全文获取类型
收费全文 | 997篇 |
免费 | 78篇 |
国内免费 | 377篇 |
专业分类
安全科学 | 40篇 |
废物处理 | 25篇 |
环保管理 | 138篇 |
综合类 | 684篇 |
基础理论 | 277篇 |
环境理论 | 1篇 |
污染及防治 | 146篇 |
评价与监测 | 83篇 |
社会与环境 | 57篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 5篇 |
2023年 | 19篇 |
2022年 | 35篇 |
2021年 | 53篇 |
2020年 | 43篇 |
2019年 | 38篇 |
2018年 | 45篇 |
2017年 | 46篇 |
2016年 | 55篇 |
2015年 | 58篇 |
2014年 | 66篇 |
2013年 | 128篇 |
2012年 | 78篇 |
2011年 | 116篇 |
2010年 | 69篇 |
2009年 | 60篇 |
2008年 | 46篇 |
2007年 | 83篇 |
2006年 | 84篇 |
2005年 | 66篇 |
2004年 | 30篇 |
2003年 | 40篇 |
2002年 | 22篇 |
2001年 | 23篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 4篇 |
1969年 | 1篇 |
排序方式: 共有1452条查询结果,搜索用时 31 毫秒
71.
Adrian Shindala Melville S. Priest 《Journal of the American Water Resources Association》1971,7(4):717-725
ABSTRACT The direction of heated effluents from large thermal power plants into streams and lakes has been a matter of public concern for some time, and the collection of prototype data related to the hydraulic aspects has taken on massive proportions. Unfortunately, most of the data are proprietary and not available for public analysis. The authors have endeavored to collect such data as are available to them for the initiation of steps toward generalization and the discussion of some of the more evident hydraulic considerations. The study is primarily concerned with rivers, including estuaries, with some interest in cooling ponds. 相似文献
72.
73.
74.
During a survey of tropospheric ozone pollution carried out using tobacco plants (Nicotiana tabacum L.) cv. Bel-W3, ozone- supersensitive, and cv. Bel-B, ozone-resistant, as bioindicators, the effectiveness of the traditional biomonitoring method, based on the use of adult plants, was compared with an innovative miniaturized kit of seedlings. The ratio of foliar and cotyledonar necrosis, respectively, was estimated as ozone injury rate. The miniaturized kit proved to be advantageous, since seedlings need only easy growth procedures and a large number of individuals can be placed in a small space, supplying good data amounts for statistical elaboration. Moreover, correlation studies among cotyledonar and foliar injury index and ozone levels monitored through physico-chemical measurements and results of analysis of variance tests highlighted the high sensitivity of the innovative methodology. 相似文献
75.
渠烨 《辽宁城乡环境科技》2013,(5):41-43
综述了水生植物对氮、磷、重金属及有毒有机物等各类污染物的清除作用及其在污染治理中的应用实践,同时对水生植物在废水处理和湖泊治理方面的应用提出了相应的建议。 相似文献
76.
Elevated CO2 can stimulate wetland carbon(C) and nitrogen(N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant–water–soil system. The results showed:(1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively.(2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0–15 cm layer, and22.7% and 26.0% in the 15–30 cm soil layer.(3) Averaged across the rice growing period,elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%,respectively.(4) The TOC/TN ratio and natural δ15N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns. 相似文献
77.
为构建辽宁省典型城市道路尘源成分谱,分别采集了鞍山市和盘锦市道路尘样品,分析了其化学组分特征,用富集因子法和比值法分析了其主要来源,用分歧系数法分析了两个城市成分谱的相似度.结果表明:盘锦市和鞍山市道路尘PM2.5中的化学组成以有机碳组分(OC)和地壳类元素(Al、Ca、Mg、Fe和K)为主.除Cu和V元素外,其余元素均表现为鞍山市的富集因子大于盘锦市.由比值法可得,盘锦市和鞍山市OC/EC分别为(13.20±6.26)和(3.94±0.63),均存在二次污染现象;NO3-/SO42-的均值分别为(0.52±0.55)和(0.46±0.13),说明其道路尘PM2.5受固定源影响更大.盘锦市与鞍山市道路尘成分谱分歧系数为0.354,说明两个源成分谱可能相似. 相似文献
78.
The purpose of the present research is to collect information about accidents and incidents that have occurred at fuel ethanol facilities from 1998 to October 2014, and to keep complete unified records of them in a database. The developed database contains general information about the accident or incident, its sequence, mitigation measures, its causes and consequences for humans, environment and for the plant. Until now, this information is not available. The work consisted in gathering information from different documental sources and subsequent organization in a database. It complements the previous work made for biodiesel industry and fills the existing gap in the field of ethanol. Knowledge about this information enables us to manage plant risks, since the accidents that are more likely to occur and the main sources of risk can be easily identified. Also, it makes it possible to exchange information with interested third parties. Statistical analysis shows that accident frequency has an oscillatory behavior, rising in the last year. Fire is the most common type of accident, while equipment mechanical failure is the main cause of accident. Partial material loss has been identified as the most common consequence. Finally, some conclusions are obtained concerning to the importance of having an updated and complete accident and incident database. 相似文献
79.
提出了一套基于神经网络分类器的城市污水处理厂水力负荷冲击预警系统,以期对进水水量骤增现象进行提前1天的预报,使污水处理厂可根据预报结果提前采取水力冲击防护措施,从而保证各单元的平稳运行.根据进水水量的涨幅将某污水处理厂12年日进水水量监测数据分为"常规"和"冲击"两类,重点对"冲击"数据进行提前1天的预测,并采用冲击漏报率、冲击误报率和报准率对模型的预测精度进行评价;同时,基于同样的建模方法和不同的训练、验证样本建立了N(1)、N(2)和N(3)3个平行模型,以对模型的鲁棒性和建模方法的可重复性进行考察.结果显示,3个模型对2010年、2011年和2012年3年测试样本的预测效果良好,冲击漏报率和报准率两项指标数值均较为稳定,分别在0~0.167和0.981~0.995之间浮动,冲击误报率虽然在数值上的浮动较大,最低为0.143,最高为0.500,平均为0.310,但仍在工程上的可承受范围内.该结果表明,本研究基于神经网络分类器所建立的3个神经网络模型预测精度高、鲁棒性好,显示出良好的性能,有望为污水处理厂水力冲击防护工作提供有力参考. 相似文献
80.
Piriformospora indica, a root-colonizing endophytic fungus of Sebacinales, promotes plant growth and confers resistance against biotic and abiotic stresses. In order to confirm the influence of P. indica on growth, proline, malondialdehyde (MDA), chlorophyll, and cadmium (Cd) amounts in Nicotiana tabacum under Cd stress, hydroponics, pot and field trials were conducted. The results showed that P. indica can store Cd in plant roots and reduce leaf Cd content, reduce the concentration of MDA, and increase the proline and chlorophyll content and the activities of catalase, peroxidase, and superoxide dismutase under hydroponic Cd stress. RT-PCR analysis showed that the relative expression level of genes Gsh2, TaPCS1, oas1, GPX, and Hsp70 in colonized plants was 4.3, 1.4, 2.9, 1.7, and 6.9 fold higher than in un-colonized plants respectively. Cd exposure significantly reduced un-colonized plants'' agronomic traits compared to P. indica-colonized ones. Our results suggested that P. indica can sequester Cd in roots, so that much less cadmium was transported to leaves, and the increased concentrations of antioxidant enzymes, pigments and proline contents, as well as the higher expression of stress-related phytochelatin biosynthesis genes in P. indica-inoculated plants, may also serve to protect N. tabacum plants against oxidative damage, enhancing Cd tolerance. 相似文献