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   508篇
  免费   11篇
  国内免费   9篇
安全科学   21篇
废物处理   13篇
环保管理   137篇
综合类   50篇
基础理论   94篇
污染及防治   135篇
评价与监测   46篇
社会与环境   21篇
灾害及防治   11篇
  2023年   4篇
  2021年   6篇
  2020年   2篇
  2019年   5篇
  2018年   5篇
  2017年   6篇
  2016年   8篇
  2015年   14篇
  2014年   15篇
  2013年   65篇
  2012年   20篇
  2011年   22篇
  2010年   20篇
  2009年   17篇
  2008年   21篇
  2007年   27篇
  2006年   24篇
  2005年   20篇
  2004年   13篇
  2003年   19篇
  2002年   13篇
  2001年   9篇
  2000年   12篇
  1999年   8篇
  1998年   6篇
  1997年   5篇
  1996年   4篇
  1995年   9篇
  1994年   13篇
  1993年   9篇
  1992年   7篇
  1991年   8篇
  1990年   7篇
  1989年   4篇
  1988年   7篇
  1987年   4篇
  1986年   3篇
  1985年   2篇
  1984年   3篇
  1983年   9篇
  1982年   8篇
  1981年   8篇
  1980年   11篇
  1979年   8篇
  1978年   5篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1973年   2篇
  1968年   1篇
排序方式: 共有528条查询结果,搜索用时 10 毫秒
341.
Advances and challenges in flash flood warnings   总被引:1,自引:0,他引:1  
  相似文献   
342.
Inductively coupled plasma with mass spectrometric detection (ICP-MS) has been used for clinical analysis of cobalt (Co) due to its sensitivity and specificity; however, media-specific validation studies are lacking. This study provides data on performance variables affecting differences between selected analytical platforms (Perkin Elmer and Agilent), tissue sample preparation, storage, and interferences affecting measurements in whole blood, serum, and synovial fluid. The limits of detection (LOD) range from 0.2–0.5 µg/L in serum and synovial fluid, and 0.6–1.7 µg Co/L in whole blood. The Agilent platform with collision reaction cell is more sensitive, while the Perkin Elmer platform with dynamic reaction cell demonstrates more polyatomic interferences near the LOD for serum and whole blood. Split sample analysis showed good accuracy, precision, and reproducibility between serum Co measurements using acid digestion or detergent dilution preparations for persons with metal hip implants or following supplement intake. The results demonstrated reliability of the ICP-MS methodology across the two analytical platforms and between two commercial laboratories for Co concentrations above 5 µg Co/L, but digestion procedures and polyatomic interferences may affect measurements in some media at lower concentrations. These studies validate the described ICP-MS methodology for clinical purposes with precautions at low cobalt concentrations (<5 µg Co/L).  相似文献   
343.
Sources of mercury contamination in aquatic systems were studied in a comprehensive literature review. The results show that the most important anthropogenic sources of mercury pollution in aquatic systems are: (1) atmospheric deposition, (2) erosion, (3) urban discharges, (4) agricultural materials, (5) mining, and (6) combustion and industrial discharges. Capping and dredging are two possible remedial approaches to mercury contamination in aquatic systems, and natural attenuation is a passive decontamination alternative. Capping seems to be an economical and effective remedial approach to mercury-contaminated aquatic systems. Dredging is an expensive remedial approach. However, for heavily polluted systems, dredging may be more effective. Natural attenuation, involving little or no cost, is a possible and very economical choice for less contaminated sites. Proper risk assessment is necessary to evaluate the effectiveness of remedial and passive decontamination methods as well as their potential adverse environmental effects. Modeling tools have a bright future in the remediation and passive decontamination of mercury contamination in aquatic systems. Existing mercury transport and transformation models were reviewed and compared.  相似文献   
344.
345.
OBJECTIVE: This November 2003 pilot study investigates the correlation between serum IgE and residential endotoxin levels from a group of 18 pregnant women living in Trujillo, Peru, and investigates the impact of the demographic and lifestyle factors of this group on the IgE and endotoxin levels measured. METHODS: Serum samples were collected from 19 subjects and analyzed for IgE. Dust samples were collected from the mattresses of 18 subjects and measured for endotoxin levels. A questionnaire was used to obtain demographic, socioeconomic, and lifestyle information for each subject. RESULTS: Geometric means for IgE and endotoxin were 246.8 (GSD=4.3, n=19) IU/mL and 66.5 EU/mg (GSD=1.7, n=18), respectively. Log-transformed IgE and endotoxin were not correlated (R2=0.02; p=0.60). CONCLUSIONS: Residential endotoxin and serum IgE were not correlated in this group. Potential selection bias and sample size are major limitations of the study. However, 74% (14/19) of the subjects in this study had an IgE over 100 IU/mL, a level generally considered elevated.  相似文献   
346.
347.
Abstract

Passive samplers have been shown to be an inexpensive alternative to direct sampling. Diffusion denuders have been developed to measure the concentration of species such as ammonia (NH3), which is in equilibrium with particulate ammonium nitrate. Conventional denuder sampling that inherently requires air pumps and, therefore, electrical power. To estimate emissions of NH3 from a fugitive source would require an array of active samplers and meteorological measurements to estimate the flux. A recently developed fabric denuder was configured in an open tube to passively sample NH3 flux. Passive and active samplers were collocated at a dairy farm at the California State University, Fresno, Agricultural Research Facility. During this comparison study, NH3 flux measurements were made at the dairy farm lagoon before and after the lagoon underwent acidification. Comparisons were made of the flux measurements obtained directly from the passive flux denuder and those calculated from an active filter pack sampler and wind velocity. The results show significant correlation between the two methods, although a correction factor needed to be applied to directly compare the two techniques. This passive sampling approach significantly reduces the cost and complexity of sampling and has the potential to economically develop a larger inventory base for ambient NH3 emissions.  相似文献   
348.
Abstract

Field data for coarse particulate matter ([PM] PM10) and fine particulate matter (PM2.5) were collected at selected sites in Southeast Kansas from March 1999 to October 2000, using portable MiniVol particulate samplers. The purpose was to assess the influence on air quality of four industrial facilities that burn hazardous waste in the area located in the communities of Chanute, Independence, Fredonia, and Coffeyville. Both spatial and temporal variation were observed in the data. Variation because of sampling site was found to be statistically significant for PM10 but not for PM2.5. PM10 concentrations were typically slightly higher at sites located within the four study communities than at background sites. Sampling sites were located north and south of the four targeted sources to provide upwind and downwind monitoring pairs. No statistically significant differences were found between upwind and downwind samples for either PM10 or PM2.5, indicating that the targeted sources did not contribute significantly to PM concentrations. Wind direction can frequently contribute to temporal variation in air pollutant concentrations and was investigated in this study. Sampling days were divided into four classifications: predominantly south winds, predominantly north winds, calm/variable winds, and winds from other directions. The effect of wind direction was found to be statistically significant for both PM10 and PM2.5. For both size ranges, PM concentrations were typically highest on days with predominantly south winds; days with calm/variable winds generally produced higher concentrations than did those with predominantly north winds or those with winds from “other” directions. The significant effect of wind direction suggests that regional sources may exert a large influence on PM concentrations in the area.  相似文献   
349.
Fifty years ago electrostatic precipitation, which had been used successfully for collection of sulfuric acid mist, was first applied to a power plant installation for control of fly ash from pulverized fuel. This is the history of the design and application of the principle as the power generation industry adapted to changing environmental problems and concerns.  相似文献   
350.
Forested riparian buffers are retained along streams during forest harvest to maintain a number of ecological functions. In this paper, we examine how recently established riparian buffers along northern Swedish streams provide deadwood, a key objective for riparian buffer management in Sweden. We used observational and experimental data to show that the investigated buffers provided large volumes of deadwood to streams and riparian zones shortly after their establishment, likely jeopardizing continued recruitment over the long term. Deadwood volume decreased with increasing buffer width, and the narrowest buffers tended to blow down completely. Wider buffers (~ 15 m) provided similar volumes of deadwood as narrow buffers due to blowdowns but were, overall, more resistant to wind-felling. It is clear from our study, that wider buffers are currently a safer strategy for riparian management that aims to sustain provision of deadwood and other ecological objectives continuously on the long term.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01793-1.  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