全文获取类型
收费全文 | 18083篇 |
免费 | 1583篇 |
国内免费 | 2613篇 |
专业分类
安全科学 | 1752篇 |
废物处理 | 291篇 |
环保管理 | 4291篇 |
综合类 | 9894篇 |
基础理论 | 1756篇 |
环境理论 | 47篇 |
污染及防治 | 955篇 |
评价与监测 | 2186篇 |
社会与环境 | 997篇 |
灾害及防治 | 110篇 |
出版年
2024年 | 63篇 |
2023年 | 276篇 |
2022年 | 370篇 |
2021年 | 499篇 |
2020年 | 535篇 |
2019年 | 507篇 |
2018年 | 496篇 |
2017年 | 794篇 |
2016年 | 852篇 |
2015年 | 924篇 |
2014年 | 903篇 |
2013年 | 1256篇 |
2012年 | 1278篇 |
2011年 | 1306篇 |
2010年 | 988篇 |
2009年 | 986篇 |
2008年 | 763篇 |
2007年 | 1160篇 |
2006年 | 1180篇 |
2005年 | 982篇 |
2004年 | 852篇 |
2003年 | 858篇 |
2002年 | 687篇 |
2001年 | 641篇 |
2000年 | 597篇 |
1999年 | 421篇 |
1998年 | 313篇 |
1997年 | 282篇 |
1996年 | 243篇 |
1995年 | 230篇 |
1994年 | 158篇 |
1993年 | 129篇 |
1992年 | 95篇 |
1991年 | 83篇 |
1990年 | 60篇 |
1989年 | 49篇 |
1988年 | 45篇 |
1987年 | 39篇 |
1986年 | 29篇 |
1985年 | 21篇 |
1984年 | 26篇 |
1983年 | 23篇 |
1982年 | 33篇 |
1981年 | 32篇 |
1980年 | 34篇 |
1979年 | 36篇 |
1978年 | 20篇 |
1977年 | 21篇 |
1975年 | 20篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
101.
对室内装饰装修材料检测中甲醛分析方法的研究 总被引:2,自引:0,他引:2
目前室内装饰装修材料中甲醛含量的检测有六个类别,分析方法不统一,且没有一定的质量控制措施.文章对分析方法进行了改进,并且研究用水中的甲醛标样来对检测过程进行质量控制,结果较好. 相似文献
102.
103.
104.
105.
106.
Fence for traffic noise control sometimes causes adverse effect on air pollution. Thus in this study, performance of porous fence as a tool for control of both air pollution and noise pollution was evaluated. A two-dimensional numerical model for flow and pollutant concentration and an analytical model for traffic noise were utilized in the analysis of a double-decked road structure with fences only at ground (Case 1) and at both ground and upper deck (Case 2). Porous fences were assumed only at the ground level since the solid fences at the upper deck usually leads to desirable result on air pollution. Effects of the variable porosity on air quality and noise level near road were evaluated. Obtained results showed: (1) flow pattern in leeward of fence was drastically changed at 40–50% porosity in Case 1 and 50% in Case 2. The porosity larger than 40% excluded presence of a circulation behind the fence. (2) Effect of porous fence on air pollution was different in Cases 1 and 2. In Case 1, the porous fence generally resulted in the reduction of air pollution at the ground level; on the other hand, in Case 2, it rather led to increase of the concentration. (3) Traffic noise level was also largely changed by the porosity of the fence; an example of simultaneous evaluation of the effects of porous fence on both air and noise pollution in Case 1 showed that the fence of 60% porosity leads to reduction of air pollution by 20% compared with solid fence case, and reduction of noise pollution by 4–6% in dB compared with no fence case, at l m high and 10 m from the road. 相似文献
107.
Heavy metals in honey are of interest not only for quality control, but also for determination environmental contamination.
The objective of this work was to determine distribution of the levels of selected heavy metals. Levels of copper (Cu), cadmium
(Cd), manganese (Mn), Iron (Fe), magnesium (Mg) and nickel (Ni) in honey samples (21) in Kahramanmaraş region were determined
by atomic absorption spectrometer (AAS). The mean values for Cu, Cd, Mn, Fe, and Mg were 0.01, 0.32, 0.03, 0.36 and 10.45
ppm, respectively. Nickel was not detected in honey samples. Kahramanmaraş honey samples were not free of heavy metals but
the levels of them were found well below the permitted levels. The results suggested that honey may be useful for assessing
the presence of environmental contaminants. 相似文献
108.
Risk-Based Prioritization of Air Pollution Monitoring Using Fuzzy Synthetic Evaluation Technique 总被引:1,自引:0,他引:1
Air pollution monitoring programs aim to monitor pollutants and their probable adverse effects at various locations over concerned area. Either sensitivity of receptors/location or concentration of pollutants is used for prioritizing the monitoring locations. The exposure-based approach prioritizes the monitoring locations based on population density and/or location sensitivity. The hazard-based approach prioritizes the monitoring locations using intensity (concentrations) of air pollutants at various locations. Exposure and hazard-based approaches focus on frequency (probability of occurrence) and potential hazard (consequence of damage), respectively. Adverse effects should be measured only if receptors are exposed to these air pollutants. The existing methods of monitoring location prioritization do not consider both factors (hazard and exposure) at a time. Towards this, a risk-based approach has been proposed which combines both factors: exposure frequency (probability of occurrence/exposure) and potential hazard (consequence).This paper discusses the use of fuzzy synthetic evaluation technique in risk computation and prioritization of air pollution monitoring locations. To demonstrate the application, common air pollutants like CO, NOx, PM10 and SOx are used as hazard parameters. Fuzzy evaluation matrices for hazard parameters are established for different locations in the area. Similarly, fuzzy evaluation matrices for exposure parameters: population density, location and population sensitivity are also developed. Subsequently, fuzzy risk is determined at these locations using fuzzy compositional rules. Finally, these locations are prioritized based on defuzzified risk (crisp value of risk, defined as risk score) and the five most important monitoring locations are identified (out of 35 potential locations). These locations differ from the existing monitoring locations. 相似文献
109.
Mehaffey MH Nash MS Wade TG Ebert DW Jones KB Rager A 《Environmental monitoring and assessment》2005,107(1-3):29-44
The Catskill/Delaware reservoirs supply 90% of New York City’s drinking water. The City has implemented a series of watershed protection measures, including land acquisition, aimed at preserving water quality in the Catskill/Delaware watersheds. The objective of this study was to examine how relationships between landscape and surface water measurements change between years. Thirty-two drainage areas delineated from surface water sample points (total nitrogen, total phosphorus, and fecal coliform bacteria concentrations) were used in step-wise regression analyses to test landscape and surface-water quality relationships. Two measurements of land use, percent agriculture and percent urban development, were positively related to water quality and consistently present in all regression models. Together these two land uses explained 25 to 75% of the regression model variation. However, the contribution of agriculture to water quality condition showed a decreasing trend with time as overall agricultural land cover decreased. Results from this study demonstrate that relationships between land cover and surface water concentrations of total nitrogen, total phosphorus, and fecal coliform bacteria counts over a large area can be evaluated using a relatively simple geographic information system method. Land managers may find this method useful for targeting resources in relation to a particular water quality concern, focusing best management efforts, and maximizing benefits to water quality with minimal costs.The United States Environmental Protection Agency through its Office of Research and Development funded and managed the research described here. It has been subjected to Agency’s administrative review and approved for publication as an EPA document. 相似文献
110.
The increasing use of the landscape by humans has led to important diminutions of natural surfaces. The remaining patches
of wild habitat are small and isolated from each other among a matrix of inhospitable land-uses. This habitat fragmentation,
by disabling population movements and stopping their spread to new habitats, is a major threat to the survival of numerous
plant and animal species. We developed a general model, adaptable for specific species, capable of identifying suitable habitat
patches within fragmented landscapes and investigating the capacity of populations to move between these patches. This approach
combines GIS analysis of a landscape, with spatial dynamic modeling. Suitable habitat is identified using a threshold area
to perimeter ratio. Potential movement pathways of species between habitat patches are modeled using a cellular automaton.
Habitat connectivity is estimated by overlaying habitat patches with movement pathways. The maximum potential population is
calculated within and between connected habitat patches and potential risk of inbreeding within meta-populations is considered.
The model was tested on a sample map and applied to scenario maps of predicted land-use change in the Peoria Tri-county region
(IL). It (1) showed area of natural area alone was insufficient to estimate the consequences on animal populations; (2) underscored
the necessity to use approaches investigating the effect of land-use change spatially through the landscape and the importance
of considering species-specific life history characteristics; and (3) highlighted the model's potential utility as an indicator
of species likelihood to be affected negatively by land-use scenarios and therefore requiring detailed investigation. 相似文献