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   787篇
  免费   33篇
  国内免费   34篇
安全科学   95篇
废物处理   18篇
环保管理   86篇
综合类   183篇
基础理论   389篇
污染及防治   24篇
评价与监测   23篇
社会与环境   30篇
灾害及防治   6篇
  2023年   3篇
  2022年   7篇
  2021年   12篇
  2020年   13篇
  2019年   8篇
  2018年   8篇
  2017年   16篇
  2016年   22篇
  2015年   15篇
  2014年   17篇
  2013年   29篇
  2012年   34篇
  2011年   49篇
  2010年   45篇
  2009年   48篇
  2008年   69篇
  2007年   70篇
  2006年   70篇
  2005年   51篇
  2004年   40篇
  2003年   29篇
  2002年   17篇
  2001年   18篇
  2000年   24篇
  1999年   30篇
  1998年   19篇
  1997年   20篇
  1996年   20篇
  1995年   18篇
  1994年   12篇
  1993年   5篇
  1992年   5篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1985年   1篇
  1982年   1篇
  1979年   1篇
  1977年   2篇
  1975年   1篇
排序方式: 共有854条查询结果,搜索用时 437 毫秒
651.
应用地理信息系统进行垃圾填埋场选址的初步研究   总被引:2,自引:0,他引:2       下载免费PDF全文
在ArcGIS 8.3软件空间分析模块(spatial analysis)支持下,以江苏省长江以南市辖区为研究对象,进行了空间叠加和空间复合查询分析,以确定垃圾填埋场候选区域分布,并同已有的垃圾填埋场监测点进行比较,结果表明,利用地理信息系统技术进行垃圾填埋场辅助分析是可行的.  相似文献   
652.
Effective public expenditure currently dominates the management focus of many protected areas. This calls for explicit modeling of constraints and motivations that, respectively, obstruct and stimulate visits to selected outdoor destinations. Choice set formation is the result of screening and/or inclusion of specific sites (alternatives) to form the set of sites considered in real choices. Evidence shows that the omission of a structural representation of choice set formation is harmful to econometric inference. Yet, the literature has largely ignored the underlying behavioral phenomenon. We show, using a discrete choice experiment involving selection among seven recreational sites in an Italian national park, that choice set formation is behaviorally relevant, even after controlling for preference discrimination. Motivations (why visit?) are important determinants of preliminary site screening for choice set inclusion, as well as site selection, justifying the additional value of such modeling extension.  相似文献   
653.
This study presents an innovative approach for the integration of flood hazard into the site selection of detention basins. The site selection process is conducted by taking into account multiple criteria and disciplines. Hydraulic modeling results derived from stormwater management model are employed by Technique for the Order of Prioritization by Similarity to Ideal Solution (TOPSIS) to determine flood hazard score. The score generated by TOPSIS is used in a spatial multi-criteria decision-making site selection framework. Applying the framework, a suitability map is generated in which primary locations for detention basin placement are determined. The method is demonstrated through the case study of Darakeh River Catchment, which is located in northern Tehran, Iran. The presented framework can be easily utilized for site selection of other stormwater management techniques, such as low impact development and best management practices, due to its versatility.  相似文献   
654.
Data collection for economic valuation by using Internet surveys and pre-recruited Internet panels can be associated with severe disadvantages. Problems concerning sample coverage and sample representativeness can be expected. Representation errors may occur since people can choose whether to be part of an Internet panel and subsequently whether they wish to participate in the survey, thereby introducing two elements of potential self-selection. These elements may be correlated with preferences, thus making the respondents a non-random and non-representative sample, ultimately biasing results. This paper analyses a sample used for an Internet contingent valuation method survey eliciting preferences for improvements in water quality of a river. We find that some variables that affect the survey participation decision also affect willingness-to-pay, consequently biasing our welfare estimates. We show how adjusting willingness-to-pay for this bias can be accomplished by using a grouped data model incorporating a correlation parameter to account for selection.  相似文献   
655.
为避免事故、降低损失,合理地对加油站进行选址,提出了一种加油站安全选址风险评价指标体系,通过层次分析法确定各指标权重,利用加权平均算子合成模型。该模型从加油站选址的自然条件、区域条件、社会条件、加油站规模和应急救援条件五个方面对加油站选址的风险进行综合评估,并以重庆市璧山区某待建加油站作为案例论述了该模型的应用。结果表明通过最大隶属法和赋值法都得出案例加油站安全选址风险评价等级为“较好”,二者结论一致,并且与案例加油站的实际状况相符合。  相似文献   
656.
为分析街区尺寸对应急救援车辆行程时间的影响,基于小(120 m)、中(264 m)、大(440 m)3种典型街区尺寸,将救援车辆行程时间分为街区内、外2部分,以总行程时间最小为目标,构建基于背景流量水平的救援车辆路径选择仿真模型。设置4种救援场景,分别求解各救援场景在不同街区尺寸下的最短路径时间、冗余度及复杂度。结果表明:街区尺寸对街区内、外部救援时间均有影响,而前者在救援路径距离较短、街区尺寸较大的路网中占据较大比例(可达50%以上);救援路径包含路段的流量较小时,中、大街区尺寸路网表现类似,而高流量下大尺寸具备更优的救援时间;街区尺寸越小,救援路径冗余度与复杂度均越大。  相似文献   
657.
结合石灰石-石膏湿法烟气脱硫控制系统的特点,通过比较DCS和PLC两种系统控制器的处理能力、数据通信、组态维护、人机交换装置、安全性以及发展方向等,给出了脱硫控制系统选型建议。  相似文献   
658.
火力发电厂烟囱选型   总被引:2,自引:0,他引:2  
以铁岭发电厂二期2×600MW超超临界机组工程240m烟囱型式的选择为例,在简要介绍烟囱的一般型式、烟囱的选型原则和国内烟囱选型情况的基础上,进行比选并确定最终方案。  相似文献   
659.
Food preference of wood mice from two with heavy metals polluted sites and two unpolluted sites was tested under laboratory and field conditions with two-way choice experiments. In the laboratory, wood mice preferred to eat acorns from unpolluted sites over acorns from polluted sites. Previous experience with polluted food had no influence on food choice. Preference was negatively related to acorn metal content. Furthermore, the nutrient content of the acorn endosperm was consistently lower in polluted sites. We therefore conclude that wood mice used absolute metal concentration in the acorn, nutrient content, or both as a food selection cue. The results of the laboratory experiment could not be confirmed under field conditions. We hypothesized that search time constraints due to the presence of predators, competitors and/or other stress factors in the field have prevented the mice to forage selectively.  相似文献   
660.
建设项目环境影响评价因子应从污染物的等标污染负荷、影响的范围、影响可恢复性、环境质量现状和社会关注度 5方面综合考虑 ,采用层次分析法确定了这 5个因素的权重 ,对各污染因子进行分级予以定量打分 ,按得分进行环境影响评价因子筛选。  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