全文获取类型
收费全文 | 94篇 |
免费 | 4篇 |
国内免费 | 46篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 5篇 |
环保管理 | 8篇 |
综合类 | 68篇 |
基础理论 | 15篇 |
污染及防治 | 29篇 |
评价与监测 | 5篇 |
社会与环境 | 3篇 |
灾害及防治 | 1篇 |
出版年
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 22篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2007年 | 5篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 31 毫秒
71.
《Atmospheric environment (Oxford, England : 1994)》2002,36(14):2405-2419
For 41 days between 25 May 1996 and 27 March 1997, peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) have been measured by electron capture gas chromatography at Santa Rita near Porto Alegre, RS, Brazil, where light-duty vehicles used either ethanol or a gasoline–MTBE blend. Daily maximum concentrations ranged from 0.19 to 6.67 ppb for PAN and 0.06 to 0.72 ppb for PPN. Linear regression of maximum PPN vs. maximum PAN yielded a slope of 0.105±0.004 (R2=0.974). Diurnal variations of ambient PAN often followed those of ozone with respect to time of day but not with respect to amplitude. This was reflected in the large relative standard deviations associated with the study-averaged PAN/ozone concentration ratio, 0.037±0.105 (ppb/ppb, n=789) and the maximum PAN/maximum ozone concentration ratio, 0.028±0.015 (ppb/ppb, range 0.005–0.078, n=41). On several days PAN accounted for large fractions of the total ambient NOx in the late morning and afternoon hours, e.g., PAN/NOx⩽0.58 and PAN/(NOx–NO) ⩽0.76 on 27 March 1997. The amount of PAN lost by thermal decomposition (TPAN) was comparable in magnitude to that present in ambient air. The ratios TPAN/(PAN+TPAN) were up to 0.53, 0.67 and 0.64 during the warm afternoons of 25, 26 and 27 March 1997, respectively. The highest calculated value of TPAN was 5.6 ppb on 27 March 1997. On that day the 24 h-averaged value of TPAN (1.01 ppb) was nearly the same as that of PAN (1.09 ppb). Using computer kinetic modeling (SAPRC 97 chemical mechanism) and sensitivity analysis of VOC incremental reactivity, we ranked VOC present in Porto Alegre ambient air for their importance as precursors to PAN and to PPN. Using as input data the averages of VOC concentrations measured in downtown Porto Alegre during the ca. 1 yr period March 1996–April 1997, we calculated that the most important precursors to PAN and PPN were the SAPRC 97 model species ARO2 (which includes the aromatics xylenes, trimethylbenzenes, ethyltoluenes, etc.), which accounted for ca. 17% of the total PAN and total PPN formation potentials. Overall, the results indicate a major role for aromatics and alkenes and a minor role for acetaldehyde and ethanol as precursors to peroxyacyl nitrates in the Porto Alegre urban area. 相似文献
72.
73.
74.
《Atmospheric Environment. Part A. General Topics》1993,27(5):793-799
A nonlinear filter is developed for use with finite element methods in solving the atmospheric diffusion equation. Usually, high-order accurate finite element methods lead to ripples near sharp gradients. This is an undesirable feature in air quality modeling. The filter eliminates these ripples by adding artificial diffusion along the direction of the streamlines. Since it is applied only in regions where the ripples are located, the accuracy of the solution is maintained. Here, the filter was used with the streamline upwind Petrov-Galerkin method. It displayed good performance characteristics in the standard rotating puff test, and in a new test where the angular velocity profile is parabolic. It did not cause excessive crosswind diffusion that was present in a previously developed two-dimensional filter, or Forester filters applied to one-dimensional, spatially split algorithms. The new test problem was designed specifically to show that the rotating puff test may not always be the appropriate test to evaluate the performance of transport schemes, especially those that split the horizontal transport into one-dimensional operators. As expected, a one-dimensional splitting scheme (Chapeau function) displayed worse performance than fully two-dimensional schemes under more severe conditions of the new test problem. 相似文献
75.
净初级生产力的人类占用:一种衡量区域可持续发展的新方法 总被引:2,自引:0,他引:2
可持续发展的生态评估是当前国际生态经济学与可持续发展研究的前沿问题之一,净初级生产力的人类占用从生态系统初级生产力的角度可以定量评估一个国家或地区发展的生态持续性程度,是近年来国际上一种重要的生物物理量衡量方法。论文简要介绍了净初级生产力人类占用的基本理论与核算方法,分析了该方法应用于区域可持续发展生态评估的基本原理。综合国外相关研究的最新进展,研究认为,定量表征区域可持续发展的生态上限是净初级生产力人类占用方法的最大优点,而该方法应用于区域可持续发展生态评估的不足之处则主要表现在关键参数的不确定性、可持续性的评价阈值、研究数据的缺乏和生物量进出口问题等4方面。 相似文献
76.
依托实际处理工程,针对酱油废水处理难点,开展膜生物反应器处理酱油废水的中试研究,分析了水力停留时间,溶解氧,pH和MLSS对出水水质的影响。在确定膜生物反应器适宜运行条件的基础上,对比了MBR和实际运行的二级SBR+气浮工艺的处理效率。研究表明,在水力停留时间为10h,ρ(DO)为2 5mg L,pH为7 8,ρ(MLSS)为8~9g L的条件下,膜生物反应器具有较好的处理效果,出水稳定达到一级排放标准,避免了在SBR中存在的CODCr和色度不能同步去除的问题。膜生物反应器中生物相研究表明,菌胶团、丝状菌、原生动物等构成膜生物反应器更为复杂的生态系统,使膜生物器的抗冲击性负荷的能力更强,在高、低负荷时都有稳定的处理效果。 相似文献
77.
78.
《Spill Science & Technology Bulletin》2000,6(3-4):263-271
Although the presence of Langmuir circulation (LC) cells is evident from observations in lakes, ponds, and coastal waters, the effects of these cells on oil slicks have received less attention. This paper considers the effects as inferred from field data of LC cells on oil slicks. Examples from observed experimental oil slicks in the field are presented. The importance of these LC cells is discussed from the point of view of oil spill contingency. 相似文献
79.
80.
酸性矿山废水(acid mine drainage,AMD)污染是阻碍矿山生态自然恢复的最大难题。利用以植物修复为主的生物策略控制矿山潜在污染的效费比更好且更可持续,但修复土壤存量污染、遏制增量污染仍是首要问题。其中土壤存量污染是短期内植被恢复能否成功的决定因素,而增量污染是植被恢复能否持续的决定因素。本文以铜矿排土场为例,采用石灰+鸡粪+钙镁磷肥+微生物的原位综合改良方法与栽植乔灌木袋苗+混播乔灌草种子的直接植被快速重建模式,开展了基于生态复垦的污染土壤综合改良修复效应研究。结果显示:综合改良修复后的土壤pH由改良前的2.84上升到7.83,生态复垦1 a后则轻微下降到6.72,而土壤阳离子交换量(CEC)、有机质(OM)、全氮(TN)、全磷(TP)、全钾(TK)等含量相比改良前分别增加1.98倍、32.96倍、11.74倍、2.38倍、3.64倍,生态复垦1 a后除TK含量略有下降外,CEC、OM、TN、TP含量相比改良后则分别增加了1.08倍、1.29倍、1.25倍、1.03倍;综合改良修复后的土壤净产酸量(net acid generation,NAG)、酸性中和能力(acid... 相似文献