全文获取类型
收费全文 | 224篇 |
免费 | 78篇 |
国内免费 | 60篇 |
专业分类
安全科学 | 36篇 |
废物处理 | 4篇 |
环保管理 | 22篇 |
综合类 | 139篇 |
基础理论 | 100篇 |
污染及防治 | 27篇 |
评价与监测 | 9篇 |
社会与环境 | 17篇 |
灾害及防治 | 8篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 71篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 24篇 |
2011年 | 22篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 17篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有362条查询结果,搜索用时 406 毫秒
301.
The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils 总被引:1,自引:0,他引:1
Liu Z He Y Xu J Huang P Jilani G 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):163-171
Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface. 相似文献
302.
303.
Cesar Fensterseifer Daniel G. Allasia Adriano R. Paz 《Journal of the American Water Resources Association》2016,52(2):367-375
The increase in the use of satellite‐derived precipitation products generated by different methods and algorithms emphasizes the need for a deeper analysis of their quality and accuracy. Using the contingency table method, we evaluated the accuracy of versions 6 and 7 of the Tropical Rainfall Measuring Mission Precipitation (TRMM) 3B42 product in southern Brazil by comparing daily precipitation over 13 years (V6 was tested for historical context). The interpolated data from 25 rain gauges were compared with both versions of TRMM. The V7 product tended to produce a slight increase in PC (proportion correct). V7 also showed a slight increase in the correlation coefficient (CC) and a significant increase in the H (hit rate) and CSI (critical success) indexes. However, the upgraded version shows an undesirable increase in the false alarm ratio. When the rainfall volumes were compared, V6 clearly underestimated the total rainfall over the entire period, but the V7 product slightly overestimated the cumulative volume (11%) which still represented a more reliable estimate than from V6. Furthermore, the main improvement in V7 was a large increase in the quantitative recognition of extreme precipitation events: V6 detected only 1% of the daily rainfalls above 60 mm, whereas V7 detected 57% of the events. 相似文献
304.
The polyfluorinated carboxylic acids 5:3 acid (C5F11CH2CH2CO2H) and 7:3 acid (C7F15CH2CH2CO2H) are major products from 6:2 FTOH (C6F13CH2CH2OH) and 8:2 FTOH (C8F17CH2CH2OH) aerobic biotransformation, respectively. The 5:3 and 7:3 acids were dosed into domestic WWTP activated sludge for 90 d to determine their biodegradability. The 7:3 acid aerobic biodegradability was low, only 1.7 mol% conversion to perfluoroheptanoic acid (PFHpA), whereas no transformation was observed previously in soil. In stark contrast, 5:3 acid aerobic biodegradability was enhanced 10 times in activated sludge compared to soil. The 5:3 acid was not activated by acyl CoEnzyme A (CoA) synthetase, a key step required for further α- or ß-oxidation. Instead, 5:3 acid was directly converted to 4:3 acid (C4F9CH2CH2CO2H, 14.2 mol%) and 3:3 acid (C3F7CH2CH2CO2H, 0.9 mol%) via “one-carbon removal pathways”. The 5:3 acid biotransformation also yielded perfluoropentanoic acid (PFPeA, 5.9 mol%) and perfluorobutanoic acid (PFBA, 0.8 mol%). This is the first report to identify key biotransformation intermediates which demonstrate novel one-carbon removal pathways with sequential removal of CF2 groups. Identified biotransformation intermediates (10.2 mol% in sum) were 5:3 Uacid, α-OH 5:3 acid, 5:2 acid, and 5:2 Uacid. The 5:2 Uacid and 5:2 acid are novel intermediates identified for the first time which confirm the proposed pathways. In the biodegradation pathways, the genesis of the one carbon removal is CO2 elimination from α-OH 5:3 acid. These results suggest that there are enzymatic mechanisms available in the environment that can lead to 6:2 FTOH and 5:3 acid mineralization. The dehydrogenation from 5:3 acid to 5:3 Uacid was the rate-limiting enzymatic step for 5:3 acid conversion to 4:3 acid. 相似文献
305.
306.
为将具有高精度、非接触性和全场观测等优点的数字散斑技术应用到煤矿相似模拟实验中,完成裂隙发育、应力变形和上覆岩层位移分析,介绍数字散斑的基本原理、相关系数和搜索方式等关键性环节,并利用MATLAB建立实用性强的数字散斑软件系统、硬件测量系统和像素位移转化系统,并进行图像二值化处理。结果表明:在利用数字散斑分析方法对煤层开挖过程中的覆岩下沉量进行定量分析时,不仅方便快捷,而且误差较小,证明数字散斑在相似模拟实验中具有较高的可靠度。这将在一定程度上促进数字散斑技术在煤矿领域的实际应用。 相似文献
307.
MATLAB是集数学、图形处理和程序设计语言于一体的实用性很高的数学软件。应用该软件编制了一套GM(1,1)灰色预测模型程序,弥补了灰色预测模型在矩阵计算中的问题,并将该程序运用到了秦皇岛市城市区平原地下水水位预测评价中,从实例看出用MAT-LAB所编制的程序可读性强,容易理解,操作简单灵活,直接面向用户,精度较高。 相似文献
308.
基于郑州市2017年1月1日—2022年2月28日环境空气细颗粒物(PM2.5)逐日质量浓度监测数据和同期气象数据,利用反向传播(BP)神经网络构建了环境空气PM2.5质量浓度预报模型,实现了对郑州市后1日环境空气PM2.5质量浓度日均值进行预报。构建了考虑大气氧化性因素(情景一)和不考虑大气氧化性因素(情景二)这2种情景,并对2种情景下的预报效果进行评价。结果显示,在情景一下,各季节PM2.5预报质量浓度与实况质量浓度的标准化平均偏差(NMB)和均方根误差(RMSE)均处于较低水平,表明预报效果均具有较好的稳定性;各季节PM2.5实况质量浓度与预报质量浓度之间的相关系数(r)、一致性指数(IA)、准确率(Q)和级别预报准确率(G)均处于较高水平,其中Q值均>79%,G值均>80%,表明各季节PM2.5实况质量浓度与预报质量浓度趋势的吻合程度较高。情景一各季节PM2.5预报质量浓度与实况质量浓度的NMB和RMSE均低于情景... 相似文献
309.
有限单元算法在水质模拟中的应用研究 总被引:1,自引:1,他引:0
利用模拟河流水质的二维水质模型和有限单元算法,使用MATLAB软件进行计算程序的编写,开展该模型和有限单元算法在三峡库区水质模拟的适用性研究。有限单元法的基本思路是把一个连续的环境空间离散为若干个单元,每一个单元都可以是作为一个完全混合的子系统,通过对每一个单元建立质量平衡方程,从而建立起体系模型。模拟因子包括:BOD5、COD、NH3-N三项。由计算值与监测值进行比较后可知,与监测值误差最大的为NH3-N,可达23.8%;最小的为BOD5,误差为5.3%。由此可以说明,本课题的用于三峡水库水质预测的二维水质模型具有较高的精度,能够用来模拟预测三峡水库蓄水以后的水质变化状况。 相似文献
310.
长江口水体中重金属形态交换过程的研究 总被引:12,自引:2,他引:10
研究了重金属在水体中溶解态和颗粒态的含量分布,并以一个代表性水平剖面和垂直剖面分析了金属形态交换过程。其动态交换是,重金属由颗粒态沿水平方向交换时向溶解态转化,形态转化强度为Ni〉Fe〉Co〉Cu〉Mn〉Pb;重金属的垂向交换过程,都是被铁锰(水合)氧化物及有机质吸附,向金属铁锰氧化物态转化,形态转化强度为Pb〉Cu〉Mn〉Fe〉Ni〉Co,最后得出长江口海域金属污染程度及环境现状。 相似文献