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   214篇
  免费   6篇
  国内免费   3篇
安全科学   13篇
废物处理   16篇
环保管理   25篇
综合类   49篇
基础理论   45篇
污染及防治   53篇
评价与监测   11篇
社会与环境   10篇
灾害及防治   1篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   2篇
  2019年   5篇
  2018年   8篇
  2017年   5篇
  2016年   10篇
  2015年   8篇
  2014年   10篇
  2013年   15篇
  2012年   18篇
  2011年   13篇
  2010年   14篇
  2009年   12篇
  2008年   14篇
  2007年   9篇
  2006年   15篇
  2005年   7篇
  2004年   10篇
  2003年   5篇
  2002年   6篇
  2001年   2篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   4篇
  1995年   1篇
  1994年   6篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1979年   1篇
排序方式: 共有223条查询结果,搜索用时 31 毫秒
61.
Engaging in networking behaviors, by attempting to develop and maintain relationships with others who have the potential to provide work or career assistance, is considered to be an important career management strategy. This study explores the relationship between networking behavior and career outcomes (i.e., number of promotions, total compensation, perceived career success) in a sample of managerial and professional employees. Furthermore, we investigate whether networking behavior is as beneficial for women as it is for men. Results indicated that some types of networking behavior were related to both objective and perceived career outcomes. In addition, gender differences do impact the utility of networking behavior as a career‐enhancing strategy. Explanations of our results and implications for engaging in networking behavior are discussed. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
62.
The US Department of Defense (DOD) manages over 10.1 million ha of land, much of which is used for training military personnel. However, vast sections receive little or no use, and military lands have become refuges for many species. At Fort McCoy, Wisconsin, USA, populations of the endangered Karner blue butterfly (Lycaeides melissa samuelis) are found in oak and pine barren communities where wild lupine (Lupinus perennis), a perennial forb required by Karner blue butterfly larvae, still occurs. Oak and pine barren communities are disturbance-dependent, and the barrens ecosystems in the Midwest have declined in extent by 98% because of fire suppression, succession, and habitat fragmentation. We studied the effects of disturbance by military manuever training on the density of lupine and Karner blue butterfly at Fort McCoy. We also wanted to determine whether military training activity could enhance Karner blue butterfly habitat. At locations where tracked vehicles had driven through lupine patches, the abundance of lupine and nectar-producing plants was greater in the median strip between vehicle ruts than in vehicle ruts or 5 m outside the vehicle ruts. The proportion of lupine stems with Karner blue butterfly larvae feeding sign (the ratio of stems fed upon to stems examined) was greater in areas where military vehicles had traveled than where they had not. The proportion of lupine stems with feeding sign and lupine stem density was also positively related to the occurrence of prior bivouacs and fires caused by military munitions. Shrub and forest canopy abundance were lower in areas traveled by tracked vehicles. At the scale of the lupine patch, lupine abundance and the proportion of lupine stems with feeding sign were positively correlated with military training activities, suggesting that maintenance of lupine habitat can be achieved in concert with military training.  相似文献   
63.
The Metropolitan Region of Santiago has been declared as nonattainment area for carbon monoxide (CO). The data was based on seven air monitoring stations that do not necessarily represent the real population exposure. Usually, a series of coefficients that relates the concentration of pollutants with health effects (betas of the concentration–response equations) are used. For the calculation of these betas, normally, a city average air pollution concentration is used; nevertheless, these betas do not necessarily represent the real risk of exposure that the inhabitants are experimented. For this reason, this study estimates two aspects that are unknown and that are necessary to policymakers in public health decisions. First, estimate the exposure at a lower spatial resolution level and, second, estimate a concentration–response curve that differs spatially and depends on the proportion of susceptible groups. We followed the Air Pollution and Health, European Approach/Spanish Multicenter Study on the Relationship Between Air Pollution and the Mortality methodology for the determination of the short-term health effect due to CO population exposure at the three spatial levels (city, zone, and county). We found that there are different risks in cardiorespiratory mortality in the group over 64 years old associated to an unequal exposure to CO in Santiago city. The higher risks are in counties located to the south–east of the city. These finding confirm the necessity to face, in a different way, the approach when evaluating control strategies and policy decision to control air pollution in Santiago.  相似文献   
64.
Many international agreements, such as the 1992 UN Convention on Biological Diversity, posit that successful community-oriented (community-based) wildlife conservation depends on partnerships with stakeholders of different class, ethnicity, and gender. Gender is of particular interest because it often relates to environmental use, attitudes, and knowledge and operates across other key categories. This study uses fieldwork, interviews, and a survey of 52 project heads in India to address two research questions: (1) How are gender issues viewed by supervisors of community-based wildlife conservation projects, in relation to their work? (2) What types of resources would be most useful to project heads seeking to promote gender equity through their conservation work? The results suggest that while there is widespread support for integrating gender equity issues into community-oriented wildlife conservation, many believe that gender may be a potentially distracting and secondary issue. Several reasons for the variation in views were identified including the following: the dearth of relevant empirical research about gender issues in wildlife conservation; ambiguities about the concept of gender itself; and a lack of opportunities to critically discuss the role of gender equity issues for conservation. These factors may contribute to a disconnection between international rhetoric and on-the-ground practice as it relates to gender and community-oriented wildlife conservation. Increased opportunities for professional capacity building among project supervisors and staff members, coupled with increased collaboration between social and natural scientists, will be important for strengthening the links between international conservation policy and on-the-ground practice.  相似文献   
65.
An assessment of the off-site migration of pesticides from agricultural activity into the environment in the Neuquen River Valley was performed. The aim of this study was to evaluate the distribution of pesticides in several compartments of a small agricultural sub-catchment. Soil, surface water, shallow groundwater and drift deposition were analyzed for pesticide residues. Results showed the presence of some pesticide residues in soil, surface water and shallow groundwater compartments. The highest detection frequencies in water (surface and subsurface) were found for azinphos-methyl and chlorpyrifos (>70%). In terms of concentration, the highest levels were observed in shallow groundwater for azinphos methyl (22.5 μg/L) and carbaryl (45.7 μg/L). In the soil, even before the application period had started, accumulation of residues was present. These residues increased during the period studied. Spray drift during pesticide application was found to be a significant pathway for the migration of pesticide residues in surface water, while leaching and preferential flows were the main transport routes contributing to subsurface contamination.  相似文献   
66.
Chromate-resistant bacterial strain isolated from the soil of tannery was studied for Cr(VI) bioaccumulation in free and immobilised cells to evaluate its applicability in chromium removal from aqueous solution. Based on the comparative analysis of the 16S rRNA gene, and phenotypic and biochemical characterization, this strain was identified as Paenibacillus xylanilyticus MR12. Mechanism of Cr adsorption was also ascertained by chemical modifications of the bacterial biomass followed by Fourier transform infrared spectroscopy analysis of the cell wall constituents. The equilibrium biosorption analysed using isotherms (Langmuir, Freundlich and Dubinin–Redushkevich) and kinetics models (pseudo-first-order, second-order and Weber–Morris) revealed that the Langmuir model best correlated to experimental data, and Weber–Morris equation well described Cr(VI) biosorption kinetics. Polyvinyl alcohol alginate immobilised cells had the highest Cr(VI) removal efficiency than that of free cells and could also be reused four times for Cr(VI) removal. Complete reduction of chromate in simulated effluent containing Cu2+, Mg2+, Mn2+ and Zn2+ by immobilised cells, demonstrated potential applications of a novel immobilised bacterial strain MR12, as a vital bioresource in Cr(VI) bioremediation technology.  相似文献   
67.

Purpose  

This paper analyses the presence of polychlorinated biphenyls (PCBs) in escaped: farmed and wild salmons in southern Chile, analysing their concentrations and congener profiles in two species (Oncorhynchus kisutch and Oncorhynchus mykiss).  相似文献   
68.
Mechanisms underlying cadmium (Cd) detoxification were compared in two aquatic macrophytes commonly used in phytoremediation, namely Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms. To simulate Cd pollution in the open environment, plants growing in outdoor artificial lakes were exposed for 21d to either 25 or 100microM Cd, in two consecutive years. Toxicity symptoms were absent or mild in both species. Metal accumulation was much higher in the roots of P. stratiotes, whereas in E. crassipes a comparatively higher fraction was translocated to the leaves. In both species, Cd was neither included in phenolic polymers or Ca-oxalate crystals, nor altered the levels of Cd-complexing organic acids. Glutathione levels were constitutively remarkably higher and much more responsive to Cd exposure in P. stratiotes than in E. crassipes. Abundant phytochelatin synthesis occurred only in P. stratiotes, both in roots and in leaves. In E. crassipes, on the other side, the constitutive levels of some antioxidant enzymes and ascorbate were higher and more responsive to Cd than in P. stratiotes. Thus, in these two aquatic plants grown in the open, different detoxification mechanisms might come into play to counterbalance Cd acute stress.  相似文献   
69.
70.
Herbicide runoff and the effects of a narrow vegetative filter strip (VFS) were studied on an arable field in the low-lying plains of the Veneto Region (north-east Italy). Cultivated plots were compared with and without a 6m wide VFS composed of trees, shrubs and grass. Natural and simulated runoff were monitored during 2000 and 2001. Herbicides applied on the field were: metolachlor (2184-2254 g ha(-1)), terbuthylazine (1000-1127 g ha(-1)) and isoproturon (1000 g ha(-1)). The VFS reduced both runoff depth (10.2-91.2%) and herbicide losses (85.7-97.9%) in the monitored rainfall events. Total herbicide loss with runoff was low (0.69-3.98 g ha(-1) without VFS, less than 0.27 g ha(-1) with VFS), but concentrations were sometimes very high, especially of terbuthylazine and isoproturon during the first events after treatment. In these events there was a high probability of exceeding the ecotoxicological endpoint for algae, but the VFS helped to reduce the potential risk. Two VFS effectiveness mechanisms were identified: (i) dilution, and (ii) a "sponge-like" effect, which temporarily trapped chemicals inside the VFS before releasing them.  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