全文获取类型
收费全文 | 2017篇 |
免费 | 121篇 |
国内免费 | 413篇 |
专业分类
安全科学 | 140篇 |
废物处理 | 76篇 |
环保管理 | 162篇 |
综合类 | 917篇 |
基础理论 | 432篇 |
环境理论 | 1篇 |
污染及防治 | 521篇 |
评价与监测 | 140篇 |
社会与环境 | 115篇 |
灾害及防治 | 47篇 |
出版年
2024年 | 4篇 |
2023年 | 36篇 |
2022年 | 89篇 |
2021年 | 78篇 |
2020年 | 73篇 |
2019年 | 71篇 |
2018年 | 80篇 |
2017年 | 90篇 |
2016年 | 109篇 |
2015年 | 112篇 |
2014年 | 120篇 |
2013年 | 201篇 |
2012年 | 202篇 |
2011年 | 207篇 |
2010年 | 173篇 |
2009年 | 164篇 |
2008年 | 164篇 |
2007年 | 161篇 |
2006年 | 147篇 |
2005年 | 73篇 |
2004年 | 44篇 |
2003年 | 25篇 |
2002年 | 33篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 9篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有2551条查询结果,搜索用时 468 毫秒
211.
Esther del Val Juan Carlos Senar Juan Garrido-Fernández Manuel Jarén Antoni Borràs Josep Cabrera Juan José Negro 《Die Naturwissenschaften》2009,96(7):797-801
Carotenoids may provide numerous health benefits and are also responsible for the integumentary coloration of many bird species.
Despite their importance, many aspects of their metabolism are still poorly known, and even basic issues such as the anatomical
sites of conversion remain controversial. Recent studies suggest that the transformation of carotenoid pigments takes place
directly in the follicles during feather growth, even though the liver has been previously recognised as a storing organ for
these pigments with a certain potential for conversion. In this context, we analysed the carotenoid profile of plasma, liver,
skin and feathers of male Common Crossbills (Loxia curvirostra). Interestingly, the derivative feather pigment 3-hydroxy-echinenone was detected in the liver and in the bloodstream (i.e.
the necessary vehicle to transport metabolites to colourful peripheral tissues). Our results demonstrate for the first time
with empirical data that the liver may act as the main site for the synthesis of integumentary carotenoids. This finding contradicts
previous assumptions and raises the question of possible inter-specific differences in the site of carotenoid conversion in
birds. 相似文献
212.
213.
Jos L. Mateos Paloma Fern ndez Del Pino Francisco J. Guti rrez Ma ero Marí a Ruiz Palomino Juan J. Colon Jos A. Lucas Garcí a Agustí n Probanza 《Chemistry and Ecology》2000,17(2):125-152
Microbial communities (phospholipid fatty acid pattern, bacterial growing strategies, eco-physiological index (EPI) and total bacteria counts, as a number of heterotrophic cuhurable bacteria), substrate-induced respiration (SIR), and nitrogen mineralization were studied in three Mediterranean soils at three different depth levels (A, B and C). Soils were experimentally treated with a final concentration of 1000 ppm of trace metals (Cu2+, Zn2+, Al3+, Fe2+, Pb2+, Ni2+, Mn2+, Cr3+ and Cd2+). Soils were stored in 571 plastic containers for one year, and watered with 1001 during this period. Leachate was recovered through a bottom tap. Samples of the three depths were studied. Soil microbial communities showed different effects to other studies presented in the literature, but carried out on non-Mediterranean soils. Dramatic differences were found between treated soils and untreated ones, but not between soils or horizons. the treated soil displayed a decrease in CFUs, SIR N-mineralization and EPI together with a dominance of r-growing strategists. the relative moles percent of several PLFAs, especially 15:0, 16: 1ω7, cy17: 0, br18:0 and 18: 1ω7 decreased because of the pollution of soils, whereas 10Me16, 18:2ω6, cy19:0, i16:0 and br17:0 showed higher values than in untreated soils. 相似文献
214.
Valme Jurado Angel Fernandez-Cortes Soledad Cuezva Leonila Laiz Juan Carlos Cañaveras Sergio Sanchez-Moral Cesareo Saiz-Jimenez 《Die Naturwissenschaften》2009,96(9):1027-1034
The conservation of rock-art paintings in European caves is a matter of increasing interest. This derives from the bacterial
colonisation of Altamira Cave, Spain and the recent fungal outbreak of Lascaux Cave, France—both included in the UNESCO World
Heritage List. Here, we show direct evidence of a fungal colonisation of rock tablets in a testing system exposed in Altamira
Cave. After 2 months, the tablets, previously sterilised, were heavily colonised by fungi and bacteria. Most fungi isolated
were labelled as entomopathogens, while the bacteria were those regularly identified in the cave. Rock colonisation was probably
promoted by the dissolved organic carbon supplied with the dripping and condensation waters and favoured by the displacement
of aerosols towards the interior of the cave, which contributed to the dissemination of microorganisms. The role of arthropods
in the dispersal of spores may also help in understanding fungal colonisation. This study evidences the fragility of rock-art
caves and demonstrates that microorganisms can easily colonise bare rocks and materials introduced into the cavity. 相似文献
215.
首先简单介绍了单轴压缩试验的具体情况。对于拉裂破坏模式,提出了相应的力学计算模型,并建立了抗压强度和抗拉强度的关系式。对于由拉裂面的存在而导致试件最终破坏的计算模型,提出了4种相应的假设。其中,对4种特征的拉裂面建立了抗压强度和抗拉强度的关系式。 相似文献
216.
Cai Kui Du Juan Dai Cong Hu Huabin . Center for Rural Development Studies Yunnan University Kunming Yunnan China . Institute of Ethnology Yunnan Academy of Social Science Kunming Yunnan China . Institute of Economics Yunnan Academy of Social Science Kunming Yunnan China . Xishuangbanna Tropical Botany Garden Chinese Academy of Sciences Kunming Yunan China 《中国人口.资源与环境(英文版)》2007,5(2):78-83
A three-year study over the Bai, Jingpo and Huayaodai communities in Yunnan Province reveals that the community development is significantly influenced in various ways by such cultural factors as the concepts of development; concepts and traditions of inter-community relationships, consumption, mar- riage and gender; patterns of decision-making and production, resource and income allocation; as well as the role of information dissemination systems, religion and ritual. Based on the analysis over the interactive relevance between each factor and community development, some strategies and methods for dealing with such a cultural relevance in development projects are recommended. 相似文献
217.
Patrícia Pereira Susana Carvalho Fábio Pereira Hilda de Pablo Miguel B. Gaspar Mário Pacheco Carlos Vale 《Environmental monitoring and assessment》2012,184(12):7141-7151
Macroinvertebrate benthic communities are one of the key biological components considered for the assessment of benthic integrity in the context of the Water Framework Directive (WFD). However, under moderate contamination scenarios, the assessment of macrobenthic alterations at community level alone could be insufficient to discriminate the environmental quality of coastal and transitional waters. Keeping this in view, sediment quality of moderately contaminated sites in a coastal lagoon (óbidos lagoon, Portugal) was assessed by the combination of sediment metal levels, Carcinus maenas biomarkers (accumulated metals and oxidative stress responses) and macrobenthic communities. Two sites were selected in confined inner branches (BS and BB) and a third one in the middle lagoon (ML). The site BB presented slightly higher levels of metals in sediment but biological variables calculated for macrobenthic data were not significantly different between sites. The biotic index M-AMBI that is being applied to assess environmental quality of transitional waters in the scope of the WFD pointed either to high (site ML) or good quality status (BS and BB) in the selected sites. However, crabs from BB site presented significantly higher levels of Ni in hepatopancreas than those from ML and macrobenthic community structure was significantly different between BB and ML. Additionally, spatial differences were obtained for oxidative stress parameters suggesting that BB site presented stressors for crabs (higher GST and lower GSHt at BB site). Factor analysis (PCA) integrating sediment contamination, biomarkers in crabs and macrobenthic data also distinguished BB site as the most environmentally disturbed. On the other hand, at ML site, some macrobenthic variables (equitability and polychaetes’ diversity) were found to be enhanced by current environmental conditions, suggesting the existence of a better sediment quality. Current results pointed to the usefulness of integrating macrobenthic community alterations with responses at organism level (bioaccumulation and biochemical endpoints) in order to increase the accuracy of environmental quality assessment in lagoon systems. Moreover, the application of different statistical methods was also found to be recommendable. 相似文献
218.
219.
Cesar A García-Ubaque Juan C Moreno-Piraján Liliana Giraldo-Gutierrez Karim Sapag 《Waste management & research》2007,25(4):352-362
This paper presents the results of the lixiviation of metals from different mixtures of fly and bottom ashes that have been stabilized and solidified in clays used in the manufacture of bricks. The ashes used for this study were obtained from a Hoffmann-type brick furnace adapted for the incineration of municipal solid waste during the manufacturing of ceramic bricks. The ashes were stabilized in clay in different proportions of clay:ash mix (99:1, 95:5, 90:10, 80:20 and 60:40). Such mixes were used to manufacture bricks that were calcined at a temperature ranging from 50 to 1100 degrees C. The clay, ashes and manufactured bricks were characterized using X-ray diffraction, fluorescent X-ray, thermogravimetry, differential thermal analysis, atomic absorption spectroscopy and scanning electronic microscopy. In addition, toxicity characteristic leaching procedure lixiviation tests were performed according to the EPA 1311 method for the determination of heavy metals. The results showed an affinity between clay and ash, and also that the bricks manufactured with these mixtures present low lixiviation levels. The tests also showed the highest decrease in the concentration of arsenic, nickel, chromium, zinc and silver for 99:1 mixtures. The 95:5 mixture was found to be the most favourable for the stabilization (greater concentration decrease) of lead and cadmium. Selenium was the metal with the lowest concentration change whereas arsenic, nickel, chromium, zinc and cadmium showed the greatest concentration change in all mixtures, with the exception of cadmium in the mixture 99:1. 相似文献
220.