全文获取类型
收费全文 | 7636篇 |
免费 | 68篇 |
国内免费 | 200篇 |
专业分类
安全科学 | 141篇 |
废物处理 | 371篇 |
环保管理 | 432篇 |
综合类 | 2554篇 |
基础理论 | 1538篇 |
环境理论 | 7篇 |
污染及防治 | 1991篇 |
评价与监测 | 490篇 |
社会与环境 | 348篇 |
灾害及防治 | 32篇 |
出版年
2022年 | 128篇 |
2021年 | 80篇 |
2020年 | 54篇 |
2019年 | 73篇 |
2018年 | 189篇 |
2017年 | 105篇 |
2016年 | 155篇 |
2015年 | 150篇 |
2014年 | 195篇 |
2013年 | 454篇 |
2012年 | 217篇 |
2011年 | 255篇 |
2010年 | 256篇 |
2009年 | 284篇 |
2008年 | 299篇 |
2007年 | 349篇 |
2006年 | 257篇 |
2005年 | 221篇 |
2004年 | 242篇 |
2003年 | 266篇 |
2002年 | 206篇 |
2001年 | 328篇 |
2000年 | 226篇 |
1999年 | 150篇 |
1998年 | 99篇 |
1997年 | 100篇 |
1996年 | 68篇 |
1995年 | 90篇 |
1994年 | 94篇 |
1993年 | 72篇 |
1992年 | 58篇 |
1991年 | 71篇 |
1990年 | 68篇 |
1989年 | 66篇 |
1985年 | 50篇 |
1982年 | 51篇 |
1979年 | 49篇 |
1967年 | 57篇 |
1966年 | 53篇 |
1965年 | 58篇 |
1964年 | 63篇 |
1963年 | 62篇 |
1962年 | 59篇 |
1961年 | 63篇 |
1960年 | 56篇 |
1959年 | 65篇 |
1958年 | 60篇 |
1957年 | 70篇 |
1956年 | 50篇 |
1955年 | 49篇 |
排序方式: 共有7904条查询结果,搜索用时 296 毫秒
41.
Implications of urine-to-feces ratio in the thermophilic anaerobic digestion of swine waste. 总被引:1,自引:0,他引:1
Thermophilic anaerobic digestion of swine manure represents a potential waste treatment technology to address environmental concerns, such as odor emissions and removal of pathogenic microorganisms. However, there are concerns relative to the stability of this process when swine manure is the sole substrate. In this study, the potential of biogas production from swine manure as the sole substrate under thermophilic (50 degrees C) conditions was investigated in the laboratory, to determine whether separation of urine and feces as part of the waste collection process would benefit anaerobic digestion. Effluent from a continuously stirred tank reactor was used as the inoculum for batch tests, in which the substrate contained three different concentrations of urine (urine-free, as-excreted urine-to-feces ratio and double the as-excreted urine-to-feces ratio). Inocula were acclimated to these same urine-to-feces ratios to determine methane production. Results show that both urine-free and as-excreted substrates were not inhibitory to anaerobic inocula. Anaerobic microorganisms can be readily acclimated to substrate with double the as-excreted urine concentration, which contained nitrogen concentrations up to 7.20 g/L. Cumulative methane production reached similar levels in the batch tests, regardless of the substrate urine concentration. 相似文献
42.
Sanders SM Srivastava P Feng Y Dane JH Basile J Barnett MO 《Journal of environmental quality》2008,37(4):1510-1518
Currently, limited research on the fate of antimicrobials in the environment exists, once they are discharged in human and animal wastes. Sorption of two antimicrobials, sulfadimethoxine (SDM) and ormetoprim (OMP), was investigated in two soils and sand using a series of batch experiments. Because OMP and SDM are often administered in combination, their sorption was also investigated in combination as co-solutes. The rate of SDM and OMP sorption was rapid over the first few hours of the experiments, which then slowed considerably after 16 to 68 h. OMP sorption was enhanced at high concentrations when in combination with SDM, with linear sorption coefficients ranging from 1.3 to 58.3 L.kg(-1) in the single solute experiments and 4.96 to 89.7 L.kg(-1) in the co-solute experiments. Sorption of OMP as a single solute seems to provide a better fit with the Freundlich equation, which became more linear (n approached 1) when SDM was present. Overall, SDM sorbed less than OMP in the two soils and sand. SDM linear sorption coefficients ranged from 0.4 to 25.8 L.kg(-1) as a single solute and 2.5 to 22.1 L.kg(-1) as a co-solute. Sorption of SDM becomes more nonlinear (n < 1) when SDM is present in combination with OMP. Overall, sorption of both antimicrobials increased in the selected soils and sand as the organic matter, clay content, and cation exchange capacity increased. These experiments indicate relatively low sorption of SDM and OMP in natural soils, making them a potential threat to surface and ground water. 相似文献
43.
44.
5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy–Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
45.
46.
The effect of ambient air pollution with increased ozone concentrations on the feeding behaviour of the beech weevil Rhynchaenus fagi L. was studied. In a dual choice feeding test the beech weevil preferred leaf disks from beech saplings exposed to ambient air against those from filtered air in 65.5% of all cases. 相似文献
47.
48.
49.
50.
Hiraoka Y 《Environmental pollution (Barking, Essex : 1987)》1991,70(3):209-217
Cultured oysters from Hiroshima Bay were analysed to determine the content of nine trace elements, cadmium (Cd), lead (Pb), chromium (Cr), arsenic (As), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), and iron (Fe) and compared with oysters treated for 48 h in both artificial sea water and a solution of 0.5% ethylenediaminetetraacetic acid (EDTA) in artificial sea water. It was found that the values of As and Fe in both groups of treated oysters were significantly lower than in the untreated oysters and that the Pb and Mn levels tended to be lower. It was also found that oysters treated in 0.5% EDTA solution in artificial sea water had lower levels of Cd and Cu than the oysters treated only in artificial sea water. 相似文献