全文获取类型
收费全文 | 5651篇 |
免费 | 313篇 |
国内免费 | 2214篇 |
专业分类
安全科学 | 390篇 |
废物处理 | 344篇 |
环保管理 | 431篇 |
综合类 | 3089篇 |
基础理论 | 1009篇 |
环境理论 | 2篇 |
污染及防治 | 2184篇 |
评价与监测 | 265篇 |
社会与环境 | 205篇 |
灾害及防治 | 259篇 |
出版年
2024年 | 16篇 |
2023年 | 110篇 |
2022年 | 270篇 |
2021年 | 252篇 |
2020年 | 201篇 |
2019年 | 180篇 |
2018年 | 237篇 |
2017年 | 264篇 |
2016年 | 300篇 |
2015年 | 367篇 |
2014年 | 419篇 |
2013年 | 595篇 |
2012年 | 454篇 |
2011年 | 459篇 |
2010年 | 389篇 |
2009年 | 378篇 |
2008年 | 378篇 |
2007年 | 327篇 |
2006年 | 306篇 |
2005年 | 210篇 |
2004年 | 184篇 |
2003年 | 221篇 |
2002年 | 197篇 |
2001年 | 195篇 |
2000年 | 170篇 |
1999年 | 151篇 |
1998年 | 157篇 |
1997年 | 118篇 |
1996年 | 115篇 |
1995年 | 122篇 |
1994年 | 107篇 |
1993年 | 71篇 |
1992年 | 65篇 |
1991年 | 51篇 |
1990年 | 41篇 |
1989年 | 26篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有8178条查询结果,搜索用时 0 毫秒
971.
Suyun Xu Ammaiyappan Selvam Jonathan W.C. Wong 《Waste management (New York, N.Y.)》2014,34(2):363-369
Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35 °C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21–27% and 38–64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH4/g VSadded in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO2 respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste. 相似文献
972.
S.M. Eldridge C.R. Chen Z.H. Xu P.N. Nelson S.E. Boyd I. Meszaros K.Y. Chan 《Waste management (New York, N.Y.)》2013,33(11):2157-2169
Using solid state 13C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes. 相似文献
973.
974.
975.
976.
977.
提高“项目教学”实效性的实践研究 总被引:1,自引:0,他引:1
项目教学法是实施探究式教学模式的一种教学方法,适用于各类实践性和操作性较强的专业知识、技能的学习,可以帮助学习者提高学习效率,加强职业角色的塑造与职业能力的培养。项目教学被普遍认为是能将专业学科体系与职业行业体系紧密结合的教学模式,项目捆绑教学模式是实现高等职业教育四个合作的有效途径。研究影响这种教学模式开展的教师、学生、工程项目、教学管理等方面因素,以及总结该种模式在教学运行过程中的实效性手段,有利于提高高等职业教育的教学质量。 相似文献
978.
针对位于新型干法水泥厂附近且生活垃圾收运较为困难的村镇,提出了一种利用新型干法水泥窑协同处置垃圾的简易模式。实验将预处理后的村镇生活垃圾定量喂入水泥窑系统中,并对比了掺烧20、50和80 t村镇生活垃圾前后,水泥熟料品质、窑系统工况以及污染物排放的情况。结果表明:实验期间在80 t范围内,生活垃圾的掺烧使水泥熟料抗压强度最多降低3 MPa,但仍符合国家标准;对水泥窑衬结皮和窑工况稳定性基本没有影响;同时对水泥窑系统污染物排放量无负面影响,烟气中二恶英的含量为0.004 0 ng TEQ/m3,远远低于国家标准。 相似文献
979.
Lingzhan Miao Chao Wang Jun Hou Peifang Wang Yanhui Ao Yi Li Bowen Lv Yangyang Yang Guoxiang You Yi Xu 《Environmental science and pollution research international》2016,23(12):11611-11619
The stability of CuO nanoparticles (NPs) is expected to play a key role in the environmental risk assessment of nanotoxicity in aquatic systems. In this study, the effect of alginate (model polysaccharides) on the stability of CuO NPs in various environmentally relevant ionic strength conditions was investigated by using time-resolved dynamic light scattering. Significant aggregation of CuO NPs was observed in the presence of both monovalent and divalent cations. The critical coagulation concentrations (CCC) were 54.5 and 2.9 mM for NaNO3 and Ca(NO3)2, respectively. The presence of alginate slowed nano-CuO aggregation rates over the entire NaNO3 concentration range due to the combined electrostatic and steric effect. High concentrations of Ca2+ (>6 mM) resulted in stronger adsorption of alginate onto CuO NPs; however, enhanced aggregation of CuO NPs occurred simultaneously under the same conditions. Spectroscopic analysis revealed that the bridging interaction of alginate with Ca2+ might be an important mechanism for the enhanced aggregation. Furthermore, significant coagulation of the alginate molecules was observed in solutions of high Ca2+ concentrations, indicating a hetero-aggregation mechanism between the alginate-covered CuO NPs and the unabsorbed alginate. These results suggested a different aggregation mechanism of NPs might co-exist in aqueous systems enriched with natural organic matter, which should be taken into consideration in future studies. 相似文献
980.
催化铁内电解法处理硝基苯废水的机理与动力学研究 总被引:2,自引:0,他引:2
对催化铁内电解法处理硝基苯废水降解动力学特性进行了研究。结果表明,降解过程符合准一级动力学规律。进水浓度、pH值和反应温度强烈影响硝基苯的降解速率。在实验pH值范围内,反应速率常数依次为:强酸性>弱碱性>弱酸性>中性;循环伏安扫描图显示了硝基苯可以在铜电极上直接得电子还原,该反应在强酸和弱碱性条件下效果较好。反应速率常数随进水浓度的增大而减小。提高反应温度可改善处理效果,在30~45℃范围内,提高温度对处理效果的改善并不显著;当温度升高到45℃以上时,升温可以显著改善处理效果。 相似文献