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   924篇
  免费   71篇
  国内免费   157篇
安全科学   95篇
废物处理   20篇
环保管理   172篇
综合类   402篇
基础理论   214篇
环境理论   1篇
污染及防治   93篇
评价与监测   36篇
社会与环境   66篇
灾害及防治   53篇
  2024年   2篇
  2023年   16篇
  2022年   25篇
  2021年   31篇
  2020年   28篇
  2019年   20篇
  2018年   27篇
  2017年   27篇
  2016年   35篇
  2015年   34篇
  2014年   30篇
  2013年   54篇
  2012年   55篇
  2011年   66篇
  2010年   57篇
  2009年   51篇
  2008年   66篇
  2007年   63篇
  2006年   45篇
  2005年   41篇
  2004年   51篇
  2003年   37篇
  2002年   27篇
  2001年   34篇
  2000年   38篇
  1999年   30篇
  1998年   31篇
  1997年   18篇
  1996年   25篇
  1995年   13篇
  1994年   11篇
  1993年   3篇
  1992年   11篇
  1991年   7篇
  1990年   10篇
  1989年   2篇
  1988年   8篇
  1987年   5篇
  1986年   3篇
  1985年   1篇
  1984年   3篇
  1982年   1篇
  1981年   2篇
  1979年   2篇
  1978年   1篇
  1977年   3篇
  1974年   1篇
  1971年   1篇
排序方式: 共有1152条查询结果,搜索用时 15 毫秒
971.
Knowledge creation and reliable decision-making in complex emergencies   总被引:1,自引:0,他引:1  
Kruke BI  Olsen OE 《Disasters》2012,36(2):212-232
This paper examines how the creation of knowledge and the location of decision-making authority within relief organisations influence coordination. Information was collected from the headquarters of international non-governmental organisations in 2003, as well as from Darfur and Khartoum, Sudan, in 2005 and 2007, respectively. Relief organisations rely on quality information dissemination between the field and headquarters. Yet, reporting from the field often is overloaded with misplaced precision, making it difficult for managers at headquarters to grasp the key issues. A high turnover rate among international field officers and a lack of inclusion of local staff and partners prevent the development of accumulated knowledge. Furthermore, most relief organisations have a centralised decision-making system. The creation of 'collective-meaning structures', based on reliable information on all decision-making levels, opens the way to the decentralisation of decision-making to field officers engaged with inter-organisational coordination structures. In sum, more efficient and reliable coordination between organisations relies on improved decision-making systems within each organisation.  相似文献   
972.
陈敏  唐斌  舒珺  肖海 《四川环境》2010,29(5):119-121,126
本文以四川省威远县越溪镇为例,利用地理信息系统软件(ArcGIS9.2)为工具,以地形图为基础数据来构建不规则三角网TIN,并对该地区的TIN进行坡度坡向的提取与分析,最后提出了数字地形分析的结果可应用到退耕还林的科学决策工作上。  相似文献   
973.
利用AERMOD模型预测了我国东部某电厂"上大压小"项目污染物排放对评价区域大气环境的影响。结果发现,受厂址东南山体影响,SO2、NO2小时最大落地浓度分别为环境空气质量二级标准的552.00%和1223.33%,NO2日均最大落地浓度为环境空气质量二级标准的117.50%。据统计,SO2小时贡献值超过标准时次为1次;NO2小时贡献值超过标准时次为5次,超标发生的概率均较低。预测超标原因主要与预测模型中烟羽遇到山体后的烟羽分层简化处理与实际烟羽运行状况存在一定差异有关。  相似文献   
974.
亚铁羟基络合物还原转化水溶性偶氮染料   总被引:1,自引:1,他引:0  
偶氮染料是印染工艺中应用最广泛的一类染料,目前染料废水脱色是污水处理难题。亚铁混凝处理染料废水过程中可能存在亚铁的还原作用,本实验制备了比溶解态亚铁更具还原反应活性的亚铁羟基络合物(ferrous hydroxycomplex,FHC),以5种不同类型的水溶性偶氮染料为目标污染物,研究FHC还原水溶性偶氮染料的脱色性能。实验结果表明,FHC对活性艳红X-3B、酸性大红GR和阳离子红X-GRL有较好的还原脱色效果,仅投加含铁89.6 mg/L的FHC,染料脱色率达到90%以上,继续增大FHC投加量可以完全脱色;中性枣红GRL的FHC还原脱色效果较差,需加入313.6 mg/L的FHC才能达到90%以上脱色率;134.4 mg/L的FHC能够将直接耐酸大红4BS完全脱色,但其脱色主要以混凝沉淀为主;溶液pH对FHC的还原性能产生重要影响,FHC还原染料脱色的适宜的pH值范围为4~10。该研究为亲水性染料脱色提供了一种新的技术,也为FHC运用于印染废水脱色提供了理论基础。  相似文献   
975.
研究了以悬浮态TiO2为催化剂,在紫外光的作用下对络合铜废水进行光催化反应,分别考察了常温下TiO2投加量、反应时间、废水初始pH值、反应气氛等因素对处理效果的影响,并探讨了反应机理。结果表明:TiO2投加量为2 g/L,废水pH=4,300 W高压汞灯照射下,载入60 mL/min的空气反应40 min,120 mg/L EDTA络合铜废水的Cu(II)与COD的去除率达到最高,分别为96.56%和57.67%。  相似文献   
976.
Non-migration is an adaptive strategy that has received little attention in environmental migration studies. We explore the leveraging factors of non-migration decisions of communities at risk in coastal Bangladesh, where exposure to both rapid- and slow-onset natural disasters is high. We apply the Protection Motivation Theory (PMT) to empirical data and assess how threat perception and coping appraisal influences migration decisions in farming communities suffering from salinization of cropland. This study consists of data collected through quantitative household surveys (n = 200) and semi-structured interviews from four villages in southwest coastal Bangladesh. Results indicate that most respondents are unwilling to migrate, despite better economic conditions and reduced environmental risk in other locations. Land ownership, social connectedness, and household economic strength are the strongest predictors of non-migration decisions. This study is the first to use the PMT to understand migration-related behaviour and the findings are relevant for policy planning in vulnerable regions where exposure to climate-related risks is high but populations are choosing to remain in place.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01552-8.  相似文献   
977.
With the development of computing technology, mechanistic models are often employed to simulate processes in coastal environments. However, these predictive tools are inevitably highly specialized, involving certain assumptions and/or limitations, and can be manipulated only by experienced engineers who have a thorough understanding of the underlying theories. This results in significant constraints on their manipulation as well as large gaps in understanding and expectations between the developers and practitioners of a model. The recent advancements in artificial intelligence (AI) technologies are making it possible to integrate machine learning capabilities into numerical modeling systems in order to bridge the gaps and lessen the demands on human experts. The objective of this paper is to review the state-of-the-art in the integration of different AI technologies into coastal modeling. The algorithms and methods studied include knowledge-based systems, genetic algorithms, artificial neural networks, and fuzzy inference systems. More focus is given to knowledge-based systems, which have apparent advantages over the others in allowing more transparent transfers of knowledge in the use of models and in furnishing the intelligent manipulation of calibration parameters. Of course, the other AI methods also have their individual contributions towards accurate and reliable predictions of coastal processes. The integrated model might be very powerful, since the advantages of each technique can be combined.  相似文献   
978.
This article critically reviews the evolution of urban environmental management in Shanghai since 1978. Established in a transitional postsocialist economy and shaped by a spectacular urban redevelopment process, the current environmental management framework of Shanghai has succeeded in mitigating major industrial pollution and improving urban amenities with unprecedented pace and magnitude. However, it generally failed to take social equity and environmental justice issues into consideration. Based on Haughton’s models of sustainable urban development, this article proposes four priorities and five principles within the framework of a fair shares cities model for the future environmental management of Shanghai and briefly discusses their policy implications and implementation issues. The authors argue that Haughton’s approach is relevant to Shanghai’s case because the essence of his argument—the multidimensional equity principles—is the core of the concept of sustainable development.  相似文献   
979.
为了控制终端区飞行冲突的风险,基于复杂网络,将飞行冲突的情景演变过程转化为复杂网络进行分析计算.分析侧向交叉跑道机场的主要安全风险,构建包含527个节点与2644条边的终端区飞行冲突情景演化复杂网络模型;采用无权有向网络中的节点度、度中心性、介数中心性、聚类系数等进行风险分析;采用Dijkstra算法,确定影响飞行冲突...  相似文献   
980.
快速高架复合道路临街建筑物正面声场分析   总被引:2,自引:0,他引:2       下载免费PDF全文
采用虚声源法预测快速高架复合道路两侧临街建筑物正面声场的数学模型,其理论值与现场实测结果基本吻合,精度在±2.5dB(A)之内。得出由于建筑物正面影响,一侧有建筑物时,建筑物前1m处声级升高2dB(A),两侧有建筑物则升高5.5dB(A),同时指出这种效应只在建筑物前附近处才显著。  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