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   770篇
  免费   32篇
  国内免费   63篇
安全科学   32篇
废物处理   8篇
环保管理   111篇
综合类   413篇
基础理论   123篇
污染及防治   108篇
评价与监测   40篇
社会与环境   13篇
灾害及防治   17篇
  2023年   8篇
  2022年   15篇
  2021年   18篇
  2020年   11篇
  2019年   9篇
  2018年   12篇
  2017年   9篇
  2016年   14篇
  2015年   15篇
  2014年   16篇
  2013年   23篇
  2012年   31篇
  2011年   43篇
  2010年   24篇
  2009年   51篇
  2008年   41篇
  2007年   66篇
  2006年   59篇
  2005年   47篇
  2004年   36篇
  2003年   44篇
  2002年   37篇
  2001年   37篇
  2000年   31篇
  1999年   38篇
  1998年   26篇
  1997年   22篇
  1996年   17篇
  1995年   8篇
  1994年   14篇
  1993年   12篇
  1992年   16篇
  1991年   6篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1983年   2篇
排序方式: 共有865条查询结果,搜索用时 31 毫秒
441.
环境与发展的研究现状及内涵   总被引:3,自引:0,他引:3  
本文根据我国的现实条件,讨论了环境与持续发展的关系,阐述了各发展阶段的特征和持续发的指标体系  相似文献   
442.
废水生物处理的监测和运行管理   总被引:1,自引:0,他引:1  
提出了废水生物处理系统中进出水水质的7项指标活性污泥性状的7项指标的监测分析,污泥微生物相的观察分析、对及时了解系统的运行情况的指导意义,通过连续监测可及时发现划常情况并作了断析与相应调整,以保证系统长期地达标运行。  相似文献   
443.
着重论述了各类单个字符及显示格式的编码方式,有些编码方式在实际应用中已得证实,有些仍待研究解决。只有不断探索,才能在“人-机-环”系统中,使飞行员和“机器”能有效而可靠地工作,即“人的特性”与“机器”能有效配合,更好地发挥飞行员的技术和战术水平。由此国军标也将随着科学技术的进步而更加充实、完善、先进、合理。  相似文献   
444.
Biogas purification via water scrubbing produces effluent containing dissolved CH4, H2S, and CO2, which should be removed to reduce greenhouse gas emissions and increase its potential for water regeneration. In this study, a reactor built with air supplies at the top and bottom was utilized for the treatment of biogas purification effluent through biological oxidation and physical stripping processes. Up to 98% of CH4 was removed through biological treatment at a hydraulic retention time of 2 hr and an upper airflow rate of 2.02?L/day. Additionally, a minimum CH4 concentration of 0.04% with no trace of H2S gas was detected in the off gas. Meanwhile, a white precipitate was captured on the carrier showing the formation of sulfur. According to the developed mathematical model, an upper airflow rate of greater than 2.02?L/day showed a small deterioration in CH4 removal performance after reaching the maximum value, whereas a 50?L/day bottom airflow rate was required to strip the CO2 efficiently and raise the effluent pH from 5.64 to 7.3. Microbiological analysis confirmed the presence of type 1 methanotroph communities dominated by Methylobacter and Methylocaldum. However, bacterial communities promoting sulfide oxidation were dominated by Hyphomicrobium.  相似文献   
445.
The low activity of Anammox bacteria at low temperatures and competition from nitrite oxidation bacteria(NOB) when treating low strength wastewater have been major bottlenecks in implementing Anammox in mainstream wastewater treatment. By intermittent high strength feeding(IHSF) and stepwise temperature reduction, stable operation of a granular Anammox reactor was realized at low temperatures(down to 15°C) for 28 days when treating low strength synthetic wastewater. The nitrogen loading rate reached 1.23–1.34 kgN/m~3/day,and the total nitrogen removal rate reached 0.71–0.98 kgN/m~3/day. The IHSF enriched the Anammox sludge in high strength cycles and compensated for sludge loss in low strength cycles, and the high concentration of ammonium in high strength cycles inhibited NOB. The 16 SrRNA gene sequencing results revealed that Candidatus Kuenenia was predominant in the reactor at low temperatures.  相似文献   
446.
以南岳古镇为研究对象,在识别景观基因的基础上,从建筑特征、形态布局和参考环境三个尺度,物质形态、功能作用和文化意义三个维度,以及颜色、形状、范围和建造年代四个形态要素等角度进行了问卷和访谈调查.结果发现,南岳大庙、环境尺度、物质形态和形状因素感知度最高,方形布局、布局尺度、物质形态和文化意义感知度最低;年龄、职业、教育程度、居住时间是影响古镇景观基因居民感知的因素,性别只在景观基因尺度有影响.  相似文献   
447.
Eight conventions make up the biodiversity cluster of multilateral environmental agreements (MEAs) that provide the critical international legal framework for the conservation and sustainable use of nature. However, concerns about the rate of implementation of the conventions at the national level have triggered discussions about the effectiveness of these MEAs in halting the loss of biodiversity. Two main concerns have emerged: lack of capacity and resources and lack of coherence in implementing multiple conventions. We focused on the latter and considered the mechanisms by which international conventions are translated into national policy. Specifically, we examined how the Strategic Plan for Biodiversity 2011–2020 and the associated Aichi Biodiversity Targets have functioned as a unifying grand plan for biodiversity conservation. This strategic plan has been used to coordinate and align targets to promote and enable more effective implementation across all biodiversity-related conventions. Results of a survey of 139 key stakeholders from 88 countries suggests streamlining across ministries and agencies, improved coordination mechanisms with all relevant stakeholders, and better knowledge sharing between conventions could improve cooperation among biodiversity-related conventions. The roadmap for improving synergies among conventions agreed to at the 13th Convention on Biological Diversity's Conference of Parties in 2016 includes actions such as mechanisms to avoid duplication in national reporting and monitoring on conventions and capacity building related to information and knowledge sharing. We suggest the scientific community can actively engage and contribute to the policy process by establishing a science-policy platform to address knowledge gaps; improving data gathering, reporting, and monitoring; developing indicators that adequately support implementation of national plans and strategies; and providing evidence-based recommendations to policy makers. The latter will be particularly important as 2020 approaches and work to develop a new biodiversity agenda for the next decade is beginning.  相似文献   
448.
Genetic diversity within species represents a fundamental yet underappreciated level of biodiversity. Because genetic diversity can indicate species resilience to changing climate, its measurement is relevant to many national and global conservation policy targets. Many studies produce large amounts of genome-scale genetic diversity data for wild populations, but most (87%) do not include the associated spatial and temporal metadata necessary for them to be reused in monitoring programs or for acknowledging the sovereignty of nations or Indigenous peoples. We undertook a distributed datathon to quantify the availability of these missing metadata and to test the hypothesis that their availability decays with time. We also worked to remediate missing metadata by extracting them from associated published papers, online repositories, and direct communication with authors. Starting with 848 candidate genomic data sets (reduced representation and whole genome) from the International Nucleotide Sequence Database Collaboration, we determined that 561 contained mostly samples from wild populations. We successfully restored spatiotemporal metadata for 78% of these 561 data sets (n = 440 data sets with data on 45,105 individuals from 762 species in 17 phyla). Examining papers and online repositories was much more fruitful than contacting 351 authors, who replied to our email requests 45% of the time. Overall, 23% of our email queries to authors unearthed useful metadata. The probability of retrieving spatiotemporal metadata declined significantly as age of the data set increased. There was a 13.5% yearly decrease in metadata associated with published papers or online repositories and up to a 22% yearly decrease in metadata that were only available from authors. This rapid decay in metadata availability, mirrored in studies of other types of biological data, should motivate swift updates to data-sharing policies and researcher practices to ensure that the valuable context provided by metadata is not lost to conservation science forever.  相似文献   
449.
朱晓明 《环境与发展》2020,(4):119-119,121
随着工业化的不断发展,对于水体污染的问题越来越严重,水污染的治理是目前最为关注的话题。伴随着生物强化技术的诞生,可以保证解决水污染问题的有效性。本文首先对生物强化技术简介和来源进行了介绍,然后对生物强化技术治理水污染的作用进行了详细的阐述,最后对生物强化技术在水污染治理中的应用进行了总结分析。  相似文献   
450.
To contribute to the aspirations of recent international biodiversity conventions, protected areas (PAs) must be strategically located and not simply established on economically marginal lands as they have in the past. With refined international commitments under the Convention on Biological Diversity to target protected areas in places of “importance to biodiversity,” perhaps they may now be. We analyzed location biases in PAs globally over historic (pre‐2004) and recent periods. Specifically, we examined whether the location of protected areas are more closely associated with high concentrations of threatened vertebrate species or with areas of low agricultural opportunity costs. We found that both old and new protected areas did not target places with high concentrations of threatened vertebrate species. Instead, they appeared to be established in locations that minimize conflict with agriculturally suitable lands. This entrenchment of past trends has substantial implications for the contributions these protected areas are making to international commitments to conserve biodiversity. If protected‐area growth from 2004 to 2014 had strategically targeted unrepresented threatened vertebrates, >30 times more species (3086 or 2553 potential vs. 85 actual new species represented) would have been protected for the same area or the same cost as the actual expansion. With the land available for conservation declining, nations must urgently focus new protection on places that provide for the conservation outcomes outlined in international treaties.  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