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   354篇
  免费   3篇
  国内免费   24篇
安全科学   12篇
废物处理   1篇
环保管理   25篇
综合类   294篇
基础理论   7篇
污染及防治   19篇
评价与监测   6篇
社会与环境   9篇
灾害及防治   8篇
  2022年   2篇
  2021年   1篇
  2020年   7篇
  2018年   3篇
  2017年   5篇
  2016年   5篇
  2015年   5篇
  2014年   4篇
  2013年   20篇
  2012年   20篇
  2011年   18篇
  2010年   11篇
  2009年   11篇
  2008年   9篇
  2007年   17篇
  2006年   15篇
  2005年   7篇
  2004年   12篇
  2003年   23篇
  2002年   25篇
  2001年   36篇
  2000年   26篇
  1999年   19篇
  1998年   21篇
  1997年   13篇
  1996年   4篇
  1995年   3篇
  1994年   4篇
  1993年   5篇
  1992年   7篇
  1991年   2篇
  1990年   5篇
  1989年   5篇
  1988年   5篇
  1987年   3篇
  1984年   2篇
  1982年   1篇
排序方式: 共有381条查询结果,搜索用时 680 毫秒
111.
全球能源消费与CO2排放量   总被引:13,自引:0,他引:13  
在收集全球能源储量和流通状况的基础上,综述了世界各地区能源消费量和各国人均能源水平,汇总了全球CO2排放总量及各大洲对全球CO2排放量的贡献率,到2100年,全球C矿量预计将从目前60亿t/a增加到360亿t/a,同时,旨出1996年中世界人口18.8%的北美、欧洲、日本、CO2排放31.6亿t(碳),占全球当年CO2排放总量的52.4%。  相似文献   
112.
通过地质大调查项目和资补费项目的地质工作,发现和评价了金家坞金矿。现有资料表明金家坞金矿具有大型以上规模的资源潜力。对初查、详查以及局部勘探工作中所获的地质资料作了归纳,对地质特征进行了探讨,旨在展开讨论并对在江西北部双桥山群中寻找同类矿床起到一定的指导作用。  相似文献   
113.
从技术角度来探讨银行的存款业务创新,提出商业银行应该考虑经济发展情况、金融文化背景等因素,以满足客户的需求为目的来设计、组织存款要素,并在市场细分的基础上,提供差别化存款产品,按市场规律进行定价。  相似文献   
114.
电除尘器的设计与探讨   总被引:1,自引:0,他引:1  
介绍了电除尘器的工作原理、结构特性、基本参数和总体设计计算。这种电除尘器可广泛使用于冶金、化工、轻工 ,水泥和矿山等工业部门 ,随着人们对生态环境质量要求的不断提高 ,电除尘器将成为环保的重要设备  相似文献   
115.
利用高纯锗γ能谱分析仪测量中国华东某铀矿区附近河流沉积物的放射性核素比活度,计算γ辐射吸收剂量率(D)、有效镭浓度(Ra_(eq))、外照射指数(H_(ex))、内照射指数(H_(in))、年有效剂量当量(AEDE(室内和室外))和年性腺剂量当量(AGDE)等放射性参数,并开展沉积物的放射性危害评估,最后通过Pearson线性系数确定放射性核素比活度之间的相关性。结果表明,河流沉积物中放射性核素~(238)U、~(226)Ra、~(232)Th和40K的平均比活度分别为51.55、37.32、57.63和756.86 Bq·kg~(-1),除~(226)Ra外,其他放射性核素的比活度均高于中国平均值;距离污染区较远或存在河流稀释作用的区域,沉积物的天然放射性核素处于正常水平,作为建筑材料使用时比活度不存在超标;放射性核素~(238)U、~(226)Ra和~(232)Th之间存在显著相关性。  相似文献   
116.
A solid phase extraction method for the determination of gold(III) at trace levels by flame atomic absorption spectrometer (FAAS) was developed. The method was based on retention of gold as chloro complexes through the Amberlite XAD-2000. The effect of some analytical parameters including hydrochloric acid concentration, sample volume, sample and eluent flow rates, eluent volume, eluent concentration and interfering ions on the recovery of gold(III) was investigated. The retention of gold(III) from 1.5 mol l−1 HCl solution and the recovery of gold with 0.07 mol l−1 NH3 solution were quantitative (≥95%). The relative standard deviation (RSD) was calculated as 3.2% (n = 10). The detection limit for gold was 2 μg l−1. The accuracy was checked with the determination of gold spiked an artificial seawater and a pure copper samples.  相似文献   
117.
采用新型金膜吸附-冷原子吸收光谱法测定空气中的汞,在0μg/L~100μg/L范围内线性良好,相关系数为0.9991。方法检出限为1.6 ng/m3,RSD为0.5%~2.7%,测定两种不同浓度的汞标准样品,相对误差为6.1%和3.2%。与两种现行国标方法(巯基棉富集和高锰酸钾溶液吸附法)比较,该方法所需试剂种类少,操作简便、吸附效率好,加标回收率高。  相似文献   
118.
Abstract

The ULV spray emitted from a TBM flying in a cross wind was mapped by a scanning lidar system. The fate of the spray cloud for 2 min after release from the aircraft was followed as the material was transported downwind of the flight line. Vertical scans at 6 s intervals with 1 m‐3 resolution provided detailed insight into the entrainment of the spray into the wing‐tip vortices and ultimate release to drift or deposit. Relative concentration, dosage and deposit profiles are presented for this cross‐wind case. Vortex lifetimes were found to be significantly different for the up‐wind and downwind vortices. The majority of the near field deposit was associated with the up‐wind vortex while the drift was linked to the down‐wind vortex.  相似文献   
119.
Abstract

Spray deposits were measured on spruce foliage at tree canopy level and on glass plates at ground level, after aerial application of an emulsion formulation of fenitrothion at the rate of 0.21 kg AI in 1.46 L per ha over a 16 ha plot in a plantation forest. Fenitrothion deposits were quantified by gas‐liquid chromatography. A wide variation was observed in deposits on foliage and at the forest floor. Deposits were relatively higher on foliar samples collected from the upwind side of a tree canopy than those on the downwind side. Similarly, the glass plate placed under a tree on the upwind side received relatively higher deposit than the one on the downwind side. However, the glass plates placed in the adjacent forest openings collected markedly higher deposits. Results clearly indicate filtration of the spray droplets by canopy foliage. Assessment of the average deposit of fenitrothion at ground level (mean deposit from all sampling locations) indicated that ca. 19.4% of the applied material reached the forest floor. Within a sampling station, correlation was poor between foliar depsits and those on glass plates under the same trees or in nearby clearings. Analysis of fenitrothion deposits on foliage collected at 1 and 2 h after application indicated that the droplets took, more than 1 h for deposition on the tree canopy. On the other hand, deposition on the glass plates at ground level appeared to be practically complete within 1 h post‐treatment. This was attributed to the higher sedimentation velocities of the larger droplets which tend to travel faster to the floor level than the smaller droplets which float for a longer period near the tree canopy.  相似文献   
120.
In an effort to minimize the impact on the environment or improve the properties of choice, most engineered nanoparticles used for commercial applications are surface functionalized. The release of these functionalized engineered nanoparticles (FENPs) into the environment can be either deliberate or accidental. Scientific research to date has tended to focus on evaluating the toxicity of FENPs, with less attention being given to exposure assessments or to the study of their general behavior in natural environments. We have therefore investigated the effects of environmental parameters such as pH, NaCl concentration, and natural organic matter concentration on the aggregation kinetics of FENPs with time resolved dynamic light scattering, using functionalized gold nanoparticles (FAuNPs) as a representative of these particles. We also investigated the effects of average particle size, the type of surface capping agent, and particle concentration on FAuNP aggregation kinetics. Our results show that the physico-chemical properties of the capping agent have a greater influence on the aggregation behavior of FAuNPs than either their core composition or their particle size.  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