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831.
Carlos A. Peres 《Behavioral ecology and sociobiology》1992,31(5):339-347
Summary Tamarins of the genus Saguinus feed on a wide range of arthropods and small vertebrates, which compose a critical component of their diet. This paper examines the foraging patterns and capture success of the Avila-Peres saddle-back (S. fuscicollis avilapiresi) and the red-capped moustached tamarin (S. mystax pileatus) in very stable mixed-species groups, and whether and how any foraging benefits for either species resulted from their association. Moustached tamarins actively searched for prey items which were mainly well exposed on the midstorey foliage. Saddle-back tamarins, on the other hand, foraged at lower heights, largely by manipulating a variety of microhabitats potentially concealing embedded prey. The foraging activity of the numerically dominant and larger-bodied moustached tamarins often resulted in prey items escaping to lower substrates, usually the forest leaf-litter. The beating effect of this species substantially facilitated captures of large, mobile prey items by saddle-backs, which were highly adept at locating and retrieving flushed prey. It is estimated that, while saddle-backs obtained 66–73% of their prey biomass from flushed items, this proportion was substantially lower (2–9%) for moustached tamarins. Commensal insectivory appears to involve a highly asymmetric benefit to saddle-backs, and a low cost to moustached tamarins, which partly explains the stability of mixed-species groups.
Correspondence to the present address 相似文献
832.
Nieto JM Sarmiento AM Olías M Canovas CR Riba I Kalman J Delvalls TA 《Environment international》2007,33(4):445-455
The Tinto and Odiel rivers are seriously affected by acid mine drainage (AMD) from the long-term mining activities in Iberian Pyrite Belt (IPB). As a consequence, the Huelva estuary is heavily contaminated by metals and metalloids. This study presents an estimation of the seasonal variation, and the dissolved contaminant load transported by both rivers from February 2002 to September 2004. Besides, toxicity and bioaccumulation tests with the sediments of the estuary have been conducted in order to measure the mobility of the toxic metals. Results show that the Tinto and Odiel rivers transport enormous quantities of dissolved metals to the estuary: 7900 t yr(-1) of Iron (Fe), 5800 t yr(-1) Aluminium (Al), 3500 t yr(-1) Zinc (Zn), 1700 t yr(-1) Copper (Cu), 1600 t yr(-1) Manganese (Mn) and minor quantities of other metals and metalloids. These values represent 37% of the global gross flux of dissolved Zn transported by rivers in to the ocean, and 15% of the global gross flux of dissolved Cu. These metals and metalloids usually sink in the estuarine sediments due to pH and salinity changes. The increase of salinity in the estuary favours the adsorption and trapping of metals. For this reason, the mobility and bioavailability of metals such as Zn, Cd and Cu is higher in sediments located in the area of fresh water influence that in sediments located in the marine influenced area of the estuary, showing a higher percentage of fractionation and bioaccumulation of these metals in the station influenced by the fresh water environment. 相似文献
833.
Carlos E. Rodr′?guez-Rodr′?guez Evelyn Rodr′?guez Rigoberto Blanco Ivannia Cordero Daniel Segura 《环境科学学报(英文版)》2010,22(10):1595-1601
Because of the lack of reports, the base levels of microbial contamination on stored fuels are unknown in tropical regions and it is
unclear whether these levels have some influence on fuel quality parameters. Therefore, fungal quality in automobile fuels stored across
Costa Rican territory was evaluated during two years according to the standard ASTM D6974-04. For a total of 96 samples, counts and
identification of molds and yeasts were performed on regular gas, premium gas and diesel taken from the bottom and superior part of
the container tanks. The highest contamination was found on the bottom of the tanks, where an aqueous phase was usually identified,
showing populations over the ones present in the hydrocarbon itself (up to 108 CFU/L). Diesel was the most contaminated fuel (up to
107 CFU/L); however, an alteration on the physicochemical parameters was not observed in any kind of fuel. Seventy-five mold strains
were isolated, Penicillium sp. being the most common genus (45.8% of the samples), and ten yeast strains, from the genera Candida sp.
and Rhodotorula sp. Four of the yeasts were able to grow on diesel as the sole carbon source, at concentrations ranging from 0.5% to
25%. Increasing the frequency of tank cleaning, adding antimicrobial agents and monitoring microbial populations are recommended
strategies to improve microbial quality of stored fuels. 相似文献
834.
Protected Areas and Conservation of Biodiversity in the Tropics 总被引:7,自引:0,他引:7
G. Arturo Sánchez-Azofeifa Carlos Quesada-Mateo † Pablo Gonzalez-Quesada † S. Dayanandan ‡ AND Kamaljit S. Bawa§ 《Conservation biology》1999,13(2):407-411
Abstract: We compared deforestation rates and the extent of fragmentation inside and outside protected areas in the Sarapiquí region of Costa Rica. We determined deforestation rates using remotely sensed images with supervised classification. We georeferenced the processed images and then transformed them to vector format for final mapping and parameter quantification. The deforestation rate in protected areas was low and declined sharply from 0.56% annually between 1976 and 1986 to 0.16% from 1991 to 1995. Outside the protected areas, the rate decreased from 3.6% in 1976–1986 to 2.8% in 1986–1991, but it increased again to 3.2% in 1991–1995. Fragmentation outside the protected areas increased considerably: the number of patches increased from 537 in 1976 to 1231 in 1996, while during the same period the average size of patches decreased from 0.95 to 0.25 km2 . Forest landscapes in the Sarapiquí region are likely to lose considerable biodiversity because of the past forest loss and fragmentation even without further increases in deforestation and fragmentation. 相似文献
835.
Fernando Veloso-Gomes Ana Barroco Ana Ramos Pereira Carlos Sousa Reis Helena Calado João Gomes Ferreira Maria Da Conceição Freitas Manuel Biscoito 《Journal of Coastal Conservation》2008,12(1):3-9
This paper includes the proposals made in the report “Basis for a National Strategy for Coastal Zone Management” prepared
for the Portuguese Ministry of Environment, Territorial Planning and Regional Development. The final version of that report
was presented in June 2006. This paper describes a theme framework followed by a discussion of concepts. Nine Primary Principles,
eight Principal Objectives, and 37 Strategic Options for an Integrated Coastal Zone Management are then presented. These Strategic
Options are set hierarchically according to their sequential priority, identifying the dominant types of Associated Measures.
The analysis of these arrives at a set of Structural Measures, which interlink and aggregate various actions and propose a
new method of integrated management for the coastal zone, which includes the “Legal Basis of Coastal Zone”; the Organization
System; the Action Plan and Monitoring. 相似文献
836.
Alicia Fernández Cirelli Carlos Ojeda Mariano J. L. Castro Miquel Salgot 《Environmental Chemistry Letters》2008,6(3):135-148
Surfactants are included in different detergent formulations and are one of the most ubiquitous and important families of
organic compounds. Although the generic term applies to a great number of products, 80% of their demand is covered by only
ten types of compounds. The global surfactant market volume size is more than 18 million tons per year. Large quantities of
surfactants are continuously released into the environment, where they can or cannot be degraded depending on their structure.
The alkylbenzenesulphonate (LAS) is the most widely used surfactant. LAS can be degraded under aerobic conditions but is persistent
in the environment under anaerobic conditions. Surfactants may enter the terrestrial environment through several routes, with
the use of sewage sludge as fertiliser on agricultural land being by far the most important. High concentrations of surfactants
and their degradation products may affect the biota. On the other hand, due to their amphiphilic nature, surfactants may interact
both with inorganic as well as organic contaminants affecting their bioavailability. 相似文献
837.
Seed choice by rodents: learning or inheritance? 总被引:1,自引:0,他引:1
Learning plays a central role in animal life, and it has received special attention in the context of foraging. In this study, we have tested whether learning operates in seed choices by rodents using the Algerian mouse (Mus spretus) and Holm oak (Quercus ilex) acorns as a model. At the laboratory, those rodents captured in the field during the acorn fall period (experienced individuals) rejected weevil-infested acorns, presumably because of their lower energetic value. By contrast, rodents born in captivity and reared without any contact with acorns (naïves) predated weevil-infested acorns at similar rates than sound ones. After exposing naïves to infested and sound acorns during 15 days, they rejected infested acorns as the experienced individuals. In the field, predation on weevil-infested acorns was lower than on sound ones. Predation rates on infested acorns were lowest at the end of the acorn fall season, whereas predation rates of sound acorns increased along the same period. This might be explained by the improved ability to reject infested acorns because of the accumulated experience acquired by the initially naïve rodents along the acorn fall season. We show that learning shapes strongly seed choices by rodents, and it may be advantageous over inherited behaviors in variable unpredictable situations, such as acorn infestation rates that vary strongly between years and trees. We consider that the role of learning has to be taken into account in future studies on seed predation by rodents. 相似文献
838.
This study aims at establishing the maturation of the digestive system in Robsonella fontaniana by means of measuring the digestive enzyme activity in paralarvae after hatching. Different groups of newly hatched paralarvae were fed with Artemia sp. (FA), Lithodes santolla zoea (FL) or were starved to serve as negative control (ST), the experimental period lasted 27 days after hatching (DAH). The semi-quantitative assay api® ZYM (bioMérieux, France) was used to identify the pool of digestive enzymes present in paralarvae prior to selecting the specific enzymes acid phosphatase, total protease, trypsin and chymotrypsin for analysis. Mortality and larval protein content were also measured during the experiment. The survival of R. fontaniana hatchlings differed depending on the quality of the diet offered (ST < FA < FL), the same trend was observed with respect to paralarval protein content. Total protease and acid phosphatase activities were not related to either time of development or diet (P < 0.05). However, the activity of trypsin and chymotrypsin after DAH 10 was dependent on diet (P < 0.05). Paralarvae fed with Lithodes zoea (FL) performed better than paralarvae in the other two groups, exhibiting lower mortality, higher protein content and the highest proteolytic activity for trypsin and chymotrypsin. The results indicate that Lithodes-larvae are a better diet for R. fontaniana paralarvae than Artemia sp. 相似文献
839.
ebnem Andreani-Aksoyolu Johannes Keller Carlos Ordez Michel Tinguely Martin Schultz Andr S.H. Prvt 《Ecological modelling》2009,217(3-4):209
In this study, we investigated the effect of numerous regulations enforced since 1985 to improve air quality on ozone in Europe with the focus on Switzerland, using the Comprehensive Air Quality Model with Extensions (CAMx) for a specific summer period. Several emission scenarios for the year 2010 were also considered. The model results suggest that the emission reductions of ozone precursors should have been effective to reduce ozone production between 1985 and 2000 in northern Switzerland. However, observations do not indicate any significant change in surface ozone levels since early 1990s, except in the region of Zurich where there is a small negative trend. On the other hand, the model predictions match very well the spatial variability of the trends but the calculated trends are around 0.5 ppb year−1 lower than those observed. This difference is similar to the background ozone increase as suggested by the long-term observations at the high Alpine station Jungfraujoch. These results support the hypothesis that the decrease in local ozone production due to emission reductions might have been partly or completely compensated by the simultaneous increase in the background ozone. In 2010, a strict application of the Gothenburg Protocol in Europe would lead to a decrease in peak ozone concentrations by about 5% in Switzerland under the meteorological conditions applied. Our calculations also indicated that emission controls only in Switzerland would not be very effective to improve the air quality in the future. The further development of the background ozone will in any case be very important for the tropospheric ozone levels. 相似文献
840.
A global evaluation of metabolic theory as an explanation for terrestrial species richness gradients 总被引:5,自引:0,他引:5
Hawkins BA Albuquerque FS Araujo MB Beck J Bini LM Cabrero-Sañudo FJ Castro-Parga I Diniz-Filho JA Ferrer-Castan D Field R Gómez JF Hortal J Kerr JT Kitching IJ León-Cortés JL Lobo JM Montoya D Moreno JC Olalla-Tárraga MA Pausas JG Qian H Rahbek C Rodríguez MA Sanders NJ Williams P 《Ecology》2007,88(8):1877-1888
We compiled 46 broadscale data sets of species richness for a wide range of terrestrial plant, invertebrate, and ectothermic vertebrate groups in all parts of the world to test the ability of metabolic theory to account for observed diversity gradients. The theory makes two related predictions: (1) In-transformed richness is linearly associated with a linear, inverse transformation of annual temperature, and (2) the slope of the relationship is near -0.65. Of the 46 data sets, 14 had no significant relationship; of the remaining 32, nine were linear, meeting prediction 1. Model I (ordinary least squares, OLS) and model II (reduced major axis, RMA) regressions then tested the linear slopes against prediction 2. In the 23 data sets having nonlinear relationships between richness and temperature, split-line regression divided the data into linear components, and regressions were done on each component to test prediction 2 for subsets of the data. Of the 46 data sets analyzed in their entirety using OLS regression, one was consistent with metabolic theory (meeting both predictions), and one was possibly consistent. Using RMA regression, no data sets were consistent. Of 67 analyses of prediction 2 using OLS regression on all linear data sets and subsets, two were consistent with the prediction, and four were possibly consistent. Using RMA regression, one was consistent (albeit weakly), and four were possibly consistent. We also found that the relationship between richness and temperature is both taxonomically and geographically conditional, and there is no evidence for a universal response of diversity to temperature. Meta-analyses confirmed significant heterogeneity in slopes among data sets, and the combined slopes across studies were significantly lower than the range of slopes predicted by metabolic theory based on both OLS and RMA regressions. We conclude that metabolic theory, as currently formulated, is a poor predictor of observed diversity gradients in most terrestrial systems. 相似文献