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   2270篇
  免费   249篇
  国内免费   893篇
安全科学   134篇
废物处理   214篇
环保管理   313篇
综合类   1708篇
基础理论   314篇
环境理论   4篇
污染及防治   358篇
评价与监测   175篇
社会与环境   192篇
  2024年   13篇
  2023年   78篇
  2022年   87篇
  2021年   100篇
  2020年   88篇
  2019年   87篇
  2018年   96篇
  2017年   115篇
  2016年   143篇
  2015年   177篇
  2014年   161篇
  2013年   212篇
  2012年   224篇
  2011年   249篇
  2010年   120篇
  2009年   145篇
  2008年   117篇
  2007年   140篇
  2006年   186篇
  2005年   118篇
  2004年   87篇
  2003年   104篇
  2002年   90篇
  2001年   84篇
  2000年   80篇
  1999年   63篇
  1998年   42篇
  1997年   43篇
  1996年   45篇
  1995年   30篇
  1994年   26篇
  1993年   17篇
  1992年   11篇
  1991年   14篇
  1990年   7篇
  1989年   5篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1977年   2篇
排序方式: 共有3412条查询结果,搜索用时 578 毫秒
691.
Traditional air quality data have a spatial resolution of 1 km or above, making it challenging to resolve detailed air pollution exposure in complex urban areas. Combining urban morphology, dynamic traffic emission, regional and local meteorology, physicochemical transformations in air quality models using big data fusion technology, an ultra-fine resolution modeling system was developed to provide air quality data down to street level. Based on one-year ultra-fine resolution data, this study investigated the effects of pollution heterogeneity on the individual and population exposure to particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and ozone (O3) in Hong Kong, one of the most densely populated and urbanized cities. Sharp fine-scale variabilities in air pollution were revealed within individual city blocks. Using traditional 1 km average to represent individual exposure resulted in a positively skewed deviation of up to 200% for high-end exposure individuals. Citizens were disproportionally affected by air pollution, with annual pollutant concentrations varied by factors of 2 to 5 among 452 District Council Constituency Areas (DCCAs) in Hong Kong, indicating great environmental inequities among the population. Unfavorable city planning resulted in a positive spatial coincidence between pollution and population, which increased public exposure to air pollutants by as large as 46% among districts in Hong Kong. Our results highlight the importance of ultra-fine pollutant data in quantifying the heterogeneity in pollution exposure in the dense urban area and the critical role of smart urban planning in reducing exposure inequities.  相似文献   
692.
以日本国COSMO公司坂出炼油厂加工高含硫中东原油带来的环境问题和采取的对策为例,分析炼制高含硫原油时应注意采取的环境管理和环保治理对策  相似文献   
693.
氮肥和磷肥对稻田N2O排放的影响   总被引:14,自引:2,他引:14       下载免费PDF全文
通过模拟南方稻田施用不同量的氮肥和磷肥的实验来探讨N和P对稻田释放N2O的影响.结果表明,水稻田N2O排放通量的较大值主要出现在3次烤田期;氮肥和磷肥对土壤中产生N2O的贡献主要在水稻生长中后期,从第1次烤田起(移栽后34d),氮肥和磷肥都表现为对N2O排放有促进作用;而低氮对N2O排放的刺激作用没有高氮的作用明显,且N2处理(180kg/hm2)、N1处理(90kg/hm2)和N0处理(没有施肥)之间的平均N2O排放差异不显著.在水稻生长中后期(第1次烤田后),N3处理(270kg/hm2)和N4处理(360kg/hm2)的较高水平的氮肥加入能强烈刺激N2O排放.  相似文献   
694.
Recoveryandchemicalutilizationofcarbondioxidefromfossil-fuelburningindustrialsourcesYinXiaolong(DepartmentofAppliedChemistry,...  相似文献   
695.
Time series of fossil fuel carbon emissions from 1960–2000 for each of the U.S. states and the District of Columbia are presented and discussed. Comparison of the nationally summarized results with other national datasets shows generally good agreement, usually within 2%, and gives insight into the quality of all the data series. Our extension of the state-by-state emissions estimates back to 1960 reveals patterns of change that are coherent across states and can be related to historic events such as energy crises and federal legislation. Most notable is the changing pattern of coal usage, as coal-producing states produce increasingly more energy (mostly for electricity) for other states so that per capita CO2 emissions diverge for states that import as opposed to those that export electricity. The decline in carbon emissions from petroleum products following the 1970s is also evident. Per capita emissions range over an order of magnitude for the different states. The data suggest that differences in per capita emissions arise from differences in many technological, physical, resource, social, and economic factors. The data presented here and the few correlations briefly noted pose a challenge for trying to use per capita emissions as a measure of equity or to provide mitigation targets.  相似文献   
696.
IntroductionUsingcomplexphosphatetotreatmanganesewastewaterfromtitaniumdioxideplantwaspresentedinthispaper.Comparingwithother?..  相似文献   
697.
二氧化碳的回收和利用   总被引:4,自引:0,他引:4  
炼油厂的制氢尾气中含有大量二氧化碳,将其分离回收并加以利用具有一定的社会效益和经济效益。  相似文献   
698.
从晶相组成、晶格缺陷密度、表面羟基含量、晶粒尺寸以及比表面积等方面阐述了热处理温度与TiO2光催化剂结构性质的关系,并就混晶效应、载流子输运/俘获以及尺寸量子效应等对光催化活性的影响进行了讨论。此外,还汇总了对水中典型有机污染物的光催化氧化研究以及相关的催化剂结构性质。  相似文献   
699.
大气二氧化碳含量正在以每年0.4%的速度增加,对森林产生越来越明显的影响,对未来林业提出七个方面的挑战:温度变化、水的变化、气候变化、虫害和火灾变化、新基因的需要、造林与经营、加速研究进程,对此应尽快作出估价。  相似文献   
700.
An econometrically estimated family ofresponse functions is developed forcharacterizing potential responses togreenhouse gas mitigation policies by theagriculture and forestry sectors in theU.S. The response functions are estimatedbased on results of anagricultural/forestry sector model. Theyprovide estimates of sequestration andemission reductions in forestry andagriculture along with levels of sectoralproduction, prices, welfare, andenvironmental attributes given a carbonprice, levels of demand for agriculturalgoods, and the energy price. Sixalternative mitigation policiesrepresenting types of greenhouse gasoffsets allowed are considered. Resultsindicate that the largest quantity ofgreenhouse gas offset consistently appearswith the mitigation policy that pays forall opportunities. Restricting carbonpayments (emission tax or sequestrationsubsidy) only to aff/deforestation or onlyto agricultural sequestration substantiallyreduces potential mitigation. Highercarbon prices lead to more sequestration,less emissions, reduced consumer and totalwelfare, improved environmental indicatorsand increased producer welfare.  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