全文获取类型
收费全文 | 267篇 |
免费 | 19篇 |
国内免费 | 61篇 |
专业分类
安全科学 | 12篇 |
环保管理 | 101篇 |
综合类 | 126篇 |
基础理论 | 25篇 |
污染及防治 | 70篇 |
评价与监测 | 6篇 |
社会与环境 | 2篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 22篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 27篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有347条查询结果,搜索用时 15 毫秒
71.
进出水方式对高负荷浅层渗滤净化生活污水效果的影响 总被引:2,自引:0,他引:2
为研究农村分散住户用水不均匀和排放泵井运行不连续条件下高负荷地下浅层渗滤系统的净化效果,建立渗滤试验柱,以实际生活污水为进水,在12.5 cm.d-1日均水力负荷下,比较连续进水、间歇进水和自由排水、间歇排水对实际生活污水净化效果的影响。结果表明,各渗滤柱对NH4+-N的平均去除率均大于96%。对COD的平均去除率为41.2%~67.7%,其中采用间歇进水、间歇排水方式的渗滤柱去除率最低,但出水仍可达到GB8978—1996《污水综合排放标准》中二级标准。各渗滤柱对TN的平均去除率为17.5%~37.2%,其中采用间歇进水、间歇排水的渗滤柱平均去除率最高,表明强化反硝化作用是提高脱氮效率的主要途径。对TP的平均去除率为51.0%~78.0%,其中采用连续进水、间歇排水的渗滤柱平均去除率最高,表明延长污水停留时间、增加与填料的接触面积能增强对TP的去除效果。间歇进水、间歇排水方式下,渗滤柱对COD的去除效果有所下降,但是对N、P营养盐的综合去除效果最好。 相似文献
72.
通过工程实例讨论了人工快速渗滤系统(CRI)的工艺过程和处理效果,结果除总磷外,处理生活污水其出水CODCr为5. 0~2 6 . 0mg L ,SS为1 .7~10. 0mg L ,NH3 N为0 . 30~2 .31mg L ;处理受污染的河流水时,其出水CODCr为8. 0~2 6 . 0mg L ,BOD5为1. 0~6 . 0mg L ,SS为2. 0~6 .0mg L ,NH3 N为0 . 17~2. 5 4mg L ,均能达到相应的处理要求,是值得推广的一项新型处理工艺。 相似文献
73.
Wesley P. James John Warinner Michael Reedy 《Journal of the American Water Resources Association》1992,28(3):623-635
ABSTRACT: A computer model was developed, based on the Green-Ampt infiltration equation, to computed rainfall excess for a single precipitation event. The model requires an estimate of parameters related to hydraulic conductivity, wetting front section, and fillable porosity of the soil layers. Values of parameters were estimated from soil textural averages or regression equations based on percent sand, percent clay, and porosity. Average values of effective porosity and wetting front suction were largely acceptable due to the relatively low variability and low model sensitivity to the parameters. Hydraulic conductivity was the most erratic constituent of the loss rate computation due to the high variability and the high sensitivity of the computed infiltration to the parameter. The performance of the Green-Ampt infiltration model was tested through a comparison with the SCS curve number procedure. Seven watersheds and 23 storms with precipitation of one inch or greater were used in the comparison. For storms with less than one inch of rainfall excess, the SCS curve number procedure generally gave the best results; however, for six of the seven storms with precipitation excess greater than one inch, the Green-Ampt procedure delivered better results. In this comparison, both procedures used the same initial abstractions. The separation of rainfall losses into infiltration, interception, and surface retention is, in theory, an accurate method of estimating precipitation excess. In the second phase of the study using nine watersheds and 39 storms, interception and surface retention losses were computed by the Horton equations. Green-Ampt and interception parameters were estimated from value sin the literature, while the surface retention parameter was calibrated so that the computed runoff volumes matched observed volumes. A relationship was found between the surface retention storage capacity and the 15-day antecedent precipitation index, month of year, and precipitation amount. 相似文献
74.
D. G. Guerrant W. W. Miller C. N. Mahannah R. Narayanan 《Journal of the American Water Resources Association》1990,26(1):127-134
ABSTRACT: Little quantitative site-specific infiltration, runoff and sediment transport data for Tahoe Basin soils under varying storm events or stage of development are available. Modular (Ml), F-type (M2), Impact nozzle (M3), and Impact-Fan nozzle (M4) rainfall simulators were evaluated as to their practicality and ability to characterize infiltration for the Cagwin Soil Series within the Tahoe Basin. Three slope (0–15,15–30, >30%) and four plot conditions (natural with duff [P1], natural without duff [P2], disturbed without duff [P3], and disturbed with duff [P4]) were studied. The measured data were incorporated into a modified Philip's infiltration model and multiple non-linear regression analyses were used to examine relationships between method, slope, plot condition, and infiltration characteristics.t Simulation methods Ml and M4 produced statistically similar (P=0.01) infiltration data, as did M2 and M3 which produced lower infiltration rates. All were found suitable for use in Sierra Nevada watersheds. Ml was considered most practical. Slope had negligible effect on infiltration. The plot condition was found to significantly influence infiltration, and the effect of each plot condition was significantly different. Final infiltration rates ranged from 4.7 to 6.2 cm/hr. Thus, the Cagwin soil demonstrated moderate to high infiltration rates even when exposed to extreme storm conditions (8–10 cm/hr). 相似文献
75.
Wesley P. James Keu Whan Kim 《Journal of the American Water Resources Association》1990,26(4):587-596
ABSTRACT: A distributed watershed model was developed to mathematically simulate overland and channel flow for a single-event storm. The modeled watersheds in the study were subdivided into rectangular grid elements. All hydrologically significant parameters, such as land slope, rainfall and precipitation excess, were assumed to be uniform within each element. The Green-Ampt method was adopted to generate precipitation excess for each element during the simulation period. A two-dimensional diffusion wave model was used for overland flow routing and an iterative Alternative Direction Implicit scheme was used to solve the simultaneous overland flow equations. Once the overland flow became inflow to the channel, a one-dimensional dynamic wave flood routing technique, based on a four-point, implicit, non-linear finite difference solution of the St. Venant equation of unsteady flow, was applied. A limited number of comparisons were made between simulated and observed hydrographs for areas of about one square mile. Given the appropriate parameters, the model was able to accurately simulate runoff for single-event storms. This paper describes a distributed watershed model developed to simulate overland and channel flow. Comparisons were made between simulated and observed hydrographs for three watersheds. The model was able to accurately simulate the runoff for single-event storms using 61-m by 61-m (200 ft by 200 ft) watershed grid elements. 相似文献
76.
77.
78.
79.
Flushing soils contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) with a permanganate (MnO4−) solution has been shown to reduce the solvent content of the soil. Experiments were performed to quantify the rate at which KMnO4 oxidizes aqueous solutions of PCE over a range of concentrations. In a series of homogeneous reactors, aqueous phase PCE concentrations were monitored over time in nine experimental trials with excess oxidant concentrations ranging from 5 to 30 g/l. Analysis of the data was performed to quantify the oxidation reaction order with respect to PCE and KMnO4 and the reaction rate constant. The reaction between PCE and KMnO4 was determined to be first-order with respect to both PCE and KMnO4 with an overall specific reaction rate coefficient of 2.45±0.65 M−1 min−1. 相似文献
80.
人工快速渗滤系统对污染物的去除机制 总被引:9,自引:0,他引:9
人工快速渗滤系统(CRI)是在传统的污水快速渗滤处理系统(RI)的基础上发展起来的一种新型的污水土地处理技术.通过对CRI的模拟,揭示了非生物机制与生物机制对有机物、营养元素的降解机制.结果表明,CRI对污水中污染物的去除是在非生物机制与生物机制协同作用下完成的.对污水中的有机物和氮的降解以生物机制为主、非生物机制为辅;对磷的降解则以非生物机制为主、生物机制为辅.生物机制对有机物、氮的去除占70%以上,非生物机制对磷的去除占61.9%.系统中氮转化以硝化效果为主,反硝化效果较弱. 相似文献