全文获取类型
收费全文 | 3127篇 |
免费 | 190篇 |
国内免费 | 840篇 |
专业分类
安全科学 | 265篇 |
废物处理 | 190篇 |
环保管理 | 604篇 |
综合类 | 2033篇 |
基础理论 | 328篇 |
污染及防治 | 500篇 |
评价与监测 | 100篇 |
社会与环境 | 38篇 |
灾害及防治 | 99篇 |
出版年
2024年 | 4篇 |
2023年 | 24篇 |
2022年 | 61篇 |
2021年 | 77篇 |
2020年 | 106篇 |
2019年 | 72篇 |
2018年 | 77篇 |
2017年 | 98篇 |
2016年 | 134篇 |
2015年 | 144篇 |
2014年 | 240篇 |
2013年 | 274篇 |
2012年 | 272篇 |
2011年 | 292篇 |
2010年 | 217篇 |
2009年 | 195篇 |
2008年 | 153篇 |
2007年 | 207篇 |
2006年 | 250篇 |
2005年 | 181篇 |
2004年 | 145篇 |
2003年 | 142篇 |
2002年 | 112篇 |
2001年 | 109篇 |
2000年 | 122篇 |
1999年 | 108篇 |
1998年 | 48篇 |
1997年 | 60篇 |
1996年 | 57篇 |
1995年 | 46篇 |
1994年 | 35篇 |
1993年 | 21篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有4157条查询结果,搜索用时 15 毫秒
991.
The useful life of consumer electronic devices is relatively short, and decreasing as a result of rapid changes in equipment features and capabilities. This creates a large waste stream of obsolete electronic equipment, electronic waste (e-waste).Even though there are conventional disposal methods for e-waste, these methods have disadvantages from both the economic and environmental viewpoints. As a result, new e-waste management options need to be considered, for example, recycling. But electronic recycling has a short history, so there is not yet a solid infrastructure in place.In this paper, the first half describes trends in the amount of e-waste, existing recycling programs, and collection methods. The second half describes various methods available to recover materials from e-waste. In particular, various recycling technologies for the glass, plastics, and metals found in e-waste are discussed. For glass, glass-to-glass recycling and glass-to-lead recycling technologies are presented. For plastics, chemical (feedstock) recycling, mechanical recycling, and thermal recycling methods are analyzed. Recovery processes for copper, lead, and precious metals such as silver, gold, platinum, and palladium are reviewed. These processes are described and compared on the basis of available technologies, resources, and material input–output systems. 相似文献
992.
FeS引发储油罐着火温度动态变化曲线的研究 总被引:11,自引:2,他引:11
储油罐着火事故被推测是由硫腐蚀产生的FeS氧化引起的。笔者阐述了储罐中FeS形成的原因 ,并采用自然发火绝热测试系统对FeS自然氧化进行 1 9h的跟踪实验 ,观察FeS绝热氧化过程中温度动态变化特性。实验发现 ,FeS氧化由诱导氧化期、中速氧化期和加速氧化期 3个阶段组成。诱导氧化期是积蓄能量 ,激发FeS活性的过程 ,试样温度基本未发生变化 ;中速氧化期是FeS试样表面的分子活性被激发 ,与FeS试样表面吸附的氧气发生氧化反应的过程 ,温度增加较慢 ;加速氧化期是FeS分子内部的活性被激活并进行氧化反应的过程 ,温度迅速升高。结果证明 :随着反应的进行 ,温度随反应时间变化的幅度越来越大 ,氧化反应的反应热不能及时散开而急剧地积累 ,温度急剧地升高 ,将引起油品自燃。此外 ,通过X衍射图和氧化升温曲线证明 ,水是影响FeS氧化的重要因素。 相似文献
993.
994.
995.
Brian K. Richards Brendan M. Schulte Arik Heilig Tammo S. Steenhuis Murray B. McBride Ellen Z. Harrison Philip Dickson 《Journal of the American Water Resources Association》2004,40(4):1025-1042
ABSTRACT: Farms that once spread only manures are now also applying sewage biosolids (sludge) and/or other wastes such as those from food processing. The objective of this study was to monitor environmental impacts at a dairy farm applying these materials. Fields were selected representing recent waste applications of manure (M1, M2), sewage biosolids (B1, B2), or fertilizer only control (F1, F2), although most fields had historical biosolids applications. Fields representing each treatment were not experimental replicates because of varying applications and soil characteristics. Septage and food processing wastes were also applied. Soil percolates were collected with wick lysimeters. Runoff was sampled at seven stream sites. Test field soils and alfalfa (Medicago sativa) were analyzed for trace elements. Cumulative trace metal loadings were low, at most only 1 percent of USEPA Part 503 limits. Surface soil enrichment was most evident for Mo, P, and S. Alfalfa tissue showed no trends of concern. The B2 site had the greatest percolate concentrations for 6 of 13 elements. Percolate Cu was somewhat elevated at Sites M1, M2, B2, and Fl. Percolate sodium was elevated on all M and B fields and sulfur was greatest at M2, B1, and B2. Soluble orthophosphate correlated with stream discharge during intensive monitoring of Stream Sites S1 (fertilizer) and S2 (biosolids). Peaks in S2 streamwater Mo lagged large runoff events by five days. Total streamwater export of Cu, Na, Mo, and soluble P were greater from the S2 biosolids subwatershed than from the S1 fertilizer subwatershed. Percolate concentrations exceeded corresponding streamwater concentrations in most cases. 相似文献
996.
填埋场场地复用技术与展望 总被引:4,自引:0,他引:4
城市垃圾卫生填埋场场地复用技术是一种能增大填埋场填埋能力,避免过高的填埋场地费用的新方法。该技术在德国和美国的实践都已取得了成功。为使该技术能在我国得到推广和应用,文中介绍了该技术的实施条件,列举了部分应用实例,分析了该技术的优势及潜在问题,最后对其在我国的应用前景进行了展望。 相似文献
997.
我国废电池的回收与处理 总被引:5,自引:0,他引:5
本文详细介绍了国内外常见的各种废电池的种类、有害成分,处理方法,分析了目前我国在度电池回收处理过程中所存在的诸多问题,并有针对性的提出建议。 相似文献
998.
The National Vegetation Classification Standard (NVCS) was implemented at two US National Park Service (NPS) sites in Texas,
the Padre Island National Seashore (PINS) and the Lake Meredith National Recreation Area (LMNRA), to provide information for
NPS oil and gas management plans. Because NVCS landcover classifications did not exist for these two areas prior to this study,
we created landcover classes, through intensive ground and aerial reconnaissance, that characterized the general landscape
features and at the same time complied with NVCS guidelines. The created landcover classes were useful for the resource management
and were conducive to classification with optical remote sensing systems, such as the Landsat Thematic Mapper (TM). In the
LMNRA, topographic elevation data were added to the TM data to reduce confusion between cliff, high plains, and forest classes.
Classification accuracies (kappa statistics) of 89.9% (0.89) and 88.2% (0.87) in PINS and LMNRA, respectively, verified that
the two NPS landholdings were adequately mapped with TM data. Improved sensor systems with higher spectral and spatial resolutions
will ultimately refine the broad classes defined in this classification; however, the landcover classifications created in
this study have already provided valuable information for the management of both NPS lands. Habitat information provided by
the classifications has aided in the placement of inventory and monitoring plots, has assisted oil and gas operators by providing
information on sensitive habitats, and has allowed park managers to better use resources when fighting wildland fires and
in protecting visitors and the infrastructure of NPS lands. 相似文献
999.
1000.