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   2408篇
  免费   162篇
  国内免费   347篇
安全科学   313篇
废物处理   94篇
环保管理   975篇
综合类   897篇
基础理论   203篇
污染及防治   105篇
评价与监测   147篇
社会与环境   100篇
灾害及防治   83篇
  2024年   3篇
  2023年   20篇
  2022年   48篇
  2021年   66篇
  2020年   67篇
  2019年   61篇
  2018年   44篇
  2017年   67篇
  2016年   82篇
  2015年   62篇
  2014年   83篇
  2013年   85篇
  2012年   101篇
  2011年   93篇
  2010年   75篇
  2009年   67篇
  2008年   88篇
  2007年   79篇
  2006年   76篇
  2005年   55篇
  2004年   68篇
  2003年   97篇
  2002年   178篇
  2001年   160篇
  2000年   182篇
  1999年   157篇
  1998年   122篇
  1997年   91篇
  1996年   220篇
  1995年   72篇
  1994年   31篇
  1993年   25篇
  1992年   15篇
  1991年   17篇
  1990年   4篇
  1989年   11篇
  1988年   4篇
  1987年   3篇
  1986年   2篇
  1985年   22篇
  1984年   39篇
  1983年   35篇
  1982年   4篇
  1981年   2篇
  1980年   9篇
  1978年   5篇
  1977年   2篇
  1973年   2篇
  1971年   14篇
  1967年   1篇
排序方式: 共有2917条查询结果,搜索用时 453 毫秒
321.
为考察并掌握典型平原地区生活垃圾焚烧厂周边土壤中重金属Cd、Cr、Cu、Pb、Ni和Zn的污染现状,以上海市某生活垃圾焚烧厂为例,研究其周边土壤中重金属赋存形态分布特征及生物有效性,采用Tessier连续提取法结合电感耦合等离子体发射光谱检测分析表层土壤中目标重金属总量及形态分布,并利用风险评估编码法(RAC)评价其生态风险水平.结果表明:研究区域土壤中Pb和Zn主要以Fe-Mn氧化物结合态和残渣态为主(>80%);Cr、Cu和Ni则以残渣态为主(>60%);Cd虽以残渣态为主(>50%),但与其他重金属相比,其碳酸盐结合态占比相对较高.生物有效性分析结果显示,Cr、Cu和Ni以惰性态为主,生物有效性低,而潜在可利用态Cd、Pb和Zn占比较高,存在较高的释放风险.土壤中各重金属潜在生态风险水平由高到低依次为Cd > Zn > Pb > Cu > Ni > Cr,其中,Cu、Pb和Zn处于低风险水平,Cr和Ni处于无风险水平,而Cd处于中等风险水平.研究显示,该垃圾焚烧厂周边土壤中重金属已存在不同程度的污染累积,其中,潜在可利用态Cd的占比较高,已达中等风险水平,应引起重视.   相似文献   
322.
介绍了安全仪表系统安全完整性等级(SIL)评估方法,并将SIL评估技术在柴油加氢装置进行应用,系统全面分析了装置安全仪表系统的可靠性,并提出合理可行的建议措施,对于提高装置安全稳定运行水平具有重要作用。  相似文献   
323.
在现代煤矿里,灾害和事故仍然是不可避免的。采取减小组织内成员的自由度来强化专业救灾机构的整体功能固然重要,但非专业化的辅助矿山救护队的建设工作更应加强。因为他们亲临现场,熟悉灾情,又处于救灾的黄金时间里。因此,对是否酿成灾害和灾害中损失的控制问题,辅助矿山救护队有更多的优势。  相似文献   
324.
NADH:ubiquinone oxidoreductase (complex I of the mitochondrial respiratory chain) deficiency is a severe disorder with an often early fatal outcome. Prenatal diagnosis for complex I defects currently relies mainly on biochemical assays of complex I in fetal tissues such as chorionic villi (CV), and is only in a minority of cases possible by means of mutational analysis of nuclear-encoded genes of complex I. We report on our experience to date with prenatal diagnosis in pregnancies at risk for complex I deficiency. We measured complex I activity in native CV and/or cultured CV in 23 pregnancies in 15 families. In accordance with the results of the investigations in CV, 15 children were born clinically unaffected. Two prenatally diagnosed unaffected fetuses and two prenatally diagnosed affected fetuses were lost prematurely with spontaneous or provoked abortions, respectively. Two affected children were born (prenatally found to be affected). In two pregnancies a discrepancy between native and cultured cells was found. We conclude that prenatal diagnosis for complex I deficiency can be reliably performed. Pitfalls were encountered in using cultured CV as a result of maternal cell contamination (MCC). Future research on pathogenic nuclear mutations underlying complex I deficiency will extend the possibilities for prenatal diagnosis at the molecular level. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
325.
/ To understand the total impact of humans on the carbon cycle, themodeling and quantifying of the transfer of carbon from terrestrial pools tothe atmosphere is becoming more critical. Using previously published data,this research sought to assess the change in carbon pools caused by humans inthe Lower Fraser Basin (LFB) in British Columbia, Canada, since 1827 anddefine the long-term, regional contribution of carbon to the atmosphere. Theresults indicate that there has been a transfer of 270 Mt of carbon frombiomass pools in the LFB to other pools, primarily the atmosphere. The majorlosses of biomass carbon have been from logged forests (42%), wetlands(14%), and soils (43%). Approximately 48% of the forestbiomass, almost 20% of the carbon of the LFB, lies within old-growthforest, which covers only 19% of the study area. Landfills are nowbecoming a major sink of carbon, containing 5% of the biomass carbonin the LFB, while biomass carbon in buildings, urban vegetation, mammals, andagriculture is negligible. Approximately 26% of logged forest biomasswould still be in a terrestrial biomass pool, leaving 238 Mt of carbon thathas been released to the atmosphere. On an area basis, this is 29 times theaverage global emissions of carbon, providing an indication of the pastcontributions of developed countries such as Canada to global warming andpossible contributions from further clearing of rainforest in both tropicaland temperate regions.KEY WORDS: Carbon pools; Global warming; Carbon release to atmosphere;Greenhouse effect  相似文献   
326.
Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.  相似文献   
327.
/ Environmental impact assessment (EIA) has been identified as an important instrument for facilitating sustainability. However, to do so requires the integration of sustainability into EIA theory and practice. The sustainability concept is a valid and important environmental management perspective. However, many issues and obstacles need to be addressed further if the concept is to be translated into practical strategies. Sustainability can potentially infuse EIA with a clearer sense of direction, an ethical foundation, a mechanism for establishing priorities and assessing choices, and a means of linking EIA to other environmental management instruments. Conceptually, EIA and sustainability can be integrated, but frameworks should be refined, adpated to context, and linked to related initiatives. Sustainability should be explicitly incorporated into EIA legislation, guidelines, and institutional arrangements. An experimental approach to testing, assessing, and sharing experiences is suggested.A framework is first presented that defines and characterizes the sustainability concept. A further framework is then described for integrating sustainability into EIA at the conceptual level. The integration of sustainability and EIA at the regulatory level is next addressed through an overview of sustainability initiatives in EIA requirements in Canada. The Canadian examples include many promising initiatives but these and other experiences will need to be monitored, shared, and integrated into comprehensive environmental management strategies. Finally, means of incorporating sustainability into each activity in the EIA planning process are identified.KEY WORDS: Sustainability; Environmental impact assessment  相似文献   
328.
胡国强 《化工环保》1996,16(6):369-372
以由地洛试剂为氧化剂,用分光光度法测定染料废水中对氨基酚的含量,进行了波长,贝特洛试剂用量及显色时间等分析条件的选择。精密度和准确度实验结果表明,该准确,快速,可用于染料废水中对氨基酚的测定。  相似文献   
329.
/ It has been suggested that the general public should be moreinvolved in environmental policy and decision making. It is important forthem to realize that they will have to live with the consequences ofenvironmental policies and decisions. Consequently, policy makers shouldconsider the concerns and opinions of the general public before makingdecisions on environmental issues. This raises questions such as: How can weintegrate the perceptions and reactions of the general population inenvironmental decisions? What kind of public participation should weconsider? In the present study, using a new regional ecosystem model, weattempted to integrate these aspects in its decision making model byincluding the formation of an advisory committee to resolve problems relatedto waste management. The advisory committee requested the activeparticipation of representatives from all levels of the community: economic,municipal, and governmental intervenors; environmental groups; and citizens.Their mandates were to examine different management strategies available inthe region, considering all the interdisciplinary aspects of each strategy,elaborate recommendations concerning the management strategies that are mostsuitable for all, and collaborate in communication of the information to thegeneral population. The results showed that at least in small municipalitiessuch an advisory committee can be a powerful tool in environmental decisionmaking. Conditions required for a successful consultation process, such aseveryday lay language and the presence of a facilitator other than ascientific expert, are discussed.KEY WORDS: Public consultation; Environmental policies;Interdisciplinary aspects; Municipal sewage sludge management; Generalpopulation; Decision-making process  相似文献   
330.
本文分析评价了永嘉县岩头镇农业综合开发的优势条件、开发潜力,提出了开发农业的方向、区域布局和开发项目和开发措施。  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