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   143篇
  免费   3篇
  国内免费   2篇
安全科学   1篇
废物处理   19篇
环保管理   27篇
综合类   17篇
基础理论   34篇
污染及防治   33篇
评价与监测   8篇
社会与环境   8篇
灾害及防治   1篇
  2022年   5篇
  2021年   1篇
  2020年   3篇
  2019年   2篇
  2018年   2篇
  2017年   6篇
  2016年   5篇
  2015年   3篇
  2014年   11篇
  2013年   11篇
  2012年   7篇
  2011年   13篇
  2010年   6篇
  2009年   10篇
  2008年   8篇
  2007年   4篇
  2006年   6篇
  2005年   4篇
  2004年   8篇
  2003年   5篇
  2002年   7篇
  2001年   1篇
  2000年   1篇
  1999年   3篇
  1997年   2篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1980年   1篇
排序方式: 共有148条查询结果,搜索用时 15 毫秒
71.
The successful use of the Superfund program involves developing partnerships with all of the stakeholders early in the process. Citizens living near Superfund sites are the primary stakeholders, falling victim to many health risks and economic costs. When equipped with technical advisors, citizens can play a primary role in the remediation decisions being made at hazardous waste sites. This article illustrates the important role and impact of concerned citizens living near the Niagara Mohawk Power Corporation Superfund site in Saratoga Springs, New York. The Superfund program was used successfully at this site in a number of ways, mainly in that it provided technical advisors through a technical assistance grant (TAG) for the citizens, which resulted in a thorough and conclusive remedial investigation.  相似文献   
72.
73.
According to the classic life history theory, selection for longevity depends on age-dependant extrinsic mortality and fecundity. In social insects, the common life history trade-off between fecundity and longevity appears to be reversed, as the most fecund individual, the queen, often exceeds workers in lifespan several fold. But does fecundity directly affect intrinsic mortality also in social insect workers? And what is the effect of task on worker mortality? Here, we studied how social environment and behavioral caste affect intrinsic mortality of ant workers. We compared worker survival between queenless and queenright Temnothorax longispinosus nests and demonstrate that workers survive longer under the queens’ absence. Temnothorax ant workers fight over reproduction when the queen is absent and dominant workers lay eggs. Worker fertility might therefore increase lifespan, possibly due to a positive physiological link between fecundity and longevity, or better care for fertile workers. In social insects, division of labor among workers is age-dependant with young workers caring for the brood and old ones going out to forage. We therefore expected nurses to survive longer than foragers, which is what we found. Surprisingly, inactive inside workers showed a lower survival than nurses but comparable to that of foragers. The reduced longevity of inactive workers could be due to them being older than the nurses, or due to a positive effect of activity on lifespan. Overall, our study points to behavioral caste-dependent intrinsic mortality rates and a positive association between fertility and longevity not only in queens but also in ant workers.  相似文献   
74.
Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to interactions with the soil temperature and moisture profile, as well as on long (years to centuries) time scale because of depth-specific stabilization mechanisms of organic matter. It is likely that a representation of the SOM profile and surface organic layers in SOM models can improve predictions of the response of land surface fluxes to climate and environmental variability. Although models capable of simulating the vertical SOM profile exist, these were generally not developed for large scale predictive simulations and do not adequately represent surface organic horizons. We present SOMPROF, a vertically explicit SOM model, designed for implementation into large scale ecosystem and land surface models. The model dynamically simulates the vertical SOM profile and organic layer stocks based on mechanistic representations of bioturbation, liquid phase transport of organic matter, and vertical distribution of root litter input. We tested the model based on data from an old growth deciduous forest (Hainich) in Germany, and performed a sensitivity analysis of the transport parameters, and the effects of the vertical SOM distribution on temporal variation of heterotrophic respiration. Model results compare well with measured organic carbon profiles and stocks. SOMPROF is able to simulate a wide range of SOM profiles, using parameter values that are realistic compared to those found in previous studies. Results of the sensitivity analysis show that the vertical SOM distribution strongly affects temporal variation of heterotrophic respiration due to interactions with the soil temperature and moisture profile.  相似文献   
75.
76.
The present study examines antagonistic relationships between different microorganisms inhabiting brackish water and includes a systematic screening for bacteriolytic prokaryotes in the brackish waters of the Southern Baltic Sea (Nordruegenscher Bodden) sampled in July/August 2009. Ten of the 35 marine bacteriolytic isolates belong to the genus Bacillus. Five isolates (B. pumilus, B. subtilis, B. megaterium, B. licheniformis) lysed living microbial cells such as the bacteria Arthrobacter citreus, Arthrobacter protophormiae, Micrococcus luteus, Pseudomonas putida and the yeast Trichosporon mucoides. These and other bacteria (Aeromonas sp., Bacillus subtilis, Chromobacterium violaceum, Citrobacter freundii, Enterobacter aerogenes, Proteus mirabilis, Pseudomonas aeruginosa and Serratia marcescens) were also lysed as autoclaved and pasteurized cells on agar plates. One isolate of Bacillus pumilus showed a distinct bacteriolysis activity against pasteurized cells of A. citreus in liquid culture. Our results suggest that Bacillus species may play a role as opportunistic predators in the marine microbial food web.  相似文献   
77.
Glucocorticoid hormones (GCs) are important mediators of physiological and behavioral responses to stress. While many studies have evaluated the environmental, behavioral, or physiological correlates of GCs and their effects on reproductive performances, further work is needed to clarify the relationship between GCs and fitness. Assessing the effects of increased GC levels on specific behaviors of breeding animals should improve our understanding of how GCs affect parental care. In this experimental study, we measured the effects of an experimental increase in corticosterone (CORT, the main avian GC) levels on the behavior of free-living male Adélie penguins (Pygoscelis adeliae) within the colony, their reproductive output, and the indirect consequences of both on the behavior of their partners. We show that increased CORT levels in males decreased their foraging time at sea while increased their attendance at the nest, although their attentiveness toward the nest itself decreased. In addition, treated males spent more time on comfort behaviors (e.g., preening), vocalizing, and engaging in positive social interactions relative to controls. Treatment further affected the behavior of their partners, but not chick begging and feeding rates. Penguins with increased CORT levels also exhibited decreased reproductive output. Previous studies of Adélie penguins in different life history stages and environmental conditions suggest that the consequences of CORT treatment on reproductive performance are context-dependent. In addition to the potential delay in the effects of increased CORT levels on reproduction, this context dependence should be taken into account when studying the behavior of free-living animals in relation to stress-inducing situations.  相似文献   
78.
In this paper, we analyze the insect resistance management (IRM) plan put in place by the US Environmental Protection Agency (EPA) to delay the evolution of resistance to Bt corn in natural populations of the European corn borer, Ostrinia nubilalis Hübner. This IRM plan is the most impressive mandatory IRM system ever developed. It forms a coherent whole and includes mandatory refuges, actions to increase growers' compliance and a program for monitoring the evolution of resistance. However, our analysis suggests that two components of this IRM plan are not entirely satisfactory: growers' compliance and monitoring of the evolution of resistance. Moreover, the implementation of these two components of IRM has been required of the registrants, whose incentives for IRM are probably lower than the social optimum. Our analysis suggests that alternatives to the IRM plan currently in place could improve these two components.  相似文献   
79.
A recreation impact monitoring system was developed and applied in 1984–1986 and in 1991 to all backcountry river-accessed campsites within Delaware Water Gap National Recreation Area, Pennsylvania and New Jersey. Results suggest that actions implemented by park managers in response to problems identified by the initial survey were highly effective in reducing resource degradation caused by camping. In particular, the elimination of some designated campsites and installation of anchored firegrates reduced the total area of disturbance by 50%. Firegrate installation provided a focal point that increased the concentration of camping activities, allowing peripheral areas to recover. As suggested by predictive models, additional resource degradation caused by increased camping intensities is more than offset by improvements in the condition of areas where use is eliminated. The capabilities and management utility of recreation impact monitoring programs, illustrated by the Delaware Water Gap monitoring program, are also presented and discussed.  相似文献   
80.
How do birds recognize their own eggs? Do they have a stored template for their own egg characteristics, or do they use another mechanism? Intraspecific brood parasitism is considered to be an additional reproductive tactic where females can increase their own reproductive success. Because of the costs involved in rearing young that are not their own, it will pay females to detect and reject the eggs of a parasite, although it is not known how they do this. Here, we show experimentally that moorhens will cease laying in a nest when their first egg is replaced with another hen’s egg but not when it is replaced with their own egg taken from an earlier clutch. This provides good evidence that birds have an internal representation of their own eggs and use this in decisions about whether to reject foreign eggs.  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