全文获取类型
收费全文 | 2050篇 |
免费 | 162篇 |
国内免费 | 876篇 |
专业分类
安全科学 | 166篇 |
废物处理 | 48篇 |
环保管理 | 397篇 |
综合类 | 1733篇 |
基础理论 | 274篇 |
污染及防治 | 373篇 |
评价与监测 | 59篇 |
社会与环境 | 23篇 |
灾害及防治 | 15篇 |
出版年
2024年 | 4篇 |
2023年 | 20篇 |
2022年 | 47篇 |
2021年 | 70篇 |
2020年 | 79篇 |
2019年 | 65篇 |
2018年 | 61篇 |
2017年 | 89篇 |
2016年 | 116篇 |
2015年 | 134篇 |
2014年 | 158篇 |
2013年 | 177篇 |
2012年 | 224篇 |
2011年 | 234篇 |
2010年 | 181篇 |
2009年 | 145篇 |
2008年 | 110篇 |
2007年 | 157篇 |
2006年 | 193篇 |
2005年 | 149篇 |
2004年 | 117篇 |
2003年 | 79篇 |
2002年 | 69篇 |
2001年 | 76篇 |
2000年 | 77篇 |
1999年 | 64篇 |
1998年 | 24篇 |
1997年 | 39篇 |
1996年 | 31篇 |
1995年 | 26篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有3088条查询结果,搜索用时 593 毫秒
221.
Recycling of plant materials and agricultural residues for biomethanation was attempted in vials. The methanogenic activities of certain sewage samples have also been tested. Both sterilized and non-sterilized biomasses were used. Biomethanation was carried out with dung samples (cow, goat, buffalo, piggery wastes and poultry wash) as wild populations of microbes and in combination with other microbial isolates (isolated in the laboratory).Biomethanation had been observed to be good in most cases and particularly with the sterilized biomass. Mixed inoculum (dung samples and poultry wash) was found to be best for biomethanation. Of the microbe isolates, isolates from buffalo, pig and paper mill wastes appear to be most effective. Pretreated sawdust and rice straw were found to be good subtrates for biomethanation. Of the different plant biomass used Spirogyra (algae), Ipomea and water hyacinth were most effective whereas Jatropa gossypifolia and Parthenium sp. were the least effective. Biomethanation of Spirogyra was carried out both in anoxic and oxic conditions. Though methane production decreased enormously under oxic conditions, definite methane production continued indicating that the biomethanation process is not exclusively anoxic. Similarly, biomethanation of sewage samples from different sewage treatment plants were carried out with and without isolated methanogens and methane production was found to be moderate. 相似文献
222.
223.
氯化法处理医院废水的研究 总被引:2,自引:0,他引:2
介绍了次氯酸钠法和液氯法2种目前常用的处理医院废水的方法.对2家医院的废水处理过程进行了测试及实验研究.结果表明,这2家医院的废水处理后细菌总数和余氯量未达到国家规定的排放标准.主要原因是加氯量不精确,加氯后的停留时间不足,不能有效杀死废水中的病菌.对加氯量和停留时间的实验研究表明,每吨医院废水中次氯酸钠和液氯的最佳投入量分别为90 g和9 g,加氯后的停留时间不少于60min. 相似文献
224.
C. B. Cluff K. J. DeCook W. G. Matlock 《Journal of the American Water Resources Association》1971,7(4):726-739
ABSTRACT .Many growing municipalities near irrigated agriculture are advocating a transfer of water now utilized for irrigation to municipal use. Alternatives are presented whereby this water can be transferred to municipal use in exchange for treated sewage effluent. The irrigation water would in effect be cycled through the municipal system prior to use on the farms. A case study of the Tucson region illustrates the relevant legal, economic and technical aspects. Effluent could be delivered to irrigators in Avra Valley at a cost less than that now paid for water pumped from declining water tables. In return the City of Tucson could import ground water now being used for irrigation through an existing pipeline which presently cannot be used because of a court injunction obtained by the irrigators. It appears that such an exchange agreement could be made without modification of existing statutory law. Similar exchange arrangements may prove to be feasible in other regions containing irrigated agriculture. Increased efficiency of water use can be achieved avoiding external effects which commonly arise in a direct transfer and are difficult to evaluate. High quality water is allocated to municipal use whereas nutrient-rich sewage effluent is transferred to irrigation. 相似文献
225.
为了探讨火电厂除灰水中的粉煤灰(含炉渣)对炼油厂含碱污水中石油类、COD(cr)等污染物的吸附处理效果,根据某单位现场情况,将炼油厂含碱污水送入火电厂除灰沟→经充分混合排入储灰场→并经长时间沉降分离的流程进行模拟试验,结果表明:由于粉煤灰的吸附作用,显著降低了炼油厂含碱污水中的石油类、COD(cr)、挥发酚、碳化匕物等污染物。 相似文献
226.
227.
区域洪涝灾害风险的模糊综合评价与预测 总被引:1,自引:0,他引:1
以广西1992~2006年洪涝灾情数据为基础,选取适当的评价指标,用基于遗传算法、特征值法和优化算法的投影寻踪法和层次分析法确定各评价指标的分类权重和排序权重,用优化算法进行综合得到组合权重,经过加权求和得出洪涝灾害的模糊综合评价,进而对15个评价对象进行了分类排序,其分类结果很好地反映了洪涝灾情的实际情况。在以上模糊综合评价结果的基础上,利用距离贴近度进一步计算和分析各个评价指标之间的贴近度,并由择近原则确定各个评价指标之间在洪涝灾害评价中的相关程度。同时,建立了基于改进的灰色GM(1,1)的时间响应式的灾变年份预测模型。 相似文献
228.
结合我国热电联产项目发展现状,对其存在的主要问题进行了系统分析,从优化布局、清洁生产、节能降耗、推广热电冷联供、强化运行和管理等方面,提出了促进热电联产项目健康发展的对策建议. 相似文献
229.
Peter N. Nemetz Herbert D. Drechsler 《Journal of the American Water Resources Association》1979,15(5):1374-1384
ABSTRACT: There is a significant misallocation of resources in the construction and operation of municipal sewage treatment systems in North America. Central to this misallocation is the inadequate evaluation of alternative treatment technologies, alternative distributions of responsibility for waste treatment, and alternative mechanisms for inducing compliance with treatment system requirements. Perverse incentives in the current institutional structure limit the scope of alternatives examined by decisionmakers. Determination of the least cost solution to the problem of urban effluent abatement requires mathematical modeling for the delineation of optimal treatment strategies on a system wide basis. The adoption of modern methods of systems analysis can identify significant opportunities for the reduction of economic waste in the treatment of municipal sewage. 相似文献
230.
Michael Donovan Charles A. Job William C. Sonzogni 《Journal of the American Water Resources Association》1981,17(1):23-28
ABSTRACT: The Illinois v. Milwaukee Federal District Court decision is the most far reaching application yet of the federal common law of nuisance to interstate water pollution conflicts. Although a Federal Appelate Court recently rescinded part of the district court decision, Milwaukee must still upgrade its metropolitan sewage system to a level beyond that required by federal and state regulations. The improvements must be completed with or without federal aid. The case points out the apparent inability of the Clean Water Act, the most comprehensive federal legislation affecting the nation's water quality, to deal with certain interstate water quality conflicts. The Milwaukee decision could set a precedent for similar settlements elsewhere which may in turn affect the U.S. Environmental Protection Agency's water quality clean up program. A more integrated, ecosystem conscious approach to management of shared water resources (e.g., the Great Lakes) would help reduce the need for court decisions like Illinois v. Milwaukee. 相似文献