全文获取类型
收费全文 | 2603篇 |
免费 | 284篇 |
国内免费 | 1495篇 |
专业分类
安全科学 | 137篇 |
废物处理 | 319篇 |
环保管理 | 164篇 |
综合类 | 2178篇 |
基础理论 | 633篇 |
污染及防治 | 743篇 |
评价与监测 | 176篇 |
社会与环境 | 21篇 |
灾害及防治 | 11篇 |
出版年
2024年 | 7篇 |
2023年 | 55篇 |
2022年 | 77篇 |
2021年 | 97篇 |
2020年 | 100篇 |
2019年 | 92篇 |
2018年 | 119篇 |
2017年 | 154篇 |
2016年 | 196篇 |
2015年 | 187篇 |
2014年 | 188篇 |
2013年 | 301篇 |
2012年 | 254篇 |
2011年 | 238篇 |
2010年 | 196篇 |
2009年 | 190篇 |
2008年 | 168篇 |
2007年 | 230篇 |
2006年 | 212篇 |
2005年 | 163篇 |
2004年 | 135篇 |
2003年 | 131篇 |
2002年 | 122篇 |
2001年 | 93篇 |
2000年 | 89篇 |
1999年 | 94篇 |
1998年 | 94篇 |
1997年 | 71篇 |
1996年 | 66篇 |
1995年 | 53篇 |
1994年 | 35篇 |
1993年 | 25篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有4382条查询结果,搜索用时 0 毫秒
81.
82.
ABSTRACT: A study was conducted to elucidate some of the chemical factors affecting the rate and pathways of N transformations in lake sediments. The main emphasis was placed on modifying a noncalcareous sediment with CaCO3 to approximate the composition of a calcareous sediment. Additionally, the effects of Ca2+, CO32-, Mg2+ and OH- were evaluated by using appropriate chemicals. Further, the effect of aluminum sulfate was evaluated with both sediment types. Sediment pH at 7 days was not affected by CaCO3, but was decreased by aluminum sulfate. The CaCO3 treatment increased the rate of ammonification, nitrification, reduction of acetylene to ethylene and methane formation, while with few exceptions the other treatments decreased the rate of the transformations studied. Aluminum sulfate, which has been proposed as a lake restoration treatment, increased ammonification but decreased most of the other transformations. 相似文献
83.
M. W. Kress R. Baker S. J. Ursic 《Journal of the American Water Resources Association》1990,26(5):747-756
ABSTRACT: The deposition and chemistry of precipitation were estimated for one year in two forest ecosystems in the South-Central United States. Precipitation, throughfall, litter leachate, and soil leachate were analyzed for a small catchment of pine-hardwoods in southeastern Oklahoma and for a catchment of loblolly pines (Pinus taeda L.) in northern Mississippi. In the pine-hardwood forest, 98 percent of the acid deposition was neutralized, 50 percent in the forest canopy, and 48 percent in the forest floor. In the pine forest, 75 percent of the acid deposition was neutralized, all in the forest floor. The pine-hardwood ecosystem accumulated sulfate, nitrate, and ammonia ions, and lost base cations. During seasons of deficient precipitation, dry deposition appeared to enrich the concentrations of hydrogen, nitrate, sulfate, and ammonia ions in throughfall samples at both locations. 相似文献
84.
通过对膨润土的羟基铝改性实验大大提高了膨润土对染料废水的处理效率。实验结果表明:改性膨润土对变色酸有很好的去除效果,对H酸有较好的去除效果,对T酸处理效果一般,对吐氏酸几乎没有效果。 相似文献
85.
86.
黄腐酸的萃取和性质研究 总被引:3,自引:0,他引:3
黄腐酸是腐植酸中最具活力的组成部分,蕴藏量丰富,萃取方法简便。研究了从红原1#泥炭中萃取黄腐酸和降解物。它的分子量较小,易溶于水,抗絮凝性能好,分子内含有较多的活性官能团,具有很高的化学活性和生物活性,用途广泛。 相似文献
87.
Fe-pillared clay as a Fenton-type heterogeneous catalyst for cinnamic acid degradation 总被引:2,自引:0,他引:2
Fe-pillared montmorillonite has been used as a Fenton-type heterogeneous catalyst for the removal of cinnamic acid in water. The influences of the cinnamic acid, catalyst and H2O2 concentrations and pH on the removal rate of cinnamic acid have been studied. The results show that the efficiency of Fe-pillared montmorillonite is higher than that of the Fe ions in the homogeneous phase, and less sensitive to pH. 相似文献
88.
Justin M. Langridge R. Joel Gustafsson Paul T. Griffiths R. Anthony Cox Richard M. Lambert Roderic L. Jones 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):5128-5131
The photoenhanced uptake of nitrogen dioxide (NO2) to the surface of commercially available self-cleaning window glass has been studied under controlled laboratory conditions. This material is one of an array of modern building products which incorporate titanium dioxide (TiO2) nanoparticles and are finding increasing use in populated urban areas. Amongst the principal drivers for the use of these materials is that they are thought to facilitate the irreversible removal of pollutants such as NO2 and organic molecules from the atmosphere and thus act to remediate air quality. While it appears that TiO2 materials do indeed remove organic molecules from built environments, in this study we show that the photoenhanced uptake of NO2 to one example material, self-cleaning window glass, is in fact accompanied by the substantial formation (50–70%) of gaseous nitrous acid (HONO). This finding has direct and serious implications for the use of these materials in urban areas. Not only is HONO a harmful respiratory irritant, it is also readily photolysed by solar radiation leading to the formation of hydroxyl radicals (OH) together with the re-release of NOx as NO. The net effect of subsequent OH initiated chemistry can then be the further degradation of air quality through the formation of secondary pollutants such as ozone and VOC oxidation products. In summary, we suggest that a scientifically conceived technical strategy for air quality remediation based on this technology, while widely perceived as universally beneficial, could in fact have effects precisely opposite to those intended. 相似文献
89.
George F. Antonious Eric T. Turley Regina R. Hill John C. Snyder 《Journal of environmental science and health. Part. B》2013,48(4):299-304
Organic matter and nutrients in municipal sewage sludge (SS) and chicken manure (CM) could be recycled and used for land farming to enhance fertility and physical properties of soils. Three soil management practices were used at Kentucky State University Research Farm, Franklin County, to study the impact of soil amendments on kale (Brassica oleracea cv. Winterbar) and collard (Brassica oleracea cv. Top Bunch) yields and quality. The three soil management practices were: (i) SS mixed with native soil at 15 t acre?1, (ii) CM mixed with native soil at 15 t acre?1, and (iii) no-mulch (NM) native soil for comparison purposes. At harvest, collard and kale green plants were graded according to USDA standards. Plants grown in CM and SS amended soil produced the greatest number of U.S. No. 1 grade of collard and kale greens compared to NM native soil. Across all treatments, concentrations of ascorbic acid and phenols were generally greater in kale than in collards. Overall, CM and SS enhanced total phenols and ascorbic acid contents of kale and collard compared to NM native soil. We investigated the chemical and physical properties of each of the three soil treatments that might explain variability among treatments and the impact of soil amendments on yield, phenols, and ascorbic acid contents of kale and collard green grown under this practice. 相似文献
90.
DSD酸氧化缩合废水浓缩液回用试验研究 总被引:4,自引:1,他引:4
研究了DSD酸氧化缩合废水浓缩液回用到原生产过程的可行性。对DSD酸氧化缩合废水可采用萃取技术分离出其中97%的有机物,反萃产生的4-8倍的浓缩液返回到DSD酸生产中的氧化缩合单元后,可提高DNS酸的收率约7.43%,且不会明显影响产品的纯度,浓缩液8次循环磁用试验的结果表明,虽然DSD酸氧化缩合废水的COD从15000-20000mg/L提高到20000-29000mg/L,但没有显著持续增长的趋势,表明反应液中副产物的浓度得到了有效的控制。 相似文献