全文获取类型
收费全文 | 3831篇 |
免费 | 104篇 |
国内免费 | 1361篇 |
专业分类
安全科学 | 212篇 |
废物处理 | 216篇 |
环保管理 | 306篇 |
综合类 | 1876篇 |
基础理论 | 702篇 |
环境理论 | 1篇 |
污染及防治 | 1550篇 |
评价与监测 | 148篇 |
社会与环境 | 124篇 |
灾害及防治 | 161篇 |
出版年
2024年 | 1篇 |
2023年 | 63篇 |
2022年 | 187篇 |
2021年 | 128篇 |
2020年 | 100篇 |
2019年 | 88篇 |
2018年 | 147篇 |
2017年 | 162篇 |
2016年 | 168篇 |
2015年 | 210篇 |
2014年 | 302篇 |
2013年 | 370篇 |
2012年 | 333篇 |
2011年 | 306篇 |
2010年 | 234篇 |
2009年 | 272篇 |
2008年 | 265篇 |
2007年 | 221篇 |
2006年 | 210篇 |
2005年 | 150篇 |
2004年 | 114篇 |
2003年 | 144篇 |
2002年 | 129篇 |
2001年 | 111篇 |
2000年 | 120篇 |
1999年 | 130篇 |
1998年 | 142篇 |
1997年 | 84篇 |
1996年 | 77篇 |
1995年 | 74篇 |
1994年 | 59篇 |
1993年 | 55篇 |
1992年 | 48篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有5296条查询结果,搜索用时 296 毫秒
581.
582.
The kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE) in aqueous solutions at various pH, temperature, oxidant concentration and ionic strength levels was studied. The MTBE degradation was found to follow a pseudo-first-order decay model. The pseudo-first-order rate constants of MTBE degradation by persulfate (31.5 mM) at pH 7.0 and ionic strength 0.11 M are approximately 0.13 x 10(-4), 0.48 x 10(-4), 2.4 x 10(-4) and 5.8 x 10(-4) S(-1) at 20, 30, 40 and 50 degrees C, respectively. Under the above reaction conditions, the reaction has an activation energy of 24.5 +/- 1.6 kcal/ mol and is influenced by temperature, oxidant concentration, pH and ionic strength. Raising the reaction temperature and persulfate concentration may significantly accelerate the MTBE degradation. However, increasing both pH (over the range of 2.5-11) and ionic strength (over the range of 0.11-0.53 M) will decrease the reaction rate. Reaction intermediates including tert-butyl formate, tert-butyl alcohol, acetone and methyl acetate were observed. These intermediate compounds were also degraded by persulfate under the experimental conditions. Additionally, MTBE degradation by persulfate in a groundwater was much slower than in phosphate-buffer solutions, most likely due to the presence of bicarbonate ions (radical scavengers) in the groundwater. 相似文献
583.
Chemical kinetic modeling of de novo synthesis of PCDD/F in municipal waste incinerators 总被引:3,自引:0,他引:3
A kinetic model is developed for de novo synthesis of PCDD/F from carbon in incinerator fly ash. The main mechanistic steps considered in the model are carbon gasification, PCDD/F formation, desorption and degradation. Rate equations are derived which can relate PCDD/F formation with process variables including carbon concentration of fly ash, partial pressure of oxygen, reaction temperature and time. The kinetic model has been verified using laboratory de novo synthesis data reported in the literature. When the model is applied to industrial incinerator conditions, PCDD/F formation levels of 0.1-0.5 microg/N m3 in the gas phase and 0.1-1.2 microg/g in the solid phase are calculated, and both are in good agreement with incinerator measurements. 相似文献
584.
Forecasts using neural network versus Box-Jenkins methodology for ambient air quality monitoring data 总被引:5,自引:0,他引:5
This study explores ambient air quality forecasts using the conventional time-series approach and a neural network. Sulfur dioxide and ozone monitoring data collected from two background stations and an industrial station are used. Various learning methods and varied numbers of hidden layer processing units of the neural network model are tested. Results obtained from the time-series and neural network models are discussed and compared on the basis of their performance for 1-step-ahead and 24-step-ahead forecasts. Although both models perform well for 1-step-ahead prediction, some neural network results reveal a slightly better forecast without manually adjusting model parameters, according to the results. For a 24-step-ahead forecast, most neural network results are as good as or superior to those of the time-series model. With the advantages of self-learning, self-adaptation, and parallel processing, the neural network approach is a promising technique for developing an automated short-term ambient air quality forecast system. 相似文献
585.
TiO2 photocatalytic degradation of PCBs in soil-water systems containing fluoro surfactant 总被引:4,自引:0,他引:4
Titanium dioxide-mediated photodegradation of Polychlorinated biphenyls (PCBs) in soil/aqueous systems with added fluorinated surfactant was investigated. PCBs can bind tightly to organic matter in the soil, especially in aged, contaminated soil. Experiments showed an effective PCB photocatalytic degradation in mixed systems of soil/clay with anionic fluorinated surfactant FC-143 and TiO2. The FC-143 surfactant is stable in this photochemical process. PCB degradation rates in samples followed the order: spiked clay > spiked soil > Hudson River bank soil. The results suggest that anionic fluorinated surfactant may form semimicelles and/or admicelles on the surface of positively charged TiO2. The hydrophobic surface of TiO2 can provide a nonpolar phase that acts as a partioning medium for hydrophobic PCBs. Therefore, PCBs in soil can be released to the semimicelle and/or admicelle on the TiO2 surface and are effectively photodegraded in a dispersion containing anionic fluorinated surfactant. The combination of surfactant extraction and photooxidation forms the basis for a novel two-stage process for the removal and destruction of PCBs from soil. 相似文献
586.
Catalytic decomposition of hydrogen peroxide and 4-chlorophenol in the presence of modified activated carbons 总被引:1,自引:0,他引:1
The objective of this research was to examine the heterogeneous catalytic decomposition of H(2)O(2) and 4-chlorophenol (4-CP) in the presence of activated carbons modified with chemical pretreatments. The decomposition of H(2)O(2) was suppressed significantly by the change of surface properties including the decreased pH(pzc) modified with oxidizing agent and the reduced active sites occupied by the adsorption of 4-CP. The apparent reaction rate of H(2)O(2) decomposition was dominated by the intrinsic reaction rates on the surface of activated carbon rather than the mass transfer rate of H(2)O(2) to the solid surface. By the detection of chloride ion in suspension, the reduction of 4-CP was not only attributed to the advanced adsorption but also the degradation of 4-CP. The catalytic activity toward 4-CP for the activated carbon followed the inverse sequence of the activity toward H(2)O(2), suggesting that acidic surface functional group could retard the H(2)O(2) loss and reduce the effect of surface scavenging resulting in the increase of the 4-CP degradation efficiency. Few effective radicals were expected to react with 4-CP for the strong effect of surface scavenging, which could explain why the degradation rate of 4-CP observed in this study was so slow and the dechlorination efficiency was independent of the 4-CP concentration in aqueous phase. Results show that the combination of H(2)O(2) and granular activated carbon (GAC) did increase the total removal of 4-CP than that by single GAC adsorption. 相似文献
587.
588.
589.
The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment. 相似文献
590.