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   696篇
  免费   45篇
  国内免费   20篇
安全科学   241篇
废物处理   6篇
环保管理   88篇
综合类   202篇
基础理论   48篇
污染及防治   14篇
评价与监测   31篇
社会与环境   33篇
灾害及防治   98篇
  2023年   5篇
  2022年   19篇
  2021年   18篇
  2020年   22篇
  2019年   18篇
  2018年   13篇
  2017年   25篇
  2016年   20篇
  2015年   27篇
  2014年   28篇
  2013年   37篇
  2012年   60篇
  2011年   48篇
  2010年   42篇
  2009年   45篇
  2008年   38篇
  2007年   38篇
  2006年   56篇
  2005年   28篇
  2004年   30篇
  2003年   29篇
  2002年   29篇
  2001年   27篇
  2000年   14篇
  1999年   14篇
  1998年   5篇
  1997年   7篇
  1996年   2篇
  1995年   6篇
  1994年   2篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1986年   1篇
  1982年   1篇
  1981年   1篇
  1973年   1篇
排序方式: 共有761条查询结果,搜索用时 31 毫秒
141.
任静  于鲁冀 《四川环境》2011,30(6):149-154
改革开放以来,在我国经济快速发展的同时,产生了巨大的环境问题,为此,原国家环保总局审时度势,开展了创建国家环境保护模范城市的活动。本文对“创模”考核指标的调整情况进行概括,从总体情况、所属行政区、所属行政区级别、面积4个方面对目前“环保模范”城市状况进行了深入地分析,并对日后的“创模”工作进行了展望。  相似文献   
142.
为了对大空间建筑烟气填充研究方法进行对比分析。以一个废弃的大空间仓库为研究对象,采用了全尺寸火灾实验、计算机数值模拟和理论分析相互应用验证的研究方法,研究理论及数值模拟两种火灾烟气层高度的描述方法的准确性。结果表明当采用t2火模型时,在与现实的吻合程度方面,数值模拟〉Zukoski理论模型〉Yamana-Tanaka理论模型;随着火灾的不断发展,相对误差逐渐增大。通过对比分析发现,全尺寸实验、理论模型和数值模拟三种方法相互验证可以更好地保证研究的准确性;总结得到了两种与现实较吻合的描述烟气层高度的理论方法,并且提出减小误差应注意的几点事项,包括尽可能提高火源热释放速率、烟气层温度描述的准确性;不考虑火源热量通过建筑边界结构散失等。  相似文献   
143.
王晓青 《灾害学》2011,(4):103-105
2008年四川汶川8.0级地震造成了惨重的人员伤亡和巨大的经济损失。在震后灾害监测、应急指挥与抢险救援、灾害调查、损失评估、灾民安置、恢复重建以及地震科学研究等工作中,遥感技术发挥了重要作用。《汶川地震建筑物震害遥感解译图集》根据地震后地震现场建筑物震害遥感比对科学考察资料和震害遥感资料分析处理结果,按照科学性、知识性和资料性的编制原则编制而成。主要包括汶川大地震发生的地震地质、地势和社会环境,灾区遥感影像获取、建筑物震害影像特点与实际震害表现、震害遥感定量评估方法、汶川大地震灾区(Ⅷ度及以上地区)震害遥感定量评估模型,以及主要城市和乡镇震害遥感影像和震害评估结果等。  相似文献   
144.
The willingness of private individuals in Israel to invest in energy-saving retrofit of the envelope of residential buildings was studied by means of a survey. Responses show that awareness of the need to conserve energy is high, but that willingness to participate in a retrofit project is modest and is limited to relatively small outlays. The decision on whether to retrofit at all, and then how much to invest in the project, is characterized as a two-stage process in which different factors may affect the outcome of each of the two stages. The major barrier to building retrofit is the perception (justified, in most cases) that the direct economic benefit to the homeowner from the resulting energy saving is small, and that given Israel's relatively mild climate, the payback period is very long. The stamp of approval provided by a government subsidy of 25% would have a large non-proportional effect on willingness to undertake building retrofit. Funding for the subsidy could be obtained from a Pigovian levy on electricity, applied for a limited period, and its environmental benefits outweigh the cost of the subsidy itself.  相似文献   
145.
为提升紧急情况下复杂建筑空间中应急疏散引导的疏散效率,采用仿真模拟方法,提出1套可适用于复杂建筑空间人员应急疏散的无人机引导模型,该模型通过改进传统算法和构建新方法,实现无人机空间遍历移动规则寻优、无人机引导路径寻优以及基于“障碍物空间场域”建筑空间区域划分。研究结果表明:相较于没有无人机引导,采用单无人机和多无人机协同引导疏散,可大幅缩短整体疏散时间,有效减少疏散路径当量长度,提高疏散效率并保证路径安全,为无人机在应急救援和疏散的应用提供新思路。  相似文献   
146.
大空间建筑火灾中热烟气层发展规律的理论分析   总被引:16,自引:0,他引:16  
对几类典型的大空间建筑火灾中热烟气层的发展规律进行了理论分析,并和文献中的实验结果进行了对比。理论分析表明热烟气层的发展速率除了与火源的功率和大空间的几何尺寸有关外,还取决于火羽流的种类。给出了轴对称火羽流、二维线性溢流和沿墙壁的二维线性火羽流情况下的热烟气层发展速率的表达式,对大空间建筑的火灾安全设计与灾害预测具有指导意义。  相似文献   
147.
利用数值模拟确定致病微生物浓度的时空分布,建立了基于瞬时浓度判据和积累浓度判据的污染物暴露评价模型,得到了建筑群内瞬时风险区域和人们在污染区域的最大停留时间。结果显示:瞬时风险区域面积基本与微生物生长曲线一致,即在2000s时达到最大,然后逐渐减小,至6000s后基本不变;最大停留时间与微生物的增长率有关,增长率大,最大停留时间变小。  相似文献   
148.
建筑火灾中值得深入研究的几个问题   总被引:4,自引:2,他引:2  
马晓茜  管霖 《火灾科学》2000,9(4):25-31
提出了一些建筑火灾中值得进一步研究的,流动、传热、热解、燃烧、污染物生成等方面的基础问题。着重讨论了烟气扩散、流动中的混沌现象,提出了建立建筑火灾数据库、专家系统的设想,和建立非线性燃烧模型、开发智能型火灾自动报警系统的技术思路。  相似文献   
149.
Parental care is a costly part of reproduction. Hence, natural selection should favor males which avoid caring for unrelated young. However, the decision to abandon or reduce care requires cues which are evaluated to give information on potential reproductive value of the offspring. The prediction that male sand gobies, Pomatoschistus minutus, care for foreign eggs as long as they were spawned in their own nest and at least some of such cues are fulfilled was tested. Egg-guarding males that had recently taken part in a spawning event were given a clutch of eggs that was sired either by themselves or another male, in either their own or another male’s aquarium. Males that had not taken part in a spawning event were used as controls and were given eggs sired by another male. We measured the amount of filial cannibalism and nest building. Control group males did not care for eggs and ate them all before rebuilding the nest. In the other treatments, there were no significant effects of paternity, though males moved to another male’s aquarium increased their clutch area threshold and completely consumed larger clutches than males that were not moved. There was no intermediate response in any treatment in the form of increased partial filial cannibalism or less well-constructed nests. Our results suggest that egg-guarding males cannot distinguish between eggs sired by themselves and those sired by other males but are able to react to cues indicating paternity state. Males do not adopt eggs to attract females in P. minutus.  相似文献   
150.
We applied the complex ecosystem model EMMO, which was adopted to the shallow lake Müggelsee (Germany), in order to evaluate a large set of ecological scenarios. By means of EMMO, 33 scenarios and 17 indicators were defined to characterize their effects on the lake ecosystem. The indicators were based on model outputs of EMMO and can be separated into biological indicators, such as chlorophyll-a and cyanobacteria, and hydro-chemical indicators, such as phosphorus. The question to be solved was, what is the ranking of the scenarios based on their characterization by these 17 indicators? And how can we handle high quantities of complex data within evaluation procedures? The scenario evaluation was performed by partial order theory which, however, did not provide a clear result. By subsequently applying the hierarchical cluster analysis (complete linkage) it was possible to reduce the data matrix to indicator and scenario representatives. Even though this step implies losses of information, it simplifies the application of partial order theory and the post processing by METEOR. METEOR is derived from partial order theory and allows the stepwise aggregation of indicators, which subsequently leads to a distinct and clear decision. In the final evaluation result the best scenario was the one which defines a minimum nutrient input and no phosphorus release from the sediment while the worst scenario is characterized by a maximum nutrient input and extensive phosphorus release from the sediment. The reasonable and comprehensive results show that the combination of partial order, cluster analysis and METEOR can handle big amounts of data in a very clear and transparent way, and therefore is ideal in the context of complex ecosystem models, like that we applied.  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