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   1807篇
  免费   28篇
  国内免费   16篇
安全科学   53篇
废物处理   67篇
环保管理   298篇
综合类   304篇
基础理论   431篇
环境理论   4篇
污染及防治   472篇
评价与监测   134篇
社会与环境   83篇
灾害及防治   5篇
  2023年   22篇
  2022年   20篇
  2021年   25篇
  2020年   24篇
  2019年   23篇
  2018年   39篇
  2017年   47篇
  2016年   43篇
  2015年   46篇
  2014年   50篇
  2013年   127篇
  2012年   73篇
  2011年   108篇
  2010年   77篇
  2009年   92篇
  2008年   95篇
  2007年   115篇
  2006年   84篇
  2005年   73篇
  2004年   72篇
  2003年   67篇
  2002年   78篇
  2001年   33篇
  2000年   26篇
  1999年   18篇
  1998年   20篇
  1997年   23篇
  1996年   18篇
  1995年   23篇
  1994年   25篇
  1993年   13篇
  1992年   16篇
  1991年   15篇
  1990年   12篇
  1989年   12篇
  1988年   17篇
  1987年   12篇
  1986年   15篇
  1984年   8篇
  1983年   10篇
  1982年   11篇
  1981年   9篇
  1980年   7篇
  1979年   10篇
  1978年   7篇
  1977年   5篇
  1976年   6篇
  1974年   6篇
  1955年   5篇
  1954年   8篇
排序方式: 共有1851条查询结果,搜索用时 15 毫秒
991.
In this paper we argue that organizational identification is predictive of employee interests and concerns during periods of organizational change. More specifically, we assert that organizational identification may largely determine whether employees may be focused upon the change related outcomes (e.g., salary, expenses, etc.), or on the change processes (e.g., procedures, voice and participation options, etc.). Data of both a scenario experiment and a survey are presented indicating that high and low identifiers indeed are differentially interested in process and outcome information. The results suggest that people who identify less with the organization are more likely to be focused upon the change outcomes then on the change process, while people who identify highly (i.e., deep structure) with the organization are more likely to be focused upon the change processes then on the change outcomes. The benefits of awareness of organizational members' level of identification for organizational change management are discussed. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
992.
Least flycatchers (Empidonax minimus) and American redstarts (Setophaga ruticilla) overlap in the use of food resources on their breeding grounds, promoting high levels of interspecific aggression by the socially dominant flycatcher. We examined the role of song in this interspecific aggression by using repeated-measures-designed playback experiments and observational data on induced aggressive interactions. Flycatchers were more likely to approach the speaker during presentation of redstart song than during intervals of no song or presentation of control song. Approach was close enough to enable visual contact with a singing redstart. In contrast, redstarts made significantly fewer flights following presentation of flycatcher song, when risk of flycatcher attack may be greatest. Reducing the number of flights likely reduces the risk of flycatcher attack on the redstart, as flycatchers do not attack stationary redstart models and are apparently dependent on cues from redstart flight for visual heterospecific recognition. Flycatcher-specific responses of redstarts and marked differences in song morphology rule out misdirected intraspecific aggression as a proximate or ultimate cause of interspecific response to song. Results indicate that song is an important component in aggressive interactions between these two species, and reflect the dominant role of the flycatcher in such interactions. Our results also illustrate the capacity for interspecific interference competition to influence behavior and heterospecific song recognition in two distant avian taxa. Received: 10 January 1995/Accepted after revision: 8 June 1996  相似文献   
993.
994.
Environmental Science and Pollution Research - Approximately 33% of food produced around the world is wasted. In the distribution sector, erroneous orders or demand predictions result in products...  相似文献   
995.

The advent of automated vehicles is already taking place and will significantly disrupt the motor insurance industry. The shift from the human driver to the system as the driver cannot be reflected in the current insurance risk assessment. This call for an amendment of the insurance underwriting was discussed with German experts from both the primary insurance and reinsurance sector with their professional background on motor insurance. Based on the findings, we propose an alternative method to underwrite automated vehicles of level 4 & 5 using an enhanced telematics approach which considers new risk categories such as systems used and the transformed role of the driver as the general user of the automated vehicle.

  相似文献   
996.
Shipping is an important source of pollution affecting both atmospheric and aquatic environments. To allow for efficient mitigation of environmental degradation, it is essential to know the extent of the impacts of shipping in relation to other sources of pollution. Here, we give a perspective on a holistic approach to studies of the environmental impacts of operational shipping through presentation of an assessment framework developed and applied on a case of shipping in the Baltic Sea. Through transfer of knowledge and concepts, previously used in assessments of air pollution, now applied to assessments of marine pollution and underwater noise, the horizon of understanding of shipping-related impacts is significantly improved. It identifies the main areas of environmental degradation caused by shipping and potential improvements through legislation and technological development. However, as the vast majority of contaminants discharged into the sea are not routinely monitored and assessed, the links between pressure of contaminants from shipping and environmental state and impacts will not be caught in the current environmental regulatory frameworks.  相似文献   
997.
The aim of the project is to study heavy metals accumulation by the selected plants in both laboratory and field conditions. Within the experiments the aspen (Populus tremula × tremuloides), sunflower (Helianthus annuus) and corn (Zea mays) plants were studied. The reasons for this selection were: a fast growth of these plants, an accumulation capacity and an ability to survive in different types of soils. The study was carried out on the aspen plantlets grown in vitro. The plants were exposed to the aqueous solutions having concentrations 0.1 mM, 0.5 mM of Pb2+ or Ni2+, respectively. The accumulation capacityfor aspen, was about 70% of Pb2+ originally present in the solution. The starting concentration of Pb2+ (0.5 mM) exhibited no negative impact on the growth. Besides in vitro expositions, a pilot-scale phytoremediation experiment was carried out at the polluted industrial area (Zn – 75000 mg/kg), (Pb – 16000 mg/kg), (Cr – 590 mg/kg), (Cd – 90 mg/kg) and (Cu – 1700 mg/kg).  相似文献   
998.
Bacterial growth and its interaction with water flow was investigated in a two-dimensional flow field in a saturated porous medium. A flow cell (56 x 44 x 1 cm) was filled with glass beads and operated under a continuous flow of a mineral medium containing nitrate as electron acceptor. A glucose solution was injected through an injection port, simulating a point source contamination. Visible light transmission was used to observe the distribution of the growing biomass and water flow during the experiment. At the end of the experiment (on day 31), porous medium samples were destructively collected and analyzed for abundance of total and active bacterial cells, bacterial cell volume and concentration of polysaccharides and proteins. Microbial growth was observed in two stripes along the length of the flow cell, starting at the glucose injection port, where highest biomass concentrations were obtained. The spatial distribution of biomass indicated that microbial activity was limited by transverse mixing between glucose and nitrate media, as only in the mixing zone between the media high biological activities were achieved. The ability of the biomass to change the flow pattern in the flow cell was observed, indicating that the biomass was locally reducing the hydraulic conductivity of the porous medium. This bioclogging effect became evident when the injection of the glucose solution was turned off and water flow still bypassed the area around the glucose injection port, preserving the flow pattern as it was during the injection of the glucose solution. As flow bypass was possible in this system, the average hydraulic properties of the flow cell were not affected by the produced biomass. Even in the vicinity of the injection port, the total volume of the bacterial cells remained below 0.01% of the pore space and was unlikely to be responsible for the bioclogging. However, the bacteria produced large amounts of extracellular polymeric substances (EPS), which likely caused the observed bioclogging effects.  相似文献   
999.
Putschew A  Mania M  Jekel M 《Chemosphere》2003,52(2):399-407
Monitoring of organic halogen compounds, measured as adsorbable organically bound bromine (AOBr), in an eutrophic lake, which is influenced by treated waste water, revealed repeatedly high concentrations of organobromine compounds in late summer, whereas five times lower values were measured during the rest of the year. It was possible to reproduce the in situ observed AOBr increase in the laboratory. Batch experiments were performed with lake water from two different lakes and an algae culture. It could be shown that the AOBr production is not limited to strong waste water influenced lakes. Furthermore, the AOBr formation requires light and the presence of algae, and thus is most probably biotic in nature. A low content of nutrients favours the formation of organic bromine compounds. To our knowledge this is the first report about the seasonally occurrence of naturally produced organic bromine compounds in lakes/surface waters.  相似文献   
1000.
Regional monitoring of heavy metal pollution   总被引:1,自引:0,他引: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