全文获取类型
收费全文 | 1875篇 |
免费 | 107篇 |
国内免费 | 577篇 |
专业分类
安全科学 | 136篇 |
废物处理 | 116篇 |
环保管理 | 140篇 |
综合类 | 1078篇 |
基础理论 | 309篇 |
污染及防治 | 555篇 |
评价与监测 | 98篇 |
社会与环境 | 64篇 |
灾害及防治 | 63篇 |
出版年
2024年 | 6篇 |
2023年 | 48篇 |
2022年 | 132篇 |
2021年 | 102篇 |
2020年 | 77篇 |
2019年 | 81篇 |
2018年 | 76篇 |
2017年 | 86篇 |
2016年 | 103篇 |
2015年 | 104篇 |
2014年 | 126篇 |
2013年 | 182篇 |
2012年 | 149篇 |
2011年 | 161篇 |
2010年 | 120篇 |
2009年 | 112篇 |
2008年 | 108篇 |
2007年 | 113篇 |
2006年 | 75篇 |
2005年 | 60篇 |
2004年 | 39篇 |
2003年 | 56篇 |
2002年 | 63篇 |
2001年 | 44篇 |
2000年 | 48篇 |
1999年 | 46篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 42篇 |
1995年 | 25篇 |
1994年 | 12篇 |
1993年 | 25篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1958年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有2559条查询结果,搜索用时 865 毫秒
251.
为了提高油田采油(气)污水处理能力,胜利油田开发研制出新型絮凝浮选剂PS-01,以聚合铝为主,配以常用的助凝剂二氧化硅气溶胶,工业用硫酸镁等,按比例混合在一起配置而成。在试验中将它们与油田内广泛使用的絮凝浮选剂SG-01,JX-01,NA-1等进行比较。结果表明:PS-01絮凝浮选剂的原料来源广泛,合成工艺简单,易于操作;对采油(气)污水处理效果好,加药量少,处理成本低;应用的pH范围较宽,反应迅速,可缩短混合反应时间;适用性强,低温时效果不受影响;对投药设备的腐蚀性小,性质稳定,无沉淀产生;同时各种原料的不同配比对絮凝浮选效果影响很大,要控制好比例。 相似文献
252.
253.
254.
通过构建RAM-SFA-RAM三阶段工业绿色全要素水资源效率测度模型,对其不同层面的效率值进行多维测度与比较分析,并利用空间Tobit模型对工业绿色全要素水资源效率的驱动机制进行实证检验.效率测度结果表明,环境因素与统计噪音是效率值计算中不可忽视的重要影响因素;全国样本的效率值在2000~2017年期间总体变化趋势是以持续上升为主,但距离理想发展状态还存在较大差距,具体阶段上可划分为“稳增期”、“振落期”和“提速期”;区域层面的检验中,东部效率具有较为显著的领先优势,而中部和东北部效率差异性相对较小,其变化曲线存在明显的“交互性”现象,西部则整体效率偏低;主要经济带的检验中,京津冀地区的工业绿色全要素水资源效率整体上要高于泛珠三角和泛长三角地区.驱动机制检验表明,基于全国样本维度的水资源禀赋、企业技术创新、用水结构和环境规制对工业绿色全要素水资源效率具有正向促进作用,而产业结构、城镇化率表现为负向抑制效应;在区域样本检验中,各影响要素在不同区域之间所呈现出的作用效果存在一定差异性,但产业结构调整、城镇化水平等应引起重视,不同区域需要依据其实际特点采取针对性的改进措施. 相似文献
255.
Seasonal variations of monoterpene emissions from coniferous trees of different ages in Korea 总被引:2,自引:0,他引:2
Seasonal variations of emission rates and compositions from coniferous species were measured under controlled conditions using a vegetation enclosure method. Total emission rates and compositions of monoterpene compounds from young and adult trees in different seasons were compared.
It was found that the total emission rates and the components of monoterpene varied significantly with tree species, age, and season. Total emissions from C. japonica and P. koraiensis were higher for older trees than for younger trees; however, significantly higher emissions were found from younger trees for C. obtusa. Higher monoterpene emission rates from each plant were found in spring and summer compared with autumn and winter emissions. 相似文献
256.
257.
258.
259.
Mussel watch: a review of Cu and other metals in various marine organisms in Taiwan, 1991-98 总被引:1,自引:0,他引:1
Jeng MS Jeng WL Hung TC Yeh CY Tseng RJ Meng PJ Han BC 《Environmental pollution (Barking, Essex : 1987)》2000,110(2):207-215
This study presents the distribution of Cu, Zn, Pb, Cd, Hg and As in various marine organisms collected along the western coast of Taiwan from 1991 to 1998, and also evaluates the time variation of Cu in oysters before (1980-85) and after (1986-98) the "green oyster" incident. The results show that relatively high geometric mean (GM) concentrations of Cu, Zn, Pb, Cd, As and Hg were generally found in Crassostrea gigas (Cu=229 microg/g, Zn=783 microg/g), Gomphina aeguialtera (Pb=30.3 microg/g), Tegillarca granosa (Cd=2.85 microg/g), Thais clavigera (As=96.9 microg/g) and Parapenaeopsis cornuta (Hg=1.35 microg/g), respectively. Especially, maximum Cu and Zn concentrations (GM=229 and 783 microg/g, respectively) in oysters (C. gigas) from different culture areas were much higher than those of the other organisms by about 1.13-458 and 2.40-63.7 times, respectively. Similarly, rock-shells (Thais clavigera) had a high capacity for accumulating Cu (GM=202 microg/g) and Zn (GM=326 microg/g) under the same physico-chemical conditions. The highest GM Cu and Zn concentrations of 1108 (range from 113 to 2806) and 1567 (range from 303 to 3593) microg/g were obtained in oysters from the Hsiangshan coastal area, one of the most important oyster culture areas in Taiwan. However, the highest GM Cd and As concentrations of 6.82 and 19.3 microg/g were found in oysters from the Machu Islands. Mean Cu concentrations in the oysters from the Erhjin Chi estuary declined from 2194+/-212 microg/g in 1986-90 to 545 microg/g (GM) in 1991-96. In the Hsiganshan area, GM Cu concentrations of 909 microg/g (1991-96) and 1351 microg/g (1997-98) in oysters were significantly higher than those of 201 microg/g (1980-85) and 682 microg/g (1986-90). The gradually increasing levels of Cu and Zn in the oysters from the Hsiangshan area have been observed year by year. 相似文献
260.