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   226篇
  免费   3篇
  国内免费   3篇
安全科学   14篇
废物处理   5篇
环保管理   82篇
综合类   10篇
基础理论   49篇
污染及防治   40篇
评价与监测   14篇
社会与环境   11篇
灾害及防治   7篇
  2022年   2篇
  2021年   1篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   9篇
  2015年   7篇
  2014年   3篇
  2013年   24篇
  2012年   9篇
  2011年   5篇
  2010年   7篇
  2009年   7篇
  2008年   11篇
  2007年   8篇
  2006年   13篇
  2005年   9篇
  2004年   6篇
  2003年   7篇
  2002年   12篇
  2001年   5篇
  2000年   1篇
  1999年   5篇
  1998年   3篇
  1997年   2篇
  1996年   7篇
  1995年   5篇
  1994年   2篇
  1993年   7篇
  1992年   4篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   3篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1971年   1篇
  1968年   1篇
  1931年   1篇
  1924年   1篇
排序方式: 共有232条查询结果,搜索用时 283 毫秒
201.
Climate change risks to the coast and coastal developments have been well-documented. In spite of these warnings, new coastal developments are still proposed and built. Australian research has demonstrated how State-level planning documents fail to incorporate recent sea-level rise projections, with researchers demanding more responsiveness to coastal science from planners, policy-makers and developers. This paper takes an alternative approach to the science, planning and coastal development nexus by developing a relational understanding of the barriers to the uptake of science into coastal development decisions. Drawing on qualitative interview material from two recent and non-routine South Australian cases where sea-level rise (SLR) science was contested, and inspiration from actor-network theory's concepts of obligatory passage points, translation, intermediaries and mediators, this research foregrounds the malleability of scientific knowledge and planning protocols. We find that skilful social actors negotiate and re-frame science and planning; clear scientific recommendations can be subsumed to planning process, while clear planning process creates internecine disputes between nomothetic and idiographic science. An implication of this analysis is that the broad narrative of a lack of scientific uptake into coastal development needs to be sensitized to how science and planning interact in practice to legitimate decisions.  相似文献   
202.
This is an evaluation of the regional approach to controlling air pollution, in the light of the New York metropolitan experience, and recent federal and state legislative developments. Regional airsheds are defined and their administrative advantages delineated. The political difficulties involved in establishing and managing regional control districts, such as jurisdictional and regulatory problems, are also discussed. This paper touches upon the extent and adequacy of present day coordination and cooperation between agencies in the New York metropolitan area, as illustrated by the failure of the alert system during the Thanksgiving 1966 air pollution “episode.” The conflicting approaches of regional air quality commissions and the Mid-Atlantic States Air Pollution Control Compact are stressed. The desirability of such federal and state legislative proposals, and the advantages and drawbacks of special districts and other institutional arrangements to solve regional problems are also evaluated.  相似文献   
203.
Large quantities of nahcolite ore, a naturally occurring mineral containing between 70 and 90% sodium bicarbonate are known to occur in the Green River Formation of the Piceance Creek Basin of northwestern Colorado.1 Deposits occur in two major forms, as either bedded or disseminated ore. In the latter case, the host rock is oil shale, a dolomitic marlstone containing kerogen material. Bench and pilot scale studies have shown finely divided nahcolite ore to be an effective SO2 sorbent in baghouse filters.2 These studies form the basis of the nahcolite ore injection process as a means for controlling SO2 emissions to the environment.3 Although there have been published investigations of reactions of SO2 with Na2CO3and NaHCO3, 4 no reference could be found to a systematic study of nahcolite ore reacting with SO2.  相似文献   
204.
Solid growth is seen for the air pollution control industry for the rest of the century. Over the next twelve years purchases of particulate control equipment in the U.S. will grow at a rate considerably better than the GNP; growth rates in developing countries will be even higher. The portion of air pollution control expenditures represented by FGD systems is predicted to rise from its current level of 12 percent to 62 percent in 1991 if acid rain legislation is passed as predicted. A significant market is seen also for municipal, industrial and agricultural waste incinerators. Geography plays an important role in the strength of the industry; in the future, industrialized countries will be the sites of new designs and applications, while developing countries will be the life extension of the tried and proven designs. Industrywide, new product development is seen as an underused route to success.  相似文献   
205.
In Houston, some of the highest measured 8-hr ozone (O3) peaks are characterized by sudden increases in observed concentrations of at least 40 ppb in 1 hr, or 60 ppb in 2 hr. Measurements show that these large hourly changes appear at only a few monitors and span a narrow geographic area, suggesting a spatially heterogeneous field of O3 concentrations. This study assessed whether a regulatory air quality model (AQM) can simulate this observed behavior. The AQM did not reproduce the magnitude or location of some of the highest observed hourly O3 changes, and it also failed to capture the limited spatial extent. On days with measured large hourly changes in O3 concentrations, the AQM predicted high O3 over large regions of Houston, resulting in overpredictions at several monitors. This analysis shows that the model can make high O3, but on these days the predicted spatial field suggests that the model had a different cause. Some observed large hourly changes in O3 concentrations have been linked to random releases of industrial volatile organic compounds (VOCs). In the AQM emission inventory, there are several emission events when an industrial point source increases VOC emissions in excess of 10,000 mol/hr. One instance increased predicted downwind O3 concentrations up to 25 ppb. These results show that the modeling system is responsive to a large VOC release, but the timing and location of the release, and meteorological conditions, are critical requirements. Attainment of the O3 standard requires the use of observational data and AQM predictions. If the large observed hourly changes are indicative of a separate cause of high O3, then the model may not include that cause, which might result in regulators enacting control strategies that could be ineffective.

Implications To show the attainment of the O3 standard, the U.S. Environmental Protection Agency (EPA) requires the use of observations and model predictions under the assumption that simulations are capable of reproducing observed phenomena. The regulatory model is unable to reproduce observed behavior measured in the observational database. If the large observed hourly changes were indicative of a separate cause of high O3, then the model would not include that cause. Inaccurate model predictions may prompt air quality regulators to enact control strategies that are effective in the modeling system, but prove ineffective in the real world.  相似文献   
206.
Recent research into the physical and ecological status of rivers has focused upon rapid field-based assessments of mesoscale habitat features in order to satisfy international regulatory requirements for habitat inventory and appraisal. Despite the low cost and time efficient nature of rapid field surveys, the robustness of such techniques remains uncertain. This paper uses data from over 4000 surveyed UK river reaches in the UK River Habitat Survey (RHS) database in order to seek linkages between surface flow conditions (flow biotopes), local channel morphology (physical biotopes) and biologically distinct vegetative and minerogenic habitat units (functional habitats). Attempts to identify one-to-one connections between surface flow types, units of channel morphology and functional habitats oversimplify a complex and dynamic hydraulic environment. Instead, a nested hierarchy of reach-scale physical and ecological habitat structures exists, characterised by transferable assemblages of habitat units. Five flow biotopes show strong correlations with functional habitats, and differing combinations of three of these account for over 60% of the distribution for all functional habitats. On this basis, a classification of environments for ecological purposes is proposed. Principal components analysis and agglomerative hierarchical clustering analysis are employed to objectively validate the proposed classification. Flow biotope assemblages may also represent reach-scale channel morphologies (step-pool, riffle-pool and glide-pool), although functional habitats exhibit differing 'preferences' for rougher or more tranquil environments within these. While the data and analysis are specific to the UK RHS, the methods and findings have wider application in situations, where rapid field appraisal methods and associated databases are deployed in water resource inventory and river rehabilitation design.  相似文献   
207.
208.
ABSTRACT: The purpose of this paper is to present a theory and model for assessing the financial health of public water systems. Using financial information from 25 water utilities in Georgia, the paper seeks to identify the causal relationships between the financial performance of a water utility and its fiscal position. The need for a theoretical understanding of water utility financial health is the result of the increasingly stringent performance requirements under the Safe Drinking Water Act (SDWA). The issue has become particularly important for small water systems that will be exposed to significant financial demands. A set of financial ratios were developed and tested in a model that was based on liquid asset theory. The model contained five variables designed to account for the size of liquid assets, current debt, cash-flow, and the level of expenses. The variables fit the need of water utilities: to provide an adequate level of operation and maintenance to meet current and future system needs as well as SDWA standards.  相似文献   
209.
In the Portland, Oregon, metropolitan region, an urban growth boundary (UGB) was established in 1979 to protect farm and forest lands from urban encroachment. Most of the literature on the impact of Oregon's land-use legislation has been on the urban side of the issue--primarily the relative success Portland has had in containing urban sprawl. The landscape component of this rural transformation is typically considered only as a passive backdrop to urban expansion. Portland provides an excellent site to examine the relationship city-dwellers have to nearby agricultural areas. Rapid urban growth in the 1990s pushed suburban development to the edge of the UGB creating stark contrasts between urban and rural land uses in parts of the metropolitan area. This study examines the impact of the UGB on rural landscape change in Portland. We combine findings from land-use analysis and surveys of urban and rural residents to suggest ways to merge the amenity values of landscape with planning policy regarding the UGB.  相似文献   
210.
Carnivore home-range size,metabolic needs and ecology   总被引:8,自引:0,他引:8  
Summary Relationships between home-range size, metabolic needs of the animals occupying the homerange, and ecology are examined across species in the order Carnivora. Home-range size increases with metabolic needs, irrespective of taxonomic affinity. When the effects of metabolic needs are removed, among ecological variables (including activity pattern, habitat, diet and zonation) only diet shows a significant influence on home-range size. Carnivores with a large proportion of flesh in their diets have particularly large home-ranges. Intraspecific variation in feeding patterns as a determinant of variation in home-range size is emphasized.  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