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   331篇
  免费   4篇
  国内免费   3篇
安全科学   31篇
废物处理   18篇
环保管理   84篇
综合类   32篇
基础理论   72篇
污染及防治   76篇
评价与监测   7篇
社会与环境   16篇
灾害及防治   2篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   2篇
  2018年   4篇
  2017年   7篇
  2016年   3篇
  2015年   4篇
  2014年   6篇
  2013年   33篇
  2012年   12篇
  2011年   20篇
  2010年   14篇
  2009年   13篇
  2008年   8篇
  2007年   14篇
  2006年   21篇
  2005年   13篇
  2004年   15篇
  2003年   11篇
  2002年   9篇
  2001年   2篇
  2000年   7篇
  1999年   3篇
  1998年   3篇
  1997年   3篇
  1996年   3篇
  1995年   10篇
  1994年   6篇
  1993年   3篇
  1992年   6篇
  1991年   2篇
  1990年   4篇
  1988年   3篇
  1987年   4篇
  1986年   7篇
  1985年   5篇
  1984年   10篇
  1983年   7篇
  1982年   11篇
  1981年   2篇
  1979年   6篇
  1977年   2篇
  1975年   2篇
  1974年   1篇
  1972年   2篇
  1969年   1篇
  1967年   1篇
  1962年   1篇
  1952年   1篇
排序方式: 共有338条查询结果,搜索用时 15 毫秒
11.
Partnerships and co-operative environmental management are increasing worldwide as is the call for scientific input in the public process of ecosystem management. In Hawaii, private landowners, non-governmental organizations, and state and federal agencies have formed watershed partnerships to conserve and better manage upland forested watersheds. In this paper, findings of an international workshop convened in Hawaii to explore the strengths of approaches used to assess stakeholder values of environmental resources and foster consensus in the public process of ecosystem management are presented. Authors draw upon field experience in projects throughout Hawaii, Southeast Asia, Africa and the US mainland to derive a set of lessons learned that can be applied to Hawaiian and other watershed partnerships in an effort to promote consensus and sustainable ecosystem management. Interdisciplinary science-based models can serve as effective tools to identify areas of potential consensus in the process of ecosystem management. Effective integration of scientific input in co-operative ecosystem management depends on the role of science, the stakeholders and decision-makers involved, and the common language utilized to compare tradeoffs. Trust is essential to consensus building and the integration of scientific input must be transparent and inclusive of public feedback. Consideration of all relevant stakeholders and the actual benefits and costs of management activities to each stakeholder is essential. Perceptions and intuitive responses of people can be as influential as analytical processes in decision-making and must be addressed. Deliberative, dynamic and iterative decision-making processes all influence the level of stakeholder achievement of consensus. In Hawaii, application of lessons learned can promote more informed and democratic decision processes, quality scientific analysis that is relevant, and legitimacy and public acceptance of ecosystem management.  相似文献   
12.
Generally, one expects evapotranspiration (ET) maps derived from optical/thermal Landsat and MODIS satellite imagery to improve decision support tools and lead to superior decisions regarding water resources management. However, there is lack of supportive evidence to accept or reject this expectation. We “benchmark” three existing hydrologic decision support tools with the following benchmarks: annual ET for the ET Toolbox developed by the United States Bureau of Reclamation, predicted rainfall‐runoff hydrographs for the Gridded Surface/Subsurface Hydrologic Analysis model developed by the U.S. Army Corps of Engineers, and the average annual groundwater recharge for the Distributed Parameter Watershed Model used by Daniel B. Stephens & Associates. The conclusion of this benchmark study is that the use of NASA/USGS optical/thermal satellite imagery can considerably improve hydrologic decision support tools compared to their traditional implementations. The benefits of improved decision making, resulting from more accurate results of hydrologic support systems using optical/thermal satellite imagery, should substantially exceed the costs for acquiring such imagery and implementing the remote sensing algorithms. In fact, the value of reduced error in estimating average annual groundwater recharge in the San Gabriel Mountains, California alone, in terms of value of water, may be as large as $1 billion, more than sufficient to pay for one new Landsat satellite.  相似文献   
13.
Stormwater runoff from the University of California, Davis/U.S. Department of Energy Laboratory for Energy‐Related Health Research (UCD/US DOE LEHR) Superfund site located on the University of California campus in Davis, California, has been found to contain over 500 ng/L of total recoverable mercury, which is about ten times the California Toxics Rule criterion. This stormwater runoff is discharged to Putah Creek, which is Clean Water Act Section 303(d) listed as impaired for excessive mercury bioaccumulation in edible fish. A discussion is presented on the potential impact of the mercury in stormwater runoff from LEHR leading to excessive bioaccumulation of mercury in Putah Creek fish. The mercury in the stormwater runoff is derived from former flooding of the soils near the creek, which contains mercury derived from abandoned upstream mercury mines located in the Coast Range Vaca Hills to the west of LEHR. The implications of this situation for implementing a Total Maximum Daily Load (TMDL) to control mercury in stormwater runoff to Putah Creek are presented. © 2009 Wiley Periodicals, Inc.  相似文献   
14.
This paper presents and tests an integrative model of voluntary learning behavior. Drawing on social exchange theory, we argue that individuals are more likely to pursue learning activities when they identify with their employing organization and have a high quality leader–member exchange (LMX) relationship with their supervisor. We further argue that organizational identification is enhanced by both distributive and procedural fairness, whereas LMX quality is enhanced by interpersonal and informational fairness. Moreover, we contend that effective learning behavior improves job performance. The model was tested with a sample of 398 employees from a large automobile dealership. Results supported most predictions. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
15.
Johnson CD  Worrall F 《Chemosphere》2007,68(6):1153-1162
This paper reports the preparation and properties of a new low density granular absorbent material based on a zeolite/vermiculite composite. The composite prepared addresses a number of important issues relating to the use of zeolites in environmental and waste management applications. The material prepared has large particle size due to binderless adhesion of zeolite crystals within the protective lamellar matrix provided by the vermiculite granule. Additionally, the porous nature of new material ensures that it outperforms natural zeolite grains in ion-exchange tests. The material was shown to have a low bulk density (0.75 g cm(-3)) adding the benefit that the majority of grains float on water for over 15 h. The conclusion of the study is that the use of composite matrices enable the preparation of materials which show the physical properties of the host, (e.g., granular and low density), whilst maintaining the powder-like properties (e.g., high ion-exchange and small crystal size) of the active component. The resulting material can be easily handled and separated from aqueous waste streams using either flotation or exploiting its granular nature.  相似文献   
16.
Raptors are good sentinels of environmental contamination and there is good capability for raptor biomonitoring in Europe. Raptor biomonitoring can benefit from natural history museums (NHMs), environmental specimen banks (ESBs) and other collections (e.g. specialist raptor specimen collections). Europe’s NHMs, ESBs and other collections hold large numbers of raptor specimens and samples, covering long periods of time. These collections are potentially a valuable resource for contaminant studies over time and space. There are strong needs to monitor contaminants in the environment to support EU and national chemical management. However, data on raptor specimens in NHMs, ESBs and other collections are dispersed, few are digitised, and they are thus not easy to access. Specimen coverage is patchy in terms of species, space and time. Contaminant research with raptors would be facilitated by creating a framework to link relevant collections, digitising all collections, developing a searchable meta-database covering all existing collections, making them more visible and accessible for contaminant research. This would also help identify gaps in coverage and stimulate specimen collection to fill gaps in support of prioritised contaminant monitoring. Collections can further support raptor biomonitoring by making samples available for analysis on request.  相似文献   
17.
18.
ABSTRACT

This study examined the spatial distribution of the weekday/weekend difference in Baltimore, MD, and vicinity. The difference in Baltimore was characterized by having ~39% more NOx , ~59% more CO, and ~27% more volatile organic compounds (VOCs) on the average weekday, but there was ~13% more O3 on the weekend day. Spatially, the difference was elongated in the northeast-southwest direction. It decreased from 13% more O3 in Baltimore to 6% at ~20 km west of Baltimore and to 4% at ~40 km south of Baltimore. It also appeared to decrease to the east, but the magnitude of the decrease could not be determined because of the lack of data east of the Chesapeake Bay. However, the difference increased to the north, reaching a value of almost 18% at a northern Delaware site.  相似文献   
19.
Abstract

Particulate-phase exhaust properties from two different types of ground-based jet aircraft engines—high-thrust and turboshaft—were studied with real-time instruments on a portable pallet and additional time-integrated sampling devices. The real-time instruments successfully characterized rapidly changing particulate mass, light absorption, and polycyclic aromatic hydrocarbon (PAH) content. The integrated measurements included particulate-size distributions, PAH, and carbon concentrations for an entire test run (i.e., “run-integrated” measurements). In all cases, the particle-size distributions showed single modes peaking at 20–40nm diameter. Measurements of exhaust from high-thrust F404 engines showed relatively low-light absorption compared with exhaust from a turboshaft engine. Particulate-phase PAH measurements generally varied in phase with both net particulate mass and with light-absorbing particulate concentrations. Unexplained response behavior sometimes occurred with the real-time PAH analyzer, although on average the real-time and integrated PAH methods agreed within the same order of magnitude found in earlier investigations.  相似文献   
20.
Measurements of OH, H2SO4, and MSA at South Pole (SP) Antarctica were recorded as a part of the 2003 Antarctic Chemistry Investigation (ANTCI 2003). The time period 22 November, 2003–2 January, 2004 provided a unique opportunity to observe atmospheric chemistry at SP under both natural conditions as well as those uniquely defined by a solar eclipse event. Results under natural solar conditions generally confirmed those reported previously in the year 2000. In both years the major chemical driver leading to large scale fluctuations in OH was shifts in the concentration levels of NO. Like in 2000, however, the 2003 observational data were systematically lower than model predictions. This can be interpreted as indicating that the model mechanism is still missing a significant HOx sink reaction(s); or, alternatively, that the OH calibration source may have problems. Still a final possibility could involve the integrity of the OH sampling scheme which involved a fixed building site. As expected, during the peak in the solar eclipse both NO and OH showed large decreases in their respective concentrations. Interestingly, the observational OH profile could only be approximated by the model mechanism upon adding an additional HOx radical source in the form of snow emissions of CH2O and/or H2O2. This would lead one to think that either CH2O and/or H2O2 snow emissions represent a significant HOx radical source under summertime conditions at SP. Observations of H2SO4 and MSA revealed both species to be present at very low concentrations (e.g., 5 × 105 and 1 × 105 molec cm?3, respectively), but similar to those reported in 2000. The first measurements of SO2 at SP demonstrated a close coupling with the oxidation product H2SO4. The observed low concentrations of MSA appear to be counter to the most recent thinking by glacio-chemists who have suggested that the plateau's lower atmosphere should have elevated levels of MSA. We speculate here that the absence of MSA may reflect efficient atmospheric removal mechanisms for this species involving either dynamical and/or chemical processes.  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