5 μg/g body mass). After 5 days,
eight fish of control and T-treated groups were sampled. The same day, eight fish of each group were transferred to low salinity
water (LSW, 6 ppt, hypoosmotic test), seawater (SW, 38 ppt, control test) and high salinity water (HSW, 55 ppt, hyperosmotic
test) and sampled 9 days later. Gill Na+, K+-ATPase activity increased in HSW-acclimated fish with respect to SW- and LSW-acclimated fish in both control and T-treated
groups. Kidney Na+, K+-ATPase activity was also enhanced in HSW-acclimated fish, but only in T-treated group. From a metabolic point of view, most
of the changes observed can be attributed to the action of salinity and T treatment alone, since few interactions between
T treatment and osmotic acclimation to different salinities were observed. Those interactions included in treated fish: in
the liver, decreased capacity in using glucose in fish acclimated to extreme salinities; in the gills, decreased capacity
in using amino acids in HSW; in the kidneys increased capacity in using amino acids in extreme salinities; and in the brain,
decreased glycogen and acetoacetate levels of fish in LSW. 相似文献
272.
Marco Antonio Leonel Caetano Douglas Francisco Marcolino Gherardi Takashi Yoneyama 《Ecological modelling》2008
In recent years, the world has witnessed an ever-growing concern towards global warming caused by greenhouse gases, such as carbon dioxide (CO2). In order to reduce the emissions of CO2 without limiting economic growth, substantial investments should target the development of clean technology and the expansion of forested areas. Considering the limited availability of resources, investments must be used in the most effective way. The present work proposes a method to efficiently manage these resources by applying the optimal control theory to a new mathematical model that describes the dynamics of the atmospheric CO2. The contributions of this work are twofold: (1) present a model that describes the dynamic relation of CO2 emission with investment in reforestation and clean technology and (2) present a method to efficiently manage the available resources by casting an optimal control problem. The mathematical model uses ordinary differential equations to relate the production of CO2 with forest area and Gross Domestic Product (GDP). The model parameters are adjusted to fit the actual published data. Given an appropriate performance index, the optimal solution is found by numerically solving the Two-Point Boundary Value Problem (TPBVP) that arises from the application of Pontriagyn's Maximum Principle. The sensitivity of the obtained numerical solution is evaluated with respect to the uncertainties in the model parameters. The main objective of this work is to provide a quantitative tool for the efficient allocation of resources to reduce the greenhouse effect caused CO2 emissions. 相似文献
273.
Pavão Diogo C. Porteiro João Ventura Maria A. Borges Silva Lurdes Medeiros António Moniz Ana Moura Mónica Moreira Francisco Silva Luís 《Environment, Development and Sustainability》2021,23(11):16504-16528
Environment, Development and Sustainability - Tourists have become increasingly interested in certain aspects of their destination, including landscape and biodiversity elements, thereby promoting... 相似文献
274.
Carlos F. Mena Francisco Laso Patricia Martinez Carolina Sampedro 《Journal of Land Use Science》2017,12(6):477-492
In the Ecuadorian Amazon roads play the major role in transforming land cover. Since the beginning of the oil development in this region, oil exploration and road building have been linked. The objectives of this paper are twofold: First, to present a scenario of future deforestation as result of expanding the oil frontier in the Ecuadorian Amazon until the year 2030. Second, to produce an analysis of possible carbon emission scenarios as results of the deforestation produced. This paper tries to shed light into how the development of new oil concessions impact land associated environmental services. The paper uses spatial explicit simulations, that are based on parameters built using past land transitions from areas that experimented oil development, and that explain possible outcomes in the year 2030 using current and predicted road network. Simulations indicate that under current transition probabilities and a conservative scenario road construction, more than 2 million hectares will be affected, which is 35% of the area covered by concessions, which would release 51 to 148 MT of carbon to the atmosphere. This paper illustrates the strong links between road building and deforestation, where even small amount of road construction can have large effects on land cover. 相似文献
275.
Ponce Roberto D. Fernández Francisco Stehr Alejandra Vásquez-Lavín Felipe Godoy-Faúndez Alex 《Regional Environmental Change》2017,17(6):1811-1821
Regional Environmental Change - Agriculture is one of the most vulnerable economic sectors to the impacts of climate change, specifically those related with expected changes in water availability.... 相似文献
276.
González Gallero FJ Galán Vallejo M Umbría A Gervilla Baena J 《Environmental monitoring and assessment》2006,119(1-3):405-423
A complete statistical analysis of meteorological and air pollution data was carried out in the ‘Campo de Gibraltar’ region (in the South of Spain) from 1999 to 2002. This is a heavy industrialized area where, up to date, very few air pollution studies have been made. The main objectives of the study presented here have been the characterization of the meteorological and (gaseous and particulate) air pollution conditions in the area, and the relations between them. Multivariate statistical techniques, such as Principal Component Analysis (PCA), have been applied to the data. The results show that air quality in the area is highly dependent on meteorological conditions such as wind persistence and direction, dispersion capability of the atmosphere, and humidity content. On average, sulphur dioxide and nitrogen oxide air pollution, mainly caused by fuel-oil combustion and traffic, respectively, is not very high. However, an important number of exceedences of the limits established by the EU Directive 1999 for PM10 (particulate matter with a diameter less than 10 μm) have been observed in some points of the area. A significant percentage of these exceedences (about 22% on average) are likely caused by African dust intrusions, which usually take place from May to August. From gaseous and particulate air correlations, it seems that anthropogenic activities contribute with about 19% on average. 相似文献
277.
Cram S Sommer I Morales LM Oropeza O Carmona E González-Medrano F 《Journal of environmental management》2006,80(1):13-24
A land suitability study was carried out by applying a multiple-criteria technique to 12 different vegetation types in Mexico's Tamaulipas state to help select potentially suitable sites for hazardous waste treatment plants. Species richness, spatial distribution, and uniqueness were selected as the criteria for estimating a vegetation type's suitability. Using the analytical hierarchy process, we ranked and mapped vegetation types, then compared the results with rankings of the same vegetation types based only on their number of endemic species. The suitabilities of the various vegetation types were ordered in more or less the same way by both methods, except in two cases for which the results were very different. The method proved to be a useful tool despite the availability of only partial (mostly qualitative) information; under such circumstances, expert experience can be incorporated in the evaluation process to a limited degree. The technique described in this paper has a high potential to aid decisions when many opinions and options must be considered simultaneously. 相似文献
278.
Gustavo Cruz-Cárdenas José Teodoro Silva Salvador Ochoa-Estrada Francisco Estrada-Godoy Jaime Nava-Velázquez 《Environmental Modeling and Assessment》2017,22(3):257-266
Environmental or hydrological landscape units can integrate various environmental characteristics to support proper management of natural resources. To delineate these units, quantitative methods such as ordination, clustering, and classification of abiotic factor information are used. In the present work, environmental units were delineated in the Duero River watershed of Michoacán, Mexico. This will enhance understanding of the hydrologic landscape, which is a fundamental to natural resource management. A digital elevation model was used to generate sub-basins. Climatic data were obtained from 16 meteorological stations. Sixty-nine soil and 150 water samples were collected and analyzed in the laboratory. Geostatistical methods for spatial prediction of the environmental variables were used. Mean data for each sub-basin were obtained from the environmental variable grids, generating an abiotic factor data matrix. A multivariate analysis was conducted. Exponential, linear, spherical, and Gaussian models were fit to an empirical variogram. Spatial prediction of the environmental data was done via universal and ordinary kriging. Based on principal component analysis, abiotic factors evaporation, total nitrogen, soil pH, and sodium absorption ratio of water were selected for cluster analysis. Five environmental units were delineated in the Duero watershed. One environmental unit (number 4) provided greater than 50 % of the payment for ecosystem services. The general trend is an increase of urban area. The urban surface in 1983 and 2014 was 1724 and 4750 ha, respectively, an increase of 275 %. Environmental unit 1 showed the greatest urban area growth (1336 ha) during the latter period. 相似文献
279.
Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile 总被引:4,自引:0,他引:4
Espejo L Kretschmer N Oyarzún J Meza F Núñez J Maturana H Soto G Oyarzo P Garrido M Suckel F Amezaga J Oyarzún R 《Environmental monitoring and assessment》2012,184(9):5571-5588
Surface water quality has increasing importance worldwide and is particularly relevant in the semiarid North-Central Chile, where agriculture and mining activities are imposing heavy pressure on limited water resources. The current study presents the application of a water quality index in four watersheds of the 29°-33°S realm for the period 1999-2008, based on the Canadian Council of Ministers for the Environment approach and the Chilean regulation for irrigation water quality. In addition, two modifications to the index are tested and a comprehensive characterization of the existing monitoring network is performed through cluster analysis. The basins studied show fairly good water quality in the overall, specially the Limarí basin. On the other hand, the lower index values were obtained for the headwaters of Elqui, associated with the El Indio mining district. The first modification of the indicator (i.e., to consider parameters differentially according to their effect on human health or the environment) did not produce major differences with respect to the original index, given the generally good water quality. The second modification (i.e., to consider as threshold values the more restrictive figures derived from a set of regulations) yielded important differences in the indicator values. Finally, an adequate characterization of the monitoring network was obtained. The results presented spatial coherence and the information can be used as a basis for the optimization of the monitoring network if required. 相似文献
280.
Francisco Encina-Montoya Rolando Vega-Aguayo Oscar Díaz Carlos Esse Jorge Nimptsch Andrés Muñoz-Pedreros 《Environmental monitoring and assessment》2017,189(11):584
The suitability of Mazzaella laminarioides and Sarcothalia crispata as heavy metal biomonitors of Cd, Cu, Hg, Pb, and Zn was assessed by comparing bioaccumulation of these elements in different life stages and frond sizes in samples from three locations, San Vicente Bay (industrial area), Coliumo, and Quidico (the latter as a reference station), where different degrees of heavy metal pollution are recorded. Bioaccumulation and bioconcentration factors of Cd, Cu, Hg, Pb, and Zn were evaluated. The two macroalgae species showed similar patterns, with higher values of Cu, Hg, Pb, and Zn in polluted areas. M. laminarioides bioaccumulated higher concentrations of all metals assessed than S. crispata, independent of life stage and frond size. The results also showed significantly higher Cu, Hg, Pb, and Zn concentrations (p < 0.05) in water samples from San Vicente Bay than those measured in Coliumo and Quidico. Concentrations of Cd, Hg, Pb, and Zn in San Vicente Bay and Cd, Hg, and Pb in Coliumo and Quidico exceed the mean values considered to represent natural concentrations (Cu = 3.00 μg L?1; Zn = 5.00 μg L?1; Pb = 0.03 μg L?1; Cd = 0.05 μg L?1; Hg = 0.05 μg L?1); however, the concentrations recorded do not cause negative effects on the growth and survival of macroalgae. The assessment of heavy metals bioaccumulated in M. laminarioides and S. crispata, particularly Hg, Pb, and Zn, offers a reliable approach for pollution assessment in rocky intertidal environments. Cu and Cd concentrations in seawater samples from San Vicente and Coliumo Bays were significantly higher than in those from Quidico (p value < 0.05); no significant differences in Cd concentrations were observed between San Vicente and Coliumo Bays (p < 0.05). Exceptionally, Cd is bioaccumulated at high levels independent of its availability in the water, thus reaching high concentrations in control areas. High concentrations of metals like Cu and Zn may limit or inhibit Cd uptake in macroalgae, since the transport channels are saturated by some metals, reducing the accumulation of others. These macroalgae species offer good potential for the development of suitable heavy metal pollution survey tools in rocky intertidal environments. 相似文献