全文获取类型
收费全文 | 3191篇 |
免费 | 201篇 |
国内免费 | 283篇 |
专业分类
安全科学 | 331篇 |
废物处理 | 58篇 |
环保管理 | 501篇 |
综合类 | 1761篇 |
基础理论 | 229篇 |
环境理论 | 6篇 |
污染及防治 | 244篇 |
评价与监测 | 389篇 |
社会与环境 | 96篇 |
灾害及防治 | 60篇 |
出版年
2024年 | 10篇 |
2023年 | 46篇 |
2022年 | 54篇 |
2021年 | 84篇 |
2020年 | 92篇 |
2019年 | 61篇 |
2018年 | 68篇 |
2017年 | 88篇 |
2016年 | 119篇 |
2015年 | 111篇 |
2014年 | 157篇 |
2013年 | 194篇 |
2012年 | 201篇 |
2011年 | 246篇 |
2010年 | 144篇 |
2009年 | 182篇 |
2008年 | 163篇 |
2007年 | 192篇 |
2006年 | 180篇 |
2005年 | 141篇 |
2004年 | 95篇 |
2003年 | 147篇 |
2002年 | 118篇 |
2001年 | 103篇 |
2000年 | 85篇 |
1999年 | 107篇 |
1998年 | 90篇 |
1997年 | 80篇 |
1996年 | 58篇 |
1995年 | 45篇 |
1994年 | 52篇 |
1993年 | 43篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1971年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有3675条查询结果,搜索用时 750 毫秒
881.
通过对江苏省苏南地区大气环境中主要污染因子二氧化硫、二氧化氮及可吸入颗粒物2009年及2005~2009五年来变化情况及原因进行分析,提出污染控制对策和治理措施。 相似文献
882.
通过多年实地调研,认为拦网养殖、湖滩地种植、过度捕捞、沿湖城镇生活污水污染等是渔业资源不断减少主要原因,并根据实际情况提出防治对策。 相似文献
883.
In an analytical model of symmetric countries with mobile capital and local or transboundary pollution we investigate whether competition in emissions taxes (or emissions caps) and capital taxes leads to efficient outcomes when governments act strategically. When they have capital taxes and emissions caps at their disposal, they refrain from taxing capital and set their caps inefficiently lax [efficient] for transboundary [local] pollution. When they have the option to tax capital and emissions, capital is subsidized [untaxed] and emissions taxes are inefficiently low [efficient] for transboundary [local] pollution. In case of transboundary pollution emissions caps are Pareto-superior to emissions taxes. That holds regardless of whether the environmental policy is applied as stand-alone policy or combined with capital tax competition. 相似文献
884.
Jeannine H. Richards 《Conservation biology》2021,35(5):1496-1506
Epiphytes, air plants that are structurally dependent on trees, are a keystone group in tropical forests; they support the food and habitat needs of animals and influence water and nutrient cycles. They reach peak diversity in humid montane forests. Climate predictions for Central American mountains include increased temperatures, altered precipitation seasonality, and increased cloud base heights, all of which may challenge epiphytes. Although remaining montane forests are highly fragmented, many tropical agricultural systems include trees that host epiphytes, allowing epiphyte communities to persist even in landscapes with lower forest connectivity. I used structural equations models to test the relative effects of climate, land use, tree characteristics, and biotic interactions on vascular epiphyte diversity with data from 31 shade coffee farms and 2 protected forests in northern Nicaragua. I also tested substrate preferences of common species with randomization tests. Tree size, tree diversity, and climate all affected epiphyte richness, but the effect of climate was almost entirely mediated by bryophyte cover. Bryophytes showed strong sensitivity to mean annual temperature and insolation. Many ferns and some orchids were positively associated with bryophyte mats, whereas bromeliads tended to establish among lichen or on bare bark. The tight relationships between bryophytes and climate and between bryophytes and vascular epiphytes indicated that relatively small climate changes could result in rapid, cascading losses of montane epiphyte communities. Currently, shade coffee farms can support high bryophyte cover and diverse vascular epiphyte assemblages when larger, older trees are present. Agroforests serve as valuable reservoirs for epiphyte biodiversity and may be important early-warning systems as the climate changes. 相似文献
885.
886.
Oscar Wambuguh 《Resources, Conservation and Recycling》2011,55(8):782-784
Although systematic studies tracking junk mail sent to residential homes are lacking, available reports indicate it is a growing problem in many urban centers worldwide. Junk mail increases the number of trees harvested each year, consumes a substantial amount of energy, causes pollution to air, water and soil and wastes a substantial amount of time sorting, mailing and recycling. Junk mail collected at one residence in the United States for a period of one full year is analyzed to find out the main contributors to this urban problem, what residents should do to reduce or eliminate it. Results indicate that three major businesses are responsible for over 70% of total junk mail sent (n = 1255) including credit card, mortgage and insurance corporations. To encourage environmental sustainability, several strategies that can help businesses reduce junk mail are suggested including new advertising techniques, use of other outlets like billboards, outreach events in social functions and adopting eco-friendly techniques in any junk mail production. Considering the revenue and jobs created from junk mail business, and the absence of government regulation and lack of consensus amongst individuals, environmental groups and businesses on what needs to be done; individuals are urged to explore ways to mitigate the problem and a number of recommendations are given. 相似文献
887.
城市区域大气环境与各天气状况下的辐射特征 总被引:2,自引:0,他引:2
以低纬高原城市昆明为研究对象,分析了各种天气状况下城市内,外不同波长辐射的分布特征,变化规律及其差异,得出1.造成城内外差异的主要原因午前是大气污染状况,而在污染程度较小的午后,则是天气状况;2.各波长辐射日总量对午前总量的分配率受大气环境和天气状况的影响,城内外差异十分显著;3.红外和紫外辐射的百分率值均大于大气上界的百分率值,而可见光则反之;各辐射百分率城内外差值午前午后显相反分布。 相似文献
888.
针对现有防火分隔技术的不足,以细水雾幕作为新的防火分隔技术,开展了不同细水雾幕雾特性对衰减热辐射影响的数值模拟研究。通过建立长通道模型,在火源和被保护物体中间设置细水雾幕系统,测量有无细水雾幕及不同细水雾特性条件下被保护侧温度及热辐射强度值,来定性定量研究细水雾幕衰减热辐射的效率。模拟结果表明:细水雾幕可以很好的降低被保护侧空间的温度和热辐射强度;衰减热辐射效率随雾滴粒径的减小,喷雾流量的增大,喷头排数增加而增大;另外,其衰减热辐射效率与喷头布置方式有关,上喷方式明显优于下喷方式。研究结果将对现有防火分隔技术的改善提供帮助和技术支持。 相似文献
889.
火电厂较一般的工业项目源强较多,以某35万千瓦超临界间接空冷火电厂为例,采用Cadna/A噪声预测软件预测了投产后产生的噪声影响,预测结果表明火电厂企业采取相应的降噪措施后,厂界噪声能够满足《工业企业厂界环境噪声排放标准》(GB12348-2008)中的3类标准要求,对环境敏感点昼夜噪声预测值能满足《声环境质量标准》(GB3096-2008)的2类标准要求,说明该项目的降噪设计可行。 相似文献
890.
We investigated the efficiency and kinetics of the degradation of soluble dyes over the p H range 5.0–9.0 using a method employing microwave radiation in combination with nanoscale zero-valent iron(MW–n ZVI). The n ZVI particles(40–70 nm in diameter) were prepared by a liquid-phase chemical reduction method employing starch as a dispersant.Compared to the removal of Solvent Blue 36 and Reactive Yellow K-RN using only n ZVI,more rapid and efficient dye removal and total organic carbon removal were achieved using MW–n ZVI. The dye removal efficiency increased significantly with decreasing p H, but was negligibly affected by variation in the microwave power. The kinetics of dye removal by MW–n ZVI followed both an empirical equation and the pseudo first-order model, while the kinetics of dye removal using n ZVI could only be described by an empirical equation. It was also concluded that microwave heating of the dye solutions as well as acceleration of corrosion of n ZVI and consumption of Fe(II) were possible reasons behind the enhanced dye degradation. 相似文献