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   19445篇
  免费   198篇
  国内免费   169篇
安全科学   555篇
废物处理   814篇
环保管理   2639篇
综合类   2593篇
基础理论   5098篇
环境理论   7篇
污染及防治   5745篇
评价与监测   1304篇
社会与环境   928篇
灾害及防治   129篇
  2022年   162篇
  2021年   195篇
  2020年   115篇
  2019年   156篇
  2018年   266篇
  2017年   284篇
  2016年   462篇
  2015年   391篇
  2014年   590篇
  2013年   1685篇
  2012年   697篇
  2011年   870篇
  2010年   680篇
  2009年   778篇
  2008年   913篇
  2007年   948篇
  2006年   843篇
  2005年   691篇
  2004年   708篇
  2003年   652篇
  2002年   660篇
  2001年   775篇
  2000年   564篇
  1999年   320篇
  1998年   242篇
  1997年   228篇
  1996年   277篇
  1995年   277篇
  1994年   263篇
  1993年   233篇
  1992年   208篇
  1991年   192篇
  1990年   210篇
  1989年   191篇
  1988年   180篇
  1987年   171篇
  1986年   150篇
  1985年   146篇
  1984年   176篇
  1983年   176篇
  1982年   168篇
  1981年   169篇
  1980年   136篇
  1979年   159篇
  1978年   108篇
  1977年   102篇
  1976年   89篇
  1975年   95篇
  1973年   93篇
  1972年   99篇
排序方式: 共有10000条查询结果,搜索用时 906 毫秒
451.
Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and the carbon cycle. Isoprene is quantitatively the most important of the non-methane BVOCs (NMBVOCs), with an annual emission of about 400–600 TgC; about 90% of this is emitted by terrestrial plants. Incorporating a mechanistic treatment of isoprene emissions within land-surface schemes has recently become a focus for the modelling community, the aim being to quantify the potential magnitude of associated climate feedbacks. However, these efforts are hampered by major uncertainties about why plants emit isoprene and the relative importance of different environmental controls on isoprene emission. The availability and reliability of observations of isoprene fluxes from different types of vegetation is limited, and this also imposes constraints on model development. Nevertheless, progress is being made towards the development of mechanistic models of isoprene emission which, in conjunction with atmospheric chemistry models, will ultimately allow improved quantification of the feedbacks between the terrestrial biosphere and climate under past and future climate states.  相似文献   
452.
453.
Most of the mitigation measures against natural hazards can not be perfectly allocated via the common market mechanism, given their principle character of being a public good. Thus, different instruments need to be applied to retrieve their values. Economic valuation tools are one alternative to estimate preferences of individuals towards these goods. These methods are often difficult to operationalise and are not a feasible task for every single project. An alternative is offered by direct preference representation through involving affected interest groups actively in decisions. A critical question is whether the decision on protection measures can be left to public participation or should remain in the experts’ decision responsibility. It can be observed that the latter mode shows inefficiencies. In this paper, it is argued that participation could be one way to bring about the desired goal of increasing efficiency. The present work offers a discussion of the relevant political economic concepts in order to introduce the idea that participation can increase efficiency through achieving the Pareto criterion claimed in the realm of constitutional economics. Furthermore it will be shown that decision aiding tools, namely multi-criteria analysis, can integrate participation into actual decision making processes in a structured way.  相似文献   
454.
455.
456.
Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes.  相似文献   
457.
Mountain ecosystems are considered vulnerable to early impacts of climate change. Whether and how local residents of these areas perceive these changes, however, remain under-studied questions. By conducting a household survey in the Khumbu region of Nepal, this study assessed local residents’ experience-based perception of changes in climate trends and patterns, perceived risk, and attitudes towards climate issues. Multivariate cluster analysis based on residents’ climate change beliefs revealed three segments: “Cautious,” “Disengaged,” and “Alarmed.” A comparison of these segments along key psychosocial constructs of Protection Motivation Theory (PMT) revealed significant inter-segment differences in residents’ perception of severity, vulnerability, response efficacy, self-efficacy, and response cost associated with engaging in mitigating behavior. Results shed light on how residents of high elevation areas that are considered to be exposed to early impacts of climate change perceive the risk and intend to respond. These findings could also assist stakeholders working in other similar mountain ecosystems in understanding vulnerability and in working towards climate readiness.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01369-x) contains supplementary material, which is available to authorized users.  相似文献   
458.
Environmental Science and Pollution Research - The order Odonata has been regularly used as an indicator of the ecosystem’s condition. The objective of this review was to analyze the...  相似文献   
459.
Environmental Science and Pollution Research - In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were...  相似文献   
460.
Environmental Science and Pollution Research - The scientific knowledge produced by academic research can be valued in all sectors of human activity, including private sector. The ROVALTAIN...  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