全文获取类型
收费全文 | 3207篇 |
免费 | 766篇 |
国内免费 | 1758篇 |
专业分类
安全科学 | 268篇 |
废物处理 | 241篇 |
环保管理 | 197篇 |
综合类 | 2450篇 |
基础理论 | 1578篇 |
污染及防治 | 785篇 |
评价与监测 | 139篇 |
社会与环境 | 33篇 |
灾害及防治 | 40篇 |
出版年
2024年 | 18篇 |
2023年 | 116篇 |
2022年 | 171篇 |
2021年 | 199篇 |
2020年 | 159篇 |
2019年 | 196篇 |
2018年 | 282篇 |
2017年 | 319篇 |
2016年 | 344篇 |
2015年 | 359篇 |
2014年 | 354篇 |
2013年 | 386篇 |
2012年 | 395篇 |
2011年 | 327篇 |
2010年 | 304篇 |
2009年 | 290篇 |
2008年 | 209篇 |
2007年 | 218篇 |
2006年 | 185篇 |
2005年 | 156篇 |
2004年 | 105篇 |
2003年 | 91篇 |
2002年 | 91篇 |
2001年 | 84篇 |
2000年 | 68篇 |
1999年 | 66篇 |
1998年 | 33篇 |
1997年 | 43篇 |
1996年 | 24篇 |
1995年 | 32篇 |
1994年 | 25篇 |
1993年 | 24篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
排序方式: 共有5731条查询结果,搜索用时 15 毫秒
61.
以“grafting to”法制备的氧化石墨烯/聚酰胺-胺(GO/PAMAMs)作为吸附剂,研究了Cu(Ⅱ)和Cd(Ⅱ)在GO/PAMAMs上的竞争吸附行为,考察了溶液pH值、吸附时间、初始离子浓度及吸附剂用量等因素对吸附过程的影响,探讨了Cu(Ⅱ)和Cd(Ⅱ)在GO/PAMAMs上的竞争吸附机理。研究表明:GO/PAMAMs对Cu(Ⅱ)的吸附最佳pH值是5.0,Cd(Ⅱ)的最佳pH值为5.5;Cu(Ⅱ)和Cd(Ⅱ)在GO/PAMAMs上的竞争吸附过程符合Lagergren准二级动力学模型,等温吸附过程遵循Langmuir模型;热力学研究表明Cu(Ⅱ)和Cd(Ⅱ)在GO/PAMAMs上的吸附是自发进行的吸热过程,且属于物理吸附。 相似文献
62.
介绍了氧化铁黄生产中的废水治理情况,同时其产生的废渣可回收利用。经过治理产生的环境、经济和社会效益显著。 相似文献
63.
The nitrous oxide emissions were measured at three tundra sites and one snowpack on the Fildes Peninsula in the maritime Antarctic in the summertime of 2002. The average fluxes at two normal tundra sites were 1.1 ± 2.2 and 0.6 ± 1.7 μg N2O m−2 h−1, respectively. The average flux from tundra soil site with penguin dropping addition was 3.7 ± 2.0 μg N2O m−2 h−1, 3–6 times those from the normal tundra soils, suggesting that the deposition of fresh droppings enhanced N2O emissions during penguin breeding period. The summer precipitation had an important effect on N2O emissions; the flux decreased when heavy precipitation occurred. The diurnal cycle of the N2O fluxes from Antarctic tundra soils was not obtained due to local fluky weather conditions. The N2O fluxes through four snowpack sites were obtained by the vertical N2O concentration gradient and their average fluxes were 0.94, 1.36, 0.81 and 0.85 μg N2O m−2 h−1, respectively. The tundra soils under snowpack emitted N2O in the maritime Antarctic and increased local atmospheric N2O concentrations; therefore these fluxes could constitute an important part of the annual N2O budget for Antarctic tundra ecosystem. 相似文献
64.
The present study performed a roadside data analysis to provide baseline data for exploring associations between environmental exposure to four gaseous pollutants and health effects on residents living near roadways. The yearly roadside concentrations of CO and SO2 showed a well-defined decreasing trend, whereas those of NO2 and O3 exhibited the reverse trend. In most cases, the diurnal trends of the roadside concentrations were well-defined for all seasons, plus the daytime concentrations were higher than the nighttime concentrations. In contrast to the other target pollutants, the daytime O3 concentrations observed at the roadside sites were lower than those observed at the residential site, likely due to high-levels of fresh NO from traffic emissions that rapidly react with O3, thereby reducing the O3 roadside level. The Sunday roadside concentrations of CO, NO2, and SO2 were similar to or somewhat lower than the weekday concentrations. Conversely, for O3, the Sunday roadside concentrations were similar to or somewhat higher than the weekday concentrations. The higher O3 concentrations on Sunday may be due to the reduced titration from a decrease in NOx emissions under VOC-limited conditions (low VOC/NOx conditions). The monthly averages of O3 concentrations exhibited the reverse seasonal variation to the other target compounds, with peak O3 concentrations between April and June, and the second peak between August and October. It is also suggested that for O3, the 8-h standard is more stringent than the 1-h standard, while for NO2 and SO2, the 1-h standard is more stringent than the 24-h standard. The multiple regression equations obtained from the relationship between the concentrations and five meteorological parameters indicated that the number and type of meteorological variables in the equations varied according to the pollutant, monitoring station, or season. 相似文献
65.
为研究NaHCO3对玉米淀粉爆炸的抑制效果,采用20 L球形爆炸装置测试玉米淀粉在添加不同抑制比NaHCO3及其固态分解产物Na2 CO3后爆炸参数变化规律,并分析NaHCO3抑制淀粉爆炸过程.结果表明:NaHCO3及Na2 CO3对玉米淀粉爆炸均有抑制作用,NaHCO3抑制效果优于Na2 CO3;混合粉尘的最大爆炸压... 相似文献
66.
毛竹遗态 Fe2O3/Fe3O4/C 复合材料对水中锑(III)的吸附研究 总被引:1,自引:0,他引:1
以毛竹遗态Fe2 O3/Fe3 O4/C复合材料为吸附剂,锑(III )初始含量、溶液初始pH值、吸附剂投加量以及吸附剂粒径为影响因素开展吸附影响研究。结果表明,随着锑(III )初始浓度的升高,毛竹遗态Fe2 O3/Fe3 O4/C复合材料对锑(III )的吸附量逐渐增加;初始溶液pH为7时,对锑(III )的吸附效果最好,吸附量为4.7821 mg/g;块状吸附剂对水中锑(III )的去除率和吸附量与粉末状吸附剂吸附效果相当。 相似文献
67.
68.
用2,3-二羟基苯甲酸经羟基保护、酰胺化、酯化和去保护4步反应,生成一种新型的四齿丙二酸二(2-(2,3-二羟基苯甲酰胺)乙基)酯配体.采用傅里叶变换红外光谱(FT-IR)、紫外-可见光谱(UV-Vis)、核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)和质谱(MS)对其结构进行了表征.在中性pH值条件下,研究了这种配体对铀酰离子的络合能力.结果表明,丙二酸二(2-(2,3-二羟基苯甲酰胺)乙基)酯配体与铀酰离子的螯合常数为23.2. 相似文献
69.
ABSTRACTUrban planning has become a widely concern for minimizing the negative effects of urban expansion on terrestrial ecosystems. We developed an interdisciplinary modeling framework to evaluate the effectiveness and shortcomings of urban expansion management strategies. A three-step method was applied to Yinchuan Plain in the northwestern of China, including (1) analyzing the relationship between landscape pattern and ecosystem service values through mathematical statistics; (2) predicting landscape pattern and ecosystem services change under different scenarios based on cellular automaton model (SLEUTH-3r model); and (3) designing and validating optimized scenario through integrating historical analysis experiments and future multi-comparison suggestions. Results have suggested that landscape composition and configuration can significantly affect regional ecosystem service values, especially the connectivity and shape of landscape. Compact urban growth policy and medium environment protection policy are the appropriate setting for urban expansion plan. Optimization validation of the combined designed scenario implied the reliability of this method. Our results highlighted the significance of integrating application of landscape pattern analysis, ecosystem service value evaluation, model simulation and multi-scenario prediction in urban planning. 相似文献
70.
基于ANN的土壤重金属分布和污染评价研究 总被引:1,自引:0,他引:1
农田土壤重金属污染与备受关注的农产品安全问题有密切联系,因此对其进行研究意义重大。以江苏省南通市为研究区,利用采样点实测数据,借助神经网络模型(ANN)并结合3S技术对问题进行研究,从而对土壤重金属的空间动态分布进行描述,并对各个空间位点重金属的污染状况进行评价。结果表明,神经网络模型能够智能地学习各个样点的空间位置与该点各重金属含量之间的映射关系和预先设计好的分类评价模式,并能够稳健地对各个空间插值点处的重金属含量和各个位点的重金属污染状况进行预测和评价。结论显示,南通市大部分农田土壤重金属污染较轻,但也存在局部地区的严重污染。结论与实际情况相符,表明神经网络模型可以为农田土壤重金属的研究提供一个新的思路和方法。 相似文献