全文获取类型
收费全文 | 917篇 |
免费 | 49篇 |
国内免费 | 139篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 7篇 |
环保管理 | 176篇 |
综合类 | 482篇 |
基础理论 | 199篇 |
污染及防治 | 20篇 |
评价与监测 | 59篇 |
社会与环境 | 126篇 |
灾害及防治 | 23篇 |
出版年
2024年 | 6篇 |
2023年 | 14篇 |
2022年 | 39篇 |
2021年 | 20篇 |
2020年 | 22篇 |
2019年 | 24篇 |
2018年 | 20篇 |
2017年 | 23篇 |
2016年 | 39篇 |
2015年 | 33篇 |
2014年 | 39篇 |
2013年 | 59篇 |
2012年 | 45篇 |
2011年 | 63篇 |
2010年 | 67篇 |
2009年 | 56篇 |
2008年 | 57篇 |
2007年 | 49篇 |
2006年 | 67篇 |
2005年 | 45篇 |
2004年 | 34篇 |
2003年 | 43篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 27篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有1105条查询结果,搜索用时 46 毫秒
891.
广州城区河涌水环境整治工程的实践与认识 总被引:1,自引:1,他引:0
由于生活污水和部分工业废水排入河涌,使广州城区河涌变成纳污通道,生态遭受严重破坏。文中详细分析了河涌水环境整治的有效措施和取得的成效,并对河涌水生态修复等谈了一些认识。 相似文献
892.
新疆北部沙漠边缘植被恢复可能性初探 总被引:2,自引:0,他引:2
古尔班通古特沙漠边缘植被破坏严重,沙丘活化明显,是新疆干旱植被恢复的重点地区之一,一般缺乏地表水补充,其沙丘的水分状况便成为植被生存和恢复过程的关键条件,为探究古尔班通古特沙漠边缘植被恢复的可能性,在植物生长期内对流动沙丘和固定沙丘不同部位的水分状况进行了连续监测,结果表明:沙丘大多数层次含水量月变化与月降水量分布相一致;流动沙丘含水量从上部到下部依次升高;流动沙丘中部和下部稳定湿沙层处在距沙丘表面60 cm以下,且厚度超过100 cm,固定沙丘稳定湿沙层只存在于沙丘中部距沙丘表面60~150 cm内,其厚度不超过100 cm,在一般年份,该地区利用本地种进行植被恢复是可行的. 相似文献
893.
Zoltan Szantoi Arthur H. Chappelka Russell B. Muntifering 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):840-846
Cutleaf coneflower (Rudbeckia laciniata L.) seedlings were placed into open-top chambers in May, 2004 and fumigated for 12 wks. Nine chambers were fumigated with either carbon-filtered air (CF), non-filtered air (NF) or twice-ambient (2×) ozone (O3). Ethylenediurea (EDU) was applied as a foliar spray weekly at 0 (control), 200, 400 or 600 ppm. Foliar injury occurred at ambient (30%) and elevated O3 (100%). Elevated O3 resulted in significant decreases in biomass and nutritive quality. Ethylenediurea reduced percent of leaves injured, but decreased root and total biomass. Foliar concentrations of cell-wall constituents were not affected by EDU alone; however, EDU × O3 interactions were observed for total cell-wall constituents and lignocellulose fraction. Our results demonstrated that O3 altered the physiology and productivity of cutleaf coneflower, and although reducing visible injury EDU may be phytotoxic at higher concentrations. 相似文献
894.
Here, we show for one of the Dutch Rhine River branches that large-scale riverine ecosystem rehabilitation and related vegetation
succession may lead to up to 0.6 m higher river flood levels, because of increased hydraulic roughness. We hydraulically modeled
future succession stages of embanked floodplain vegetation, following from present ecosystem rehabilitation plans for the
124-km-long river IJssel, and found flood levels exceeding the safety levels (related to dike heights). Our models take into
account river engineering measures that are presently carried out, aimed at enhancing the river discharge capacity in order
to meet required safety standards. Our study shows that there is a pressing need for integrated hydraulic-ecological evaluation
of river engineering measures and ecosystem rehabilitation plans in the Rhine embanked floodplains. An important conclusion
also is that hydraulic evaluation of planned vegetation goals only is inadequate, because flow resistance of preceding succession
stages may be higher. 相似文献
895.
选择青藏高原多年冻土区工程迹地的人工恢复植物和紫花针茅草原的优势植物以及对应的土壤样品进行对照,利用原子吸收法分析了它们的矿质元素含量特征。结果表明:多年冻土区工程迹地人工恢复区植物的元素含量:>1 000 μg/g的元素有Ca、P和Na,100~1 000 μg/g的元素有Mn、K、Fe、Mg和Al;而对照紫花针茅草原优势植物的元素含量:>1 000 μg/g的元素有Ca和Na,100~1 000 μg/g的元素有P、Mn、K、Fe、Mg和Al。人工恢复区土壤元素含量:>1 000 μg/g的元素有Ca、Fe和Mn,100~1000 μg/g的元素有Mg、K、Al、P和Na;对照紫花针茅草原土壤元素含量:>1 000 μg/g的元素有Ca、Fe,100~1 000 μg/g的元素有Mn、Mg、Al、K、P和Na。该区域植物和土壤元素含量都属于Ca > K 型。人工恢复植物和对照的紫花针茅草原植物对土壤元素的吸收能力具有较高的相似性。K和Al元素的累积与其他元素没有显著的相关关系,其他元素之间为正相关关系,元素之间的吸收累积属于协同作用,无明显的撷抗作用 相似文献
896.
897.
S. Rokia G. Séré C. Schwartz M. Deeb F. Fournier T. Nehls O. Damas L. Vidal-Beaudet 《Waste management (New York, N.Y.)》2014,34(11):2155-2162
The greening of urban and suburban areas requires large amounts of arable earth that is a non-renewable resource. However, concentration of population in cities leads to the production of high amounts of wastes and by-products that are nowadays partly recycled as a resource and quite systematically exported out of urban areas. To preserve natural soil resources, a strategy of waste recycling as fertile substitutes is proposed. Eleven wastes are selected for their environmental harmlessness and their contrasted physico-chemical properties for their potential use in pedological engineering. The aim is (i) to demonstrate the feasibility of the formulation of fertile substrates exclusively with wastes and (ii) to model their physico-chemical properties following various types, number and proportions of constitutive wastes. Twenty-five binary and ternary combinations are tested at different ratios for total carbon, Olsen available phosphorus, cation exchange capacity, water pH, water retention capacity and bulk density. Dose–response curves describe the variation of physico-chemical properties of mixtures depending on the type and ratio of selected wastes. If these mixtures mainly mimic natural soils, some of them present more extreme urban soil features, especially for pH and POlsen. The fertility of the new substrates is modelled by multilinear regressions for the main soil properties. 相似文献
898.
Mauricio E. Arias Thomas A. Cochrane David Norton Timothy J. Killeen Puthea Khon 《Ambio》2013,42(7):864-876
The Tonle Sap is the largest wetland in Southeast Asia and one of the world’s most productive inland fisheries. The Mekong River inundates the Tonle Sap every year, shaping a mosaic of natural and agricultural habitats. Ongoing hydropower development, however, will dampen the flood pulse that maintains the Tonle Sap. This study established the current underlying relationship among hydrology, vegetation, and human use. We found that vegetation is strongly influenced by flood duration; however, this relationship was heavily distorted by fire, grazing, and rice cultivation. The expected flood pulse alteration will result in higher water levels during the dry season, permanently inundating existing forests. The reduction of the maximum flood extent will facilitate agricultural expansion into natural habitats. This study is the most comprehensive field survey of the Tonle Sap to date, and it provides fundamental knowledge needed to understand the underlying processes that maintain this important wetland. 相似文献
899.
植被演替下植物组成多样性和群落稳定性与土壤团聚体的关系 总被引:1,自引:0,他引:1
为揭示植被自然恢复过程中植物组成多样性和群落稳定性与土壤团聚体的关系,防治水土流失,提高土壤质量.通过野外调查采样,确定并分析黄土高原近150年植被演替不同阶段的植被特征与土壤团聚体数据.结果表明:该过程共有种子植物39科99属128种,优势科是菊科、蔷薇科、禾本科和豆科,优势属是蒿属,单种属是该过程植物属的主体,出现频率较高的植物有大披针薹草、胡枝子、白刺花、水栒子、青蒿、虎榛子、辽东栎、茶条枫、油松、绣线菊、狗娃花等.植物地理成分在属级水平上有11个分布区类型8个变型,温带性质明显,热带性质(R值)与温带性质(T值)的比值(R/T)随恢复年限的增加而降低,R值与R/T值显著正相关,热带成分扩散分布受到限制.植物丰富度呈单峰曲线,在恢复年限为40~70年时最高.依照不同恢复年限对群落稳定性进行排序:70>120>135>150>40>10>20>0年.R值与植物种系分化度(SD值)极显著正相关,T值与稳定性极显著正相关.>5mm粒径团聚体与受热带性质物种驱动的植物丰富度有关.>0.25mm粒径团聚体总体上与群落稳定性保持一致,均受... 相似文献
900.