全文获取类型
收费全文 | 2980篇 |
免费 | 309篇 |
国内免费 | 879篇 |
专业分类
安全科学 | 353篇 |
废物处理 | 137篇 |
环保管理 | 254篇 |
综合类 | 1838篇 |
基础理论 | 452篇 |
污染及防治 | 654篇 |
评价与监测 | 153篇 |
社会与环境 | 152篇 |
灾害及防治 | 175篇 |
出版年
2024年 | 15篇 |
2023年 | 53篇 |
2022年 | 176篇 |
2021年 | 197篇 |
2020年 | 214篇 |
2019年 | 121篇 |
2018年 | 133篇 |
2017年 | 151篇 |
2016年 | 137篇 |
2015年 | 207篇 |
2014年 | 210篇 |
2013年 | 310篇 |
2012年 | 280篇 |
2011年 | 294篇 |
2010年 | 229篇 |
2009年 | 185篇 |
2008年 | 214篇 |
2007年 | 183篇 |
2006年 | 156篇 |
2005年 | 135篇 |
2004年 | 107篇 |
2003年 | 81篇 |
2002年 | 65篇 |
2001年 | 45篇 |
2000年 | 49篇 |
1999年 | 44篇 |
1998年 | 42篇 |
1997年 | 27篇 |
1996年 | 15篇 |
1995年 | 27篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有4168条查询结果,搜索用时 359 毫秒
81.
82.
83.
以地理信息系统为平台进行地震灾害研究,建立具有强大空间分析功能的信息系统,将发挥快速、准确的辅助决策作用.本文剖析了小城镇地震应急反应模式存在的弊端,明确了灾害空间的概念,并提出小城镇空间数据库的建库及三维可视化的技术方案.在基础信息数字化和可视化的基础上,开发了小城镇地震数字仿真与应急调度系统,实现了基于地震数字仿真结果,在相关数据库支持下进行地震应急调度决策.实践证明:该系统的运行,有利于小城镇抗震减灾的迅速决策;小城镇空间数据库的建库技术,贴合我国小城镇信息化的现状,技术可行、经济合理. 相似文献
84.
Effects of productivity on biodiversity in forest ecosystems across the United States and China 下载免费PDF全文
In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts. 相似文献
85.
Liang Dong 《中国人口.资源与环境(英文版)》2017,15(3)
<正>After years of complex and challenging negotiations,197countries reached a landmark climate agreement during the 2015 United Nations Framework Convention on Climate Change summit in Paris(the 21st Conference of the Parties(COP21)).Under the Paris Agreement,countries announced actions they plan to take to mitigate their greenhouse gas emissions known as Intended Nationally Determined Contributions.Although there is 相似文献
86.
Liang Lu Yuqi Jin Hongmei Liu Xiaojun Ma Kunio Yoshikawa 《Waste management (New York, N.Y.)》2014,34(1):79-85
Nitrogen evolution was studied during the co-combustion of hydrothermally treated municipal solid wastes (HT MSW) and coal in a bubbling fluidized bed (BFB). HT MSW blending ratios as 10%, 20% and 30% (wt.%) were selected and tested at 700, 800, 900 °C. Emissions of NO and N2O from blends were measured and compared with the results of mono-combustion trials. Moreover, concentrations of precursors like NH3 and HCN were also quantified. The results are summarized as follows: NO emissions were predominant in all the cases, which rose with increasing temperature. The blending of HT MSW contributed to the NO reduction. N2O emissions decreased with temperature rising and the blending of HT MSW also presented positive effects. At 30% HT MSW addition, both NO and N2O emissions showed the lowest values (391.85 ppm and 55.33 ppm, respectively at 900 °C). For the precursors, more HCN was detected than NH3 and both played important roles on the gas side nitrogen evolution. 相似文献
87.
Zhang Xiaoli Cai Xuewei Wang Zhaowei Yang Xing Li Shan Liang Guiwei Xie Xiaoyun 《Environmental science and pollution research international》2021,28(11):13375-13393
Environmental Science and Pollution Research - A large amount of biochar-derived dissolved organic matter (BDOM) will be released into the environment with biochars application into repairing... 相似文献
88.
Xu Su Gong Ping Ding Wen Wu Shengchun Yu Xinwei Liang Peng 《Environmental science and pollution research international》2021,28(47):66990-66997
Environmental Science and Pollution Research - Paspalum distichum L. was tested to evaluate their phytoremediation capacity for Hg contaminated soil through analyzing the dissipation of Hg in soil... 相似文献
89.
容积负荷对ABR-MBR工艺反硝化除磷性能的影响 总被引:2,自引:2,他引:0
采用连续流ABR-MBR组合工艺处理生活污水,研究不同容积负荷(volume loading rate,VLR)对该工艺反硝化除磷性能的影响,获得最佳工艺参数.试验考察ABR进水容积负荷(以COD计,下同)分别为0.76、1.01、1.51和2.27 kg·(m~3·d)~(-1)时系统去碳脱氮除磷的性能,并在各ABR容积负荷条件下考察MBR容积负荷对MBR反应器硝化性能的影响.结果表明,在ABR进水容积负荷为1.51 kg·(m~3·d)~(-1)的条件下,系统A2隔室COD去除量最大,并在MBR容积负荷为0.462 kg·(m~3·d)~(-1)时,MBR反应器中实现了短程硝化,系统NH_4~+-N和TN去除率分别达到90%和72%以上,厌氧释磷量为7.41 mg·L~(-1),缺氧吸磷量达到15.42 mg·L~(-1),出水PO_4~(3-)-P浓度低于0.5 mg·L~(-1),这表明短程硝化更有利于强化ABR-MBR系统的反硝化除磷性能. 相似文献
90.