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   201篇
  免费   13篇
  国内免费   23篇
安全科学   3篇
环保管理   46篇
综合类   99篇
基础理论   45篇
污染及防治   9篇
评价与监测   13篇
社会与环境   18篇
灾害及防治   4篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   4篇
  2019年   3篇
  2018年   8篇
  2017年   4篇
  2016年   6篇
  2015年   9篇
  2014年   9篇
  2013年   20篇
  2012年   14篇
  2011年   15篇
  2010年   5篇
  2009年   17篇
  2008年   9篇
  2007年   22篇
  2006年   6篇
  2005年   8篇
  2004年   8篇
  2003年   10篇
  2002年   3篇
  2001年   2篇
  2000年   2篇
  1999年   8篇
  1996年   3篇
  1995年   1篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1972年   1篇
排序方式: 共有237条查询结果,搜索用时 403 毫秒
81.
There are two approaches in the application of satellite sensors to marine pollution studies. Satellite sensors are used to observe and characterize ocean pollutants such as industrial wastes and oil. in addition, satellite observations provide information useful in illuminating processes such as eutrophi-cation or air-sea exchange of CO2, that are important in determining the distribution and fate of pollutants.

Satellite technology is an important tool in monitoring and studying ocean pollution. Visible sensors have been used to observe and characterize sewage sludge and industrial wastes dumped at sea. Oil slicks have been observed with Landsat, AVHRR and SAR imagery. Besides directly detecting pollutants, satellite sensors are useful for analyzing ocean processes that are influential in the fate of pollutants. These processes include eutrophication of coastal waters and the distribution of suspended matter. the fate of excess CO2 can be addressed using scatterometer-derived estimates of wind speeds to determine the CO2 exchange coefficient at the sea surface on a global scale.  相似文献   
82.
In the past few decades, the tourism sector has emerged as a significant economic activity in island nations, particularly in tropical regions. However, most of the tropical islands face similar constraints, viz., threat to natural resources, chances of biopiracy, impact of climate change, population pressure and unsystematic tourist management. Ecotourism, as a concept, envisages promoting tourism with due regard to natural environment and ecological sanctity of the destination. Archipelago of Andaman and Nicobar (A&N) Islands is one of picturesque geographical creation in the Bay of Bengal, India, in tropical region and is an emerging tourist destination. It was observed that around 2.2 lakhs national and international tourists visit the A&N Islands annually. With tourism sector as an integral component, the service sector with share of 56% in gross state domestic product dominates the island economy. An analysis based on primary survey from various stakeholders associated with the sector revealed that factors such as economy in travel and boarding, availability of tourist facilities and comfort, safety, etc. were major factors that determined the choice of the tourists that visited the islands. The weights given by the tourists to the natural sites in A&N Islands revealed that the landscape topped list with 91.6% score by the visitors followed by beaches (91.3%), scenery (86.5%), reserved forests (84.6%), limestone caves (66.3%) and coral sights (65.8%). Coral sites were given weight of 65.8% of tourists, cultural and historical tourism products 85.4% for the natural history. Similarly, historical sites (83.7%), museums (78.6%) and heritage sites (72.8%) were also among top cites attraction. Recent initiatives by the Andaman administration gives due to care to sustainably develop the tourism infrastructure of the islands to harness the potential of eco-friendly tourism in this picturesque tourist haven.  相似文献   
83.
崇明北湖叶绿素a浓度与环境因子的GAM回归分析   总被引:4,自引:0,他引:4       下载免费PDF全文
刘佳  黄清辉  李建华 《中国环境科学》2009,29(12):1291-1295
以崇明北湖为例,采用广义加性模型(GAM)对该湖的叶绿素a浓度与相关环境因子进行分析.结果表明,叶绿素a浓度与总氮、总磷和水温之间存在较好的非线性关系(P<0.05),叶绿素a浓度与总磷之间的关系先为单调递增,当总磷浓度达到0.12mg/L时,变为单调递减;不同总氮浓度区间上,总氮对叶绿素a浓度的影响不同,氮浓度为0.6~1.8mg/L时,对叶绿素a浓度的影响不大;水温在24~26℃时,叶绿素a浓度最高.叶绿素a浓度与氮磷比之间也存在较好的非线性关系(P<0.1),氮限制时,叶绿素浓度与氮磷比呈反比;磷限制时,叶绿素a浓度随着氮磷比单调递减.  相似文献   
84.
舟山本岛大气污染输送过程的数值模拟分析   总被引:2,自引:0,他引:2       下载免费PDF全文
利用HYSPLIT-4后向轨迹模式和NCEP(美国国家环境预报中心)的2012年GDAS(全球资料同化系统)气象数据,结合NO2、PM2.5、PM10和SO2等常规大气污染物的质量浓度数据,对舟山本岛2012年4月、7月、10月和12月的大气污染输送过程进行了模拟,并通过聚类分析和潜在源区分析〔包括PSCF(潜在源贡献)和CWT(浓度权重轨迹)计算〕,确定大气污染传输路径及影响源区. 结果表明:舟山本岛气流后向轨迹呈明显的季节变化特征,4月主要受来自黄海海面气流轨迹的影响,其占总轨迹数的36.7%,ρ(PM10)为(53.24±24.33)μg/m3;7月以途经琉球群岛和东海气流轨迹为主,占总轨迹数的48.4%,对ρ(NO2)、ρ(PM2.5)、ρ(PM10)和ρ(SO2)贡献分别为(24.63±6.33)、(28.60±4.83)、(52.89±18.76)和(8.67±3.11)μg/m3;10月气流轨迹主要来自于东海海面,占总轨迹数的49.2%;12月气流则主要来自辽宁南部和黄海,占总轨迹数的66.1%,对ρ(NO2)、ρ(PM2.5)、ρ(PM10)和ρ(SO2)贡献分别为(28.48±15.14)、(58.71±14.10)、(69.83±38.94)和(20.83±13.28)μg/m3. 舟山本岛PM2.5的潜在源主要为毗邻城市间局地污染,集中于浙江沿海城市及杭州湾、上海等地.   相似文献   
85.
为了解海南岛及邻近陆地拟细鲫(Aphyocypris normalis)的遗传分化和亲缘地理过程,采用线粒体细胞色素b(Cyt b)对9个种群共124个个体的遗传多样性和遗传分化进行评估,并探讨这一物种的亲缘地理结构及演化历史.结果显示,在1 140 bp的序列中,共检测到87个核苷酸变异位点,定义了34个单倍型.基于Cyt b序列构建的系统发育树结果将所有个体分成3个主要谱系(A、B、C),谱系A包括海南岛大部分种群和邻近陆地全部种群,昌化江全部个体形成独立的谱系B,谱系C则为海南岛万泉河上安乡全部个体,各谱系间的遗传分化指数较高(0.707 5-0.971 9).分化时间估算的结果表明,谱系C的分化时间为2.038百万年前,谱系B的分化时间为0.865百万年前.种群历史动态分析表明,绝大部分种群均没有发生种群扩张,且所有谱系在近期都发生过有效种群数量减小的事件.根据研究结果推测,海南岛内万泉河上安乡种群的分化主要是由于五指山鹦哥岭山脉的隆起而导致的,而海南岛内和邻近陆地大部分群体没有发生分化可能是由于更新世冰期期间,岛屿和邻近陆地之间的水系因海平面下降而发生连接,琼州海峡两岸的拟细鲫种群有机会发生基因交流.因此认为琼州海峡并未对拟细鲫的扩散起到物理阻隔作用,海南岛为拟细鲫这一物种的起源扩散中心.(图4表6参48)  相似文献   
86.
Islands face similar challenges for sustainability as continental areas, but their geographic situation conditions their options for development. However, thanks to their clear geographic boundaries, they are an opportunity to think about sustainability in an integrated way. The objective of the study was to explore from a local (island) and regional (archipelago) perspective strategies for sustainability. ‘Participative foresight scenario mapping’ (PFSM) methodology was used to explore the sustainable future of a small island (Flores Island, Azores, Portugal). The need to acknowledge the limit to growth is a key finding of this article. But the research also allowed us to analyse in depth specific strategies that can be applied to different sectors of activity, the most important being to: improve the quality of local products, diversify the economy and increase self-sufficiency. PFSM succeeded in identifying key themes and facilitating debate around these subjects. These findings can inform sustainable development in other islands or territories sharing similar geographic characteristics.  相似文献   
87.
In spite of the wide diversity in the economic performance of small island developing states (SIDS), the apparent prosperity of several SIDS has entailed a global misrepresentation of the economic situation of these countries. While their vulnerability to natural disasters is not denied, the general risk of economic marginalization that many SIDS face in the context of globalization may not have received sufficient attention. The paper attempts to highlight what matters most in the consideration of the economic vulnerability of SIDS and in the debate to prevent their marginalization. It examines the main types of external shocks to which SIDS are vulnerable, and discusses the economic handicaps that are fundamental causes of this vulnerability. Economic specialization (with the predominance of international trade in services) is then a central notion in the analysis of island vulnerability: a better specialization, which may involve diversification and always implies greater international competitiveness, can reduce the exposure or vulnerability of SIDS to external shocks, and induce greater economic stability in these countries. Hence the importance of developing policies to circumvent the specific handicaps of islands and facilitate the realization of new trading opportunities through an emulative use of globalization forces.  相似文献   
88.
于2020年6月—2021年5月,应用相关分析、富集因子(EF)以及正定矩阵因子分解模型(PMF)和气团来源分析对东南沿海岛屿平潭大气降水化学特征及来源进行了综合评价与分析。结果表明,平潭大气降水pH值为3.96~7.49,平均值为4.78;电导率(EC)为4.9~342.0μs/cm,平均值为24.4μs/cm,高于我国降水背景点值;大气降水中各离子组分当量浓度排序为:Cl->Na+>SO_(4)^(2)>NO-3>Ca 2+>NH+4>Mg 2+>K+>F->NO-2,Cl-和Na+是降水中占比最大的阴、阳离子,其当量浓度占总离子当量浓度的51.4%;NO-3对平潭大气降水酸化的贡献较高(55.9%),且有77%的大气降水酸度被碱性物质中和,其中铵根离子(NH+4)和钙离子(Ca 2+)有着较强的中和能力。富集因子分析结果表明,除海洋源外,地壳源和人为源也是平潭大气降水离子的主要来源;PMF模型结果显示,海洋源、人为源、地壳源和燃烧源分别贡献了平潭大气降水离子的61.1%,23.8%,10.0%和5.1%;气团来源分析结果表明,区域传输对平潭大气降水离子分布及空气质量影响显著,京津冀和长三角地区排放的人为污染物可以经海上传输通道由北至南影响我国下风向地区,给沿海地区大气细颗粒物(PM_(2.5))与臭氧(O_(3))协同控制带来挑战。  相似文献   
89.
沈阳城市热岛变化趋势及其与TSP相关关系的初步分析   总被引:6,自引:0,他引:6  
利用 1970~ 1999年 30a的沈阳市和其周边的几个观测站的年均地面温度资料、1987~ 1996年沈阳市TSP浓度的观测资料、2 0 0 2年 11月的沈阳市地面逐时温度观测资料以及 2 0 0 2年 11月的TSP浓度的观测资料 ,对沈阳市的城市热岛年际、日变化情况统计分析研究 ,找出了城市热岛的一些变化规律 ,并对这些规律与TSP浓度关系进行分析研究。结果表明 ,沈阳的热岛强度有逐年增强的趋势 ,冬季夜间增强尤为明显。TSP的浓度与热岛的增强呈正相关。  相似文献   
90.
在分析广东省湛江市东海岛的区域水文地质特征及地下水开发利用特点的基础上,构建了地下水入海排泄量估算模型,以估算地下水入海排泄量和携带入海的营养盐量。结果表明,估算得到的2009年东海岛地下水入海排泄总量为133.8×104m3,其中携带入海的营养盐总量为5 157.98kg,地下水的携带入海成为近岸海域陆域营养盐入海排泄的主要途径;研究区位于沿海地带的砂堤砂地潜水分布区以及位于海岸地带的湛江组浅部潜水—微承压水含水层分布区等局部地段,存在地下水入海排泄量的低值区,可能存在海水入侵风险。  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