全文获取类型
收费全文 | 1161篇 |
免费 | 113篇 |
国内免费 | 883篇 |
专业分类
安全科学 | 68篇 |
废物处理 | 31篇 |
环保管理 | 71篇 |
综合类 | 1118篇 |
基础理论 | 397篇 |
污染及防治 | 328篇 |
评价与监测 | 27篇 |
社会与环境 | 63篇 |
灾害及防治 | 54篇 |
出版年
2024年 | 6篇 |
2023年 | 26篇 |
2022年 | 58篇 |
2021年 | 67篇 |
2020年 | 71篇 |
2019年 | 94篇 |
2018年 | 91篇 |
2017年 | 95篇 |
2016年 | 93篇 |
2015年 | 96篇 |
2014年 | 99篇 |
2013年 | 184篇 |
2012年 | 117篇 |
2011年 | 134篇 |
2010年 | 96篇 |
2009年 | 116篇 |
2008年 | 60篇 |
2007年 | 104篇 |
2006年 | 100篇 |
2005年 | 79篇 |
2004年 | 70篇 |
2003年 | 51篇 |
2002年 | 32篇 |
2001年 | 34篇 |
2000年 | 27篇 |
1999年 | 27篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 17篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有2157条查询结果,搜索用时 15 毫秒
991.
The Pialassa Baiona is an intertidal lagoon located north from the town of Ravenna (Italy). It shows a certain degree of contamination caused by past uncontrolled discharges, and we aim at developing a bioassessment program to be used for future monitoring and conservation plans. A battery of six biomarkers (lysosome membrane stability, lipofuscin and neutral lipid accumulation, hsp70 expression, metallothionein levels and acetylcholinesterase (AChE) activity) was investigated in Mytilus galloprovincialis transplanted for 30 days in different sites. Tapes philippinarum are widely distributed within the lagoon, and we explored the possibility to use resident clams for future biosurveillance programs. Adenylyl cyclase (ACase) activity was also assessed in tissues of both bivalves as a future possible biomarker. Taken together, our results indicate that mussels are suitable sentinel organisms also within such a peculiar environment; alteration of four biomarkers was observed in tissues of mussels transplanted in two sites out of the five analyzed, indicating their low water quality. T. philippinarum showed a barely detectable AChE activity and absence of neutral lipids in digestive glands, therefore appeared unsuitable for our purpose, at least using the selected battery of biomarkers. ACase activity was not different among animals collected from the different sites. 相似文献
992.
S. Claassens L. Van Rensburg K. J. Riedel J. J. Bezuidenhout P. J. Jansen Van Rensburg 《The Environmentalist》2006,26(1):51-62
Summary Bioremediation has become an important method for the treatment of terrestrial oil spills and is often favoured over strictly
physical-chemical methods. In this study, enzymatic analyses and signature lipid biomarkers were employed to evaluate the
efficacy of selected bioremediation products on control and oil contaminated soil plots. It is envisioned that these biological
indicators may be used as possible adjuncts to the strictly physical-chemical criteria most commonly employed. The application
of the enzymatic and signature biomarker methods for product evaluation proved successful. The enzymatic assays provided a
valuable insight into shifts in the functional diversity of the soil microbial communities resultant from the various treatments.
Stimulation or inhibition of the microbial communities as a result of the various treatments was also demonstrated, particularly
with regards to dehydrogenase activity. Phospholipid fatty acid profiles proved sufficiently sensitive to allow differentiation
between products and resultant microbial communities that corresponded to satisfactory and unsatisfactory petroleum hydrocarbon
removal. 相似文献
993.
Soil erosion response to climatic change and human activity during the Quaternary on the Loess Plateau, China 总被引:9,自引:1,他引:8
We review published stratigraphic, archaeological and pedosedimentary evidence in order to reconstruct the history of soil
erosion in China. Documentary evidence of climatic and flood events of the Yellow River and modern hydrological and meteorological
data are synthesised to analyse the history of past human activity and its effects on soil erosion intensity during four nested
periods of time during the Quaternary. The most intensive period of erosion during the Quaternary was in the Holocene. During
the Holocene, intervals of intensive soil erosion occurred at 7500–7000 BP, 200 BCE–0 CE, 1000–1600 CE (Christian era) and
during the 1930s, 1950s and the later part of the 1960s of the last century. Large-scale human activity including warfare
during early Chinese history, population migration, the inner wars in 1930s, the Cultural Revolution and the recent national
campaign to aid soil and water conservation are all closely related to the rate of soil erosion on the Loess Plateau and to
sediment loads in the Yellow River. Overall, soil erosion during the transition from dry-cool to wet-warm climates was more
intense than during wet-warm and cool-dry climatic episodes, but serious accelerated soil erosion has occurred during the
last 2,500 years because of man-induced devastation of vegetation and other anthropogenic disturbance of the environment.
Modern rates of soil erosion on the Loess Plateau are a combination of both intensive natural and human-induced erosions and
are some four times greater than occurred in the geological past. The recent implementation of soil and water conservation
measures has decreased sediment load in the Yellow River by 25%. 相似文献
994.
本研究测试了某城市60例暴露于不同浓度空气铅的血铅水平、δ-ALAD活性和FEP值。结果表明其血铅水平随暴露程度的增大而升高,δ-ALAD活性则随暴露和蔼的增大而降低,经统计学分析,各组之间存在显著性差异。 相似文献
995.
Russian Journal of Ecology - 相似文献
996.
ABSTRACTForest productivity is dependent on soil quality, which in turn is related to litter; yet there is limited understanding of the relationships between litter and soil quality. The effects of litter removal treatment on tree growth and soil properties were examined in a Pinus caribaea stand with the aim of providing an understanding of consequences of litter removal on soil patterns. This knowledge is important for planning appropriate long-term forest management. Three pairs of 30 × 30 m2 plots (each pair a control and treatment) were established in the center of a P. caribaea stand in April 2002. The controls were left undisturbed with an intact litter layer, while litter was removed monthly from treated plots. The diameter and height of the P. caribaea decreased and soil quality was degraded over the experimental period in litter-removed (treated) plots. Litter removal also produced a significant increase in soil bulk density at 0–20 and 20–40 cm depths. The capillary porosity, capillary moisture capacity, and natural water content in controls at 0–20 and 20–40 cm depths were significantly greater than treated plots. The non-capillary porosity in controls at the 0–20 cm depth was also significantly higher than treated plots. The organic carbon, total nitrogen (N), total potassium (K) and alkalized N content in each layer, and available P and exchangeable K at 0–20 and 40–60 cm depths in control plots were significantly greater than litter-removed plots. The numbers of bacteria at 0–20 and 40–60 cm depths and of fungi at 20–40 and 40–60 cm depths were higher in control than treated plots. The number of actinomyces and urease, catalase, and acid phosphatase activities in controls at each depth were significantly greater than litter-removed plots. 相似文献
997.
Daijun ZHANG Cui BAI Ting TANG Qing YANG 《Frontiers of Environmental Science & Engineering》2011,5(2):291-297
Shortcut nitrification-denitrification, anaerobic ammonium oxidation (ANAMMOX), and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter (EGSB-BAF) integrated system. As fed different synthetic wastewater with chemical oxygen demand (COD) of 300–1200 mg·L-1 and N H 4 + - N of 30–120 mg·L-1 at the outer recycle ratio of 200%, the influence of influent on ANAMMOX in the integrated system was investigated in this paper. The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX; however, when an influent with the low concentration of COD was used, the opposite changes could be observed. Higher influent N H 4 + - N concentration favored ANAMMOX when the COD concentration of influent was fixed. Therefore, low C O D / N H 4 + - N ratio would decrease competition for nitrite between ANAMMOX and denitrification, which was favorable for reducing the negative effect of organic COD on ANAMMOX. The good performance of the integrated system indicated that the bacterial community of denitrification, ANAMMOX, and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent. 相似文献
998.
This article presents the results of laboratory studies of the influence of tetrazine derivatives on the growth kinetic parameters of soil bacteria. 3,6-Dihydrazinotetrazine (DHTz), 3,6- bis(3,5-dimethylpyrazol-1-yl)-dihydro-1,2,4,5-tetrazine (DMPDHT) and N,N′-bis(1,2,4,5-tetrazine-6-(3,5-dimethylpirazylo))hydrazine (BDMPT) were applied. 3,6-Dihydrazinetetrazine had the largest influence on the growth of bacteria, reflected in a significant lengthening of the lag-phase and a decrease in the specific growth rate. Dehydrogenase activity was also determined in bacterial cultures exposed to tetrazine derivatives. Dehydrogenases remained active even at DHTz concentrations of 80 mg · L?1, which completely inhibited bacterial growth. The compounds studied variously influence the kinetics of growth in the bacterial consortium; at the same time, they undergo biodegradation in soil by autochthonous microflora. 相似文献
999.
4-(5-(Methylthio)-1,3,4-thiadiazol-2-ylamino)-2-oxo-2H-chromene-3-carbaldehyde (3) and 4-(5-(ethylthio)-1,3,4-thiadiazol-2-ylamino)-2-oxo-2H-chromene-3-carbaldehyde (4) were prepared. The structures of the newly synthesized compounds were characterized by infrared (IR), nuclear magnetic resonance (NMR) spectral data and elemental analysis. The synthesized compounds were screened in vitro for their antibacterial activities. The synthesized compounds demonstrated moderate antimicrobial activity. 相似文献
1000.
Laadroui Jawad Rachida Aboufatima Ouarhach Aicha Kenza Bezza Zineb El Gabbas Ait Laaradia Mehdi 《毒物与环境化学》2013,95(1-2):129-147
AbstractThe aims of the study are to assess some effects of smoking for 3?months and of withdrawal of male weaned rats on anxiety, locomotor activity, and depression using common behavioral tests such as the marble burying, open field, and forced swim tests. Somatic signs of abstinence and histological effects were also studied. The rats present changes of the aforementioned behaviors as well as histological alterations of the lungs. 相似文献