全文获取类型
收费全文 | 632篇 |
免费 | 67篇 |
国内免费 | 160篇 |
专业分类
安全科学 | 68篇 |
废物处理 | 38篇 |
环保管理 | 36篇 |
综合类 | 335篇 |
基础理论 | 86篇 |
污染及防治 | 129篇 |
评价与监测 | 143篇 |
社会与环境 | 8篇 |
灾害及防治 | 16篇 |
出版年
2024年 | 7篇 |
2023年 | 8篇 |
2022年 | 20篇 |
2021年 | 23篇 |
2020年 | 26篇 |
2019年 | 25篇 |
2018年 | 21篇 |
2017年 | 27篇 |
2016年 | 28篇 |
2015年 | 34篇 |
2014年 | 35篇 |
2013年 | 82篇 |
2012年 | 54篇 |
2011年 | 46篇 |
2010年 | 32篇 |
2009年 | 34篇 |
2008年 | 24篇 |
2007年 | 42篇 |
2006年 | 42篇 |
2005年 | 29篇 |
2004年 | 41篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 27篇 |
2000年 | 23篇 |
1999年 | 15篇 |
1998年 | 9篇 |
1997年 | 21篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有859条查询结果,搜索用时 15 毫秒
201.
利用透明复制裂隙模型,选择两种典型LNAPL(轻非水相液体)-邻二甲苯和十二烷残留体,开展一系列水流驱替冲刷和SDS(十二烷基磺酸钠)表面活性剂增强驱替实验,直接获取了裂隙内部LNAPL残留体几何形状与分布情况,结果表明:水流驱替冲刷和SDS驱替裂隙内残留体的去除率分别为8.3%~12.3%和65.9%~82.1%.残留体累积去除率随着驱替流体雷诺数的增加而增加.水流驱替冲刷条件下,残留体离散为小液滴,数量比初始残留状态增加1.3~2.2倍.SDS表面活性剂降低了"LNAPL-水"间的界面张力,能够有效去除裂隙内较大残留体,驱替后仅残余单个面积为1mm2左右的微小液滴.由于粗糙裂隙的非均质性,水流冲刷易导致系统内的"LNAPL-水"有效界面面积增加,对LNAPL污染修复不利,表面活性剂增强修复是一种更有效的方法. 相似文献
202.
载体催化剂在许多有机反应中已证明可作为对环境有利的催化剂而取代传统催化剂(一般有腐蚀性,毒性或极难分解和重整并产生大量废物)。综述了近年来固体酸催化、固体碱催化剂和其它载体催化剂的特性及液相有机化学反应中的应用成果,催化机理及发展趋势。 相似文献
203.
204.
205.
土壤中麦草灵残留的固相萃取—高效液相色谱测定 总被引:1,自引:0,他引:1
土壤中麦草灵用酸性乙醇提取,采用固相萃取技术用Sep-Pak C18柱净化浓缩,以反相离子抑制高效液相色谱分离测定,方法简便、快速、在土壤中的检出下限为0.04mg·kg^-1回收率范围在83.8-85.8%之间。 相似文献
206.
环境样品前处理技术及其进展(二) 总被引:15,自引:0,他引:15
在前文中讨论了环境样品的制备、前处理的概况,以及超临界流体萃取法。本文将继续报导近年来环境样品制备与前处理领域中其他一些新技术和新方法,包括固相萃取(SPE)、微波溶出(MWD)和液膜萃取(SLM)法,阐述了这些方法的基本原理、操作过程、各种实验参数的影响,及其在环境样品制备与前处理中的应用,并探讨了该领域的发展动向。 相似文献
207.
An area where a free-product accumulation of trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) occurs at the bottom of a 10-m-thick surficial sand aquifer was studied to determine the integrity of the underlying, 20-m-thick, clayey silt aquitard formed of glaciolacustrine sediment. TCE concentration-versus-depth profiles determined from aquitard cores collected at five locations indicated penetration of detectable TCE 2.5 to 3.0 m into the aquitard. Two of the profiles show persistent DNAPL at the aquitard interface, while two others indicate that DNAPL, present initially, was completely dissolved away producing concentration declines at the aquitard interface. The fifth profile suggests shallow DNAPL penetration (<0.5 m) into the aquitard, however, this penetration, which was likely caused by cross-contamination during core collection or cone penetrometry (CPT) of the aquitard interface, did not increase the maximum depth of TCE penetration. Combining the field profiles with one-dimensional model simulations, downward migration of the aqueous TCE front, defined as the EPA MCL of 5 microg/l, which was below the analytical detection limit, was projected to a distance between 4 and 5 m below the top of the aquitard. Using a single set of estimated aquitard parameter values, simulations of aqueous TCE migration into the aquitard provided a good fit to four of the field profiles with a migration time of 35 to 45 years, consistent with the history of TCE use at the site. These simulations indicate aqueous TCE migration is diffusion-dominated with only small advective influence by the downward groundwater velocity of 2 to 3 cm/year or less in the aquitard due to pumping of the underlying aquifer to supply water to the facility in the past 50 years. The applicability of the parameter values was confirmed by in situ diffusion experiments of 1-year duration, in which stainless steel cylinders containing DNAPL were inserted into the aquitard. The diffusion-dominated nature of the profiles indicates that the aquitard provides long-term protection of the underlying aquifer from contamination from this DNAPL zone. Simulations of long-term migration of the TCE solute front indicate breakthrough to the lower aquifer at 1200 years for the no advection scenario and at 500 years if the strong downward hydraulic gradient persists. However, even after breakthrough, the mass flux through the aquitard to the underlying aquifer remains relatively low, and when considered in terms of potential impacts to pumping wells, concentrations are not expected to increase significantly above present-day MCLs. The use of contaminant profiles of different time and distance scales, in addition to hydraulic data, dramatically improves the ability to assess aquitard integrity, and provides improved transport parameter values for estimating contaminant arrival times and fluxes. The apparent lack of deep preferential pathways for TCE migration, such as open fractures, is probably due to the softness of the silty aquitard deposit and minimal physical or chemical weathering of the aquitard provides long-term protection of the underlying aquifer from contamination from this DNAPL zone. Simulations of long-term migration of the TCE solute front indicate breakthrough to the lower aquifer at 1200 years for the no advection scenario and at 500 years if the strong downward hydraulic gradient persists. However, even after the breakthrough, the mass flux through the aquitard to the underlying aquifer remains relatively low, and when considered in terms of potential impacts to pumping wells , concentrations are not expected to increase significantly above present-day MCLs. The use of contaminant profiles of different time and distance scales, in addition to hydraulic data, dramatically improves the ability to assess aquitard integrity, and provides improved transport parameter values for estimating contaminant arrival times and fluxes. The apparent lack of deep preferential pathways for TCE migration, such as open fractures, is probably due to the softness of the silty aquitard deposit and minimal physical or chemical weathering of the aquitard. 相似文献
208.
209.
210.
空气中挥发性有机物监测技术的研究进展 总被引:13,自引:0,他引:13
讨论了空气中挥发性有机化合物(VOCs)的监测分析方法研究进展。重点介绍了空气中VOCs的采集、分析和测定;简要叙述了样品前处理的新方法--固相微萃取法(SPME)与其它前处理方法的研究概况。 相似文献