全文获取类型
收费全文 | 913篇 |
免费 | 129篇 |
国内免费 | 500篇 |
专业分类
安全科学 | 57篇 |
废物处理 | 46篇 |
环保管理 | 71篇 |
综合类 | 987篇 |
基础理论 | 166篇 |
污染及防治 | 192篇 |
评价与监测 | 17篇 |
社会与环境 | 5篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 3篇 |
2023年 | 10篇 |
2022年 | 40篇 |
2021年 | 55篇 |
2020年 | 44篇 |
2019年 | 55篇 |
2018年 | 58篇 |
2017年 | 46篇 |
2016年 | 60篇 |
2015年 | 57篇 |
2014年 | 80篇 |
2013年 | 71篇 |
2012年 | 119篇 |
2011年 | 136篇 |
2010年 | 87篇 |
2009年 | 109篇 |
2008年 | 72篇 |
2007年 | 81篇 |
2006年 | 69篇 |
2005年 | 47篇 |
2004年 | 29篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 38篇 |
2000年 | 26篇 |
1999年 | 26篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有1542条查询结果,搜索用时 15 毫秒
991.
992.
A~2/O工艺重新启动试验的污泥活性恢复研究 总被引:1,自引:0,他引:1
以处理实际城市污水的小试规模A2/O工艺为研究对象,在处理工艺稳定运行的基础上关停装置60 d,进行了"饥饿"期内不同关停模式下系统重新启动后污泥活性恢复的研究.结果表明,循环模式、厌氧模式和微曝模式3种不同关停模式下,系统重启第4天,污泥硝化性能及反硝化性能基本恢复甚至超过关停前水平,而脱碳性能和除磷性能的恢复速度则较缓慢,重新启动后系统呈现较好的反硝化除磷能力;重启第12天后3种关停模式出水水质良好,基本满足<城镇污水处理厂污染物排放标准>(GB 18918-2002)一级B标准.不同关停模式下,系统污泥活性恢复速率及出水水质对比显示,污水处理厂故障检修期间将搅拌、曝气等动力设备完全关闭的厌氧模式下系统污泥活性恢复较快,而且能耗最低. 相似文献
993.
Water Quality Improvement Policies: Lessons Learned from the Implementation of Proposition O in Los Angeles,California 总被引:1,自引:0,他引:1
This article evaluates the implementation of Proposition O, a stormwater cleanup measure, in Los Angeles, California. The
measure was intended to create new funding to help the city comply with the Total Maximum Daily Load requirements under the
federal Clean Water Act. Funding water quality objectives through a bond measure was necessary because the city had insufficient
revenues to deploy new projects in its budget. The bond initiative required a supermajority vote (two-thirds of the voters),
hence the public had to be convinced that such funding both was necessary and would be effective. The bond act language included
project solicitation from the public, as well as multiple benefit objectives. Accordingly, nonprofit organizations mobilized
to present projects that included creating new parks, using schoolyards for flood control and groundwater recharge, and replacing
parking lots with permeable surfaces, among others. Yet few, if any, of these projects were retained for funding, as the city
itself also had a list of priorities and higher technical expertise in justifying them as delivering water quality improvements.
Our case study of the implementation of Proposition O points to the potentially different priorities for the renovation of
urban infrastructure that are held by nonprofit organizations and city agencies and the importance of structuring public processes
clearly so that there are no misimpressions about funding and implementation responsibilities that can lead to disillusionment
with government, especially under conditions of fiscal constraints. 相似文献
994.
Long-Term Variability in Bioassessments: A Twenty-Year Study from Two Northern California Streams 总被引:2,自引:2,他引:0
Long-term variability of bioassessments has not been well evaluated. We analyzed a 20-year data set (1984–2003) from four
sites in two northern California streams to examine the variability of bioassessment indices (two multivariate RIVPACS-type
O/E scores and one multimetric index of biotic integrity, IBI), as well as eight metrics. All sites were sampled in spring;
one site was also sampled in summer. Variability among years was high for most metrics (coefficients of variation, CVs ranging
from 16% to 246% in spring) but lower for indices (CVs of 22–26% for the IBI and 21–32% for O/E scores in spring), which resulted
in inconsistent assessments of biological condition. Variance components analysis showed that the time component explained
variability in all metrics and indices, ranging from 5% to 35% of total variance explained. The site component was large (i.e.,
>40%) for some metrics (e.g., EPT richness), but nearly absent from others (e.g., Diptera richness). Seasonal analysis at
one site showed that variability among seasons was small for some metrics or indices (e.g., Coleoptera richness), but large
for others (e.g., EPT richness, O/E scores). Climatic variables did not show consistent trends across all metrics, although
several were related to the El Ni?o Southern Oscillation Index at some sites. Bioassessments should incorporate temporal variability
during index calibration or include climatic variability as predictive variables to improve accuracy and precision. In addition,
these approaches may help managers anticipate alterations in reference streams caused by global climate change and high climatic
variability. 相似文献
995.
996.
臭氧/ 生物活性炭深度处理循环养殖废水 总被引:5,自引:0,他引:5
随着工厂化循环水养殖的不断发展,高浓度循环养殖废水对环境污染日益严重.为实现环境友好和资源节约,采用臭氧/生物活性炭对循环养殖废水进行深度处理中试研究.实验结果表明,臭氧化臭氧最佳投加量为4 mg/L,显著增强水体的可生化性,使TOC(总有机碳)/UV254(在波长为254 nm处的单位比色皿光程下的紫外吸光度)提高80%.臭氧/生物活性炭对循环养殖废水中的有机物和氨氮具有良好的去除效果.臭氧/生物活性炭对TOC、高锰酸盐指数和UV254的最终去除率比生物活性炭分别高11.9%、13.4%和6.5%.臭氧/生物活性炭和生物活性炭对氨氮的最终去除率分别为96.0%、90.7%. 相似文献
997.
998.
臭氧/紫外联合降解甲醛的试验研究 总被引:3,自引:0,他引:3
在臭氧单独作用、紫外光单独作用和UV/O3 3种条件下分别对甲醛进行降解试验,研究表明,臭氧和紫外在降解甲醛的试验中存在明显的协同促进作用。单独臭氧对甲醛降解效果并不显著。紫外单独作用时,对甲醛几乎没有降解作用。在UV/O3条件下,甲醛的降解率大大提高,特别是在高浓度臭氧条件下,降解率高达63%。臭氧浓度增大,降解率增大;紫外光强度增大,降解效果提高;气体流量增大,降解率下降;湿度增大,降解率提高。对甲醛降解试验进行动力学研究,结果表明,光照强度和臭氧浓度增大,一级反应速率增大,提高臭氧浓度要比加强紫外强度更能促进甲醛的降解。 相似文献
999.
考察用不同的氧化剂降解1,2,4-三氯苯(TCB),3种不同方法对TCB的去除效果存在较大差别,其处理效果依次为:H2O2〈O3〈O3/H2O2。采用响应面法优化O3/H2O2工艺降解TCB的条件。结果表明,TCB初始浓度和H2O2投加量对TCB去除效果影响较大。TCB的降解符合准一级反应动力学规律,最佳降解条件为TCB初始浓度0.3 mg/L,pH=8.13,H2O2投加量0.40 mmol/L,O3转化率75%。在此条件下,TCB的平均去除率为91.5%,与预测值93.1%吻合度较高。 相似文献
1000.