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   1143篇
  免费   18篇
  国内免费   8篇
安全科学   39篇
废物处理   47篇
环保管理   142篇
综合类   243篇
基础理论   237篇
环境理论   3篇
污染及防治   331篇
评价与监测   71篇
社会与环境   53篇
灾害及防治   3篇
  2023年   13篇
  2022年   16篇
  2021年   24篇
  2020年   16篇
  2019年   15篇
  2018年   39篇
  2017年   41篇
  2016年   44篇
  2015年   37篇
  2014年   43篇
  2013年   63篇
  2012年   50篇
  2011年   79篇
  2010年   62篇
  2009年   62篇
  2008年   72篇
  2007年   72篇
  2006年   39篇
  2005年   56篇
  2004年   30篇
  2003年   38篇
  2002年   35篇
  2001年   20篇
  2000年   15篇
  1999年   10篇
  1998年   16篇
  1997年   5篇
  1996年   11篇
  1995年   20篇
  1994年   12篇
  1993年   8篇
  1992年   12篇
  1991年   6篇
  1990年   6篇
  1989年   7篇
  1988年   6篇
  1987年   6篇
  1986年   8篇
  1984年   4篇
  1983年   5篇
  1982年   3篇
  1980年   3篇
  1978年   3篇
  1977年   3篇
  1974年   3篇
  1963年   2篇
  1961年   2篇
  1959年   3篇
  1958年   3篇
  1957年   2篇
排序方式: 共有1169条查询结果,搜索用时 31 毫秒
951.
Cleaning is a highly physically demanding job with a high frequency of awkward postures and working environments as contributing risk factors. Participatory ergonomics is a method in which end-users take an active role in identifying risk factors and solutions. The aim of this study was to apply the participatory ergonomics method to identify cleaning problems and to evaluate the effect of a low-cost improvement on cleaners' working postures in an office environment. The results show that the cleaning problem was identified, and the low-cost ergonomics solution suggested by the cleaners was implemented. Thus an improved working environment reduced the number of awkward cleaning postures and the Ovako Working Posture Analysis System (OWAS) action category for floor mopping decreased. It can be concluded that working in an improved environment can lead to better working postures which, in turn, leads to the cleaners' better health and better cleaning results.  相似文献   
952.
Mercury levels in sediment and predatory fish were measured for 53 localities in Suriname. The average mercury level in bottom sediment surpassed the Canadian standard for sediment in most localities, except the coastal plains. Of the predatory fish, 41 % had a mercury level above the European Union standard for human consumption of 0.5 μg g−1. Highest mercury levels were found in fish from the Brokopondo Reservoir and from the Upper Coppename River. High levels of mercury in fish in pristine areas are explained by atmospheric transportation of mercury with the northeastern trade winds followed by wet deposition. Contrary to gold mining areas, where mercury is bound to drifting sediments, in “pristine” areas the mercury is freely available for bio-accumulation and uptake. Impacts on piscivorous reptiles, birds, and mammals are unknown, but likely to be negative.  相似文献   
953.
Effects of chronic application of a mixture of the herbicide atrazine and the insecticide lindane were studied in indoor freshwater plankton-dominated microcosms. The macroinvertebrate community was seriously affected at all but the lowest treatment levels, the zooplankton community at the three highest treatment levels, with crustaceans, caddisflies and dipterans being the most sensitive groups. Increased abundance of the phytoplankton taxa Cyclotella sp. was found at the highest treatment level. Threshold levels for lindane, both at population and community level, corresponded well with those reported in the literature. Atrazine produced fewer effects than expected, probably due to decreased grazer stress on the algae as a result of the lindane application. The safety factors set by the Uniform Principles for individual compounds were also found to ensure protection against chronic exposure to a mixture of a herbicide and insecticide at community level, though not always at the population level.  相似文献   
954.
Biopurification systems treating pesticide contaminated water are very efficient, however they operate as a black box. Processes inside the system are not yet characterized. To optimize the performance, knowledge of degradation and retention processes needs to be generated. Therefore, displacement experiments were carried out for four pesticides (isoproturon, bentazone, metalaxyl, linuron) in columns containing different organic mixtures. Bromide, isoproturon and bentazone breakthrough curves (BTCs) were well described using the convection-dispersion equation (CDE) and a first-order degradation kinetic approach. Metalaxyl and linuron BTCs were well described using the CDE model expanded with Monod-type kinetics. Freundlich sorption, first-order degradation and Monod kinetics coefficients were fitted to the BTCs. Fitted values of the distribution coefficient Kf,column were much lower than those determined from batch experiments. Based on mobility, pesticides were ranked as: bentazone > metalaxyl - isoproturon > linuron. Based on degradability, pesticides were ranked as: linuron > metalaxyl - isoproturon > bentazone.  相似文献   
955.
Dust storm events and their relation to climate changes in Northern China during the past 1000 years were analyzed by using different paleoclimate archives such as ice cores, tree rings, and historical documents. The results show that in the semiarid region, the temperature and precipitation series were significantly negatively correlated to the dust storm frequency on a decadal timescale. Compared with temperature changes, however, there was a closer correlation between precipitation changes and dust storm events on a centennial timescale. At this timescale, precipitation accounts for 40% of the variance of dust fall variations during the last 1700 years, inferring precipitation control on the formation of dust storms. In the western arid region, both temperature and precipitation changes are important forcing factors for the occurrence of dust storms in the region on a centennial timescale. In the eastern arid region, the relationship between dust storm events and climate changes are similar like in the semiarid region. As a result, the effects of climate change on dust storm events were manifested on decadal and centennial timescales during the last millennium. However, there is a phase shift in the relation between climate change and the dust storm frequency. A 1400 years reconstruction of the strength of the Siberian High reveals that long-term variations of spring Siberian High intensity might provide a background for the dynamic conditions for the frequency of historical dust storm events in Northern China.  相似文献   
956.
The concentrations of fifteen PAH compounds in samples of sediment and blue mussel tissue (Mytilus trossulus) were measured. In addition, the biliary polycyclic aromatic hydrocarbon metabolites present in flounder (Platichthys flesus) were analysed. Two methods were used in the analysis of PAH metabolites; high performance liquid chromatography (HPLC) and fixed wavelength fluorescence (FF). The major PAH metabolite which could be measured using the HPLC method was 1-OH pyrene. It was possible to detect 1-OH Phe and 3-OH B[a]P in 70 and 24 samples respectively, of the 87 samples analysed. However, the concentrations of 1-OH Phe and 3-OH B[a]P were below or near to the LOQ (0.002 μg ml(-1) bile). The bile of flounder samples from the Gulf of Gdańsk had 1-OH Pyr concentrations which ranged from 0.019 to 0.066 μg ml(-1) bile. The high linear correlation observed between the quantity of 1-OH pyrene determined by the HPLC-F method and the content of the sum of pyrene-type PAHs obtained by the FF method indicated the FF method of determination of pyrene-type PAH metabolites can be used as a screening method. The content of ∑(15)PAHs in sediments collected in the Gulf of Gdansk, in 2008, ranged from 29.3 to 103 μg kg(-1) dw. In mussel tissue ∑(15)PAHs concentrations were between 173.2 μg kg(-1) dw and 237.7 μg kg(-1) dw. All concentrations measured in the current study, in mussel tissue, were below the OSPAR toxicity threshold values.  相似文献   
957.
Desertification, land degradation in arid, semi-arid, and dry sub-humid regions, is a global environmental problem. With respect to increasing importance of desertification and its complexity, the necessity of attention to the optimal de-desertification alternatives is essential. Therefore, this work presents an analytic hierarchy process (AHP) method to objectively select the optimal de-desertification alternatives based on the results of interviews with experts in Khezr Abad region, central Iran as the case study. This model was used in Yazd Khezr Abad region to evaluate the efficiency in presentation of better alternatives related to personal and environmental situations. Obtained results indicate that the criterion "proportion and adaptation to the environment" with the weighted average of 33.6% is the most important criterion from experts viewpoints. While prevention alternatives of land usage unsuitable of reveres and conversion with 22.88% mean weight and vegetation cover development and reclamation with 21.9% mean weight are recognized ordinarily as the most important de-desertification alternatives in region. Finally, sensitivity analysis is performed in detail by varying the objective factor decision weight, the priority weight of subjective factors, and the gain factors. After the fulfillment of sensitivity analysis and determination of the most sensitive criteria and alternatives, the former classification and ranking of alternatives does not change so much, and it was observed that unsuitable land use alternative with the preference degree of 22.7% was still in the first order of priority. The final priority of livestock grazing control alternative was replaced with the alternative of modification of ground water harvesting.  相似文献   
958.
The Galathea 3 expedition circumnavigated the globe in 2006-2007 and collected marine samples from six continents. Bivalves were collected from harbours, other impacted locations and reference sites, and samples from 57 sites were analyzed for metals and 47 for organotins, to assess current contamination levels on a global scale. Metal concentrations in nine bivalve species were normalised to the Mytilidae family using conversion factors based on cosampled species and literature bioconcentration factors. The lowest metal and tributyltin concentrations were below background assessment concentrations (BACs) agreed in the Oslo-Paris convention (OSPAR) for the North Sea, and at most harbours the concentrations were orders of magnitude above BACs. The lowest concentrations of Cd and Pb measured here suggest that the BACs should be lower in a worldwide context. The sources of metals were classified according to human impact using principal component analysis. High relative concentrations of Hg, Pb and P were source indicators for industrial activity and land use; Zn, organotins, Cd and Cu for shipping activities, and V for oil spills. Generally the concentration levels at reference sites were low, but not always lower than expected impacted areas. The most contaminated areas were harbours, where especially Copenhagen, St Croix and Sydney, can be considered hotspots of tributyltin as well as a number of metals.  相似文献   
959.
We present examples of cumulative chemical risk mapping methods developed within the NoMiracle project. The different examples illustrate the application of the concentration addition (CA) approach to pesticides at different scale, the integration in space of cumulative risks to individual organisms under the CA assumption, and two techniques to (1) integrate risks using data-driven, parametric statistical methods, and (2) cluster together areas with similar occurrence of different risk factors, respectively. The examples are used to discuss some general issues, particularly on the conventional nature of cumulative risk maps, and may provide some suggestions for the practice of cumulative risk mapping.  相似文献   
960.
Edible and medicinal macrofungi used in human diet represent not only important sources of nutritive elements but toxic substances as well (heavy metals and radionuclides). Radioactivity levels of four radionuclides (40K, 137Cs, 226Ra, 228Ra) were determined in the basidiomata (fruiting bodies of a Basidiomycetes) of six lignicolous (Fomitopsis pinicola, Ganoderma applanatum, Hericium clathroides, Megacollybia platyphylla, Pluteus cervinus, Trametes gibbosa) and three mycorrhizal (Boletus luridus, Boletus sp. 1, Boletus sp. 2) species as well as their soil (wood) substrates by gamma spectrometry (high-resolution high-purity germanium (HPGe) detector). The aim was to investigate their ability for radionuclide absorption according to transfer factors (from soil and wood), to predict potential bioindicator species as well as species with potential risk for human use. Samples were taken during years 2011 and 2012, at two sites in forest ecosystem of Tara Mountain (Serbia). Observed concentration ranges per dry weight were as follows: 29–3,020 Bq/kg (40K), 21.9–735 Bq/kg (137Cs), 3–39 Bq/kg (226Ra), and 2.0–18 Bq/kg (228Ra). Obtained results indicate that the type of basidiome (fleshy/tough), most likely due to a different metabolic rate, has a very important role in radionuclide accumulation. The highest activity concentrations of all analyzed radionuclides were found in species with fleshy basidiomata—P. cervinus, H. clathroides, M. platyphylla, and Boletus species. A species-specific influence on radionuclide uptake was more prominent comparing to habitat differences and the role of fungal trophic mode. No significant variations were observed regarding radionuclide activity among the same fungal species from different sampling sites.  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