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   206篇
  免费   20篇
  国内免费   1篇
安全科学   6篇
废物处理   2篇
环保管理   44篇
综合类   31篇
基础理论   77篇
环境理论   2篇
污染及防治   40篇
评价与监测   9篇
社会与环境   12篇
灾害及防治   4篇
  2024年   1篇
  2023年   1篇
  2022年   9篇
  2021年   5篇
  2020年   6篇
  2019年   10篇
  2018年   6篇
  2017年   10篇
  2016年   15篇
  2015年   13篇
  2014年   11篇
  2013年   16篇
  2012年   14篇
  2011年   17篇
  2010年   9篇
  2009年   12篇
  2008年   11篇
  2007年   14篇
  2006年   13篇
  2005年   5篇
  2004年   6篇
  2003年   4篇
  2002年   4篇
  2000年   1篇
  1999年   2篇
  1998年   2篇
  1995年   1篇
  1994年   2篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1981年   1篇
  1964年   1篇
排序方式: 共有227条查询结果,搜索用时 171 毫秒
181.
We examined whether sexualizing a businesswoman impacts attitudes toward subsequently evaluated, nonsexualized females applying for a corporate managerial position. Research shows that sexualized women are perceived as less warm and competent (i.e., objectified). Integrating this work with research on social cognition, we hypothesized that the negative effect of sexualization “spills over” onto other nonsexualized women, reducing their hireability. Across two experiments, initially sexualized women were perceived as less warm and competent, as were subsequently evaluated nonsexualized female job candidates. In turn, these negative perceptions reduced the applicants' probability of being hired. Sexualization of women also increased intentions to hire a subsequently evaluated male candidate. The results were robust when we controlled for evaluators' gender and age. Our findings demonstrate that female job applicants can experience detrimental effects from sexually based objectification, even when they are not the individuals initially sexualized. We discuss implications for women's careers.  相似文献   
182.
Landfill fugitive methane emissions were quantified as a function of climate type and cover type at 20 landfills using US. Environmental Protection Agency (EPA) Other Test Method (OTM)-10 vertical radial plume mapping (VRPM) with tunable diode lasers (TDLs). The VRPM data were initially collected as g CH4/sec emission rates and subsequently converted to g CH4/m2/ day rates using two recently published approaches. The first was based upon field tracer releases of methane or acetylene and multiple linear regression analysis (MLRM). The second was a virtual computer model that was based upon the Industrial Source Complex (ISC3) and Pasquill plume stability class models (PSCMs). Calculated emission results in g CH4/m2/day for each measured VRPM with the two approaches agreed well (r2 = 0.93). The VRPM data were obtained from the working face, temporary soil, intermediate soil, and final soil or synthetic covers. The data show that methane emissions to the atmosphere are a function of climate and cover type. Humid subtropical climates exhibited the highest emissions for all cover types at 207, 127, 102, and 32 g CH4/m2/day, for working face (no cover), temporary, intermediate, and final cover, respectively. Humid continental warm summers showed 67, 51, and 27 g CH4/m2/day for temporary, intermediate, and final covers. Humid continental cool summers were 135, 40, and 26 g CH4/m2/day for the working face, intermediate, and final covers. Mediterranean climates were examined for intermediate and final covers only and found to be 11 and 6 g CH4/m2/day, respectively, whereas semiarid climates showed 85, 11, 3.7, and 2.7 g CH4/m2/day for working face, temporary, intermediate, and final covers. A closed, synthetically capped landfill covered with soil and vegetation with a gas collection system in a humid continental warm summer climate gave mostly background methane readings and average emission rates of only 0.09 g CH4/m2/day flux when measurable.  相似文献   
183.
Concentrations of nutrients and heavy metals in streambank legacy sediments are needed to estimate watershed exports and to evaluate against upland inputs. Concentrations of nutrients and heavy metals were determined for legacy sediments in 15 streambanks across northeastern Maryland, southeastern Pennsylvania, and northern Delaware. Samples were collected from multiple bank depths from forested, agricultural, urban, and suburban sites. Analyses were performed for fine (<63 μm) and coarse sediment fractions. Nutrient and heavy metal concentrations were significantly higher in fine than coarse legacy sediments and water extractable nutrient concentrations were significantly greater for fine sediments. Nutrient and heavy metal concentrations were highest in streambank legacy sediments associated with urban land use, but few differences were found with bank depth. Total N (40–3,970 mg/kg) and P (25–1,293 mg/kg) and bioavailable P (0.25–48.8 mg/kg) concentrations for legacy sediments were lower than those for upland soils. This suggests that legacy sediments could serve as sink or source of N and P depending on the redox conditions and stream water nutrient concentrations. However, despite low concentrations, caution should be exercised since streambank erosion and legacy sediment mass loadings could be high, these sediments are in immediate proximity of aquatic ecosystems, and biogeochemical transformations could result in release of the nutrients.  相似文献   
184.
Environmental Science and Pollution Research - Determining alternative water sources to meet municipal water demands is important when availability is limited. The purpose of this study was to...  相似文献   
185.
Population viability analysis (PVA) is a powerful conservation tool, but it remains impractical for many species, particularly species with multiple, broadly distributed populations for which collecting suitable data can be challenging. A recently developed method of multiple-population viability analysis (MPVA), however, addresses many limitations of traditional PVA. We built on previous development of MPVA for Lahontan cutthroat trout (LCT) (Oncorhynchus clarkii henshawi), a species listed under the U.S. Endangered Species Act, that is distributed broadly across habitat fragments in the Great Basin (U.S.A.). We simulated potential management scenarios and assessed their effects on population sizes and extinction risks in 211 streams, where LCT exist or may be reintroduced. Conservation populations (those managed for recovery) tended to have lower extinction risks than nonconservation populations (mean = 19.8% vs. 52.7%), but not always. Active management or reprioritization may be warranted in some cases. Eliminating non-native trout had a strong positive effect on overall carrying capacities for LCT populations but often did not translate into lower extinction risks unless simulations also reduced associated stochasticity (to the mean for populations without non-native trout). Sixty fish or 5–10 fish/km was the minimum reintroduction number and density, respectively, that provided near-maximum reintroduction success. This modeling framework provided crucial insights and empirical justification for conservation planning and specific adaptive management actions for this threatened species. More broadly, MPVA is applicable to a wide range of species exhibiting geographic rarity and limited availability of abundance data and greatly extends the potential use of empirical PVA for conservation assessment and planning.  相似文献   
186.
In this paper we examine the characteristics of near-inertial internal Poincaré waves in Lake Michigan (USA) as discerned from field experiments and hydrodynamic simulations. The focus is on the determination of the lateral and vertical structure of the waves. Observations of near-inertial internal wave properties are presented from two field experiments in southern Lake Michigan conducted during the years 2009 and 2010 at Michigan City (IN, USA) and Muskegon (MI, USA), respectively. Spectra of thermocline displacements and baroclinic velocities show that kinetic and potential baroclinic energy is dominated by near-inertial internal Poincaré waves. Vertical structure discerned from empirical orthogonal function analysis shows that this energy is predominantly vertical mode 1. Idealized hydrodynamic simulations using stratifications from early summer (June), mid-summer (July) and fall (September) identify the basin-scale internal Poincaré wave structure as a combination of single- and two-basin cells, similar to those identified in Lake Erie by Schwab, with near-surface velocities largest in the center of the northern and southern basins. Near-inertial bottom kinetic energy is seen to have roughly constant magnitude over large swathes across the basin, with higher magnitude in the shallower areas like the Mid-lake Plateau, as compared with the deep northern and southern basins. The near-bottom near-inertial kinetic energy when mapped appears similar to the bottom topography map. The wave-induced vertical shear across thermocline is concentrated along the longitudinal axis of the lake basin, and both near-bottom velocities and thermocline shear are reasonably explained by a simple conceptual model of the expected transverse variability.  相似文献   
187.
The conservation community is increasingly focusing on the monitoring and evaluation of management, governance, ecological, and social considerations as part of a broader move toward adaptive management and evidence‐based conservation. Evidence is any information that can be used to come to a conclusion and support a judgment or, in this case, to make decisions that will improve conservation policies, actions, and outcomes. Perceptions are one type of information that is often dismissed as anecdotal by those arguing for evidence‐based conservation. In this paper, I clarify the contributions of research on perceptions of conservation to improving adaptive and evidence‐based conservation. Studies of the perceptions of local people can provide important insights into observations, understandings and interpretations of the social impacts, and ecological outcomes of conservation; the legitimacy of conservation governance; and the social acceptability of environmental management. Perceptions of these factors contribute to positive or negative local evaluations of conservation initiatives. It is positive perceptions, not just objective scientific evidence of effectiveness, that ultimately ensure the support of local constituents thus enabling the long‐term success of conservation. Research on perceptions can inform courses of action to improve conservation and governance at scales ranging from individual initiatives to national and international policies. Better incorporation of evidence from across the social and natural sciences and integration of a plurality of methods into monitoring and evaluation will provide a more complete picture on which to base conservation decisions and environmental management.  相似文献   
188.
The invasion spread of the emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is characterized by the formation of satellite populations that expand and coalesce with the continuously invading population front. As of January 2010, satellite infestations have been detected in 13 states and two Canadian provinces. Understanding how newly established satellite populations may affect economic costs can help program managers to justify and design prevention and control strategies. We estimate the economic costs caused by EAB for the 10-yr period from 2010 to 2020 for scenarios of fewer EAB satellite populations than those found from 2005 to 2010 and slower expansion of satellite populations found in 2009. We measure the projected discounted cost of treatment, removal, and replacement of ash trees (Fraxinus spp.) growing in managed landscapes in U.S. communities. Estimated costs for the base scenario with the full complement of satellites in 2005-2010 and no program to mitigate spread is $12.5 billion. Fewer EAB satellites from 2005 to 2010 delay economic costs of $1.0 to 7.4 billion. Slower expansion of 2009 satellite populations delays economic costs of $0.1 to 0.7 billion. Satellite populations that are both distant from the core EAB infestation and close to large urban areas caused more economic costs in our simulations than did other satellites. Our estimates of delayed economic costs suggest that spending on activities that prevent establishment of new satellite EAB populations or slow expansion of existing populations can be cost-effective and that continued research on the cost and effectiveness of prevention and control activities is warranted.  相似文献   
189.
We formulate and simulation-test a spatial surplus production model that provides a basis with which to undertake multispecies, multi-area, stock assessment. Movement between areas is parameterized using a simple gravity model that includes a "residency" parameter that determines the degree of stock mixing among areas. The model is deliberately simple in order to (1) accommodate nontarget species that typically have fewer available data and (2) minimize computational demand to enable simulation evaluation of spatial management strategies. Using this model, we demonstrate that careful consideration of spatial catch and effort data can provide the basis for simple yet reliable spatial stock assessments. If simple spatial dynamics can be assumed, tagging data are not required to reliably estimate spatial distribution and movement. When applied to eight stocks of Atlantic tuna and billfish, the model tracks regional catch data relatively well by approximating local depletions and exchange among high-abundance areas. We use these results to investigate and discuss the implications of using spatially aggregated stock assessment for fisheries in which the distribution of both the population and fishing vary over time.  相似文献   
190.
The electrosensory capabilities of wobbegong sharks are of particular interest, partly because very little is known about their behavioural ecology and specifically because of their unusual ambush predatory strategy and benthic lifestyle. While several biological functions of electroreception have been proposed, less consideration has been given to the functional significance of interspecific differences in the morphology and topographic distribution of the ampullary organs. The morphology of the ampullary organs was examined in four species of wobbegong shark, and the distribution of electroreceptive pores was mapped in two species. The ampullary systems of wobbegongs are similar in morphology to other marine elasmobranchs. The number of alveoli per ampullae is not significantly different between the four species; however, differences are seen between ampullary cell size in some species. Ampullary pore distribution patterns are relatively unique, with the majority of pores occurring on the dorsal region of the head. Wobbegongs feed primarily on demersal teleost fishes, and as the benthic and well-camouflaged wobbegong remains motionless, these fish could be easily detected by the dorsal pores when swimming within range.  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