全文获取类型
收费全文 | 13164篇 |
免费 | 142篇 |
国内免费 | 111篇 |
专业分类
安全科学 | 360篇 |
废物处理 | 344篇 |
环保管理 | 1980篇 |
综合类 | 3289篇 |
基础理论 | 3102篇 |
环境理论 | 6篇 |
污染及防治 | 3319篇 |
评价与监测 | 585篇 |
社会与环境 | 367篇 |
灾害及防治 | 65篇 |
出版年
2018年 | 125篇 |
2017年 | 129篇 |
2016年 | 184篇 |
2015年 | 156篇 |
2014年 | 203篇 |
2013年 | 959篇 |
2012年 | 310篇 |
2011年 | 435篇 |
2010年 | 311篇 |
2009年 | 410篇 |
2008年 | 450篇 |
2007年 | 480篇 |
2006年 | 437篇 |
2005年 | 326篇 |
2004年 | 349篇 |
2003年 | 388篇 |
2002年 | 325篇 |
2001年 | 468篇 |
2000年 | 324篇 |
1999年 | 218篇 |
1998年 | 155篇 |
1997年 | 146篇 |
1996年 | 179篇 |
1995年 | 178篇 |
1994年 | 202篇 |
1993年 | 180篇 |
1992年 | 184篇 |
1991年 | 181篇 |
1990年 | 209篇 |
1989年 | 195篇 |
1988年 | 166篇 |
1987年 | 163篇 |
1986年 | 148篇 |
1985年 | 165篇 |
1984年 | 147篇 |
1983年 | 160篇 |
1982年 | 160篇 |
1981年 | 163篇 |
1980年 | 150篇 |
1979年 | 145篇 |
1978年 | 143篇 |
1977年 | 130篇 |
1976年 | 136篇 |
1975年 | 115篇 |
1974年 | 142篇 |
1973年 | 125篇 |
1972年 | 125篇 |
1971年 | 105篇 |
1970年 | 106篇 |
1967年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
531.
532.
533.
污泥中的有机质、营养成分可为农业生产提供重要的有机肥源,但污泥中的重金属是制约污泥农用的重要因素,为检验污泥堆肥施用后对作物及土壤的影响,文章对污泥与稻草或木屑堆肥的产品进行了盆栽试验研究。结果表明,污泥与稻草或木屑的堆肥作为肥料施用于萝卜(Brassicacampestris)和菜心(Brassicaparachinensis),产量明显提高,部分堆肥产品增产效果优于化肥,且后效明显。堆肥施用使土壤中有机质、各养分含量增加,微生物活动增强、数量增加,然而作物和土壤中的重金属含量也有不同程度的提高。 相似文献
534.
The machair sand dune systems of the Outer Hebrides of Scotland are a unique habitat, which is rare within both a global and
European context. Unusually, the machair habitat also represents an agricultural resource that is very important to the Hebridean
people, having been subject to both grazing and cultivation throughout the historical period. Following designation as an
Environmentally Sensitive Area (ESA) in 1988, the machairs of South Uist have been studied with the aim of understanding the
links between agricultural practice and their plant community and ecosystem dynamics. This research focused primarily on the
effects of cultivation practices and their role in maintaining plant species richness and community and ecosystem stability.
Within two carefully selected areas, the successional plant communities of machair at different stages of recovery following
ploughing and cultivation of cereals and potato patches or ‘lazy beds’ were identified at both a macro- and micro-level. Investigations
of the vegetation recovery processes on turves taken from newly ploughed land indicated that the initial stages of recolonization
are characterized primarily by rapid vegetative reproduction and growth, although re-vegetation by seeds is also an important
factor. The implications of these findings for the long-term management of machair plant communities are discussed and in
particular the need to maintain old cultivation practices such as shallow ploughing. The need for more detailed research into
both seed banks and seed rain and into processes of vegetative reproduction is stressed.
Nomenclature: Clapham et al. (1981) and Stace (1991, 1997) for vascular plants; Hubbard (1984) for grasses; Pankhurst & Mullin (1991) for
the regional flora; Dobson (1992) for lichens; Watson (1981) for mosses and liverworts. 相似文献
535.
Russian Journal of Ecology - Temporal and spatial variations of phytoplankton community in Lake Erhai were investigated from May 2010 to April 2011. A total of 124 species belonging to 8 phyla and... 相似文献
536.
537.
T. Chen M. Liu Y. Takahashi J.D. Mullen G.C.W. Ames 《Journal of Environmental Planning and Management》2016,59(6):948-966
Three different sizes of hog farms were selected to analyze the carbon emissions reduction and the cost–benefit of three methane digester systems. The sizes of the digesters are 2,200, 2,200 and 800 m3, respectively. The sales of slaughter hogs from them are 50,000, 35,000 and 10,000 head, respectively. The carbon emissions reductions were 5,237, 4,017, and 1,334 tons, respectively. The results show that while the methane digester systems have a significant effect on carbon emissions reduction, it is difficult to operate the systems sustainably. If the carbon emissions reduction can be traded at high enough prices in the carbon offset markets, then the systems will be profitable and sustainable. Newly established China's domestic carbon offset market could provide this possibility, but more government support is needed. In addition, this study shows that scale economies make the digester adoption relatively more profitable for larger farms than smaller ones. 相似文献
538.
The ecosystem services (ES) concept is being increasingly incorporated into environmental policy formulation and management approaches. The Corporate Ecosystem Services Review (ESR) is a framework used to assess the dependence and impact that a business has on ES. The success of the corporate experience of ES assessment provides an opportunity for adaption for local authority decision making. In this paper, the ESR tool was adapted to the South African setting at a local government level, and tested at two sites in the Msunduzi Municipality, KwaZulu-Natal. In testing the tool and gathering feedback from key stakeholders, it was found that there are both opportunities and challenges to this approach. Overall, however, it provides an opportunity for the systematic inclusion of ES assessment into existing regulatory frameworks for land-use planning and Integrated Environmental Management, whether in a strategic application, at a broader spatial (municipal) scale or in a specific locale within the municipality. 相似文献
539.
540.