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   306篇
  免费   18篇
  国内免费   8篇
安全科学   11篇
废物处理   12篇
环保管理   74篇
综合类   28篇
基础理论   81篇
污染及防治   74篇
评价与监测   40篇
社会与环境   11篇
灾害及防治   1篇
  2023年   3篇
  2022年   4篇
  2021年   5篇
  2020年   2篇
  2019年   10篇
  2018年   13篇
  2017年   8篇
  2016年   9篇
  2015年   7篇
  2014年   7篇
  2013年   38篇
  2012年   13篇
  2011年   12篇
  2010年   9篇
  2009年   8篇
  2008年   12篇
  2007年   18篇
  2006年   18篇
  2005年   10篇
  2004年   7篇
  2003年   14篇
  2002年   8篇
  2001年   8篇
  2000年   6篇
  1999年   5篇
  1998年   2篇
  1996年   3篇
  1995年   5篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   4篇
  1990年   5篇
  1987年   6篇
  1985年   3篇
  1984年   7篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1979年   8篇
  1978年   1篇
  1977年   3篇
  1975年   2篇
  1974年   1篇
  1973年   3篇
  1971年   1篇
  1969年   1篇
  1966年   1篇
  1965年   1篇
  1964年   1篇
排序方式: 共有332条查询结果,搜索用时 15 毫秒
311.
This paper presents and tests a model of the impact of secure and insecure attachment styles (secure, counterdependent, and overdependent) on citizenship behavior and workplace deviance behavior through vigor at work. Employees who exhibit secure attachment styles are proposed to exhibit more vigor at work because of more effective use of physical, emotional, and cognitive resources which translates into increased organizational citizenship behaviors (OCBs) and decreased deviance. Insecurely attached employees are hypothesized to exhibit the opposite pattern. In a sample of 331 repair generalists in a large building facilities and maintenance organization, results indicate that attachment styles indirectly predicted OCBs and deviance through vigor. Implications of these results for attachment style, vigor at work, OCBs, and deviance are discussed. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
312.

Oil spills at sea remain a serious threat to coastal settlements and sensitive ecosystems. Although the impacts of spills are contingent upon a variety of environmental factors and the chemical composition of the oil itself, spill effects can be long lasting in the pelagic zone with broad impacts on sensitive bacterial, microbial, plant, and animal communities. Efforts to contain, deflect, protect, and mitigate the effects of oil are increasingly important, given the massive social, economic, and environmental fallout connected to large spills. The purpose of this paper is to provide geographic perspective for protecting coastal areas with exclusion booms during oil spill events. Specifically, we introduce a generalized, extendable, spatial optimization model that simultaneously minimizes spill effects on vulnerable shorelines and the total costs associated with dispatching booms. The multiobjective model is solved with a weighting method to produce a Pareto optimal curve that reveals how the costs and protection operations change under different priorities. A simulated tanker spill near Mobile Bay, AL, USA, is used as an illustrative example.

  相似文献   
313.
The New England Governors and Eastern Canadian Premiers (NEG/ECP) adopted the Acid Rain Action Plan in June 1998, and issued a series of action items to support its work toward a reduction of sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions in northeastern North America. One of these action items was the preparation of an updated critical load map using data from lakes in the NEG/ECP area. Critical load maps provide a more complete index of the surface water sensitivity to acidification. Combined sulfur and nitrogen critical loads and deposition exceedances were computed using Henriksen's Steady-State Water Chemistry (SSWC) model. Results show that 28% of all 2053 lakes studied have a critical load of 20 kg/ha/year or less, making them vulnerable to acid deposition. Emission reductions, and more specifically SO2 emission reductions have proven beneficial because critical loads were exceeded in 2002 for 12.3% of all studied lakes. Those lakes are located in the more sensitive areas where geology is carbonate-poor. Of these lakes, 2.9% will never recover even with a complete removal of SO4 deposition. Recovery from acidification for the remaining 9.4% of the lakes will require additional emission SO2 reductions.  相似文献   
314.
Urban ecosystems are increasingly influenced by residential yard care decisions. This had led researchers to focus on homeowner education programs when it comes to yard care. Typically, the success of programs designed to influence yard care is based on whether the target subject changes his or her behavior in a more environmentally conscious manner. This threshold, however, fails to consider if individuals share this information with their friends and neighbors, thus having a possible spillover effect. In this paper, we focus on the transmission of new lawn management information among neighbors and consider (1) if individuals discuss information they learned in a short-term educational program, (2) what factors are associated with diffusion, (3) what information individuals share, and (4) what barriers to transmission exist. In the Minneapolis–St. Paul metropolitan area, we used data from a mailed survey, group discussions, and mailed information exchanges. Results indicate that best management practices for yards can diffuse through the neighborhood (approximately 34 % shared information with their neighbors in a one-month period). In addition, factors such as (1) attending a group discussion, 2) individual social connectedness, (3) length of home ownership, and (4) the presence of children in the household were found to be positively related to increased sharing of information. Also, for lawns, the content of information shared tended to be about increasing grass height and reducing fertilizer applications. Finally, we find barriers to sharing ideas based on spatial, temporal, or perception factors but overcoming some of these barriers is possible.  相似文献   
315.
An extensive site-characterization project was conducted at a large chlorinated-solvent contaminated Superfund site in Tucson, AZ. The project consisted of several components, including traditional site-characterization activities, tracer tests, laboratory experiments conducted with core material collected from the site, and mathematical modeling. The primary focus of the work presented herein is the analysis of induced-gradient contaminant elution tests conducted in a source zone at the site, investigation of the potential occurrence of immiscible liquid in the saturated zone, characterization of the relationship between mass flux reduction and mass removal, and evaluation of the impact of source-zone management on site remediation. The results of the present study, along with those of prior work, indicate that immiscible liquid is likely present in the saturated zone at the site source zones. Extensive tailing and rebound was observed for the contaminant-elution tests, indicating nonideal transport and mass-transfer behavior. The elution data were analyzed with a source-zone-scale mathematical model, and the results indicated that nonideal immiscible-liquid dissolution was the primary cause of the observed behavior. The time-continuous relationship between mass flux reduction and mass removal associated with the plume-scale pump-and-treat operation exhibited an initial large drop in mass flux with minimal mass removed, followed by a period of minimal mass flux reduction and a second period of large reduction. This behavior reflects the impact of both source-zone and aqueous-plume mass removal dynamics. Ultimately, a greater than 90% reduction in mass flux was achieved for a mass removal of approximately 50%. The influence of source-zone management on site remediation was evaluated by conducting two predictive simulations, one for which the source zones were controlled and one for which they were not. A plume-scale model was used to simulate the composite contaminant concentrations associated with groundwater extracted with the pump-and-treat system, which were compared to measured data. The information generated from this study was used to enhance the site conceptual model, help optimize operation of the pump-and-treat system, and evaluate the utility of source-zone remediation.  相似文献   
316.
A study was conducted to determine the concentrations of algal-available P (Paa) in unfractionated samples and size-classified separates of soil eroded from wheat stubble plots during a simulated rainfall experiment conducted in Warren County, Indiana, U.S.A. Run-off samples were collected, concentrated, dispersed by sonification, separated according to size and incubated with algal cells (Selanastrum capricornutum) in P-free nutrient medium for 2 weeks. Algal-available P in soil separates was determined by decreases in sediment inorganic P (Pi) over the incubation period. The initial concentrations of dissolved molybdate-reactive Pi (DMRP), Pi extractable with NaOH (NaOH-Pi), Pi extractable with HCl (HCl-Pi), organic P (Po, and total P increased with decreasing particle size. A higher proportion of Pi was HCl-extractable in fractions > 2 μm than in clay-size separates. The level of Paa in samples increased with decreasing particle size. Available P concentrations in separates < 0.2, 0.2–2, 2–50, > 50 μm and unfractionated samples averaged 447, 282, 113, 26 and 261 μg g?1, respectively. From 42 to 69% of the Pi and 20–37% of the total P in unfractioned samples was Paa. A lower proportion of Pi in the > 50 μm fraction was Paa than in the other size fractions (34 vs. 50%). There was no relationship between particle size and the proportion of total P that was available. The majority (> 84%) of Paa originated in the Pi fraction extractable with NaOH, whereas HCl-Pi only contributed small amounts of Paa. The proportion of initial NaOH-Pi assimilated by algae in 2 weeks ranged between 43 and 77%, whereas an average of 16% of HCl-Pi in separates was Paa. On average, a greater proportion of NaOH-Pi was assimilated by algae in samples from no-till plots as compared to those from chisel-plowed plots.  相似文献   
317.
We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact.  相似文献   
318.
Halogenated 1'methyl-1,2'-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GCxGC/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests that they are either biosynthesized concomitantly with their perhalogenated counterparts or that their dehalogenation products can also bioaccumulate. The newly found compounds fit the geographic trend that has been previously noted. That is, samples from the Atlantic Ocean are dominated by the more brominated congeners while those from the Pacific are dominated by the more chlorinated congeners.  相似文献   
319.
Benzene is a carcinogenic and genotoxic pollutant which mainly affects the people health through the inhalation. Nevertheless, this pollutant is not frequently measured by air-quality networks. To solve this problem, some models have been published to estimate benzene concentrations in the atmosphere. However, the lack of measures makes difficult the application of complex models in order to get a detailed spatio-temporal analysis, namely in urban areas. In this work was developed a simple semi-empirical model to predict benzene concentrations based on the ratio of benzene and carbon monoxide concentrations in order to predict the concentrations of this pollutant in large areas and periods with lack of benzene measurements but with higher impact in the human health. The model was applied to an urban area, the Metropolitan Area of Oporto, for a period of 12 years (1995–2006). Monthly correlations between benzene and carbon monoxide concentrations at Custóias air-quality station are significant (p = 0.01) and higher in winter (r s > 0.7) than in summer (0.3 > r s > 0.7). Estimate of the monthly ratio of the concentration of these two pollutants range between 199 and 305. The methodology validation shows good results (r s = 0.81) which allow, assuming the availability of carbon monoxide data, the use of this tool for areas with low benzene recorded data. The application of this methodology in the study area shows an annual average trend decrease of benzene concentrations during the study period, which may be linked to a general trend decrease of benzene emissions in European urban areas, including the study domain.  相似文献   
320.
The release of radioactivity into the atmosphere from the damaged Fukushima Daiichi nuclear power plant started on March 12th, 2011. Among the various radionuclides released, iodine -131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific Ocean and reached the United States on 17-18 March 2011. Consequently, an elevated level of fission products (131)I, (132)I, (132)Te, (134)Cs and (137)Cs were detected in air, water, and milk samples collected across the United States between March 17 and April 4, 2011. The continuous monitoring of activities over a period of 25 days and spatial variations across more than 100 sampling locations in the United States made it possible to characterize the contaminated air masses. For the entire period, the highest detected activity values ranged from less than 1 m Bq m(-3) to 31 m Bq m(-3) for the particulate (131)I, and up to 96 m Bq m(-3) for the gaseous (131)I fraction.  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