全文获取类型
收费全文 | 4592篇 |
免费 | 629篇 |
国内免费 | 2407篇 |
专业分类
安全科学 | 226篇 |
废物处理 | 323篇 |
环保管理 | 531篇 |
综合类 | 4219篇 |
基础理论 | 798篇 |
环境理论 | 5篇 |
污染及防治 | 887篇 |
评价与监测 | 240篇 |
社会与环境 | 388篇 |
灾害及防治 | 11篇 |
出版年
2024年 | 60篇 |
2023年 | 178篇 |
2022年 | 282篇 |
2021年 | 248篇 |
2020年 | 220篇 |
2019年 | 245篇 |
2018年 | 262篇 |
2017年 | 282篇 |
2016年 | 329篇 |
2015年 | 387篇 |
2014年 | 374篇 |
2013年 | 574篇 |
2012年 | 618篇 |
2011年 | 589篇 |
2010年 | 370篇 |
2009年 | 339篇 |
2008年 | 264篇 |
2007年 | 336篇 |
2006年 | 368篇 |
2005年 | 213篇 |
2004年 | 152篇 |
2003年 | 164篇 |
2002年 | 119篇 |
2001年 | 105篇 |
2000年 | 108篇 |
1999年 | 89篇 |
1998年 | 72篇 |
1997年 | 48篇 |
1996年 | 63篇 |
1995年 | 30篇 |
1994年 | 41篇 |
1993年 | 27篇 |
1992年 | 23篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有7628条查询结果,搜索用时 718 毫秒
721.
722.
Schaeffer Roberto Logan Jeffrey Szklo Alexandre Salem Chandler William de Souza Marques João Carlos 《Mitigation and Adaptation Strategies for Global Change》2001,6(1):47-69
This study analyzes the options for meeting power demand in the Brazilianpower sector through the year 2015. Three policy cases are constructedto test economic and environmental policy measures against a baseline:advanced technologies scenario, environmental control scenario and carbon(C) elimination scenario. Least-cost modeling simulated these scenarios throughchanges in emissions fees and caps, costs for advanced technologies,demand side efficiency, and clean energy supplies. Results show that, in theabsence of alternative policies, new additions to Brazil's electric powersector will shift rapidly from hydroelectricity to combined-cycle natural gasplants. When the cost of environmental impacts are incorporated in theprice of power, the least-cost mix of electric power generation technologycould change in other ways. In all scenarios, energy efficiency andcogeneration play an important role in the least-cost power solution. Savingelectricity through increased efficiency offsets the needs for new supply andhas enormous potential in Brazil's industrial sector. Efficiency also reducesthe environmental burden associated with electricity production andtransmission, without compromising the quality of the services demandedby end users. Interesting enough, carbon dioxide (CO2) emissions will remainrelatively low under almost every conceivable scenario. 相似文献
723.
724.
介绍用活性炭和天然锰砂作反应剂交互作用处理镀水的研究,实验结果表明,活性炭:天少=2:3,加鼓氧,静置后过滤,废水处理效率更好,Zn^2+的去除率达99.8%,Fe^3+去除率达99.6%,废水PH值上升到6.0达到国家废水排放标准。 相似文献
725.
利用毛细管气相色谱法测定水和废水中的丙烯酰胺 总被引:4,自引:2,他引:4
本文采用毛细管色谱法建立了水和废水中丙烯酰胺的测定程序。以活性炭柱吸附、浓缩样品中的丙烯酰胺,用甲醇洗脱,洗脱液用FID测定。方法回收率为83.1~99.0%,相对标准偏差为5.34%,检出限为0.016mg/L。 相似文献
726.
Will Simplified Modalities and Procedures Make More Small-Scale Forestry Projects Viable Under the Clean Development Mechanism? 总被引:2,自引:0,他引:2
Bruno Locatelli Lucio Pedroni 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):621-643
Simplified modalities and procedures (M&P) are expected to increase the viability of small-scale project activities under
the Clean Development Mechanism (CDM). A small-scale afforestation or reforestation (AR) project is defined as a project removing
less than 8 kilotons of carbon dioxide equivalent (CO2e) per year. Depending on the project type and the method for measuring scale, 8 kilotons of CO2e per year correspond to highly diverse areas, possibly ranging from 200 to 6000 ha. Using a model to calculate the minimum
project scale above which the CDM is a positive financial incentive for eligible AR project activities, the paper analyzes
whether a reduction of transaction costs under simplified M&P will be a sufficient incentive to motivate small-scale participation
in the CDM. Model results show that, even under optimistic assumptions on carbon market conditions and transaction costs,
small-scale project activities will not benefit from simplified M&P. Results also show that project activities removing more
than 8 kilotons of CO2e per year and registered as small-scale would be the ones that could benefit the most from simplified M&P. It is concluded
that the participation of small-scale project activities to the CDM requires more than simplified M&P, the price of expiring
Certified Emission Reductions being one of the most critical parameters. 相似文献
727.
颗粒活性炭对UASB处理垃圾渗滤液促进作用的研究 总被引:1,自引:0,他引:1
通过对比研究,考查了用UASB处理垃圾渗滤液时,投加颗粒活性炭对加速UASB反应器中污泥颗粒化进程、缩短启动时间、提高处理效果的影响。结果显示:启动时间缩短了近1/3,最大有机负荷提高近40%且出现了更大颗粒污泥,但COD去除效率没有明显提高。 相似文献
728.
Black carbon (BC) in surface sediments from Henan section of Yellow River and Huaihe River, China, was determined. Average content of BC in Huaihe River was 0.33%, higher than that in Yellow River (n?=?23) with mean value of 0.15%. Distribution patterns of BC in Yellow River and Huaihe River were similar, namely that tributaries had higher BC content than main stream. In addition, BC content in the mainstream of Yellow River and Huaihe River decreased with altitude. The BC content presented a significant positive correlation with clay (r?=?0.672; p?<?0.01) content in Yellow River, while neither did in Huaihe River. The ratio of BC/TOC ranged from 1.8–57.4% (median 29.6%), evidencing pyrogenic fossil fuel source of BC in Yellow River. Relatively low values of BC/TOC in Huaihe River (5.3%–28.8%, median 7.5%,) reflected that the origin of BC is from burning of biomass. In addition, Pearson rank correlation analysis showed that BC was in strong correlation with lighter PAH in Yellow River, while BC was in significant correlation with heavier PAH in Huaihe River. The ratio of BC/TOC indicated that BC in Yellow River mainly came from fossil fuel combustion, while BC in Huaihe River was primarily from biomass burning. 相似文献
729.
730.
Based on hourly measurements of NOx NO2 and O3 and meteorological data, an ordinary least squares (OLS) model and a first-order autocorrelation (AR) model were developed to analyse the regression and prediction of NOx and NO2 concentrations in London. Primary emissions and wind speed are the most important factors influencing NOx concentrations; in addition to these two, reaction of NO with O3 is also a major factor influencing NO2 concentrations. The AR model resulted in high correlation coefficients (R > 0.95) for the NOx and NO2 regression based on a whole year's data, and is capable of predicting NO2 (R = 0.83) and NOx (R = 0.65) concentrations when the explanatory variables were available. The analysis of the structure of regression models by Principal Component Analysis (PCA) indicates that the regression models are stable. The results of the OLS model indicate that there was an exceptional NO2 source, other than primary emission and reaction of NO with O3, in the air pollution episode in London in December 1991. 相似文献