全文获取类型
收费全文 | 3124篇 |
免费 | 203篇 |
国内免费 | 801篇 |
专业分类
安全科学 | 211篇 |
废物处理 | 149篇 |
环保管理 | 291篇 |
综合类 | 1760篇 |
基础理论 | 515篇 |
污染及防治 | 788篇 |
评价与监测 | 153篇 |
社会与环境 | 151篇 |
灾害及防治 | 110篇 |
出版年
2024年 | 1篇 |
2023年 | 31篇 |
2022年 | 154篇 |
2021年 | 133篇 |
2020年 | 119篇 |
2019年 | 119篇 |
2018年 | 124篇 |
2017年 | 131篇 |
2016年 | 133篇 |
2015年 | 163篇 |
2014年 | 232篇 |
2013年 | 291篇 |
2012年 | 288篇 |
2011年 | 283篇 |
2010年 | 203篇 |
2009年 | 199篇 |
2008年 | 219篇 |
2007年 | 205篇 |
2006年 | 163篇 |
2005年 | 123篇 |
2004年 | 111篇 |
2003年 | 114篇 |
2002年 | 94篇 |
2001年 | 86篇 |
2000年 | 65篇 |
1999年 | 58篇 |
1998年 | 39篇 |
1997年 | 46篇 |
1996年 | 49篇 |
1995年 | 40篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
排序方式: 共有4128条查询结果,搜索用时 229 毫秒
372.
373.
雅砻江锦屏二级水电站减水河段生态需水量研究 总被引:1,自引:0,他引:1
针对雅砻江锦屏二级水电站减水河段面临的水生生物生态需水问题,提出了计算河道最小生态基流量的生态水力学法,考虑了水力生境参数的全河段变化情况,计算结果避免了单凭最低值进行判断所造成的判断失误。确定了锦屏二级水电站减水河段鱼类对流速、水深、水面宽等水力生境的需求。通过河道水力模拟,得出为满足减水河段鱼类的生存及繁衍,必须保证枯水季节猫猫滩闸址下泄45 m3/s流量,在该流量下,锦屏二级水电站减水河段中95%左右河段水力因子可满足研究中提出的河道内鱼类的生存条件;水温的变化不会影响河道内鱼类产卵;鱼类适应的缓流水、急流水、浅滩、深潭等水力形态的位置虽然发生变化,但数量保持不变。 相似文献
374.
Daily Bank Erosion Rates in the Lower Yellow River Before and After Dam Construction 总被引:1,自引:0,他引:1
Junqiang Xia Tao Li Xiaojuan Li Xiaolei Zhang Quanli Zong 《Journal of the American Water Resources Association》2014,50(5):1325-1337
During the period of water impoundment and sediment detention of the Sanmenxia Reservoir, riverbank erosion processes played a key role in the channel evolution of the Lower Yellow River (LYR). However, research into bank erosion rates of the LYR has been neglected due to the lack of direct field monitoring. In this study, an indirect method is proposed to determine bank erosion rates at daily time scales by outlining a detailed calculation procedure using measured hydrological data. A total of 810 data points of daily bank erosion rates before and after the construction of Sanmenxia Dam was calculated at seven hydrometric sections along the LYR, with the corresponding values of the bank stability coefficient and the width‐to‐depth ratio also being calculated. Empirical relations were then developed to estimate the daily bank erosion rates, using these parameters at the sections. Temporal and spatial variability in daily bank erosion rates in the LYR before and after dam construction were also investigated, revealing that: (1) the bank erosion rates had a mean value of 16.7‐29.1 m/day in the braided reach, with a maximum value of 290.0 m/day, while they were relatively low in the meandering reach, with a mean value of 2.5 m/day; (2) the erosion rates before dam construction were slightly greater than those after dam construction, with the difference reaching 5‐10 m/day in the braided reach, decreasing in the transitional reach gradually, and being slight in the meandering reach. 相似文献
375.
376.
This study was a preliminary step to evaluate the acute toxicity of 1-methyl-3-octylimidazolium chloride ([C8mim]Cl) on loach (Misgurnus anguillicaudatus) by determining the effects on hepatic antioxidant enzyme activities and by the comet assay. The results showed that [C8mim]Cl had acute toxicity at concentrations above 20 mg L?1, inducing oxidative stress and genotoxicity on fish liver cells. In respect to enzyme activities, [C8mim]Cl induced changes in the activities of superoxide dismutase, catalase, and glutathione content the livers of fish exposed at 20–80 mg L?1. [C8mim]Cl at the same exposure level caused a remarkable increase in malondialdehyde level. The comet assay indicated that [C8mim]Cl at 20–80 mg L?1 induced genotoxicity in liver cells. With increased exposure concentration and time, the two comet parameters trailing rate and tail moment were significantly increased, with significant differences (P < 0.05) observed between control group and each treatment group. The present study shows that ionic liquids can be a threat to the health of aquatic organism when accidentally released to aquatic ecosystems. 相似文献
377.
378.
Ten‐Hong Chen Jia‐Chern Wang 《Journal of environmental science and health. Part. B》2013,48(4):487-510
Abstract A closed‐loop anaerobic digestion system consisting of a leachbed (LB) and an upflow anaerobic sludge blanket (UASB) was tested as an alternative for the disposal of poultry mortalities. This paper compares the performances of three LB‐UASB treatment systems with different initial moisture contents in the LBs. Each LB was loaded with one chicken and 5, 10 or 18 liters of water. The LBs initially carried out the hydrolysis/acidification phase while the UASBs the methanogenesis phase. Due to repeated inoculation by the UASBs, the LBs with 10 and 18 liters of water started producing methane on day 5, while the one with 5 liters of water on day 19. However, methane production rates were low before day 40 for the LB with 10 liters of water and day 60 for the other LBs. Methane production gradually improved as the LBs continued to receive ungranulated sludge from the UASBs. The LBs eventually became balanced methane reactors. Continued balanced fermentation in the LBs resulted in leachates with very low substrate concentrations that could no longer support high‐rate methanogenesis in the UASBs. Consequently, methane production rates from the UASBs decreased quickly while that from the LBs reached peak levels. Cumulative methane production from each LB eventually exceeded that from its connecting UASB. After 118 days of digestion, 414, 437 and 470 liters of methane were produced from the three systems, respectively. Cumulative methane production from the LBs with 5 and 18 liters of water accounted for 63% of the total methane produced from their respective systems. The LB with 10 liters of water produced 75% of the total methane from that system. Methane yields ranged from 0.485 to 0.554 m3 (Kg TS) 1. About 86% of the initial dry weight was biodegraded. All three systems performed very well with little operational problems. Overall, the system that started with 10 liters of water in the LB performed the best. Strategy for enhancing system performances and implementing farm applications are discussed. 相似文献
379.
贸易、外商直接投资、经济增长与环境污染 总被引:52,自引:0,他引:52
选取1990—2002年中国30个省市贸易、外商直接投资(FDI)、经济和环境相关数据,从定性和定量描述的角度探讨贸易、FDI对我国环境库兹涅茨曲线(ECK)的影响。研究表明:贸易对中国的ECK没有直接影响。但考虑到贸易对经济增长的贡献,以及它在引进先进污染防治技术和环境管理思想方法方面的积极作用,积极发展对外贸易将有助于改善我国经济增长带来的环境污染问题。另一方面。FDI与污染物排放之间呈现出显著的正相关关系。在中国接受经济全球化影响的过程中,由于部分地区急于吸引外资,加之环境管理体系的不完善,外商直接投资在某些方面对我国环境造成了一定的负面影响。 相似文献
380.
Impact of Growing Income Inequality on Sustainable Development in China: A Provincial-level Analysis
Nico Heerink Ma Jia 《中国人口.资源与环境(英文版)》2006,4(1):23-32
A growing body of literature has documented the rapidly increasing income disparities that accompanied China's economic growth in the 1980s and 1990s, and the driving factors behind this. Growing income inequality in its turn may have important implications for the accumulation of physical capital, human capital, and natural capital and as a consequence for sustainable economic development. The purpose of this paper is to investigate the potential impact of income inequality on savings, human resources and the environment in China. It starts with an overview of the different causal mechanisms through which income inequality may affect the accumulation of physical capital, human capital, and natural capital, and discusses to what extent these causal relationships may be relevant in the case of China. Next, provincial data for the year 2002 are used to explore the relationship between income inequality and different elements of sustainable development in China. It is found that income inequality does not affect aggregate savings levels. Rising inequality, however, contributes to lower health and possibly also to higher fertility levels. It also lowers the use of chemical fertilizers in agriculture and therefore is likely to reduce water pollution. Other types of environmental degradation are not affected. 相似文献