全文获取类型
收费全文 | 1988篇 |
免费 | 70篇 |
国内免费 | 86篇 |
专业分类
安全科学 | 130篇 |
废物处理 | 18篇 |
环保管理 | 237篇 |
综合类 | 1175篇 |
基础理论 | 121篇 |
污染及防治 | 121篇 |
评价与监测 | 265篇 |
社会与环境 | 45篇 |
灾害及防治 | 32篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 27篇 |
2021年 | 41篇 |
2020年 | 49篇 |
2019年 | 29篇 |
2018年 | 24篇 |
2017年 | 48篇 |
2016年 | 52篇 |
2015年 | 73篇 |
2014年 | 82篇 |
2013年 | 98篇 |
2012年 | 123篇 |
2011年 | 136篇 |
2010年 | 87篇 |
2009年 | 109篇 |
2008年 | 93篇 |
2007年 | 119篇 |
2006年 | 137篇 |
2005年 | 97篇 |
2004年 | 70篇 |
2003年 | 92篇 |
2002年 | 67篇 |
2001年 | 66篇 |
2000年 | 59篇 |
1999年 | 60篇 |
1998年 | 56篇 |
1997年 | 61篇 |
1996年 | 32篇 |
1995年 | 34篇 |
1994年 | 28篇 |
1993年 | 32篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有2144条查询结果,搜索用时 515 毫秒
571.
Pollution and Self-Cleansing of an Urban River in a Developing Country: A Case Study in Dar es Salaam, Tanzania 总被引:1,自引:0,他引:1
Pollution and self-purification trends of an urban river namely, Msimbazi River, in Dar es Salaam City, Tanzania, were investigated. Site investigations and water quality analyses were done. The river is polluted in terms of high organic and nutrient concentrations, low dissolved oxygen, and high counts of indicator organisms. Biochemical oxygen demand (BOD5) concentrations were 27– 340 mg/L. Dissolved oxygen was found to be as low as 0.9 mg O2/L. Bacteriological pollution increased with distance downstream of the river, a trend attributable to an increase in the catchment of pollution sources, which are on-site sanitation systems. Although the river has an appreciable self-purification capacity, the capacity is strained by persistent pollution overloads. The pollution plight of the river is attributable to its being flanked by expanding human habitats and vibrant industrial, institutional, and socio-economic activities. Provision for pretreatment of discharges into the river is put forward as a remedial measure for the observed pollution. Matching nontechnical and techno-social remedial measures are also recommended. These include sensitization of polluters on merits of environmental protection practices such as cleaner production and strict enforcement of environmental protection laws. 相似文献
572.
承德市环境空气质量现状及对策 总被引:1,自引:0,他引:1
2003承德市空气主要污染物与2002的相比,只有SO2年均值有所增大.运用Spearman-rs秩相关系数法预测该市空气质量有好转趋势,并从城市的地理位置、卫生、交通等几方面分析其污染特征及原因,建议以行政力量为指导,提高公民环保意识,实施合理的环境规划,利用最佳实用的环保技术改善该市环境空气质量. 相似文献
573.
Thermodynamic analysis of the role of chlorine and sulfur environments during combustion and incineration processes 总被引:1,自引:0,他引:1
Iddi S.N. Mkilaha Hong Yao Ichiro Naruse 《Journal of Material Cycles and Waste Management》2002,4(2):143-149
In order to control the emission of trace metals from combustion and incineration systems, sorbents and filters are sometimes
used. However, the effectiveness of these methods is greatly affected by the volatility of the metals and the way in which
they speciate during combustion, and afterwards during condensation, and physical or chemical sorption. Although there has
been a lot of research into the mechanisms by which trace metals speciate and subsequently appear in submicron particles,
the details of these mechanisms are not yet thoroughly understood. In this study, a chemical equilibrium approach was used
to qualitatively determine the speciation of lead, cadmium, and chromium in Cl and S environments. The reaction conditions
of sorbents were also tested numerically in order to understand the reaction behavior of metals with sorbents. This article
reports the influence of different concentrations of Cl and SO2 on Pb, Cd, and Cr speciation, as representatives of other trace elements. The partitioning behavior of metals during combustion
was also examined for Cl and S. The results obtained indicate that most metals exist in the vapor phase, even at low temperatures,
when chlorine is present. However, the addition of SO2 enhances the formation of the condensed phase, except at extremely high temperatures. This observation was not significant
for Cd or Cr. The higher the concentration of Cl the higher the retention of trace metals in the vapor phase, even at low
temperatures. Results from comparisons of the reactivities of mixed metals with Cl indicate that the presence of Fe limits
the reactivity of most trace metals with Cl except at higher concentrations. In the presence of Fe, alkali metals are the
first to react with Cl. If Fe is not present, most trace metals react with Cl, and the activity increases with higher concentrations.
On the other hand, the partitioning characteristics of S show that its presence generally means that metals remain in the
condensed phase. Sulfur is more reactive with alkali metals than with other trace metals.
Received: June 6, 2001 / Accepted: April 30, 2002 相似文献
574.
四川的环境现状及改善环境的对策措施 总被引:3,自引:2,他引:3
四川环境恶化的趋势得到基本控制,环境质量总体在低水平上基本保持稳定,但环境污染仍然严重,生态环境还十分脆弱,环境形势依然严峻。分析和研究四川面临的环境形势,采取改善环境的对策措施,促进全省经济,社会,环境协调发展。 相似文献
575.
首先论述了农村人力资源开发的重要地位和作用,然后通过对西部地区雅安市对岩镇村人力资源状况的调查与分析,结合实际及当前经济发展的需要,就如何搞好对岩镇农村人力资源的开发以服务于地方经济,提出了一系列切实可行的措施,以供西部地区的类似小镇借鉴。 相似文献
576.
577.
578.
579.
580.
Does air quality regulation in the European Union (EU) foster polluting activity in emerging and developing countries? In this paper, we propose an original variable that evaluates regulation stringency, based on the EU Air Quality Framework Directive. Focusing on the underlying mechanism and controlling for endogeneity in the relation between regulation and trade, we provide robust evidence that EU countries implementing more stringent air pollution regulations import relatively more in pollution-intensive sectors from developing and emerging countries in Europe and Central Asia. 相似文献