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   153篇
  免费   4篇
  国内免费   2篇
安全科学   18篇
废物处理   2篇
环保管理   7篇
综合类   59篇
基础理论   12篇
污染及防治   26篇
评价与监测   18篇
社会与环境   16篇
灾害及防治   1篇
  2023年   1篇
  2022年   4篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   1篇
  2015年   4篇
  2014年   4篇
  2013年   10篇
  2012年   6篇
  2011年   18篇
  2010年   7篇
  2009年   10篇
  2008年   12篇
  2007年   9篇
  2006年   9篇
  2005年   8篇
  2004年   6篇
  2003年   5篇
  2002年   1篇
  2001年   3篇
  2000年   4篇
  1999年   3篇
  1998年   7篇
  1997年   4篇
  1996年   5篇
  1994年   5篇
  1993年   2篇
  1992年   4篇
  1990年   1篇
排序方式: 共有159条查询结果,搜索用时 15 毫秒
1.
采用2013年环境空气自动监测数据,分析杭州市空气中黑碳质量浓度的变化规律,并对变化特征的产生原因进行探讨。结果表明:黑碳测定年均值为4.10μg/m3,日变化有明显双峰结构,峰值出现在早7时和晚8时左右;从季节看,黑碳质量浓度冬季高(5.20μg/m3)、夏季低(3.00μg/m3);黑碳质量浓度与NO2、CO、PM10、PM2.5显著相关,与O3、风速、气温呈负相关,降水对黑碳的清除作用明显。  相似文献   
2.
长江感潮河段水流与污染排放引起的浓度场复杂多变,基于EFDC(Environmental Fluid Dynamic Code)模型,采用正交曲线网格拟合自然河道边界,建立了长江常州段的水动力和水质模型。采用现场同步实测资料,与计算结果比对,证明该模型在水动力和水质两个方面都与实测数据吻合较好,满足了实际工程的需要;同时由于长江水流运动较快,一阶降解动力学已经满足了化学需氧量(COD)、氨氮(NH3-N)和总磷(TP)浓度计算要求,可以不考虑它们复杂的生化反应过程。  相似文献   
3.
There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom.  相似文献   
4.
Tracer gas was released upwind of a two-compartment complex shaped building under unstable atmospheric conditions. The mean wind direction was normal to or at 45° to the long face of the building. The general patterns of concentration distribution on the building external walls and inside the building were analysed and the influence of natural and mechanical ventilation on indoor concentration distributions was discussed. Mean concentration levels, as well as the concentration fluctuation intensity, were higher on the windward walls of the building, although concentration levels varied along each wall. Concentration fluctuations measured inside the building were lower than those measured outside. Inside the two compartments of the building, the time series of concentrations had a similar general behaviour; however, gas concentrations took approximately 1.5 times longer to reach the mean maximum concentration value at the downwind compartment 02 while they also decreased more rapidly in the upwind compartment 01 after the source was turned off. The highest indoor concentration and concentration fluctuation values were observed at the detectors located close to the windward walls, especially when the building windows were open. Experiments with and without natural ventilation suggested that infiltration and exfiltration of contaminants is much faster when the building windows are open, resulting to higher indoor concentration levels. Furthermore, mechanical ventilation tends to homogenize concentrations and suppress concentration fluctuations, leading to lower maximum concentration values.  相似文献   
5.
论开展主要环境质量指标浓度考核   总被引:1,自引:1,他引:0  
针对现行环境质量考核体系中存在问题,选取主要的环境质量考核指标,提出逐步推行浓度值考核设想,并对比分析该考核办法与现行比例考核办法的优劣。  相似文献   
6.
高温热表面油液蒸发的时变性热质传递模型与实验研究   总被引:1,自引:0,他引:1  
针对高温热表面油液蒸发热质传递过程的时变性,考虑这一过程中的对流传质传热,建立了热环境作用下油液蒸发的热质传递模型方程,通过无量纲变换,求得空间浓度分布和温度场随时间的变化规律。以庚烷为试验对象,对高温热表面油液蒸发过程进行了实验研究。理论分析与实验表明:庚烷蒸发过程中,刘易斯数大于1,传热速率大于传质速率;蒸发导致的质量损失与时间平方根的成正比,与液面的面积成正比,且与质量扩散系数的平方根成正比,饱和蒸气浓度越大,蒸发速率也越大。油液蒸发计算结果与试验结果基本一致,表明了模型的有效性。  相似文献   
7.
CALPUFF模型在某露天煤矿煤尘模拟中的应用   总被引:1,自引:0,他引:1  
煤炭露天开采是我国煤炭生产的主要方法,为了验证CALPUFF模型在露天开采中,对煤尘浓度的模拟情况,本文耦合使用MM5/CALMET及CALPUFF软件,对某露天煤矿煤尘浓度进行模拟,并与监测值进行对比分析,发现监测值和模拟值的相关系数最高可达0.88,说明模拟值具有较高可信度.  相似文献   
8.
Empirical relations between the 90Sr concentration factor (CF) and the calcium concentration in freshwater aquatic systems have previously been determined in studies based on data obtained prior to the Chernobyl accident. The purpose of the present research is to review and compare these models, and to test them against a database of post-Chernobyl measurements from rivers and lakes in Ukraine, Russia, Belarus and Finland. It was found that two independently developed models, based on pre-Chernobyl empirical data, are in close agreement with each other, and with empirical data. Testing of both models against new data obtained after the Chernobyl accident confirms the models’ predictive ability. An investigation of the influence of fish size on 90Sr accumulation showed no significant relationship, though the data set was somewhat limited.  相似文献   
9.
工业废水中钡的排放限值研究   总被引:1,自引:0,他引:1  
帅星  谢家理 《环境保护科学》2011,37(4):10-12,21
在查阅大量文献资料基础上,总结了环境中钡的来源和特性,采用电感耦合等离子原子发射光谱方法测定地表水及稀土废水中的钡元素含量.对仪器的工作参数和被测元素的分析谱线进行了优化和选择,结合钡的化学毒性,提出了废水中钡的标准是5mg/L的建议.  相似文献   
10.
The current research provides guidance on the prevention and mitigation of dust explosion using a Quantitative Risk Management Framework (QRMF). Using concepts drawn from previous studies, the framework consists of three main steps: (i) a new combined safety management protocol, (ii) the use of DESC (Dust Explosion Simulation Code) and FTA (Fault Tree Analysis) to assess explosion consequences and likelihood, respectively, and (iii) application of the hierarchy of controls (inherent, engineered and procedural safety). QRMF assessment of an industrial case study showed that the original process was at high risk. DESC simulations and Probit equations determined the destructive percentages. FTAs revealed high probabilities of explosion occurrence; in addition, detailed individual and societal risks calculations were made, before and after the framework was applied. Based on the hierarchy of controls technique, the framework showed significant risk reduction to the point where the residual risk was acceptable for the process.  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