全文获取类型
收费全文 | 920篇 |
免费 | 122篇 |
国内免费 | 339篇 |
专业分类
安全科学 | 121篇 |
废物处理 | 11篇 |
环保管理 | 86篇 |
综合类 | 702篇 |
基础理论 | 122篇 |
污染及防治 | 73篇 |
评价与监测 | 120篇 |
社会与环境 | 49篇 |
灾害及防治 | 97篇 |
出版年
2024年 | 10篇 |
2023年 | 34篇 |
2022年 | 56篇 |
2021年 | 82篇 |
2020年 | 71篇 |
2019年 | 56篇 |
2018年 | 60篇 |
2017年 | 48篇 |
2016年 | 64篇 |
2015年 | 78篇 |
2014年 | 61篇 |
2013年 | 90篇 |
2012年 | 80篇 |
2011年 | 75篇 |
2010年 | 50篇 |
2009年 | 55篇 |
2008年 | 41篇 |
2007年 | 63篇 |
2006年 | 42篇 |
2005年 | 42篇 |
2004年 | 34篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1990年 | 5篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1381条查询结果,搜索用时 672 毫秒
331.
332.
333.
MapInfo是目前流行的地理信息系统 (GIS)应用软件之一 ,由于其强大的地图功能 ,在地震监测预报中得到了越来越广泛的应用。安徽省地震局合肥遥测台网不久前完成了台网自己的速报软件的开发研制工作 ,其中运用了MapInfo部分图形操作功能。本文介绍MapInfo技术在台肥遥测台网地震速报中的一些具体应用 相似文献
334.
335.
336.
A. N. Papanicolaou A. Bdour N. Evangelopoulos N. Tallebeydokhti 《Journal of the American Water Resources Association》2003,39(1):191-203
ABSTRACT: This paper presents the results of a statistical analysis performed for the watershed and stream corridor in the South Fork of the Clearwater River (SFCR) basin, in north central Idaho. The analysis was performed for 61 six‐field hydrological unit codes (HUCs) of the SFCR basin using an extensive record (up to 100 years) for 50 watershed and in‐stream parameters, including hydrologic, flow, fish, anthropogenic, and natural activity data. The objective of this research was twofold: first, the development of quantitative relations that describe the Index of Fish Density (IFD) of particular fish species as a function of watershed and instream parameters; and second, to provide a robust confirmation for the effects of some of these parameters, previously recorded by the fisheries profession, by using well established statistical techniques. The uniqueness of this work is the compilation and statistical analysis of large data sets to quantitatively describe the impacts of watershed and instream parameters on the IFD of all salmonids and specific fish species. Factor analysis was employed to regroup parameters that are highly correlated to each other into a set of single factors and to relate the IFD to these factors. Using factor extraction, 12 factors were developed from the 50 watershed and instream parameters. Multiple regression diagnostic tests indicated that only 7 of the 12 factors are strong predictors offish indicators. The strongest predictors are longitude, latitude, elevation, watershed gradient, and water temperature. The analysis indicated that the present model has reasonable predictive power, considering the uncertainty involved in estimating the interdependence of IFD with watershed parameters. 相似文献
337.
粉煤灰静电脱炭技术研究 总被引:1,自引:0,他引:1
本文介绍粉煤灰静电脱炭资源化利用技术的试验研究.利用YNDF-I型立式电场粉煤灰脱炭装置进行优化试验,提出电压、极板间距、摩擦分散器材料、粉尘浓度及气体流量等运行工艺特性参数与静电脱炭率的相关关系.试验结果表明,该立式电场脱炭装置在最优工艺参数条件下运行时,可使粉煤灰脱炭后的精灰含炭量降低到1.20%,脱炭率达86.74%,能够直接代替水泥用作建筑材料或修筑公路路面,具有较高的经济效益、社会效益和环境效益,为粉煤灰资源化利用提供了一种新的途径. 相似文献
338.
液相络合-铁粉还原-酸吸收回收法脱除烟气中NO 总被引:8,自引:0,他引:8
提出了Fe2+螯合剂络合-铁粉还原-酸吸收回收法脱除烟气中NO的新工艺,重点研究了模拟烟气中O2含量对NO络合量的影响,以及铁粉用量、铁粉粒径和搅拌速度对脱氮效率的影响,确定了最佳的铁粉脱氮工艺条件,并对铁粉和铁屑的脱氮效果进行了比较.结果表明:烟气中φ(O2)从0增加到4.2%,NO络合量下降90.2%;脱氮效率随铁粉用量和反应器搅拌速度的增加而增加,随铁粉粒径的增加而降低;最佳工艺参数为,铁粉用量0.8 g,铁粉粒径≥200目(≤0.077 mm),搅拌速度900 r/min,在该条件下,对φ(O2)为5%的模拟烟气在搅拌反应器中可取得90%以上的脱氮效率;用铁粉在1台搅拌反应器中取得的脱氮效率和用铁屑在2个鼓泡反应器串联时所取得的效率相当. 相似文献
339.
340.
Atmospheric CO2 concentration (CC) near land surface and meteorological variables have been measured at four sites,named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge) and Ejina (lower desert),respectively, in Heihe River Basin, northwest China. The results showed that, the half hourly CC at night was larger than in daytime,and the daily averaged CC was the largest in winter. The averaged CC of 932 d at the Linze was about 418 ppm, was about 366 ppm in the 762 d at the Ejina. In the same period from September 23 to November 9, 2004, the averaged CC was about 625,334, 436 and 353 ppm, at Yeniugou, Xishui, Linze and Ejina, respectively. The linear relationship between daily averaged CC and air temperature T was negative, between CC and relative humidity (RH) was positive. The linear CC-atmospheric pressure (A P) relationship was negative at the Linze and Yeniugou, was positive at the Ejina. The relationship between CC and global radiation R was exponent, and soil temperature Ts was negative linear, and soil water content was complex. The correlation between CC and wind speed was not existent.Using meteorological variables together to simulate CC, could give good results. 相似文献