全文获取类型
收费全文 | 63篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 1篇 |
环保管理 | 3篇 |
综合类 | 25篇 |
基础理论 | 18篇 |
污染及防治 | 7篇 |
评价与监测 | 3篇 |
社会与环境 | 6篇 |
灾害及防治 | 3篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 1篇 |
2007年 | 7篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有72条查询结果,搜索用时 296 毫秒
61.
在宁夏盐池毛乌素沙地选取50 m×50 m规格的典型无明显结皮的半固定沙地和有明显结皮的固定沙地各1块,应用Ripley's K函数的双变量点格局分析方法,对飞播条件下混播区油蒿(Artemisia ordosica)、羊柴(Hedysarum laeve)和花棒(Hedysarurn scoparium)3种常用治沙植物种内和种间的空间关联性进行了研究.结果表明,3种飞播植物在不同的演替阶段基本上以集群分布为主要特征,在尺度为0~25m范围内,单种分布格局均出现了最大集聚强度.如果实施单独飞播,油蒿密度不宜过高,以集聚强度高的集群分布形式为最佳,羊柴以集聚强度低的集群分布形式为最佳,花棒由于其散生的特性而不适合单独飞播.油蒿和羊柴之间空间关联性呈显著负相关关系,故油蒿和羊柴不适合大面积高密度混播;羊柴和花棒之间呈正相关关系,因此以羊柴为主混播一定比例的花棒效果较好;花棒和油蒿不适合同时混播,但是可将油蒿飞播到有大花棒生长的沙地中. 相似文献
62.
Ivana Teodorović Sonja Kaišarević Kristina Pogrmić-Majkić Ivana Planojević Svetlana Fa Vanja Dakić Jelena Hrubik Branka Glišić Radmila Kovačević 《Environmental Sciences Europe》2011,23(1):1-9
Background
In order to map exceedances of critical atmospheric deposition loads for nitrogen (N) surface data on the atmospheric deposition of N compounds to terrestrial ecosystems are needed. Across Europe such information is provided by the international European Monitoring and Evaluation Programme (EMEP) in a resolution of 50 km by 50 km, relying on both emission data and measurement data on atmospheric depositions. The objective of the article at hand is on the improvement of the spatial resolution of the EMEP maps by combining them with data on the N concentration in mosses provided by the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation) of the United Nations Economic Commission for Europe (UNECE) Long-range Transboundary Air Pollution (LTRAP) Convention.Methods
The map on atmospheric depositions of total N as modelled by EMEP was intersected with geostatistical surface estimations on the N concentration in mosses at a resolution of 5 km by 5 km. The medians of the N estimations in mosses were then calculated for each 50 km by 50 km grid cell. Both medians of moss estimations and corresponding modelled deposition values were ln-transformed and their relationship investigated and modelled by linear regression analysis. The regression equations were applied on the moss kriging estimates of the N concentration in mosses. The respective residuals were projected onto the centres of the EMEP grid cells and were mapped using variogram analysis and kriging procedures. Finally, the residual and the regression map were summed up to the map of total N deposition in terrestrial ecosystems throughout Europe.Results and discussion
The regression analysis of the estimated N concentrations in mosses and the modelled EMEP depositions resulted in clear linear regression patterns with coefficients of determination of r 2 = 0.62 and Pearson correlations of r p = 0.79 and Spearman correlations of r s = 0.70, respectively. Regarding the German territory a nationwide mean of 18.1 kg/ha/a (standard deviation: 3.49 kg/ha/a) could be derived from the resulting map on total N deposition in a resolution of 5 km by 5 km. Recent updates of the modelled atmospheric deposition of N provided a similar estimate for Germany.Conclusions
The linking of modelled EMEP data on the atmospheric depositions of total N and the accumulation of N in mosses allows to map the deposition of total N in a high resolution of 5 km by 5 km using empirical moss data. The mapping relies on the strong statistical relationship between both processes that are physically and chemically related to each other. The mapping approach thereby relies on available data that are both based on European wide harmonized methodologies. From an ecotoxicological point of view the linking of data on N depositions and those on N bioaccumulation can be considered a substantial progress. 相似文献63.
64.
分析了南昌市绿化的地理背景、存在的差距和主要问题。从重建城市生态及完善城市防灾体系的角度,因地制宜地提出了发展特色鲜明的城市绿地系统的相应对策与措施。 相似文献
65.
基于连续介质力学及有限变形理论 ,建立了用于三维板料成形过程模拟的有限元模型 ,开发了动力显式算法的板料成形过程模拟的有限元分析程序DESSFORMM3D。最后 ,用笔者新开发的动力显式弹粘塑性有限元程序对不同压边情况下半球形件的拉深过程进行分析 ,并把数值结果与实验进行对比 ,验证了软件的计算结果。 相似文献
66.
This study describes three couples a t risk for homozygous β-thalassaemia in which one of the partners carried a short deletion β-thalassaemia defect. Detection of short deletions in trophoblast DNA was accomplished by the very simple procedure of non-denaturing polyacrylamide gel electrophoresis. This method may be applied to detect β-thalassaemia mutations due to deletion or addition of more than two nucleotides. 相似文献
67.
68.
三峡库区(湖北部分)珍稀濒危保护植物资源现状 总被引:3,自引:1,他引:2
对长江三峡库区(湖北部分)宜昌,兴山,秭归和巴东4县的调查表明,三峡库区天然分布有殂稀濒危植物40种,隶属27科36属,分别占湖北省总数62种和全国总数388种的64.5%和10.3%;天然分布有国家重点保护植物131种,隶属27科73属,分别占湖北省总数的206种和全国总数的1700多种的63.6%和7.7%,其中国家一级保护植物有红豆杉、南方红豆杉、珙酮、光叶珙酮4种。国家二级保护植物有金毛狗 相似文献
69.
70.
较详细地介绍了一种高效除砷剂的实验室除砷应用研究。该除砷剂可用两种不同的活化方式进行活化处理,可用于不同的使用场合。一种适用于高砷地区的家庭生活饮用水除砷处理,另一种可用于高含砷量的工业废水或矿井水除砷处理。 相似文献