全文获取类型
收费全文 | 13687篇 |
免费 | 393篇 |
国内免费 | 1376篇 |
专业分类
安全科学 | 451篇 |
废物处理 | 946篇 |
环保管理 | 1585篇 |
综合类 | 3411篇 |
基础理论 | 3699篇 |
污染及防治 | 2734篇 |
评价与监测 | 1272篇 |
社会与环境 | 1147篇 |
灾害及防治 | 211篇 |
出版年
2024年 | 28篇 |
2023年 | 81篇 |
2022年 | 201篇 |
2021年 | 172篇 |
2020年 | 201篇 |
2019年 | 178篇 |
2018年 | 1620篇 |
2017年 | 1575篇 |
2016年 | 1392篇 |
2015年 | 388篇 |
2014年 | 322篇 |
2013年 | 343篇 |
2012年 | 846篇 |
2011年 | 1699篇 |
2010年 | 1010篇 |
2009年 | 902篇 |
2008年 | 1217篇 |
2007年 | 1498篇 |
2006年 | 271篇 |
2005年 | 251篇 |
2004年 | 212篇 |
2003年 | 201篇 |
2002年 | 246篇 |
2001年 | 130篇 |
2000年 | 102篇 |
1999年 | 65篇 |
1998年 | 56篇 |
1997年 | 46篇 |
1996年 | 40篇 |
1995年 | 29篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1956年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
841.
There are two principal strategies for managing climate change risks: mitigation and adaptation. Until recently, mitigation
and adaptation have been considered separately in both climate change science and policy. Mitigation has been treated as an
issue for developed countries, which hold the greatest responsibility for climate change, while adaptation is seen as a priority
for the South, where mitigative capacity is low and vulnerability is high. This conceptual divide has hindered progress against
the achievement of the fundamental sustainable development challenges of climate change. Recent attention to exploring the
synergies between mitigation and adaptation suggests that an integrated approach could go some way to bridging the gap between
the development and adaptation priorities of the South and the need to achieve global engagement in mitigation. These issues
are explored through a case study analysis of climate change policy and practice in Bangladesh. Using the example of waste-to-compost
projects, a mitigation-adaptation-development nexus is demonstrated, as projects contribute to mitigation through reducing
methane emissions; adaptation through soil improvement in drought-prone areas; and sustainable development, because poverty
is exacerbated when climate change reduces the flows of ecosystem services. Further, linking adaptation to mitigation makes
mitigation action more relevant to policymakers in Bangladesh, increasing engagement in the international climate change agenda
in preparation for a post-Kyoto global strategy. This case study strengthens the argument that while combining mitigation
and adaptation is not a magic bullet for climate policy, synergies, particularly at the project level, can contribute to the
sustainable development goals of climate change and are worth exploring. 相似文献
842.
The fate and transport processes of a toxic chemical such as atrazine, an herbicide, in a reservoir are significantly influenced
by hydrodynamic regimes of the reservoir. The two-dimensional (2D) laterally-integrated hydrodynamics and mass transport model,
CE-QUAL-W2, was enhanced by incorporating a submodel for toxic contaminants and applied to Saylorville Reservoir, Iowa. The
submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions
of a toxic chemical. The simulation results from the enhanced 2D reservoir model were validated by measured temperatures and
atrazine concentrations in the reservoir. Although a strong thermal stratification was not identified from both observed and
predicted water temperatures, the spatial variation of atrazine concentrations was largely affected by seasonal flow circulation
patterns in the reservoir. In particular, the results showed the effect of flow circulation on spatial distribution of atrazine
during summer months as the river flow formed an underflow within the reservoir and resulted in greater concentrations near
the surface of the reservoir. Atrazine concentrations in the reservoir peaked around the end of May and early June. A good
agreement between predicted and observed times and magnitudes of peak concentrations was obtained. The use of time-variable
decay rates of atrazine led to more accurate prediction of atrazine concentrations, while the use of a constant half-life
(60 days) over the entire period resulted in a 40% overestimation of peak concentrations. The results provide a better understanding
of the fate and transport of atrazine in the reservoir and information useful in the development of reservoir operation strategies
with respect to timing, amount, and depth of withdrawal. 相似文献
843.
844.
Vernon G. Thomas 《The Environmentalist》2010,30(2):206-210
Lead from spent ammunition causes preventable lead exposure in wildlife and humans that may ingest it. Nontoxic substitutes
for lead ammunition exist but are not adopted widely because of hunter opposition. Other forms of lead exposure in the human
environment have been heavily regulated because there is no safe level of exposure. The use of lead ammunition should be regulated
similarly to protect wildlife from this common disease. 相似文献
845.
Vellidis G Smith MC Leibowitz SG Ainslie WB Pruitt BA 《Environmental management》2003,31(2):0301-0312
In a climate of limited resources, it is often necessary to prioritize restoration efforts geographically. The synoptic approach
is an ecologically based tool for geographic prioritization of wetland protection and restoration efforts. The approach was
specifically designed to incorporate best professional judgment in cases where information and resources are otherwise limited.
Synoptic assessments calculate indices for functional criteria in subunits (watersheds, counties, etc.) of a region and then
rank the subunits. Ranks can be visualized in region-scale maps which enable managers to identify areas where efforts optimize
functional performance on a regional scale. In this paper, we develop a conceptual model for prioritizing watersheds whose
wetlands can be restored to reduce total sediment yield at the watershed outlet. The conceptual model is designed to rank
watersheds but not individual wetlands within a watershed. The synoptic approach is valid for applying the sediment yield
reduction model because there is high demand for prioritizing disturbed wetlands for restoration, but there is limited, quantitative,
accurate information available with which to make decisions. Furthermore, the cost of creating a comprehensive database is
prohibitively high. Finally, because the model will be used for planning purposes, and, specifically, for prioritizing based
on multiple decisions rather than optimizing a single decision, the consequence of prioritization errors is low. Model results
cannot be treated as scientific findings. The conclusions of an assessment are based on judgement, but this judgement is guided
by scientific principles and a general understanding of relevant ecological processes. The conceptual model was developed
as the first step towards prioritizing of wetland restoration for sediment yield reduction in US EPA Region 4. 相似文献
846.
环境价值评估方法综述 总被引:15,自引:1,他引:15
对目前国内外的环境价值评估方法进行了综述,并提出了一套适合我国国情的价值评估方法,该方法分为14类29个指标,作为完善我国环境价值评估体系的一种建议提出。 相似文献
847.
848.
849.
2株苯胺降解的分离鉴定及其降解特性研究 总被引:8,自引:0,他引:8
从处理印染废水的活性污泥中分离得到2株苯胺降解菌,从菌落、细胞形态、生理生化及16S rRNA基因扩增测序等方面对2株菌进行了鉴定,并比较分析2株菌在好氧与缺氧条件下的苯胺降解、偶氮染料脱色及苯胺脱氨氧化酶基因tdnQ和黄素还原酶基因(fre)的携带情况.结果表明,2株菌属于Pseudomonas属和Shewanella属,分别命名为Pseudomonas sp.AN30和Shewanella sp.DN425.AN30菌株在振荡好氧条件下72h内对250mg/L苯胺的降解率为96.1%,DN425菌株的降解率为13.8%;在静置缺氧条件下AN30菌株的苯胺降解率为39.6%,DN425菌株的降解率仅为8.6%.DN425菌株在静置缺氧条件下4h内可将初始浓度为50 mg/L的偶氮染料酸性大红彻底脱色,而AN30菌株对酸性大红不具有脱色能力.以总DNA为模板,分别用tdnQ基因和fre基因特异性引物进行扩增,2株菌均能扩增出大小分别为380bp和630bp左右的目标条带,显示2菌株均携带有苯胺脱氨氧化酶基因和黄素还原酶基因. 相似文献
850.