首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1644篇
  免费   173篇
  国内免费   239篇
安全科学   192篇
废物处理   23篇
环保管理   307篇
综合类   738篇
基础理论   217篇
环境理论   1篇
污染及防治   124篇
评价与监测   44篇
社会与环境   192篇
灾害及防治   218篇
  2024年   8篇
  2023年   27篇
  2022年   50篇
  2021年   51篇
  2020年   53篇
  2019年   50篇
  2018年   56篇
  2017年   64篇
  2016年   66篇
  2015年   55篇
  2014年   63篇
  2013年   127篇
  2012年   122篇
  2011年   128篇
  2010年   91篇
  2009年   77篇
  2008年   55篇
  2007年   122篇
  2006年   103篇
  2005年   106篇
  2004年   86篇
  2003年   67篇
  2002年   66篇
  2001年   48篇
  2000年   51篇
  1999年   68篇
  1998年   18篇
  1997年   26篇
  1996年   24篇
  1995年   21篇
  1994年   15篇
  1993年   28篇
  1992年   20篇
  1991年   16篇
  1990年   12篇
  1989年   5篇
  1988年   4篇
  1987年   1篇
  1986年   1篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
排序方式: 共有2056条查询结果,搜索用时 305 毫秒
71.
兴仁高砷煤矿区溪流水系环境中砷自然净化的初步研究   总被引:1,自引:0,他引:1  
为了解矿山环境中砷的自然净化能力及其净化机制,对兴仁典型高砷煤矿区溪流水系环境进行采样分析。结果表明,研究区水体和沉积物中砷含量从上游到下游均呈不断降低的变化趋势,水体显示较强的自净能力。上游水体中砷含量的降低主要是吸附沉淀作用,而溪流的简单稀释作用在下游也显得非常重要。  相似文献   
72.
液化天然气(LNG)瞬时泄漏扩散的模拟研究   总被引:1,自引:0,他引:1  
对液化天然气泄漏扩散过程进行了分析,考虑其泄漏后发生闪蒸时的液滴夹带以及混合空气量,将闪蒸完的状态作为箱模型的初始状态,考虑空气的湿度影响建立了重气扩散过程的箱模型,并应用实例进行了验证,得出了泄漏后有火灾爆炸危险性的区域以及距离泄漏源的位置,为应急救援预案的制定提供参考,模拟结果显示了重气扩散过程中的重力沉降,空气夹带等一般特征,同时云团初始闪蒸时的液滴夹带对云团的扩散行为具有一定的影响,不能忽略.最后提出了今后的研究方向.  相似文献   
73.
Humic substances   总被引:2,自引:1,他引:1  
GOAL, SCOPE AND BACKGROUND: Freshwater bodies which chemistry is dominated by dissolved humic substances (HS) seem to be the major type on Earth, due to huge non-calcareous geological formations in the Northern Hemisphere and in the tropics. Based on the paradigm of the inertness of being organic, direct interactions of dissolved HS with freshwater organisms are mostly neglected. However, dissolved organic carbon, the majority of which being HS, are natural environmental chemicals and should therefore directly interact with organisms. Major results that widened our perspective on humic substance ecology come from experiments with the compost nematode, Caenorhabditis elegans, which behaved contradictorily to textbook knowledge and provoked an in-depth re-consideration of some paradigms. APPROACH: To overcome old paradigms on HS and their potential interactions with organisms, we reviewed recent international literature, as well as 'grey' literature. We also include results from own ongoing studies. RESULTS: This review focuses on direct interactions of dissolved HS with freshwater organisms and disregards indirect effects, such as under-water light quenching. Instead we show with some macrophyte and algal species that HS adversely interfere with photosynthesis and growth, whereby closely related algal species show different response patterns. In addition to this, HS suppress cyanobacteria more than eukaryotic algae. Quinones in the HS appear to be the effective structure. Furthermore, HS can modulate the offspring numbers in the nematode C. elegans and cause feminization of fish and amphibians--they possess hormone-like properties. The ecological consequences of this potential remain obscure at present. HS also have the potential to act as chemical attractants as shown with C. elegans and exert a mild chemical stress upon aquatic organisms in many ways: induction of molecular chaperons (stress proteins), induction and modulation of biotransformation and anti-oxidant enzymes. Furthermore, they produce an oxidative stress with lipidperoxidation as one clear symptom or even stress defense strategy. Stronger chemical stresses by HS may even lead to teratogenic effects as shown with fish embryos; all physiological responses to HS-mediated stress require energy, which were compensated on the expense of yolk as shown with zebra fish embryos. One Finnish field survey supports the view of a strong chemical stress, as the weight yield in fish species decreases with increasing HS content in the lakes. DISCUSSION: HS exert a variety of stress symptoms in aquatic and compost organisms. According to current paradigms of ecotoxicology, these symptoms have to be considered adverse, because their compensation consumes energy which is deducted from the main metabolism. However, the nematode C. elegans looks actively for such stressful environments, and this behavior is only understandable in the light of new paradigms of aging mechanisms, particularly the Green Theory of Aging. In this respect, we discuss the mild HS-mediated stress to aquatic and compost organisms. New empirical findings with HS themselves and HS building blocks appear to be consistent with this emerging paradigm and show that the individual lifespan may be expanded. At present the ecological consequences of these findings remain obscure. However, a multiple-stress resistance may be acquired which improves the individual fitness in a fluctuating environment. CONCLUSIONS: It appears that dissolved HS have to be considered abiotic ecological driving forces, somewhat less obvious than temperature, nutrients, or light. PERSPECTIVES: The understanding of the ecological control by dissolved humic substances is still fragmentary and needs to be studied in more details.  相似文献   
74.
针对目前国内污泥处理处置存在的问题,为实现污泥浓缩消化一体化,开发了污泥一体化强化渗滤浓缩自然干化与消化新工艺反应器,并进行了城市水厂污泥处理试验.结果表明,在有机负荷为0.8 kg VSS/(m3·d)、平均水力停留时间为8.3 d、污泥停留时间为120 d的条件下,污泥有机物去除率可达到44.4%,排泥含水率达到79.1%,污泥消化与浓缩过程起到了相互促进的作用.渗滤液须抽回至污水处理厂处理.  相似文献   
75.
20世纪重大自然灾害评析   总被引:24,自引:8,他引:16  
人类在科学技术上取得了辉煌成绩的同时,在认识自然和改造自然方面也得到了才识和新的认识,这一教训主要是来自自然灾害。根据收集到的全球自然灾害有关数据,对20世纪全球主要自然灾害特征分布特点进行了分析,并对其成因提出了看法。  相似文献   
76.
物元理论在区域减灾中的应用   总被引:4,自引:0,他引:4  
物元分析是解决矛盾问题的规律和方法,是系统科学,思维科学和数学的交叉学科,本文通过具体的事例分析说明自然灾害研究具有发散性,可扩性,相关性的共轭性的特点,鉴于自然灾害的特性,提出了减灾工作应在传统理论研究的基础上,应用物元理论采用可拓学的方法。  相似文献   
77.
防灾减灾:西海固地区可持续发展的基础   总被引:1,自引:0,他引:1  
根据调查和有关资料,本文研究了西海固地区自然灾害的基本特征,分析了自然灾害对可持续发展的影响和制约作用,探讨了防治自然灾害,实现可持续发展的基本对策。  相似文献   
78.
In 2017, the United States experienced a series of natural hazards (hurricanes, wildfires, and blizzards) that resulted in significant loss of life and property. Emphasizing the role of climate change in these events might offer an important tool for engagement, particularly with skeptical audiences. However, in a survey experiment (N?=?1504) involving three different natural hazards – hurricanes, wildfires, and blizzards – we find that emphasizing the role of climate change in these hazards produced unintended effects for climate change skeptics. In particular, skeptics experienced resistance to the news article, which associated with reduced perceived hazard severity. These backfiring effects likely serve as a defensive mechanism used by skeptics to maintain their prior views of climate change, illustrating the challenges faced in communicating climate change to skeptical audiences. These findings offer additional insight for those attempting to communicate climate-related risk information to skeptical audiences.  相似文献   
79.
There has been a shift in natural resource management worldwide. This paper describes how modern institutions and policies influence management and shape access to and utilization of resources by rural communities in the Okavango Delta, Botswana. It is rooted in the framework of adaptive co‐governance within social‐ecological systems, and employs a critical literature review to analyse access to and use of natural resources in rural Botswana. Prior to the establishment of community‐based natural resource management (CBNRM) in Botswana in 1989, resource governance was dominated by strong traditional institutions that were responsible for natural resource management and decision‐making. Contemporary natural resource governance is characterized by a bureaucratic system that invariably undermines the role of traditional institutions in natural resource governance. Findings indicate that policies and regulatory instruments deny rural communities adequate access to and utilization of resources available within their immediate environment. In spite of an orientation towards an anthropocentric approach to natural resource management (as in the case of CBNRM), the current governance system continues to undermine the inclusion of local resource users as legitimate stakeholders in the decision‐making process.  相似文献   
80.
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号