首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   229篇
  免费   1篇
  国内免费   5篇
安全科学   6篇
废物处理   12篇
环保管理   22篇
综合类   21篇
基础理论   68篇
污染及防治   76篇
评价与监测   18篇
社会与环境   10篇
灾害及防治   2篇
  2023年   4篇
  2022年   7篇
  2021年   5篇
  2020年   1篇
  2019年   2篇
  2018年   6篇
  2017年   5篇
  2016年   18篇
  2015年   4篇
  2014年   8篇
  2013年   22篇
  2012年   19篇
  2011年   18篇
  2010年   15篇
  2009年   12篇
  2008年   17篇
  2007年   11篇
  2006年   15篇
  2005年   8篇
  2004年   8篇
  2003年   5篇
  2002年   2篇
  2001年   4篇
  2000年   2篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1994年   3篇
  1991年   1篇
  1990年   1篇
  1986年   3篇
  1985年   1篇
  1982年   1篇
  1959年   1篇
  1958年   1篇
排序方式: 共有235条查询结果,搜索用时 359 毫秒
111.
Meeting environmental, economic, and societal targets in energy policy is complex and requires a multicriteria assessment framework capable of exploring trade-offs among alternative energy options. In this study, we integrated economic analysis and biophysical accounting methods to investigate the performance of electricity production in Finland at plant and national level. Economic and environmental costs of electricity generation technologies were assessed by evaluating economic features (direct monetary production cost), direct and indirect use of fossil fuels (GER cost), environmental impact (CO2 emissions), and global environmental support (emergy cost). Three scenarios for Finland's energy future in 2025 and 2050 were also drawn and compared with the reference year 2008. Accounting for an emission permit of 25 €/t CO2, the production costs calculated for CHP, gas, coal, and peat power plants resulted in 42, 67, 68, and 74 €/MWh, respectively. For wind and nuclear power a production cost of 63 and 35 €/MWh were calculated. The sensitivity analysis confirmed wind power's competitiveness when the price of emission permits overcomes 20 €/t CO2. Hydro, wind, and nuclear power were characterized by a minor dependence on fossil fuels, showing a GER cost of 0.04, 0.13, and 0.26 J/Je, and a value of direct and indirect CO2 emissions of 0.01, 0.04, and 0.07 t CO2/MWh. Instead, peat, coal, gas, and CHP plants showed a GER cost of 4.18, 4.00, 2.78, and 2.33 J/Je. At national level, a major economic and environmental load was given by CHP and nuclear power while hydro power showed a minor load in spite of its large production. The scenario analysis raised technological and environmental concerns due to the massive increase of nuclear power and wood biomass exploitation. In conclusion, we addressed the need to further develop an energy policy for Finland's energy future based on a diversified energy mix oriented to the sustainable exploitation of local, renewable, and environmentally friendly energy sources.  相似文献   
112.
Levels of total suspended particles, PM10, PM2.5 and PM1 were continuously monitored at an urban kerbside in the Metropolitan area of Barcelona from June 1999 to June 2000. The results show that hourly levels of PM2.5 and PM1 are consistent with the daily cycle of gaseous pollutants emitted by traffic, whereas TSP and PM10 do not follow the same trend, at least in the diurnal period. The PM2.5/PM10 ratio is dependent on the traffic emissions, whereas additional contribution sources for the >10 μm fraction must be taken into account in the diurnal period. Different PM10 and PM2.5 source apportionment techniques were compared. A methodology based on the chemical determination of 83% of both PM10 and PM2.5 masses allowed us to quantify the marine (4% in PM10 and <1% in PM2.5), crustal (26% in PM10 and 8% in PM2.5) and anthropogenic (54% in PM10 and 73% in PM2.5) loads. Peaks of crustal contribution to PM10 (up to 44% of the PM10 mass) were recorded under Saharan air mass intrusions. A different seasonal trend was observed for levels of sulphate and nitrate, probably as a consequence of the different thermodynamic behaviour of these PM species and the higher summer oxidation rate of SO2.  相似文献   
113.
Environmental Science and Pollution Research - This study aimed to investigate the effects of lead (Pb) exposure on parotid and submandibular glands through morphological aspects as well as the...  相似文献   
114.
115.
Climate, habitat, and species interactions are factors that control community properties (e.g., species richness, abundance) across various spatial scales. Usually, researchers study how a few properties are affected by one factor in isolation and at one scale. Hence, there are few multi-scale studies testing how multiple controlling factors simultaneously affect community properties at different scales. We ask whether climate, habitat structure, or insect resources at each of three spatial scales explains most of the variation in six community properties and which theory best explains the distribution of selected community properties across a rainfall gradient. We studied a Neotropical insectivorous bat ensemble in the Isthmus of Panama with acoustic monitoring techniques. Using climatological data, habitat surveys, and insect captures in a hierarchical sampling design we determined how much variation of the community properties was explained by the three factors employing two approaches for variance partitioning. Our results revealed that most of the variation in species richness, total abundance, and feeding activity occurred at the smallest spatial scale and was explained by habitat structure. In contrast, climate at large scales explained most of the variation in individual species' abundances. Although each species had an idiosyncratic response to the gradient, species richness peaked at intermediate levels of precipitation, whereas total abundance was very similar across sites, suggesting density compensation. All community properties responded in a different manner to the factor and scale under consideration.  相似文献   
116.
Air, marine, and terrestrial pollution are continuously critical issues to be solved in environmental sciences. Particularly with the recent disaster in the Mexico Gulf and the risk of oil spills from the continuous offshore drilling activities in the North Sea, ecotoxicological profiling requires great attention. Fjord ecosystems are particularly neglected marine ecosystems, which require better surveillance and ecotoxicological profiling. In this context, this study focuses on exploring three potential indicators for aquatic stress [polycyclic aromatic hydrocarbons (PAHs), aromatic amines (AAs), and nitroarenes (NAs)] by the study of their molecular and sub-molecular properties. The results show that the aromatic amine, 4-aminobiphenyl, gains a particularly reactive electronic potential, which can be summarized as a large change in LUMO+2 and HOMO?1 electron orbitals upon metabolic activation in the organism. This change in orbitals increases the overall electrostatic energy of the molecule, inducing a high affinity for DNA-adduct formation. Electronic analysis on nitroarenes shows in addition why 1,6-dinitropyrene is more stable than 1,8-dinitropyrene, and how the electrons favor nitrenium activation on the 6th and 8th carbon. Further analysis shows also that PAHs have a present correlation with hormonal similarity, and that their resemblance to estrogen can be correlated to mutagenicity, contributing to increased ecotoxicity. The electronic analysis of these three types of fossil pollutants shows how their toxicity is exerted from the electronic level and which structural features that determine the level of reactivity and toxicity. The summation of the background and electronic properties of these molecular toxins elucidates that PAHs, aromatic amines, and nitroarenes are all of equal importance as stress indicators for fjord systems, with particular emphasis on PAHs, which also exert hormonal structural similarities as a probable base of their carcinogenic mechanisms.  相似文献   
117.
118.
Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, \( {\text{Hg}}_{\text{gas}}^{0} \) ), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m?3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m?3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m?3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.  相似文献   
119.
120.
During 1987–1992, a mandatory program to control phosphorus discharges was implemented at dairy operations located to the north of Lake Okeechobee, Florida, USA. Thirty of 48 dairies participated in this program and implemented best management practices (BMPs), which included the construction of intensive animal waste management systems. Eighteen dairies closed their milkproducing operations under a government-funded buyout program. In this paper, we compare trends in runoff total phosphorus (TP) concentrations among the dairies that remained active and implemented BMPs. A central feature of the dairy waste management system is the high intensity area (HIA), defined as the milking barn and adjacent vegetation-free land, encircled by a drainage ditch and dike. Animal waste from the HIA is diverted into anaerobic lagoons and storage ponds, from which water is periodically removed and used for irrigation of field crops. The impacts of BMP construction on runoff TP concentrations were immediate and, in most cases, dramatic. Average TP concentrations declined significantly (P < 0.001), from 9.0 to 1.2 mg TP liter–1 at dairies in one basin (Lower Kissimmee River), and from 2.6 to 1.0 mg TP liter–1 in another (Taylor Creek/Nubbin Slough). Some sites experienced greater declines in TP than others. To elucidate possible causes for the difference in response, a multivariate statistical model was utilized. Independent variables included soil pH, soil drainage characteristics, spodic horizon depth, and the areas of different BMP components (pasture, HIA, spray fields). The analysis significantly separated dairies with the highest and lowest runoff TP concentrations. Lowest TP occurred at dairies having particular soil characteristic (shallow spodic horizon) and certain BMP features (large HIA and small heard pastures).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号