全文获取类型
收费全文 | 2809篇 |
免费 | 122篇 |
国内免费 | 418篇 |
专业分类
安全科学 | 159篇 |
废物处理 | 123篇 |
环保管理 | 240篇 |
综合类 | 978篇 |
基础理论 | 575篇 |
环境理论 | 3篇 |
污染及防治 | 823篇 |
评价与监测 | 215篇 |
社会与环境 | 185篇 |
灾害及防治 | 48篇 |
出版年
2024年 | 4篇 |
2023年 | 43篇 |
2022年 | 118篇 |
2021年 | 113篇 |
2020年 | 87篇 |
2019年 | 77篇 |
2018年 | 101篇 |
2017年 | 116篇 |
2016年 | 149篇 |
2015年 | 135篇 |
2014年 | 158篇 |
2013年 | 274篇 |
2012年 | 251篇 |
2011年 | 269篇 |
2010年 | 205篇 |
2009年 | 201篇 |
2008年 | 219篇 |
2007年 | 217篇 |
2006年 | 195篇 |
2005年 | 104篇 |
2004年 | 68篇 |
2003年 | 49篇 |
2002年 | 54篇 |
2001年 | 26篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1964年 | 1篇 |
1958年 | 2篇 |
排序方式: 共有3349条查询结果,搜索用时 31 毫秒
941.
Vijver MG Vink JP Miermans CJ van Gestel CA 《Environmental pollution (Barking, Essex : 1987)》2007,148(1):132-140
The main factors contributing to variation in metal concentrations in earthworms inhabiting floodplain soils were investigated in three floodplains differing in inundation frequency and vegetation type. Metal concentrations in epigeic earthworms showed larger seasonal variations than endogeic earthworms. Variation in internal levels between sampling intervals were largest in earthworms from floodplain sites frequently inundated. High and low frequency flooding did not result in consistent changes in internal metal concentrations. Vegetation types of the floodplains did not affect metal levels in Lumbricus rubellus, except for internal Cd levels, which were positively related to the presence of organic litter. Internal levels of most essential metals were higher in spring. In general, no clear patterns in metal uptake were found and repetition of the sampling campaign will probably yield different results. 相似文献
942.
壳聚糖混凝剂除氟的研究 总被引:1,自引:0,他引:1
合成了壳聚糖和丙烯酰胺改性壳聚糖两种高分子混凝剂,并以NaF溶液为研究对象,考察了两种壳聚糖混凝剂投加量、pH值、接触时间及温度对除氟性能的影响.实验结果表明:丙烯酰胺改性壳聚糖的除氟效果优于未改性的壳聚糖;随着两种混凝剂投量的增加,除氟效率增大,当剂量分别大于50 mg/L和60 mg/L时,除氟效率趋于稳定;壳聚糖与改性壳聚糖混凝剂分别在pH值为6.2和5.4时,获得了最佳的除氟效果;接触时间小于12 min时,随着接触时间延长,除氟效率快速增加,大于20 min时,除氟率趋于稳定;混凝温度升高有利于提高除氟率,两种混凝剂在25℃即达到最大除氟率. 相似文献
943.
944.
人工神经网络在深圳市水库富营养化评价中的应用 总被引:1,自引:0,他引:1
对富营养化评价标准进行插值获取大量的样本,建立了基于BP人工神经网络的富营养化评价模型。将模型应用于评价深圳市13座主要水库的富营养化状况,对其成因进行分析,并提出了对策与建议。研究结果表明,石岩水库与深圳水库为轻度富营养化,占评价水库总数的15.4%;西丽水库等11座水库为中营养,占评价水库总数的84.6%。人工神经网络用于建立湖库富营养评价模型是适合的。 相似文献
945.
The management of swine manure is becoming an important environmental issue in Chile. One option for the final disposal of
manure is to use it as a biofertilizer, but this practice could impact the surrounding environment. To assess the potential
environmental impacts of the use of swine manure as a biofertilizer, we propose a method to identify zones of environmental
risk through indices. The method considers two processes: nutrient runoff and solute leaching, and uses available information
about soils, crops and management practices (irrigation, fertilization, and rotation). We applied the method to qualitatively
assess the environmental risk associated with the use of swine manure as a biofertilizer in an 8,000-pig farm located in Central
Chile. Results showed that the farm has a moderate environmental risk, but some specific locations have high environmental
risks, especially those associated with impacts on areas surrounding water resources. This information could assist the definition
of better farm-level management practices, as well as the preservation of riparian vegetation acting as buffer strips. The
main advantage of our approach is that it combines qualitative and quantitative information, including particular situations
or field features based on expert knowledge. The method is flexible, simple, and can be easily extended or adapted to other
processes. 相似文献
946.
947.
José E. Celis Winfred Espejo Daniel González-Acuña Solange Jara Ricardo Barra 《Environmental monitoring and assessment》2014,186(3):1815-1824
To add data on trace metal contamination of Humboldt penguins in the South Pacific, levels of trace metals (As, Hg, Pb, Cu, Zn, and Cd) and porphyrins (copro-, uro-, and proto-) in excreta of Humboldt penguins that inhabit some important nesting sites on the northern coast of Chile were determined. Fresh excreta were collected on Pan de Azúcar Island, Chañaral Island, and Cachagua Island, from December 2011 to January 2012. Concentration of metals was determined by flame atomic absorption spectrophotometry, whereas porphyrins levels were measured by fluorimetric analysis. Concentrations (dry weight) of Cu (199.67 μg g?1), As (7.85 μg g?1), and Pb (12.78 μg g?1) were higher (p?≤?0.05) in Cachagua Island. Colonies from Pan de Azúcar Island showed the highest levels of Hg (0.76 μg g?1), Cd (47.70 μg g?1), and Zn (487.10 μg g?1). Samples from Cachagua Island showed the highest (p?≤?0.05) levels of copro- (2.16 nmol g?1), uro- (2.20 nmol g?1), and protoporphyrins (2.23 nmol g?1). There was a positive correlation between the metals As, Pb, and Cu with uro-, copro-, and protoporphyrins. The results indicated that penguin colonies from Cachagua Island are more exposed to metal contamination than penguin colonies from Pan de Azúcar and Chañaral Islands, thus being more likely to develop certain diseases caused by contamination with metals. Considering biomagnification, the metals detected in the excreta of Humboldt penguins can be a source of contamination from marine environments to terrestrial ecosystems, which could also affect other living organisms. 相似文献
948.
Galante-Oliveira S Oliveira I Santos JA Pereira Mde L Pacheco M Barroso CM 《Journal of environmental monitoring : JEM》2010,12(5):1055-1063
Nucella lapillus (L.) is a marine gastropod mollusc widely used as a bioindicator of TBT pollution in the North Atlantic coastlines. The species reproductive cycle and the male penis length seasonal/spatial variation were studied at a single site at Aveiro seashore (NW Portugal) between December 2005 and June 2007. The main objective of this work is to assess if the "Relative Penis Size Index" (RPSI)--an important imposex assessment index--varies seasonally and spatially in the same sampling site and how this can affect results obtained in imposex monitoring programmes. Animals able to reproduce were found every month but a seasonal pattern in N. lapillus reproductive cycle was evident. Female gametogenic maturation varied seasonally and a decrease in capsule gland volume and condition factor occurred in late summer/early autumn. The gametogenesis in males did not show a significant seasonal variation as in females but the condition factor, penis length, amount of sperm and prostate volume also diminished in late summer/early autumn. On the other hand, males that were close to egg capsules clusters had larger penises than those far away from clusters. The temporal and spatial male penis length variation introduces a bias on imposex assessment results when using RPSI and the magnitude of the error involved is evaluated for different TBT pollution levels scenarios. We consider that RPSI provides interesting and complementary information that should not be excluded from monitoring programmes, but temporal or spatial comparisons of imposex should be based on other more reliable imposex indices like the VDSI. 相似文献
949.
长三角区域环境空气质量预测预警体系建设的思考 总被引:10,自引:8,他引:2
世博会期间长三角区域空气质量自动监测网络和数据共享平台的成功搭建和有效运行,为探索长三角区域空气质量预测预警长期合作模式提供了宝贵的经验和启示。需要建立全方位区域空气质量监测网络和数据资源共享系统、源排放清单、开发区域多模式集合预报系统,构建区域多层面运作机制和会商制度,建设一批专业技术和复合型人才队伍。区域不同层面有效的管理体制机制的保障是区域环境空气质量预测预警体系的基础支撑。 相似文献
950.
道路机动车活动水平调查及其污染物排放测算应用——上海案例研究 总被引:2,自引:0,他引:2
采用上海市车辆数据和机动车年检站实地调查方式获取车辆技术及分布,用GPS设备采集机动车行驶工况,通过交通流量录像的现场计数的方法获得道路车流分布。调查结果显示,在用汽车排放水平85%以上都达到或超过国Ⅱ标准;在低速、怠速工况区间内,社会车辆的比功率比例最低;道路轻型客车(含出租车)日平均车流量占总车流量的80%以上。机动车活动水平的详细调查将有助于上海实际道路机动车排放清单的精确计算,并获取主要的排放源及其影响因素。 相似文献