全文获取类型
收费全文 | 8660篇 |
免费 | 125篇 |
国内免费 | 432篇 |
专业分类
安全科学 | 622篇 |
废物处理 | 352篇 |
环保管理 | 945篇 |
综合类 | 1748篇 |
基础理论 | 613篇 |
污染及防治 | 3448篇 |
评价与监测 | 882篇 |
社会与环境 | 468篇 |
灾害及防治 | 139篇 |
出版年
2024年 | 13篇 |
2023年 | 42篇 |
2022年 | 58篇 |
2021年 | 48篇 |
2020年 | 42篇 |
2019年 | 57篇 |
2018年 | 51篇 |
2017年 | 39篇 |
2016年 | 38篇 |
2015年 | 56篇 |
2014年 | 111篇 |
2013年 | 87篇 |
2012年 | 729篇 |
2011年 | 1011篇 |
2010年 | 159篇 |
2009年 | 263篇 |
2008年 | 871篇 |
2007年 | 882篇 |
2006年 | 689篇 |
2005年 | 584篇 |
2004年 | 511篇 |
2003年 | 496篇 |
2002年 | 452篇 |
2001年 | 331篇 |
2000年 | 261篇 |
1999年 | 155篇 |
1998年 | 62篇 |
1997年 | 58篇 |
1996年 | 86篇 |
1995年 | 84篇 |
1994年 | 72篇 |
1993年 | 78篇 |
1992年 | 64篇 |
1991年 | 69篇 |
1990年 | 59篇 |
1989年 | 60篇 |
1988年 | 65篇 |
1987年 | 60篇 |
1986年 | 41篇 |
1985年 | 65篇 |
1984年 | 43篇 |
1983年 | 55篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 31篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1975年 | 11篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有9217条查询结果,搜索用时 31 毫秒
191.
一种新型脱色剂的合成和应用 总被引:5,自引:0,他引:5
以壳聚糖、双氰胺为主要原料合成了一种新型、高效的脱色剂处理染料废水,该脱色剂对四种典型的染料的脱色率都接近90%。实验表明:当合成温度控制在50℃左右,壳聚糖结构单元:双氰胺物质量比为1∶2,反应pH为2,反应时间为3 h时,合成的脱色剂对染料废水的脱色效果为最佳。实验同时比较了壳聚糖的盐酸溶液与脱色剂加入到染料废水后的紫外光谱变化,发现脱色剂对染料废水的脱色率要远远高于壳聚糖的盐酸溶液。实验研究了合成的脱色剂对上虞污水厂废水的处理效果,发现其COD去除率比该厂使用的PAC提高20%以上。 相似文献
192.
<正> 关于稀土元素丰度的研究对岩石成因模式讨论要求建立快速测定各种不同的火成岩、沉积岩和造岩矿物中稀土元素的分析方法。早先报道了一种测定某些矿物岩石中的 Y、Nd、Eu、Dy、Ho、Er、Tm 和 Yb 的原子吸收光谱法,它是将样品溶液(含1%La 作光谱缓冲剂的高氯酸盐乙醇介质)直接抽吸进入氧化亚氮-乙炔焰。而稀土元素(REE)是先通过草酸钙共 相似文献
193.
194.
一种化纤废水处理的运行及分析 总被引:5,自引:0,他引:5
化纤废水含有各种难降解有机物,国内外一直未能提出一套较好的处理方法,本文介绍了一种化纤废水的研究,处理工艺及其主要设计参数以及运行管理,事实证明了这种方法是可行的,其具有处理效果稳产,产泥量少,具有一定的消泡作用等优点。 相似文献
195.
The application of ultrasonic-electrolysis process for the removal of copper is studied.In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution.Thus increases metal deposition on the cathode surface.The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution. 相似文献
196.
<正> 北美第四纪沉积物曾有过一段漫长而有趣的历史。内布拉斯加州的第四纪沉积物是很重要的,因为许多经济活动都依赖于这些堆积物上发育的土壤和从沉积物中汲出的水,建筑材料也采自这些沉积物。从某种意义上说,几乎所有从事陆地上工作的人都是第四纪研究者,农民注意各种土类的差异和散布于内布拉斯加东部冰川作用区周围的奇特“外来石”景观,打井工人都熟悉这些沉积地层和埋藏在古河道中呈“脉状” 相似文献
197.
In this experiment, the impacts of pulp mill effluent irrigation, Fraser cottonwood (Populus deltoides 'Fraser') seedlings, and pulp sludge and manure soil amendments on sodium accumulation and distribution in the soil profile were evaluated during a 6 month greenhouse study. Sludge soil amendments and wastewater irrigation did not reduce stem biomass production of the cottonwood. Increased stem biomass production associated with manure soil amendments resulted in greater total uptake of sodium into stem material. This uptake was 0.002% of wastewater sodium inputs. In containers with seedlings, sodium concentrations were less in the surface horizon and more in the lower horizons than in containers with no seedlings. Infiltration rates and total sodium accumulation in the soil profile were not affected by the presence of Fraser cottonwood or the application of sludge or manure amendments to soil. 相似文献
198.
Sequential extraction analysis of heavy metals using a chelating agent (NTA) to counteract resorption 总被引:3,自引:0,他引:3
The geochemical partitioning of Pb, Ni and Zn in contaminated quartz-rich sediment and soil samples was characterized by sequential extraction analysis in the presence and absence of nitrilotriacetic acid (NTA). With NTA, levels of metals recovered are higher in the earlier steps and lower in the later steps of the procedure. This suggests that post-extraction resorption is effectively counteracted by chelation, thereby improving the accuracy of the method. An NTA concentration of 200 mg liter(-1) appears to be sufficient for counteracting resorption without causing significant dissolution of non-targeted phases in the samples studied. However, experiments using reference materials spiked with solutions containing Pb, Ni, Cu and Zn suggest that resorption will remain a problem when large amounts of strong sorbents such as organic matter are present. The results also show that although post-extraction resorption does occur in the absence of NTA, the magnitude of resorption is small (<20 to 30% of the summed total of metal present in the sample) in quartz-rich sediments. 相似文献
199.
Lepp NW Hartley J Toti M Dickinson NM 《Environmental pollution (Barking, Essex : 1987)》1997,95(3):363-369
Patterns of soil copper contamination have been examined in the vicinity of a copper rod rolling plant in Prescot, Merseyside, UK. The site, established in 1975, was found to possess clear patterns of soil copper contamination, with the highest levels of HNO3 and water-extractable fractions encountered in the factory grounds adjacent to the location of the furnace chimney. The majority of the copper had accumulated in the upper soil horizons. The site is surrounded by planted lawns, established at different times after the commissioning of the plant. The species composition of the extant grassland communities, found at sites with differing soil copper levels, was compared to the composition of the original seed mixtures sown at each of ten sites. These surveys clearly showed that different levels of soil copper contamination had produced significant changes in grassland composition with time. At the most polluted site, copper tolerant Agrostis capillaris clones were the main grasses present only two years after the area was sown with a four-species mixture of non-tolerant grass seed. Lolium perenne possessed extreme sensitivity to copper. A number of dicotyledonous species, normally considered sensitive to elevated copper levels, were found to be unaffected where such conditions had arisen after plants had established from seed. 相似文献
200.