全文获取类型
收费全文 | 2467篇 |
免费 | 265篇 |
国内免费 | 922篇 |
专业分类
安全科学 | 517篇 |
废物处理 | 28篇 |
环保管理 | 145篇 |
综合类 | 1891篇 |
基础理论 | 522篇 |
污染及防治 | 157篇 |
评价与监测 | 100篇 |
社会与环境 | 132篇 |
灾害及防治 | 162篇 |
出版年
2024年 | 19篇 |
2023年 | 80篇 |
2022年 | 67篇 |
2021年 | 99篇 |
2020年 | 99篇 |
2019年 | 88篇 |
2018年 | 79篇 |
2017年 | 84篇 |
2016年 | 103篇 |
2015年 | 142篇 |
2014年 | 285篇 |
2013年 | 159篇 |
2012年 | 158篇 |
2011年 | 152篇 |
2010年 | 158篇 |
2009年 | 191篇 |
2008年 | 217篇 |
2007年 | 140篇 |
2006年 | 111篇 |
2005年 | 99篇 |
2004年 | 67篇 |
2003年 | 74篇 |
2002年 | 46篇 |
2001年 | 62篇 |
2000年 | 61篇 |
1999年 | 75篇 |
1998年 | 86篇 |
1997年 | 84篇 |
1996年 | 88篇 |
1995年 | 99篇 |
1994年 | 90篇 |
1993年 | 64篇 |
1992年 | 46篇 |
1991年 | 86篇 |
1990年 | 32篇 |
1989年 | 54篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 2篇 |
排序方式: 共有3654条查询结果,搜索用时 62 毫秒
91.
水温对氧转移速度的影响研究 总被引:2,自引:0,他引:2
通过对上澳塘水体的曝气充氧实验,研究了温度对氧转移速率的影响,测定了温度系数,为上澳塘水体曝气化的工程实践提供了可靠的技术参数。 相似文献
92.
Optimizationofharmoniousdevelopmentonregionalenergy-economy-atmosphericenvironmentsystem¥NingDatong,WangLei(ChineseRealEstate... 相似文献
93.
Microwavedigestionmethodinenvironmentalanalysis¥ZhangYue(WadsworthCentre,NewYorkStateDepartmentofHealthSchoolofPublicHealth,S... 相似文献
94.
介绍由一级动力学模式推导废水处理实用公式。文中探讨了20℃降解速率系数K20和温度修正系数θ,仅是某种水质和生化条件下的对应值,不能任意通用。 相似文献
95.
The waterquality of the downstream of Nanfei River and the northwest area of Lake Chao is evaluated from organic analysis aspect. PAHs such as fluoranthene, pyrene are detected in the waters collected from downstream river and river mouth. More phenolic compounds are found in the river water. Some halogenated hydrocarbons are present in the river and lake waters. A great many of aliphatic hydrocarbons and benzene hydrocarbons found in all the water samples are about one third of the total organics detected. The hydrophobic components are found to be present not only in water but also in suspended sediment. The ratio of the amount existing is 0.4 in sediment and 1 in particle-free water. The quantity of humic materials existing in lake water is larger than that in river water. The proportion of the humic materials in lake water to that in river water is 1.9 to 1. In the lake water, some natural substances, such as dimethyl disulfide, alpha-pinene, azulene, and 6- methyl -2-heptanone are observed. 相似文献
96.
A study for the photochemical behavior of some polyaromatic hydrocarbons (PAH), for example B(a )P, B( k )F and fluoranthene in coal smoke particles was performed by using indoor Teflon smog chamber.Experiments suggest that the photochemical reaction of PAH is first order reaction and kinetic rates of some PAH were obtained. It was shown that the reaction rate constant is proportional to light intensity and water vapor concentration. Temperature and PAH loading also have influence on PAH decay rate. A model for PAH loss has been set up on the basis of the results of our experiments and the simulating results of this model suggest that coal particle PAH half lives are of the order of a period of days in winter and a few hours in summer. Other factors which may have effect on the photochemical reaction of PAH have also been discussed. 相似文献
97.
This paper, based on the autonomy concept, continues to investigate hierarchical forms and spatial structure of ecosystems. The former can lead to limits for the selection of the component parts of an ecosystem and a distinction between its endogenous and exogenous variables; and the latter can be lead to a hypothesis of the space of an ecosystem: the space of an ecosystem = its habitat area + supporting area + impact area, and two characteristics of ecosystems, space-overlapping and the area of ecosystem space, have been further studied referring to human activities. 相似文献
98.
The effects of different aluminium chloride concentrations together with varying calciumchloride concentrations on root growth, cell division and nucleoli in root tip cells of Allium cepa werestudied. The concentrations used for aluminium chloride were 10-4, 10-3 and 10-2 mol/L ; and for calcium chloride were 10-5 , 10-4 , 10-3 and 10-2 mol/L, respectively. The results showed that after thetreatments with 10-2 to 10-3 mol/L Al3+ , root growth was severely inhibited , a large nurnber of thecells with c-mitosis were induced and the nucleolar material was extruded from the nucleus into the cytoplasm. However , the treatments with 10-2 to 10-3 mol/L of Al3+ together with 10-2)to 10-5 mol/LCa2+ suggested that Ca2+ gave the obviously protective effects against Al3+ poisoning in root growth.cell division and nucleoli of the root tip cells in A. cepa. The possible mechanism of these protective effects of Ca2+) is also briefly discussed. 相似文献
99.
In this paper it was reported that PbCl2 , CdCl2 , HgCl2, and aquatic environmental samples containing Al, Cd, Cu, Pb, Sr, Zn and other heavy metal ions as well as organic chemicals suppressed thegrowth of E. coli only at higher exposed concentrations. The stimulative effects of PbCl2 and HgCl2 on thegrowth of E. coli were clearly showed at lower concentrations and longer time. It suggested that the toxic effects of heavy metal ions and other pollutants on the growth of E. coli are variable according to the differentexposed levels. 相似文献
100.
ThebufferingeffectsofaquaticsedimentsagainstacidicdepositionLiaoBohan;TangHongxiao(ResearehCenterforEco-EnvironmentalSciences... 相似文献