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   257篇
  免费   6篇
  国内免费   1篇
安全科学   5篇
废物处理   7篇
环保管理   63篇
综合类   36篇
基础理论   50篇
环境理论   3篇
污染及防治   72篇
评价与监测   13篇
社会与环境   12篇
灾害及防治   3篇
  2023年   2篇
  2022年   4篇
  2021年   2篇
  2020年   4篇
  2019年   8篇
  2018年   8篇
  2017年   9篇
  2016年   12篇
  2015年   14篇
  2014年   10篇
  2013年   14篇
  2012年   12篇
  2011年   4篇
  2010年   13篇
  2009年   20篇
  2008年   20篇
  2007年   14篇
  2006年   15篇
  2005年   5篇
  2004年   6篇
  2003年   8篇
  2002年   3篇
  2001年   9篇
  2000年   3篇
  1999年   1篇
  1998年   1篇
  1996年   4篇
  1995年   4篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1991年   4篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1971年   1篇
  1967年   1篇
  1959年   1篇
  1957年   1篇
  1955年   1篇
  1929年   1篇
排序方式: 共有264条查询结果,搜索用时 15 毫秒
41.
Bottle incubations were conducted in March, July/August and October 1992. to measure the daily rations (R) and objectively characterize the diets of the calanoid copepodsEucalanus elongatus, Undinula vulgaris, Centropages velificatus andTemora stylifera from the west Florida continental shelf. Daily rations,R, were clustered around two, order-of-magnitude different means, 1.3 and 11.2% of body C d–1, representative of quiescent and active feeding modes, respectively. The food concentration at which the transition from quiescent to active mode occurred was influenced by food particle size. In the quiescent mode, diets were dominated by nanoplankton, whereas no food type dominated the diet in the active mode. Selective feeding, defined as a statistically significant difference between the frequency distributions of foods in the diet and environment, occurred in both quiescent and active copepods. However, what appeared to be selective feeding in quiescent copepods could be explained by processes that passively modified the distribution of the diet relative to that of the food supply. Conversely, selective feeding in active copepods apparently resulted from foraging for particles >5 m in diameter in food environments dominated by nanoplankton (<5 m).  相似文献   
42.
Wind tunnel experiments on rehabilitation surfaces at Eneabba, Western Australia evaluated the techniques used by Associated Minerals Consolidated Ltd. (AMC) and Allied Eneabba Ltd. (AEL) to stabilize regions being revegetated following heavy mineral sand mining. Newly landscaped areas proved to be the most erodible, beginning to erode at 9 m sec−1 and producing a soil flux of 10 kg m−1 min−1 at 18 m sec−1 wind speeds. Sandier, more organically-rich, surfaces in the rehabilitation areas were somewhat less erodible with losses of only 2 kg m−1 min−1 at wind speeds of 18 m sec−1. The mining companies use various nurse crops and top dressing mulch for surface stabilization. Rows of oats, sparse plantings of the grass cultivar “SUDAX” (Dekalb ST6) supplied by Westfarmers Ltd. and applications of Terolas, a cold, bituminous surface binding material supplied by Shell Co. of Australia Ltd., all proved successful in reducing wind erosion in this semi-arid region where more than 25% of summer days experience winds greater than 8 m sec−1.  相似文献   
43.
An Integrated Model of Public Contact Planning for Conservation Management   总被引:1,自引:0,他引:1  
/ Public contact is a vital component of any program to manage natural resources. A well-planned public contact program uses a variety of strategies to create a sympathetic and environmentally aware public and to meet specific management-related objectives. A methodology is proposed that can be applied to planning public contact at any level, from media design for a specific project to corporate strategies for communication. The methodology integrates management-driven, client-driven and resource-driven planning to provide the connections essential to effective communication.KEY WORDS: Planning; Public contact; Interpretation; Conservation; Management  相似文献   
44.
The United States Environmental Protection Agency (USEPA) has pursued the estimation of risk of adverse health effects from exposure to chemical mixtures since the early 1980s. Methods used to calculate risk estimates of mixtures were often based on single chemical information that required assumptions of dose-addition or response-addition and did not consider possible changes in response due to interaction effects among chemicals. Full factorial designs for laboratory studies can produce interactions information, but these are expensive to perform and may not provide the information needed to evaluate specific environmentally relevant mixtures. In this research, groups of Japanese medaka (Oryzias latipes) embryos were exposed to binary mixtures of benzene and toluene as well as to each of these chemicals alone. Endpoint specific dose-response models were built for the hydrocarbon mixture under an assumption of dose-additivity, using the single chemical dose-response information on benzene and toluene. The endpoints included heart rate, heart rate progression, and lethality. Results included a synergistic response for heart rate at 72 h of development, and either additivity or antagonism for all other endpoints at 96 h of development. This work uses an established statistical method to evaluate the toxicity of an environmentally relevant mixture to ascertain whether interaction effects are occurring, thus providing additional information on toxicity.  相似文献   
45.
气候变化不仅是一个影响世界各国的全球性问题,它还对许多中低收入国家的发展进程构成颠覆甚至倒退的威胁.在支持发展中国家经济增长重点的同时,应对减缓和适应气候变化的双重挑战,是国际社会面临的一项重大考验.  相似文献   
46.
Making index insurance attractive to farmers   总被引:1,自引:0,他引:1  
There are several factors that influence whether people will want to participate in index insurance programs. A number of these influence their attractiveness on economic grounds, including both the size and timing of the premium and potential payouts, and the degree of risk aversion of the potential customers. Other factors make programs attractive for reasons that are not economic, but no less valid. These have to do with the trust that people have in the insurance product and the organizations involved in selling and managing it. Indeed, data from India, Africa, and South America show that these factors may be more important than the economic ones in influencing demand. Index insurance pilot projects, in order to estimate demand for alternative products, have typically involved a great deal of interaction with potential customers. It is important to recognize that such interaction is crucial not just as a research tool, but also as a means to build understanding and trust in the products. When scaling up from isolated pilots to operational programs, it is vital to recognize this trust building function by replicating participation efforts in every community. In this paper, we examine the role of field games in establishing and building trust in three important aspects of these projects for participants: trust in the insurance product, trust in the participating organizations, and trust in their own ability to make good decisions. While games have previously been used as a way to gauge interest in the product and to identify design features, we argue that these games are also valuable tools for constructing these kinds of trust.  相似文献   
47.
Abstract: That the greatest challenges in conservation are often not technical but rather economic or sociological has been expressed for at least the last 20 years. This raises the question of whether the training offered to tomorrow's conservation practitioners prepares them sufficiently to deal with the human dimensions of conservation. We analyzed 747 papers from seven wildlife management and conservation biology journals to determine the trends in this area of conservation management between 1985 and 1995. We found that over that time the emphasis stayed on single-species issues with a science focus, but there was a marked shift toward conservation biology issues, management-oriented research, and discussion of economic and social factors relevant to management. We also examined the handbooks of 11 Australian universities to analyze the content of 439 compulsory subjects in 12 degrees that we judged could produce wildlife managers. More than 68% of subjects were from a basic science or technology discipline, 16% from resource management, and only 13% from economics, humanities, communications, or planning. Thus, many of the skills required by contemporary wildlife managers must be learned in postgraduate training or on the job. Much of the undergraduate training syllabus, in Australia at least, does not reflect trends in the practice of wildlife management today and will not provide tomorrow's managers with the range of disciplinary understanding required. We were able, however, to identify three types of undergraduate training—ecological system managers, environmental managers, and human system managers—and we found that the curricula in human-system management contained increased emphasis on socioeconomic issues relevant to management.  相似文献   
48.
Phenological tracking enables positive species responses to climate change   总被引:1,自引:0,他引:1  
Earlier spring phenology observed in many plant species in recent decades provides compelling evidence that species are already responding to the rising global temperatures associated with anthropogenic climate change. There is great variability among species, however, in their phenological sensitivity to temperature. Species that do not phenologically "track" climate change may be at a disadvantage if their growth becomes limited by missed interactions with mutualists, or a shorter growing season relative to earlier-active competitors. Here, we set out to test the hypothesis that phenological sensitivity could be used to predict species performance in a warming climate, by synthesizing results across terrestrial warming experiments. We assembled data for 57 species across 24 studies where flowering or vegetative phenology was matched with a measure of species performance. Performance metrics included biomass, percent cover, number of flowers, or individual growth. We found that species that advanced their phenology with warming also increased their performance, whereas those that did not advance tended to decline in performance with warming. This indicates that species that cannot phenologically "track" climate may be at increased risk with future climate change, and it suggests that phenological monitoring may provide an important tool for setting future conservation priorities.  相似文献   
49.
Applying 3DCE to environmentally responsible manufacturing practices   总被引:1,自引:0,他引:1  
A review of recent literature in the fields of operations, supply chain, and management indicates there is on-going interest in improving new product development (NPD) performance. Three-dimensional concurrent engineering (3DCE), the simultaneous design of product, process and supply chain have been proposed as a way to improve traditional NPD outcomes, such as reduced time to market, lower costs, and improved customer acceptance. There appears to be a lesser concern associated with the environmental impacts of new products. Environmentally responsible manufacturing (ERM) on new product development focuses on reduced emissions, hazardous materials elimination, and lower product weight without sacrificing functionality. This paper explores the following issue: will employing 3DCE to integrate NPD and ERM yield better benefits than the separate and uncoordinated application of environmental goals and NPD initiatives?  相似文献   
50.
Assessing the impact of climate change on species and associated management objectives is a critical initial step for engaging in the adaptation planning process. Multiple approaches are available. While all possess limitations to their application associated with the uncertainties inherent in the data and models that inform their results, conducting and incorporating impact assessments into the adaptation planning process at least provides some basis for making resource management decisions that are becoming inevitable in the face of rapidly changing climate. Here we provide a non-exhaustive review of long-standing (e.g., species distribution models) and newly developed (e.g., vulnerability indices) methods used to anticipate the response to climate change of individual species as a guide for managers grappling with how to begin the climate change adaptation process. We address the limitations (e.g., uncertainties in climate change projections) associated with these methods, and other considerations for matching appropriate assessment approaches with the management questions and goals. Thorough consideration of the objectives, scope, scale, time frame and available resources for a climate impact assessment allows for informed method selection. With many data sets and tools available on-line, the capacity to undertake and/or benefit from existing species impact assessments is accessible to those engaged in resource management. With some understanding of potential impacts, even if limited, adaptation planning begins to move toward the development of management strategies and targeted actions that may help to sustain functioning ecosystems and their associated services into the future.  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