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   972篇
  免费   18篇
  国内免费   9篇
安全科学   34篇
废物处理   32篇
环保管理   175篇
综合类   111篇
基础理论   286篇
环境理论   1篇
污染及防治   244篇
评价与监测   68篇
社会与环境   42篇
灾害及防治   6篇
  2023年   27篇
  2022年   32篇
  2021年   13篇
  2020年   12篇
  2019年   28篇
  2018年   22篇
  2017年   32篇
  2016年   39篇
  2015年   24篇
  2014年   42篇
  2013年   77篇
  2012年   35篇
  2011年   81篇
  2010年   52篇
  2009年   42篇
  2008年   46篇
  2007年   57篇
  2006年   59篇
  2005年   32篇
  2004年   32篇
  2003年   35篇
  2002年   33篇
  2001年   19篇
  2000年   8篇
  1999年   3篇
  1998年   11篇
  1997年   14篇
  1996年   15篇
  1995年   5篇
  1994年   10篇
  1993年   5篇
  1992年   5篇
  1991年   2篇
  1990年   5篇
  1989年   2篇
  1988年   8篇
  1987年   3篇
  1986年   4篇
  1985年   2篇
  1984年   4篇
  1983年   5篇
  1982年   4篇
  1981年   3篇
  1980年   4篇
  1979年   2篇
  1976年   1篇
  1965年   1篇
  1941年   1篇
  1936年   1篇
排序方式: 共有999条查询结果,搜索用时 15 毫秒
991.
Previous academic research into how consumers evaluate advocacy advertising identified many possible paths involving potentially reflexive effects on how people perceive an advocacy advertising sponsor, the advocated issue and themselves. This paper has examined one possible scenario within this complicated phenomenon: that of advertising advocating a specific environmental consumer action, recycling. In the specific context of this study, structural equation modelling demonstrated clear causal relationships among consumer perceptions of the recycling advertisements’ sponsoring organization, consumer self-efficacy and perceived consumer effectiveness of complying with the advocated issue (recycling behaviour). These factors were shown to impact specific advocacy advertising goals (termed message effectiveness in this study) such as behavioural intention toward the advocated recycling issue and perceived changes in how consumers evaluate the sponsoring organization.  相似文献   
992.
Public, nonprofit and private organisations respond to large‐scale disasters domestically and overseas. Critics of these assistance efforts, as well as those involved, often cite poor interorganisational partnering as an obstacle to successful disaster response. Observers frequently call for ‘more’ and ‘better’ partnering. We found important qualitative distinctions existed within partnering behaviours. We identified four different types of interorganisational partnering activities often referred to interchangeably: communication, cooperation, coordination and collaboration—the Four Cs. We derived definitions of the Four Cs from the partnering literature. We then tested them in a case study of the response to the 2010 Haiti earthquake. We suggest that the Four Cs are distinct activities, that organisations are typically strong or weak in one or more for various reasons, and that the four terms represent a continuum of increased interorganisational embeddedness in partnering activities.  相似文献   
993.
Two pilot tests of an aerobic in situ bioreactor (ISBR) have been conducted at field sites contaminated with petroleum hydrocarbons. The two sites differed with respect to hydrocarbon concentrations. At one site, concentrations were low but persistent, and at the other site concentrations were high enough to be inhibitory to biodegradation. The ISBR unit is designed to enhance biodegradation of hydrocarbons by stimulating indigenous microorganisms. This approach builds on existing Bio‐Sep® bead technology, which provides a matrix that can be rapidly colonized by the active members of the microbial community and serves to concentrate indigenous degraders. Oxygen and nutrients are delivered to the bioreactor to maintain conditions favorable for growth and reproduction, and contaminated groundwater is treated as it is circulated through the bed of Bio‐Sep® beads. Groundwater moving through the system also transports degraders released from Bio‐Sep® beads away from the bioreactor, potentially increasing biodegradation rates throughout the aquifer. Groundwater sampling, Bio‐Traps, and molecular biological tools were used to assess ISBR performance during the two pilot tests. Groundwater monitoring indicated that contaminant concentrations decreased at both sites, and the microbial data suggested that these decreases were due to degradation by indigenous microorganisms rather than dilution or dispersion mechanisms. Taken together, these lines of evidence showed that the ISBR system effectively increased the number and activity of indigenous microbial degraders and enhanced bioremediation at the test sites. © 2013 Wiley Periodicals, Inc.  相似文献   
994.
This study characterises the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc are super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.  相似文献   
995.
In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a novel variant of the popular projection method for solving the Navier–Stokes equations has been developed and applied to produce fast and reasonably accurate parallel computational fluid dynamics (CFD) solutions for flow in complex urban areas. This model, called QUIC-CFD represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. This paper details the solution procedure and validates this model for various simple and complex urban geometries.  相似文献   
996.
997.
维多利亚湖是一个国际性水域,为沿岸社区提供着很多极其重要的环境服务,在过去50多年的时间里,该湖泊受到周边人类各项相互关联的活动越来越显著的压力,例如过度捕捞、外来物种入侵、工业污染、富营养化和泥沙淤积等.本文分析了维多利亚湖过度捕捞和污染问题产生的根源,并提出了政策性建议,这些建议有助于修复和减轻该湖的环境退化问题.  相似文献   
998.
999.

Cyclodextrins are cage-shaped molecules having the remarkable ability to trap smaller compounds, and have thus led to applications in many disciplines such as medicine to increase the bioavailability of hydrophobic drugs. This historical review summarizes the outstanding contribution of the late Professor Benito Casu to cyclodextrin research and, more generally, to the chemistry and biochemistry of linear and cyclic oligosaccharides, polysaccharides, glycosaminoglycans, and heparin. Professor Casu was the first to elucidate the structure and conformations of cyclodextrins by infrared spectroscopy and proton nuclear magnetic resonance (NMR). In particular, he showed that trapped compounds induced a shift of H peaks in NMR due to the shielding effect of cyclodextrins. He also demonstrated that the d-glucopyranose cyclodextrin units are in the C-1 chair conformation by analyzing α-cyclodextrin by NMR in dimethylsulfoxide-d6.

  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