全文获取类型
收费全文 | 314篇 |
免费 | 15篇 |
国内免费 | 11篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 11篇 |
环保管理 | 50篇 |
综合类 | 57篇 |
基础理论 | 96篇 |
污染及防治 | 58篇 |
评价与监测 | 17篇 |
社会与环境 | 18篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 2篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 13篇 |
2014年 | 9篇 |
2013年 | 34篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 23篇 |
2007年 | 18篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有340条查询结果,搜索用时 281 毫秒
31.
32.
目的 提高脉冲激光发射模块的电磁兼容性。方法 基于腔体的电磁屏蔽机理,使用HFSS软件,建立脉冲激光发射模块腔体模型,以电磁敏感度、电磁干扰2个方面对腔体电磁屏蔽效能进行仿真分析。结果 设计的双层屏蔽腔体在电磁波辐照频率为1~100 kHz时,屏蔽效能达到28 dB;电磁波辐照频率为0.2~18 GHz时,屏蔽效能达到47 dB。结论 当电磁波辐照频率在1~100 kHz时,腔体的屏蔽效能随频率的增加而增大。辐射源外部激励时,双层屏蔽腔体使用外层铁内层铜屏蔽效能较高。电磁波辐照频率在0.2~18 GHz时,腔体的屏蔽效能随频率的增大而减小,且发生了谐振效应。当腔体厚度相等时,双层屏蔽的屏蔽效能高于单层屏蔽。使用电缆连接器代替孔洞进行信号传输时,腔体屏蔽效能增加。 相似文献
33.
Monica E. Wright Dean B. Atkinson Luke Ziemba Robert Griffin Naruki Hiranuma Sarah Brooks Barry Lefer James Flynn Ryan Perna Bernhard Rappenglück Winston Luke Paul Kelley 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4035-4044
Extensive aerosol optical properties, particle size distributions, and Aerodyne quadrupole aerosol mass spectrometer measurements collected during TRAMP/TexAQS 2006 were examined in light of collocated meteorological and chemical measurements. Much of the evident variability in the observed aerosol-related air quality is due to changing synoptic meteorological situations that direct emissions from various sources to the TRAMP site near the center of the Houston-Galveston-Brazoria (HGB) metropolitan area. In this study, five distinct long-term periods have been identified. During each of these periods, observed aerosol properties have implications that are of interest to environmental quality management agencies. During three of the periods, long range transport (LRT), both intra-continental and intercontinental, appears to have played an important role in producing the observed aerosol. During late August 2006, southerly winds brought super-micron Saharan dust and sea salt to the HGB area, adding mass to fine particulate matter (PM2.5) measurements, but apparently not affecting secondary particle growth or gas-phase air pollution. A second type of LRT was associated with northerly winds in early September 2006 and with increased ozone and sub-micron particulate matter in the HGB area. Later in the study, LRT of emissions from wildfires appeared to increase the abundance of absorbing aerosols (and carbon monoxide and other chemical tracers) in the HGB area. However, the greatest impacts on Houston PM2.5 air quality are caused by periods with low-wind-speed sea breeze circulation or winds that directly transport pollutants from major industrial areas, i.e., the Houston Ship Channel, into the city center. 相似文献
34.
35.
36.
Possibilities for greater variation in landscaping during the reclamation of derelict colliery spoil heaps and the potential of a regional approach to the survey of revegetation problems are introduced. A survey method for assessing plant growth problems is described which incorporates rapid measurement of physical and chemical constraints to plant growth and which uses bioassay trials as an index of plant growth potential. The use of the survey method on 34 closed and disused sites in the Barnsley and South Yorkshire areas of the National Coal Board is outlined and suggestions for the incorporation of such data in recommendations for the reclamation of individual sites are made. 相似文献
37.
38.
Ninety-eight laboratories in 16 countries were surveyed in 1979 to determine the uniformity of methods for the assay of human viruses in BGM cells. None of the 58 responding laboratories applied identical methodology. A number of these practices were sufficiently different to assure a significant variance in liter with the assay of standardized virus samples. The results of this survey indicate a definite need for implementing uniform cell culture practices for the enumeration and identification of viruses in the environment. 相似文献
39.
Cox G Beresford NA Alvarez-Farizo B Oughton D Kis Z Eged K Thørring H Hunt J Wright S Barnett CL Gil JM Howard BJ Crout NM 《Journal of environmental radioactivity》2005,83(3):383-397
A spatially implemented model designed to assist the identification of optimal countermeasure strategies for radioactively contaminated regions is described. Collective and individual ingestion doses for people within the affected area are estimated together with collective exported ingestion dose. A range of countermeasures are incorporated within the model, and environmental restrictions have been included as appropriate. The model evaluates the effectiveness of a given combination of countermeasures through a cost function which balances the benefit obtained through the reduction in dose with the cost of implementation. The optimal countermeasure strategy is the combination of individual countermeasures (and when and where they are implemented) which gives the lowest value of the cost function. The model outputs should not be considered as definitive solutions, rather as interactive inputs to the decision making process. As a demonstration the model has been applied to a hypothetical scenario in Cumbria (UK). This scenario considered a published nuclear power plant accident scenario with a total deposition of 1.7x10(14), 1.2x10(13), 2.8x10(10) and 5.3x10(9)Bq for Cs-137, Sr-90, Pu-239/240 and Am-241, respectively. The model predicts that if no remediation measures were implemented the resulting collective dose would be approximately 36 000 person-Sv (predominantly from 137Cs) over a 10-year period post-deposition. The optimal countermeasure strategy is predicted to avert approximately 33 000 person-Sv at a cost of approximately 160 million pounds. The optimal strategy comprises a mixture of ploughing, AFCF (ammonium-ferric hexacyano-ferrate) administration, potassium fertiliser application, clean feeding of livestock and food restrictions. The model recommends specific areas within the contaminated area and time periods where these measures should be implemented. 相似文献
40.
We undertake three objectives in this Incubator. We begin with a discussion of how well‐being has been considered in organizational research. Second, we provide an overview of the relationship between employee well‐being and such workplace outcomes as job performance, employee retention, and cardiovascular health. Third, we introduce exciting research directions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献