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961.
Sundström M Ehresman DJ Bignert A Butenhoff JL Olsen GW Chang SC Bergman A 《Environment international》2011,37(1):178-183
The widespread presence of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexanesulfonate (PFHxS) in human general populations and their slow elimination profiles have led to renewed interest in understanding the potential human neonatal exposures of perfluoroalkyls (PFAs) from consumption of human milk. The objective of this study was to evaluate the concentrations of PFOS, PFHxS, and PFOA in pooled human milk samples obtained in Sweden between 1972 and 2008 (a period representing the most significant period of PFA production) and to see whether the time trend of these analytes parallels that indicated in human serum. Chemical analysis of PFOS, PFHxS, and PFOA was performed on pooled Swedish human milk samples from 1972 to 2008 after methodological refinements. The 20 samples which formed the 2007 pool were also analyzed individually to evaluate sample variations. Analyses were performed by HPLC-MS/MS. Due to the complexities of the human milk matrix and the requirement to accurately quantitate low pg/mL concentrations, meticulous attention must be paid to background contamination if accurate results are to be obtained. PFOS was the predominant analyte present in the pools and all three analytes showed statistically significant increasing trends from 1972 to 2000, with concentrations reaching a plateau in the 1990s. PFOA and PFOS showed statistically significant decreasing trends during 2001-2008. At the end of the study, in 2008, the measured concentrations of PFOS, PFHxS, and PFOA in pooled human milk were 75 pg/mL, 14 pg/mL, and 74 pg/mL, respectively. The temporal concentration trends of PFOS, PFHxS, and PFOA observed in human milk are parallel to those reported in the general population serum concentrations. 相似文献
962.
Al-Jundi J Li WB Abusini M Tschiersch J Hoeschen C Oeh U 《Journal of environmental radioactivity》2011,102(6):574-580
High indoor radon concentrations in Jordan result in internal exposures of the residents due to the inhalation of radon and its short-lived progeny. It is therefore important to quantify the annual effective dose and further the radiation risk to the radon exposure. This study describes the methodology and the biokinetic and dosimetric models used for calculation of the inhalation doses exposed to radon progeny. The regional depositions of aerosol particles in the human respiratory tract were firstly calculated. For the attached progeny, the activity median aerodynamic diameters of 50 nm, 230 nm and 2500 nm were chosen to represent the nucleation, accumulation and coarse modes of the aerosol particles, respectively. For the unattached progeny, the activity median thermodynamic diameter of 1 nm was chosen to represent the free progeny nuclide in the room air. The biokinetic models developed by the International Commission on Radiological Protection (ICRP) were used to calculate the nuclear transformations of radon progeny in the human body, and then the dosimetric model was applied to estimate the organ equivalent doses and the effective doses with the specific effective energies derived from the mathematical anthropomorphic phantoms. The dose conversion coefficient estimated in this study was 15 mSv WLM−1 which was in the range of the values of 6-20 mSv WLM−1 reported by other investigators. Implementing the average indoor radon concentration in Jordan, the annual effective doses were calculated to be 4.1 mSv y−1 and 0.08 mSv y−1 due to the inhalation of radon progeny and radon gas, respectively. The total annual effective dose estimated for Jordanian population was 4.2 mSv y−1. This high annual effective dose calculated by the dosimetric approach using ICRP biokinetic and dosimetric models resulted in an increase of a factor of two in comparison to the value by epidemiological study. This phenomenon was presented by the ICRP in its new published statement on radon. 相似文献
963.
Fukushima fallout in Northwest German environmental media 总被引:1,自引:0,他引:1
Traces of short- and long-lived fallout isotopes (131I, 134Cs and 137Cs) were found in environmental samples collected in Northwest Germany (rain water, river sediment, soil, grass and cow milk) from March to May 2011, following the radioactivity releases after the nuclear accident in Fukushima, Japan. The measured concentrations are consistent with reported concentrations in air, amount of rainfall and expected values applying simple radioecological models. The [134Cs]/[137Cs] ratio reported for air (about 1) allows for discrimination between “recent” and “old” 137Cs. Expected 136Cs values fell below the detection limits of the instrumentation, despite large sample masses and long counting times. 相似文献
964.
P. Valkering R. van der Brugge A. Offermans N. Rijkens-Klomp 《Regional Environmental Change》2011,11(2):229-241
Climate adaptation is a complex task surrounded by uncertainty. To support climate adaptation policies, a new scenario approach
is pursued to explore possible discontinuous future developments of societal perspectives on climate adaptation issues. The
scenario approach was tested for a case study on Dutch river management. In a series of scenario development workshops, a
select group of stakeholders explored the perspectives on the management of the River Meuse in the past, present, and future.
The process was supported by an analytical perspectives mapping tool to illustrate and analyze the development of perspectives
over time. The process and analytical tools contributed to insight into the drivers of perspective change for the case study
at hand. Moreover, the stakeholders highlighted the potential of the approach for water management policy for creating awareness
about the plurality of perspectives and the dynamics of perspective change, monitoring perspectives and perspective change
as part of a flexible policy approach, and anticipating on the occurrence of shock events. Further work is required to better
represent the social dynamics of perspectives change, to better empirically ground the perspective change model, and to apply
integrated water models in the scenario development process to assess water–society interactions. 相似文献
965.
Meghann E. Jarchow Justin W. Rice Rebekah M. Ritson Sarah K. Hargreaves 《Sustainability Science》2011,6(2):253-254
Conference organizers are increasingly making efforts to reduce resource use at conferences, yet few responsibilities are
placed on attendees. We hosted an ecology conference and offered attendees a discount if they took a sustainability pledge
agreeing to reduce their resource use at the conference. In a post-conference survey, 83% of respondents reported fulfilling
the pledge, but 62% indicated that convenience was the biggest obstacle impeding their ability to continue the pledge during
and after the conference. We found great willingness by attendees to reduce resource use at and beyond our conference, and
facilitating their participation was an important part of our success. 相似文献
966.
Long-term (1860–2010) catchment mass balance calculations rely on models and assumptions which are sources of uncertainty
in acidification assessments. In this article, we report on an application of MAGIC to model acidification at the four Swedish
IM forested catchments that have been subject to differing degrees of acidification stress. Uncertainties in the modeled mass
balances were mainly associated with the deposition scenario and assumptions about sulfate adsorption and soil mass. Estimated
base cation (BC) release rates (weathering) varied in a relatively narrow range of 47–62 or 42–47 meq m−2 year−1, depending on assumptions made about soil cation exchange capacity and base saturation. By varying aluminum solubility or
introducing a dynamic weathering feedback that allowed BC release to increase at more acidic pHs, a systematic effect on predicted
changes in acid neutralizing capacity (ΔANC ca. 10–41 μeq l−1) and pH (ca. ΔpH = 0.1–0.6) at all sites was observed. More robust projections of future changes in pH and ANC are dependent
on reducing uncertainties in BC release rates, the timing, and extent of natural acidification through BC uptake by plants,
temporal changes in soil element pools, and fluxes of Al between compartments. 相似文献
967.
Land use conflicts are becoming increasingly apparent from local to global scales. Surface gold mining is an extreme source
of such a conflict, but mining impacts on local livelihoods often remain unclear. Our goal here was to assess land cover change
due to gold surface mining in Western Ghana, one of the world’s leading gold mining regions, and to study how these changes
affected land use systems. We used Landsat satellite images from 1986–2002 to map land cover change and field interviews with
farmers to understand the livelihood implications of mining-related land cover change. Our results showed that surface mining
resulted in deforestation (58%), a substantial loss of farmland (45%) within mining concessions, and widespread spill-over
effects as relocated farmers expand farmland into forests. This points to rapidly eroding livelihood foundations, suggesting
that the environmental and social costs of Ghana’s gold boom may be much higher than previously thought. 相似文献
968.
Globally, urban growth will add 1.5 billion people to cities by 2030, making the difficult task of urban water provisions
even more challenging. In this article, we develop a conceptual framework of urban water provision as composed of three axes:
water availability, water quality, and water delivery. For each axis, we calculate quantitative proxy measures for all cities
with more than 50,000 residents, and then briefly discuss the strategies cities are using in response if they are deficient
on one of the axes. We show that 523 million people are in cities where water availability may be an issue, 890 million people
are in cities where water quality may be an issue, and 1.3 billion people are in cities where water delivery may be an issue.
Tapping into groundwater is a widespread response, regardless of the management challenge, with many cities unsustainably
using this resource. The strategies used by cities deficient on the water delivery axis are different than for cities deficient
on the water quantity or water quality axis, as lack of financial resources pushes cities toward a different and potentially
less effective set of strategies. 相似文献
969.
Rundqvist S Hedenås H Sandström A Emanuelsson U Eriksson H Jonasson C Callaghan TV 《Ambio》2011,40(6):683-692
Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic
Sweden. We recorded the change in coverage of shrub and tree species over a 32– to 34-year period, in three 50 × 50 m plots;
in the alpine-tree-line ecotone. The cover of shrubs and trees (<3.5 cm diameter at breast height) were estimated during 2009–2010
and compared with historical documentation from 1976 to 1977. Similarly, all tree stems (≥3.5 cm) were noted and positions
determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs
and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory. 相似文献
970.