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   532篇
  免费   80篇
  国内免费   75篇
安全科学   183篇
废物处理   1篇
环保管理   74篇
综合类   191篇
基础理论   177篇
污染及防治   12篇
评价与监测   9篇
社会与环境   30篇
灾害及防治   10篇
  2024年   3篇
  2023年   32篇
  2022年   29篇
  2021年   43篇
  2020年   34篇
  2019年   30篇
  2018年   15篇
  2017年   30篇
  2016年   30篇
  2015年   30篇
  2014年   17篇
  2013年   21篇
  2012年   28篇
  2011年   43篇
  2010年   39篇
  2009年   37篇
  2008年   33篇
  2007年   36篇
  2006年   37篇
  2005年   23篇
  2004年   13篇
  2003年   16篇
  2002年   17篇
  2001年   5篇
  2000年   5篇
  1999年   8篇
  1998年   5篇
  1997年   3篇
  1996年   2篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1985年   2篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有687条查询结果,搜索用时 15 毫秒
191.
Industrial technical accidents caused by natural disasters are defined as Natech accidents, such as earthquakes and landslides, which can cause tremendous damage to industrial storage tanks, and lead to accidental leakage and even serious fire and explosion accidents. In this study, a landslide-induced storage tank accident model under earthquake disasters was proposed, and the relationship between landslide mass impact and target impact resistance was taken into account. Also, tank failure and the formation of the pool fire were considered to be the consequences of the Natech accident. Through scenario deduction, the dynamic process of landslide Natech was transformed qualitatively into a disaster chain network diagram composed of a scenario state, a disaster-causing factor and emergency management. The Bayesian network was used to learn and deduce the parameters of the network diagram, and in this process, the prior probability and conditional probability of nodes were obtained primarily by Monte Carlo simulation, and by an improved expert scoring method based on the fuzzy set theory. Through visualization software, the sensitivity analysis of landslide Natech was achieved. Finally, a case study of a liquor storage tank area in Guizhou Province, China was carried out, and the results show that a large amount of hazardous material leakage caused by buckling is key to the formation of pool fire accidents, and several prevention measures for earthquake-induced landslide Natech was proposed according to the sensitivity analysis.  相似文献   
192.
本文以新疆石河子国家生态工业(造纸)园区的设计为例.运用产业生态学理论,深入系统地分析了生态工业园区的系统构成、工业共生关系以及生态工业链网结构.为全新型生态工业园区的设计及其运行提出了切实可行的建议。  相似文献   
193.
近40年气候变化对江西自然植被净第一性生产力的影响   总被引:1,自引:0,他引:1  
根据全球气候变化的趋势,采用植被净第一性生产力模型,对江西省南昌、吉安、赣州3地近40年气候变化对自然植被净第一性生产力(NPP)的影响进行研究,并模拟了3地自然植被NPP在未来气候3种水热条件下的变化趋势。此外还以1980年江西全省自然植被NPP为例分析了自然植被NPP的区域分布特征,结果表明:3地近40年自然植被NPP平均值分别为1319 、1311和1320 t/hm2〖DK1〗·a,总体上都呈上升的趋势。 当年均气温增加2℃且降水量增加20%时,NPP值增加了149%~1585%;随着年均气温增加2℃且降水量减少20%,NPP减少了477%~516%;当年均气温增加2℃且降水量不变时,NPP增加了530%~569%。江西自然植被NPP区域分布特征由东、南、西3个方向向北呈放射状分布,随着地形由高山向丘陵、平原的方向变化而减小。  相似文献   
194.
Actor-level data on large-scale commercial agriculture in Sub-Saharan Africa are scarce. The peculiar choice of transnational investing in African land has, therefore, been subject to conjecture. Addressing this gap, we reconstructed the underlying logics of investment location choices in a Bayesian network, using firm- and actor-level interview and spatial data from 37 transnational agriculture and forestry investments across 121 sites in Mozambique, Zambia, Tanzania, and Ethiopia. We distinguish four investment locations across gradients of resource frontiers and agglomeration economies to derive the preferred locations of different investors with varied skillsets and market reach (i.e., track record). In contrast to newcomers, investors with extensive track records are more likely to expand the land use frontier, but they are also likely to survive the high transaction costs of the pre-commercial frontier. We highlight key comparative advantages of Southern and Eastern African frontiers and map the most probable categories of investment locations.Supplementary informationThe online version contains supplementary material available at 10.1007/s13280-021-01682-z.  相似文献   
195.
文章利用模拟实验开展了平原地区缓流河道中的水质变化对河道水流速度与来水水质的响应规律研究。结果显示,当流速<0.5m/h时,河道中的各种污染物主要以沉积过程为主。当流速在0.5~1.5m/h时,水体最易受外界有机物输入的影响,容易引起局部水质的恶化。当流速>1.5m/h时,水动力条件有利于河道中的有机物的降解,但促进了底泥磷的释放,并会导致下游河道营养盐的升高。所以在河道改造、城市生态河网建设与管理中,应从区域河网整体着手,也应注意缓流河道中来水水质的管理。  相似文献   
196.
The ranking of air quality control measures according to a number of evaluation criteria and with the participation of a large number of interested publics is demonstrated. A pilot study for the South Coast Air Quality Management District of California serves as the reference point. Several methodological considerations are addressed, such as: (a) the enhancement of criterion priorities to account for the variability among the performance of the control measures when incommensurable impact levels are applied: (b) the derivation of alternative rankings according to the priorities of potential coalitions; (c) the assessment of the potential acceptability of a collective ranking given the degree of solidarity among participants with similar interest affiliations; and (b) the assessment of the extent to which the performance of specific control measures may override priority differences and lead to insignificant ranking differences.  相似文献   
197.
A new approach for evaluating water sustainability is introduced by comparing physical and economic sustainability. To achieve physical sustainability, water should be available in sufficient quantity and of good quality and used efficiently. The economic sustainability can be achieved by balancing between costs and values of water. The objectives of this study were to estimate the physical and economic sustainability of surface water in the Big Lost River, south–central Idaho. The study used a Bayesian network by building a graphical diagram of nodes representing all significant variables related with the sustainability, such as water demand, water quality, and the different costs and values of water. The study showed that the likelihood of the physical sustainability is less than that of the economic sustainability, which is attributed to the scarcity of water in the Big Lost River. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
198.
基于贝叶斯网络的人因可靠性评价   总被引:2,自引:7,他引:2  
提出一种贝叶斯网络的人因可靠性评价(HRABN)方法,其中的每个因子对应于贝叶斯网络中的节点,该方法可对人因可靠性作定量分析和定性分析。在定性分析上,节点的因果关系(HRA中的因子关系)及需要改进的薄弱节点都直观地显示在层次图中;在定量分析方面,对节点因子后验概率的推断通过HRA中的先验信息(包含仿真数据、现场操作及专家知识等)和最新信息得到。如果人因可靠性贝叶斯网络中的每个节点的先验概率分布和后验概率分布都已知,模型的可信性就可通过贝叶斯因子进行定量验证。贝叶斯网络扩展性好,当有新的节点因子需要考虑时,只需要补充对应的节点;笔者的方法也能很好地应用在不同行业的HRA。  相似文献   
199.
安徽省农民人均纯收入地域差异及其原因分析   总被引:1,自引:0,他引:1  
以SPSS V13.0、Excel、Eviews 3.1和ArcView GIS3.2为工具,运用层次聚类分析和相关分析等方法,分析了安徽省农民人均纯收入的地域差异以及引起地域差异的原因。结果表明,安徽省农民人均纯收入的地域分异由东南向西北递减,并与经济发展水平区内分异性相吻合,这种差异是由自然条件差异和社会条件差异共同造成的。本研究对安徽省农村区域发展均衡性具有一定的指导意义。  相似文献   
200.
PROBLEM: The bicycle helmet use rate is still low among teenagers despite the cumulating evidence that bicycle helmets can prevent cyclists from serious injuries and death. The objective of this study was to investigate the usefulness of the Health Belief Model (HBM; Health Education Monographs, 2 (1974) (1), Theory of Planned Behavior (TPB; Ajzen, I. (1988). Attitudes, personality and behavior. Open University Press, Milton Keynes) and Locus of Control model (LC; Psychological Monographs, (1966) (80) in understanding the intention to use bicycle helmet use among bicycle helmet owners. METHOD: Data were collected at two schools in Helsinki, Finland. Students (N=965) completed a questionnaire including three social psychological models applied to helmet use. Models were compared by structural equation modeling techniques. SUMMARY: Results showed that the TPB and LC model fitted the data well, whereas fit of the HBM model was lower than the fit of TPB and LC models. All components of TPB and external LC orientation were significantly related to the intention to use a helmet. TPB together with LC model provide a promising theoretical framework for helmet use promotion campaigns. Practical suggestions for future bicycle helmet campaigns were provided.  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