全文获取类型
收费全文 | 2381篇 |
免费 | 52篇 |
国内免费 | 356篇 |
专业分类
安全科学 | 90篇 |
废物处理 | 145篇 |
环保管理 | 204篇 |
综合类 | 778篇 |
基础理论 | 523篇 |
环境理论 | 1篇 |
污染及防治 | 714篇 |
评价与监测 | 147篇 |
社会与环境 | 154篇 |
灾害及防治 | 33篇 |
出版年
2023年 | 23篇 |
2022年 | 99篇 |
2021年 | 40篇 |
2020年 | 28篇 |
2019年 | 35篇 |
2018年 | 81篇 |
2017年 | 74篇 |
2016年 | 71篇 |
2015年 | 85篇 |
2014年 | 108篇 |
2013年 | 219篇 |
2012年 | 127篇 |
2011年 | 136篇 |
2010年 | 113篇 |
2009年 | 137篇 |
2008年 | 157篇 |
2007年 | 118篇 |
2006年 | 113篇 |
2005年 | 70篇 |
2004年 | 99篇 |
2003年 | 93篇 |
2002年 | 71篇 |
2001年 | 123篇 |
2000年 | 68篇 |
1999年 | 57篇 |
1998年 | 42篇 |
1997年 | 35篇 |
1996年 | 27篇 |
1995年 | 45篇 |
1994年 | 18篇 |
1993年 | 25篇 |
1992年 | 33篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 12篇 |
1966年 | 5篇 |
1965年 | 5篇 |
1959年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有2789条查询结果,搜索用时 140 毫秒
831.
Technical developments have now made it possible to emplace granular zero-valent iron (Fe(0)) in fractured media to create a Fe(0) fracture reactive barrier (Fe(0) FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe(0) FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe(0) FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first-order parameter that can be used directly in readily available numerical simulators. 相似文献
832.
Jeran Z Mrak T Jaćimović R Batic F Kastelec D Mavsar R Simoncic P 《Environmental pollution (Barking, Essex : 1987)》2007,146(2):324-331
Two country-wide surveys using epiphytic lichens as biomonitors of atmospheric pollution carried out during 2000 and 2001 in Slovenia were compared with surveys in 1991 and 1992. In the first survey, epiphytic lichen cover was studied in more than 500 plots of the 4 x 4 km national grid carried out within the framework of forest decline inventories. In the second survey, the epiphytic lichen Hypogymnia physodes (L.) Nyl., was collected on a 16 x 16 km bioindication grid and analysed for S, N, As, Br, Ce, Cd, Cr, K, La, Mo, Rb, Sb, Th, U and Zn contents. Only 'forested area' sampling points were included in the present study. Lichen cover was low, with about 70% of plots with less than 10% foliose lichen cover. No relationship was found between Hypogymnia trace element, N and S concentrations and foliose epiphytic lichen cover. 相似文献
833.
Recycled vertical flow constructed wetland (RVFCW)--a novel method of recycling greywater for irrigation in small communities and households 总被引:1,自引:0,他引:1
The use of greywater for irrigation is becoming increasingly common. However, raw greywater is often contaminated and can cause environmental harm and pose health risks. Nevertheless, it is often used without any significant pretreatment, a practice mistakenly considered safe. The aim of this study was to develop an economically sound, low-tech and easily maintainable treatment system that would allow safe and sustainable use of greywater for landscape irrigation in small communities and households. The system is based on a combination of vertical flow constructed wetland with water recycling and trickling filter, and is termed recycled vertical flow constructed wetland (RVFCW). The RVFCW's properties, removal efficiency, hydraulic parameters and feasibility were studied, as well as the environmental effects of the treated greywater, as reflected by soil and plant parameters over time. The RVFCW was efficient at removing virtually all of the suspended solids and biological oxygen demand, and about 80% of the chemical oxygen demand after 8h. Fecal coliforms dropped by three to four orders of magnitude from their initial concentration after 8h, but this was not always enough to meet current regulations for unlimited irrigation. The treated greywater had no significant negative impact on plants or soil during the study period. The feasibility analysis indicated a return over investment after approximately three years. We concluded that the RVFCW is a sustainable and promising treatment system for greywater use that can be run and maintained by unskilled operators. 相似文献
834.
835.
浮萍生长及其除磷效率的影响因素的研究 总被引:2,自引:0,他引:2
磷是藻类增殖的限制因子,是引起水体富营养化的关键营养物质.有效除磷,能在很大程度上减轻水体的富营养化.利用浮萍科植物吸收转化污水中的营养物质引起了越来越多研究者的关注,但对浮萍科植物除磷效果的影响因素的研究相对较少.以少根紫萍(Spirodela oligorrhiza)为供试材料,以完全培养液为处理对象,研究了培养液pH、少根紫萍初始放养密度对其生长及除磷效率的影响.结果表明:少根紫萍能够耐受的最低pH在4左右,在pH=5~9能正常生长,在pH=6~8具有较高的TP去除率,最高去除率可达84.1%;少根紫萍的相对增长率随其初始放养密度的增加而降低,但其鲜重增长量、平均增长速率、TP去除率及平均TP去除速率均随着初始放养密度的增加而增加. 相似文献
836.
837.
838.
839.
A biological test system is proposed for assessing the toxicity of multicomponent wastes stored in the natural environment, with sewage sludge being used as an example. The principles of creating a test system and ranking the samples of multicomponent masses with respect to environmental hazard are discussed. 相似文献
840.
在白银露天矿污染气象站五年的污染气象观测基础上,分析了采场粉尘浓度与污染源强度和气象因素之间的相关性,提出了粉尘污染预报的模式和方法,其准确率达到66.9%。并以粉尘污染预报模式为依据。提出了污染源控制管理模式。试验表明利用本模式对污染源实施控制管理具有实用意义和价值。 相似文献