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681.
Estrogens-sulphates such as 17beta-estradiol-3-sulphate and estrone-3-sulphate are excreted by livestock in the urine. These conjugates are precursors to the free counterparts 17beta-estradiol and estrone, which are endocrine disrupting chemicals. In this study microcosm laboratory experiments were conducted in three pasture soils from New Zealand to study the aerobic degradation and metabolite formation kinetics of 17beta-estradiol-3-sulphate at three different incubation temperatures. The degradation of 17beta-estradiol-3-sulphate followed a first-order kinetic and the temperature dependence of the rate constants was sufficiently described by the Arrhenius equation. Degradation was different between the three investigated soils and the rate constants across the soils were significantly correlated to the arylsulphatase activity at 7.5 and 15 degrees C. Estrone-3-sulphate and 17beta-estradiol were identified as primary metabolites and estrone as a secondary metabolite. Results suggest arylsulphatase activity originating from soil microbial biomass is the main driver for the degradation of 17beta-estradiol-3-sulphate. 相似文献
682.
Vulnerability and adaptation of European farmers: a multi-level analysis of yield and income responses to climate variability 总被引:6,自引:3,他引:3
Pytrik Reidsma Frank Ewert Alfons Oude Lansink Rik Leemans 《Regional Environmental Change》2009,9(1):25-40
Climate change will affect crop yields and consequently farmers’ income. The underlying relationships are not well understood,
particularly the importance of crop management and related factors at the farm and regional level. We analyze the impacts
of trends and variability in climatic conditions from 1990 to 2003 on trends and variability in yields of five crops and farmers’
income at farm type and regional level in Europe considering farm characteristics and other factors. While Mediterranean regions
are often characterized as most vulnerable to climate change, our data suggest effective adaptation to variable and changing
conditions in these regions largely attributable to the characteristic farm types in these regions. We conclude that for projections
of climate change impacts on agriculture, farm characteristics influencing management and adaptation should be considered,
as they largely influence the potential impacts. 相似文献
683.
Michael J. Mason Jeremy Mennis J. Douglas Coatsworth Thomas Valente Frank Lawrence Patricia Pate 《Journal of environmental psychology》2009
Geographic and substance use data were collected from 301 urban adolescents to compare the perceived and observed risk and safety associated with their home and activity space locations (routine locations). The geographic characteristics of the neighborhood surrounding each location was summarized according to features theorized to be risky, such as criminal activity and alcohol sales, and features theorized to be safe, such as recreation centers and churches. Data on socioeconomic status, derived from U.S. Bureau of the Census data, were also used to characterize locations. Adolescents' homes were typically perceived as safe despite observed measures of risk such as density of crimes and proximity to alcohol outlets. This held for both substance users and non-users. Differences in geographic characteristics for safe and risky activity spaces were observed for both substance users and non-users, with non-users appearing to be more sensitive to the presence of risky characteristics in the environment than substance users. Results highlight the need and provide a methodology to collect fine-grained activity space data instead of relying only on home residence when attempting to represent place and health behaviors with urban youth. 相似文献
684.
Hang Xiao Hayley Hung Ying Duan Lei Frank Wania 《Atmospheric environment (Oxford, England : 1994)》2009,43(15):2401-2409
At locations without access to the electrical grid, a flow-through sampler (FTS) collects large volumes of air for the analysis of semi-volatile organic compounds (SVOCs). To test its performance under field conditions, an FTS and a traditional pumped high volume air sampler, both using polyurethane foam (PUF) as sampling medium, were co-deployed at the campus of the University of Toronto Scarborough from August 2006 to June 2007. Polybrominated diphenyl ethers (PBDEs) and various pesticides were quantified in the samples taken by both samplers to test the FTS's applicability to relatively non-volatile and slightly polar SVOCs. Air concentrations in samples taken with the FTS over five 2-week periods compare favourably with the average of the concentrations in several 24-h active high volume samples taken during the same period. In particular, time trends, temperature dependence relationships, and isomer ratios show a reasonable agreement between the two sampling techniques. An empirical linear solvation energy relationship for predicting the apparent theoretical plate number of the PUF assembly used in the FTS illustrates the effect of chemical properties, as well as temperature and wind speed, on sampling efficiency. In the absence of electrical power, the FTS can collect SVOCs from large air volumes as reliably and quantitatively as traditional HiVol samplers, although without separating gas and particle phase. 相似文献
685.
Gallagher FJ Pechmann I Bogden JD Grabosky J Weis P 《Environmental pollution (Barking, Essex : 1987)》2008,153(2):351-361
Anthropogenic sources of toxic elements have had serious ecological and human health impacts. Analysis of the soil samples from a brownfield within Liberty State Park, Jersey City, NJ, USA, showed that arsenic, chromium, lead, zinc and vanadium exist at concentrations above those considered ambient for the area. Accumulation and translocation features were characterized for the dominant plant species of four vegetative assemblages. The trees Betula populifolia and Populus deltoides were found to be accumulating Zn in leaf tissue at extremely high levels. B. populifolia, P. deltoides and Rhus copallinum accumulated Cr primarily in the root tissue. A comparison of soil metal maps and vegetative assemblage maps indicates that areas of increasing total soil metal load were dominated by successional northern hardwoods while semi-emergent marshes consisting mostly of endemic species were restricted primarily to areas of low soil metal load. 相似文献
686.
687.
Effect of phosphogypsum and dicyandiamide as additives on NH3, N2O and CH4 emissions during composting 总被引:1,自引:0,他引:1
Yiming Luo Guoxue Li Wenhai Luo Frank Schuchardt Tao Jiang Degang Xu 《环境科学学报(英文版)》2013,25(7):1338-1345
A laboratory scale experiment of composting in a forced aeration system using pig manure with cornstalks was carried out to investigate the effects of both phosphogypsum and dicyandiamide (DCD, C2H4N4) as additives on gaseous emissions and compost quality. Besides a control, there were three amended treatments with different amounts of additives. The results indicated that the phosphogypsum addition at the rate of 10% of mixture dry weight decreased NH3 and CH4 emissions significantly during composting. The addition of DCD at the rate of 0.2% of mixture dry weight together with 10% of phosphogypsum further reduced the N2O emission by affecting the nitrification process. Reducing the phosphogypsum addition to 5% in the presence of 0.2% DCD moderately increased the NH3 emissions but not N2O emission. The additives increased the ammonium content and electrical conductivity significantly in the final compost. No adverse effect on organic matter degradation or the germination index of the compost was found in the amended treatments. It was recommended that phosphogypsum and DCD could be used in composting for the purpose of reducing NH3, CH4 and N2O emissions. Optimal conditions and dose of DCD additive during composting should be determined with different materials and composting systems in further study. 相似文献
688.
Arjan M. Boonman Martijn Boonman Frank Bretschneider Wim A. van de Grind 《Behavioral ecology and sociobiology》1998,44(2):99-107
Daubenton's bat, a trawling vespertilionid bat species, hunts for insects that fly close to, or rest on, the water surface.
During summer, many ponds at which Daubenton's bats hunt become gradually covered with duckweed. The purpose of this study
was to investigate the effects of duckweed cover on the hunting behaviour of Daubenton's bats and on the ultrasound-reflecting
properties of the water surface. Our study revealed the following. (1) Daubenton's bat avoids water surfaces covered with
duckweed. (2) Prey abundance was related to the number of foraging Daubenton's bats but was independent of duckweed cover.
(3) When mealworms were presented among standardized amounts of duckweed to naturally foraging Daubenton's bats, they caught
significantly less mealworms when the duckweed cover was increased. (4) Measurements with ultrasonic signals show that a water
surface covered with duckweed returns a much stronger background echo at small angles (i.e. parallel to the water surface)
compared to an uncovered water surface. It seems likely that a cover of duckweed on the water surface interferes with prey
detection by masking the echoes returning from prey. (5) It was relatively difficult for the bats to discriminate small patches
of duckweed from mealworms. The proposed discrimination mechanism for this trawling bat species suggests that single duckweed
patches can also be mistaken for natural prey by Daubenton's bats.
Received: 4 January 1998 / Accepted after revision: 19 July 1998 相似文献
689.
Erich Zeeck Carsten T. Müller Manfred Beckmann Jörg D. Hardege Ulrich Papke Volker Sinnwell Frank C. Schroeder Wittko Francke 《Chemoecology》1998,8(1):33-38
Summary. In the marine polychaete Nereis succinea (Frey & Leuckart 1847) a sex pheromone was isolated from the coelomic fluid of sexually mature females and identified by
NMR studies and independent synthesis. This pheromone is released by the females during reproduction together with eggs and
coelomic fluid into the free water column and induces sperm release of surrounding males. Its structure was ascertained as
L-cysteine-glutathione disulfide. It exhibited a response threshold of 0.6 · 10−7 M.
Received 15 July 1997; accepted 25 November 1997. 相似文献
690.
Using data from electroretinogram recordings, we designed a submersible light meter with a spectral luminous efficiency comparable
to that of a vertically migrating shrimp. Using this light meter on the “Johnson Sea Link” submersible, we were able to ascend
with the isolumes (preferred light levels) associated with the sergestid and euphausiid shrimp layers. The speed of the submersible's
movement was recorded and correlated with simultaneous measurements of surface irradiance. In situ measurements of the downwelling
spectral distribution were also made with a fiber optic spectrometer. The average measured speed of the sergestid isolume
was 8.8 cm s−1, while that of the shallower euphausiid isolume was 6.7 cm s−1. These values are different from those calculated using average diffuse attenuation coefficients and surface light measurements.
This difference was due to the broadening of the spectral distribution of downwelling light above 120 m and to the variability
of the diffuse attenuation coefficients with depth. These results clearly demonstrate that when investigating the relationship
between light and vertical migration patterns, it is important that: (1) the light measurements be made in situ and (2) such
measurements take into account the spectral sensitivity of the eyes of the migrators.
Received: 7 June 2000 / Accepted: 18 November 2000 相似文献