首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   477篇
  免费   16篇
  国内免费   97篇
安全科学   28篇
废物处理   38篇
环保管理   33篇
综合类   145篇
基础理论   80篇
污染及防治   205篇
评价与监测   30篇
社会与环境   23篇
灾害及防治   8篇
  2024年   1篇
  2023年   7篇
  2022年   27篇
  2021年   21篇
  2020年   18篇
  2019年   7篇
  2018年   10篇
  2017年   11篇
  2016年   14篇
  2015年   13篇
  2014年   28篇
  2013年   56篇
  2012年   39篇
  2011年   39篇
  2010年   14篇
  2009年   26篇
  2008年   25篇
  2007年   50篇
  2006年   21篇
  2005年   19篇
  2004年   13篇
  2003年   31篇
  2002年   15篇
  2001年   18篇
  2000年   12篇
  1999年   4篇
  1998年   3篇
  1997年   6篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   3篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   5篇
  1986年   2篇
  1984年   2篇
  1983年   1篇
  1979年   4篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
排序方式: 共有590条查询结果,搜索用时 218 毫秒
371.
This work investigated the formation of carbonaceous and nitrogenous disinfection by-products (C-DBPs, N-DBPs) upon chlorination of water samples collected from a surface water and a ground water treatment plant (SWTP and GWTP) where the conventional treatment processes, i.e., coagulation, sedimentation, and filtration were employed. Twenty DBPs, including four trihalomethanes, nine haloacetic acids, seven N-DBPs (dichloroacetamide, trichloroacetamide, dichloroacetonitrile, trichloroacetonitrile, bromochloroacetonitrile, dibromoacetonitrile and trichloronitromethane), and eight volatile chlorinated compounds (dichloromethane (DCM), 1,2-dichloroethane, tetrachloroethylene, chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene) were detected in the two WTPs. The concentrations of these contaminants were all below their corresponding maximum contamination levels (MCLs) regulated by the Standards for Drinking Water Quality of China (GB5749-2006) except for DCM (17.1 μg/L detected vs. 20 μg/L MCL). The SWTP had much higher concentrations of DBPs detected in the treated water as well as the DBP formation potentials tested in the filtered water than the GWTP, probably because more precursors (e.g., dissolved organic carbon, dissolved organic nitrogen) were present in the water source of the SWTP.  相似文献   
372.
对弥渡台地电场观测电极进行埋深处理,将原来埋深1.5 m电极深埋到5.0 m。改进后,三个测道长、短极距一致性较好,差值减少到个位数,相关性达到高度相关。通过电极埋深处理前后观测数据的对比分析认为:在地电场观测中,若将电极做深埋处理,则可以有效抑制来自地表干扰。  相似文献   
373.
新常态下环境保护新形势研究   总被引:2,自引:2,他引:0  
受工业化阶段转换、需求结构调整两个新常态本质因素的影响,我国经济增速、产业结构、重工业产能、能源需求及社会阶层正在发生结构性变化,经济增长新旧动力出现转换,由过去依靠劳动力成本、企业规模、资源环境低价的数量扩张型增长向依靠深化改革和创新驱动带来的效率质量提升型增长转变。经济发展阶段的新变化、新特点,使得环境压力有望高位舒缓,环境保护有望从临界点向转折点改变,生态文明建设和环境保护也呈现新问题、新要求和新特征。  相似文献   
374.
基于可达、可行、可接受的全面小康社会环境目标研究   总被引:2,自引:2,他引:0  
基于2020年我国经济社会发展情景,开展环境目标与其他目标发展协调性分析,认为环境指标负向发展突出,是全面小康社会的短板和最大制约因素。从需求侧和供给侧分析小康社会环境目标的政治、公众需求与政府的供给条件、基础和能力,通过新常态资源环境压力分析与环境质量改善国际对标研究,认为我国在社会经济发展方式转型尚未完成、环境治理投入没有持续明显提升的情况下,大幅度、全面改善环境质量还存在很大障碍。提出全面小康的环境目标定位应以环境质量为核心,响应公众对环境质量改善的期待;合理看待小康社会的历史定位,制定阶段性目标;把握生态环境可达、经济技术可行、人民群众可接受的平衡,综合确定全面小康社会的环境底线。全面小康环境目标设置应体现保底线、全覆盖、诉民生、有标杆等原则。  相似文献   
375.
海水淡化在中国沿海城市地区获得了广泛应用,海水淡化用海涉及到多方面的因素.根据海水淡化工程用海的特点,建立基于自然-生态环境-社会经济框架的指标体系,给出了评价指标量化方法.建立了模糊综合评价法的海水淡化用海适宜性评价模型,形成具有科学化、定量化等特征的海水淡化用海适宜性评价体系,研究成果可为海水淡化的开发与管理提供科学参考.  相似文献   
376.
Tropical estuary wetlands are important for aquaculture and wildlife. However, many of them receive large amounts of anthropogenic heavy metals annually. Here, the transformation of spiked heavy metals, namely, Cd, Cr, Cu, Ni, Pb, and Zn, and the effects of salinity on their transformation in wetland soils after an eight-month-long incubation under moisture-saturation conditions were studied in the Pearl River estuary in China. Cd exhibited high mobility and bioavailability, with 12.2% to 25% Cd existing in the exchangeable fraction. Other heavy metals primarily existed in the reducible and oxidisable forms, and less than 2% were bound to the exchangeable fraction. Compared with the controls, contents of none of the metals associated with residual forms were significantly altered. These results imply that most exchangeable metals, except for Cd, transformed into other stable fractions through an eight-month-long ageing process, but not into the residual fraction. Thus, transformation from non-residual to residual forms was very slow in the tropical estuary wetland environment. Addition of NaCl increased the exchangeable fractions of Cd, Pb, and Zn, suggesting that increased soil salinity induced by flood tides during the dry season may enhance their mobility.  相似文献   
377.
近几年来人们普遍感到各种事故越来越多,尤其是恶性事故的频发率很高,造成重大的人员伤亡和财产损失愈发厉害,让人惊恐不安。据国家安全生产监督管理总局、监察部的通报,在2006年处理结案特别  相似文献   
378.
In this study, we added increments of acid and base to three calcareous soils from the eastern, middle and western parts of Gansu Province (China) and to three treated soils to remove calcium carbonate, organic matter and both carbonate and organic matter, respectively. the titration curves were measured and the magnitudes of buffer capacities as a function of pH were computed. It was found that the buffer capacity of calcareous soil is mainly attributed to calcium carbonate, as expected from the chemical composition of calcareous soil, while cation exchange system, silicate buffer system and organic matter play a minor role. the results clearly show that these soils of Gansu Province will not become a problem in the near future from the entrance of H+ into these soils.  相似文献   
379.
This article developed a decomposition model of energy productivity on the basis of the economic growth model. Four factors were considered which may influence China’s energy productivity according to this model: technology improvement, resource allocation structure, industrial structure and institute arrangement. Then, an econometric model was employed to test the four factors empirically on the basis of China’s statistical data from 1978 to 2004. Results indicated that capital deepening con- tributes the most (207%) to energy efficiency improvement, and impact from labor forces (13%) is the weakest one in resource factor; industrial structure (7%) and institute innovation (9.5%) positively improve the energy productivity.  相似文献   
380.
In the present study the biotransformation of phenanthrene in the rat and guinea pig was investigated. 14C-labelled phenanthrene was administered by gavage in corn oil to Sprague-Dawley rats (10 mg/kg b.w./day) and guinea pigs (10 mg/kg b.w./day). Urine and feces were separately collected for the determination of the radioactivity content, and pooled urine was used for the analysis of metabolites. Phenanthrene was metabolized by the rat and guinea pig to free hydroxylated phenanthrenes and their conjugates. The percentages of conjugates, expressed as the total urinary radioactivity, were 39% glucuronides, 24% sulfates and 18% cysteinylglycine for rats; and 39% glucuronides, 23% sulfates and 28% cysteinylglycine for guinea pigs. Enzymatic hydrolysis of glucuronides and sulfates resulted in the formation of free 1,2-, 3,4- and 9,10-dihydrodiols of phenanthrene and 1-, 2-, 3-, and 4-hydroxyphenanthrene in both species.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号