全文获取类型
收费全文 | 281篇 |
免费 | 14篇 |
国内免费 | 168篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 12篇 |
环保管理 | 30篇 |
综合类 | 198篇 |
基础理论 | 58篇 |
污染及防治 | 117篇 |
评价与监测 | 20篇 |
社会与环境 | 5篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 22篇 |
2014年 | 24篇 |
2013年 | 32篇 |
2012年 | 27篇 |
2011年 | 22篇 |
2010年 | 29篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 18篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有463条查询结果,搜索用时 31 毫秒
61.
62.
Youkui Gong Yongzhen Peng Shuying Wang Sai Wang 《Frontiers of Environmental Science & Engineering》2014,8(4):589-597
The N2O production in two nitrogen removal processes treating domestic wastewater was investigated in laboratory-scale aerobic-anoxic sequencing batch reactors (SBRs). Results showed that N2O emission happened in the aerobic phase rather than in the anoxic phase. During the aerobic phase, the nitrogen conversion to N2O gas was 27.7% and 36.8% of NH+-N loss for conventional biologic N-removal process and short-cut biologic N-removal process. The dissolved N2O was reduced to N2 in the anoxic denitrification phase. The N2O production rate increased with the increasing of nitrite concentration and ceased when NH+-N oxidation was terminated. Higher nitrite accumulation resulted in higher NEO emission in the short-cut nitrogen removal process. Pulse-wise addition of 20 mg NO2 -N. L- 1 gave rise to 3-fold of N2O emission in the conventional N-removal process, while little change happened with 20 mg NOS-N L-1 was added to SBR1. 相似文献
63.
64.
Xijin Xu Weitang Liao Yucong Lin Yifeng Dai Zhihua Shi Xia Huo 《Environmental geochemistry and health》2018,40(4):1481-1494
Reactive oxygen species (ROS)-induced DNA damage occurs in heavy metal exposure, but the simultaneous effect on DNA repair is unknown. We investigated the influence of co-exposure of lead (Pb), cadmium (Cd), and mercury (Hg) on 8-hydroxydeoxyguanosine (8-OHdG) and human repair enzyme 8-oxoguanine DNA glycosylase (hOGG1) mRNA levels in exposed children to evaluate the imbalance of DNA damage and repair. Children within the age range of 3–6 years from a primitive electronic waste (e-waste) recycling town were chosen as participants to represent a heavy metal-exposed population. 8-OHdG in the children’s urine was assessed for heavy metal-induced oxidative effects, and the hOGG1 mRNA level in their blood represented the DNA repair ability of the children. Among the children surveyed, 88.14% (104/118) had a blood Pb level >5 μg/dL, 22.03% (26/118) had a blood Cd level >1 μg/dL, and 62.11% (59/95) had a blood Hg level >10 μg/dL. Having an e-waste workshop near the house was a risk factor contributing to high blood Pb (r s = 0.273, p < 0.01), while Cd and Hg exposure could have come from other contaminant sources. Preschool children of fathers who had a college or university education had significantly lower 8-OHdG levels (median 242.76 ng/g creatinine, range 154.62–407.79 ng/g creatinine) than did children of fathers who had less education (p = 0.035). However, we did not observe a significant difference in the mRNA expression levels of hOGG1 between the different variables. Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels (β Q2 = 0.362, 95% CI 0.111–0.542; β Q3 = 0.347, 95% CI 0.103–0.531; β Q4 = 0.314, 95% CI 0.087–0.557). Associations between blood Hg levels and 8-OHdG were less apparent. Compared with low levels of blood Hg (quartile 1), elevated blood Hg levels (quartile 2) were associated with higher 8-OHdG levels (β Q2 = 0.236, 95% CI 0.039–0.406). Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels. 相似文献
65.
聚磷菌厌氧时吸收乙酸和丙酸的代谢模型 总被引:2,自引:0,他引:2
水体中存在过多的磷是造成水体富营养化的重要原因之一,聚磷菌(polyphosphate accumulating organisms)因为能过量吸收磷而倍受关注。厌氧时,聚磷菌能大量吸收污水中的挥发性脂肪酸,经过一系列的生化反应,为好氧吸磷做准备。经过总结在厌氧条件下,聚磷菌Accumulibacter吸收乙酸和丙酸代谢转化的化学计量方程,并对模型中系数、还原力的产生、糖原降解途径以及厌氧条件下最终产物PHA的组成进行了讨论,得出挥发酸是通过主动运输进入细胞,且糖原经过ED途径提供还原力,多聚磷酸盐水解提供ATP和释放磷酸盐于体外,最终产生PHA的假设过程。但是,经过众多模型试验,一些假设仍没有得到最后的结论,所以应该进一步用富集程度较高的污泥进行精确研究。本文最终希望利用聚磷菌的代谢模型在工程运用中发挥最大效用。 相似文献
66.
67.
2008年南方低温冰雪灾害对农业的影响及对策 总被引:9,自引:0,他引:9
结合参加农业部组织的分省灾害评估调查活动,分析了2008年南方低温冰雪灾害的成因,指出是一系列天文、地球物理和大气环流异常因素构成的复杂灾害链所诱发。论述了低温冰雪灾害对南方农业生产的影响,总结了抗灾和补救的对策与措施。反思灾害中的经验教训,提出应健全预警机制和建立救灾物资储备,加强减灾和应急救援的技术储备,积极探索适合国情的农业灾害保险制度,通过提高公众素质和健全法制实现调动全社会的力量减灾。 相似文献
68.
With rapid population growth and rural to-urban migration in many Chinese cities, a large amount of natural lands have been converted to urban and agricultural lands recently. During this process of land conversion, economic development and quality of life improvement are considered as major goals, and their influences on ecological systems have often been neglected. The degradation of natural ecological systems due to land use change, however, has become severe,and may require immediate attentions from urban planners and local governments. Taking HaDaQi industrial corridor, Heilongjiang Province, China,as a case study area, this paper examined the trend of land use changes during 1990–2005, and quantified their influences on natural eco system service values. In particular, this study applied two major valuation methods, and examined whether different valuation methods generate significantly different results. Analysis of results suggests that human dominated land uses (e.g., urban and agriculture)have expanded rapidly at the cost of natural lands (e.g., wetlands and forest). Due to these land use changes, the total ecosystem service value decreased 29% (2.26% annually) from 1990 to 2005 when the first method was applied, and this rate is estimated to be 15.7% (1.13% annually)with the second approach. Moreover, the annual rate of ecosystem service value decline during 2000–2005 is about four times higher than that in 1990–2000 with both methods, suggesting much more severe ecosystem degradation during 2000–2005. 相似文献
69.
70.