全文获取类型
收费全文 | 1370篇 |
免费 | 127篇 |
国内免费 | 290篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 83篇 |
环保管理 | 313篇 |
综合类 | 865篇 |
基础理论 | 118篇 |
污染及防治 | 155篇 |
评价与监测 | 76篇 |
社会与环境 | 82篇 |
灾害及防治 | 61篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 28篇 |
2021年 | 32篇 |
2020年 | 35篇 |
2019年 | 44篇 |
2018年 | 37篇 |
2017年 | 49篇 |
2016年 | 68篇 |
2015年 | 81篇 |
2014年 | 74篇 |
2013年 | 114篇 |
2012年 | 106篇 |
2011年 | 102篇 |
2010年 | 69篇 |
2009年 | 76篇 |
2008年 | 80篇 |
2007年 | 90篇 |
2006年 | 65篇 |
2005年 | 49篇 |
2004年 | 39篇 |
2003年 | 63篇 |
2002年 | 47篇 |
2001年 | 35篇 |
2000年 | 57篇 |
1999年 | 26篇 |
1998年 | 44篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 20篇 |
1992年 | 29篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有1787条查询结果,搜索用时 984 毫秒
111.
采用电沉积法制备铈修饰的PbO2/C电极,通过SEM、XRD、XPS及循环伏安对PbO2/C、Ce-PbO2/C电极进行表征,结果表明,Ce-PbO2/C电极比PbO2/C颗粒细小,表面均匀致密,电化学氧化能力较强,修饰电极中Ce以CeO2的形态存在。以Ce-PbO2/C为工作电极,电解浓度为1 000 mg/L的高盐酸性红B模拟活性染料废水,考察了电压、pH、电解质浓度、极间距对脱色率、氨氮去除率及COD去除率的影响。确定适宜工艺条件为:初始酸性红B溶液浓度为1 000 mg/L,pH值为6,电压10 V,电解时间1 h,电极间距1.5 cm,该条件下脱色率、氨氮去除率和COD去除率分别为99.98%、97.23%和90.17%。通过UV-Vis及GC-MS初步分析了降解过程可能存在的中间产物及降解途径。 相似文献
112.
Ambient levels of phosphine (PH3) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368 ± 0.6060 ng m−3 to 24.83 ± 6.529 ng m−3 and averaged 14.25 ± 4.547 ng m−3. The highest phosphine emission flux was 22.54 ± 3.897 ng (m2 h)−1, the lowest flux was 7.64 ± 4.83 ng (m2 h)−1, and the average flux was 14.17 ± 4.977 ng (m2 h)−1. Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg−1fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts > ACP > TP. 相似文献
113.
Ungtae Kim Jagath J. Kaluarachchi Vladimir U. Smakhtin 《Journal of the American Water Resources Association》2008,44(5):1231-1247
Abstract: This work develops a methodology to project the future precipitation in large river basins under limited data and climate change while preserving the historical temporal and spatial characteristics. The computationally simple and reliable conditional generation method (CGM) is presented and applied to generate reliable monthly precipitation data in the upper Blue Nile River Basin of Ethiopia where rain‐fed agriculture is prevalent. The results showed that the temporal analysis with the CGM performs better to reproduce the historical long‐term characteristics than other methods, and the spatial analysis with the CGM reproduced the historical spatial structure accurately. A 100‐year time series analysis using the outcomes of the six general circulation models showed that precipitation changes by the 2050s (2040 through 2069) can be ?7 to 28% with a mean increase of about 11%. The seasonal results showed increasing wet conditions in all seasons with changes of mean precipitation of 5, 47, and 6% for wet, dry, and mild seasons, respectively. 相似文献
114.
In dune slacks in The Netherlands, a decline of rare mesotrophic basiphilous plant species and their plant communities has
been observed in combination with an increase of more productive systems with common, taller acidophilous plant species. This
has been attributed to both natural and anthropogenic changes. In a humid climate with a precipitation surplus, as in The
Netherlands, the calcium carbonate content of a calcareous soil increases with depth. However, soils in coastal dune slacks,
may have a higher carbonate content in the topsoil horizon than in the underlying layers. Carbonates which buffer the pH can
prolong the presence of mesotrophic basiphilous plant communities which are of high conservation value.
To explain the occurrence of calcareous surface horizons in dune slacks, hydrological and micromorphological analyses were
carried out in three dune slacks. Two slacks are situated on the Wadden Sea islands in the northern part of The Netherlands;
one on Schiermonnikoog and one on Texel. The third slack is situated in the dunes on the island of Goeree in the southwestern
part of The Netherlands. In all three slacks, carbonate occurs as mollusc and gastropod fragments (silt- or sand-sized) and
as micritic nodules in the topsoil layer, due to aeolian deposition and sedimentation by water.In situ carbonate accumulation (calcitans and calcareous crusts) due to CO2 release in inundated and/or capillary rise of calcareous groundwater near, or at the soil surface. Accumulation of carbonate
also occurs as a result of biological activity by algae in the topsoil of the Goeree site. In general, hydrological processes
maintaining high levels of calcareous groundwater are a prerequisite for the maintenance of high carbonate levels in topsoils.
Such levels are necessary for the conservation and management of basiphilous pioneer vegetation. 相似文献
115.
对承德市热电厂CG35/3.82-MX型循环流化术锅炉的脱硫除尘系统进行了改造,解决了原水膜除尘器效率低,烟法排放严重超标的问题,取得了良好的环境效益,社会效益和经济效益。 相似文献
116.
利用唐山市1976-2005年各县年降水序列,分析了该市降水的空间分布规律和时间变化特点。采用灰色系统的灾变预测方法,对各县分别建立了GM(1,1)模型,进行未来25年唐山市各站的干旱年预测。利用残差检验、后验差检验和关联度检验对各模型分别进行了精度检验。结果表明,预测模型精度较高,可以对唐山市各县未来的干旱年进行预测,从而为科学决策提供依据。 相似文献
117.
王坚 《环境监测管理与技术》2014,26(5):12-14
对地面风场的研究表明,厦门存在局地和海陆风环流,自1955年以来年平均风速、混合层厚度均呈现下降趋势,大气污染物的水平和垂直扩散能力也呈下降趋势。降水酸度随海拔高度的变化情况表明,海陆风环流有利于酸性污染物的积累,且锋面降水过程中的光化学污染加重了降水的酸化程度。 相似文献
118.
119.
酸沉降影响稻米品质的新发现 总被引:2,自引:0,他引:2
酸沉降影响了稻米质量和口感.酸雨时空分布从宏观上概括了稻米品质的地理分布.酸雨决定了酶活性相关金属离子的丰缺,继而影响淀粉合成关键酶的活性,最终影响淀粉合成质量.温度变化是表象,降雨pH值变化是条件,酶活性相关金属离子丰缺是根本,实质是酶活性相关金属离子或激活或抑制了支链淀粉合成关键酶的活性.提出了改善粮食作物质量的化控创新技术路线. 相似文献
120.
上海青浦地区大气降水的化学特征 总被引:2,自引:1,他引:1
利用上海青浦地区2003—2014年观测的大气降水监测资料,分析该区域12 a以来大气降水的酸化程度、化学组成特征,探讨降水中化学成分的不同来源及相对贡献。结果表明:降水pH年均值为4.43~6.33,酸雨频率为2.6%~86.8%,降水酸化程度大致经历了明显恶化和波动变化2个阶段。降水电导率年均值为1.77~4.01 m S/m,呈下降趋势。降水中各离子雨量加权平均当量浓度顺序为SO_4~(2-)NH_4~+Ca~(2+)NO_3~-Cl~-Na~+Mg~(2+)F-K~+,SO_4~(2-)、NH+4、Ca~(2+)和NO_3~-是降水中的主要离子,占离子总量的83.0%;降水类型由硫酸型向硫酸和硝酸混合型转变。降水离子中的二次组分SO_4~(2-)、NO_3~-和NH_4~+绝大部分来源于人为源,Ca~(2+)、Mg~(2+)和K+主要来自于土壤源和人为源的贡献,Cl~-主要来自海洋源,同时人为源的影响也不可忽视。 相似文献