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   298篇
  免费   3篇
  国内免费   7篇
安全科学   12篇
废物处理   13篇
环保管理   62篇
综合类   48篇
基础理论   63篇
环境理论   1篇
污染及防治   74篇
评价与监测   22篇
社会与环境   11篇
灾害及防治   2篇
  2023年   2篇
  2022年   3篇
  2020年   3篇
  2019年   7篇
  2018年   6篇
  2017年   4篇
  2016年   8篇
  2015年   5篇
  2014年   8篇
  2013年   32篇
  2012年   11篇
  2011年   24篇
  2010年   9篇
  2009年   8篇
  2008年   17篇
  2007年   21篇
  2006年   14篇
  2005年   20篇
  2004年   8篇
  2003年   11篇
  2002年   15篇
  2001年   7篇
  2000年   2篇
  1999年   4篇
  1998年   8篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   6篇
  1993年   4篇
  1992年   2篇
  1991年   1篇
  1990年   3篇
  1989年   2篇
  1985年   4篇
  1984年   1篇
  1983年   3篇
  1982年   3篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
  1932年   1篇
  1931年   1篇
  1930年   2篇
  1928年   1篇
  1926年   1篇
  1925年   1篇
排序方式: 共有308条查询结果,搜索用时 31 毫秒
201.
We investigated all reported Percutaneous exposure incidents (PEI) among staff from a large Australian hospital in the 3-year period, 2001-2003. There were a total of 373 PEI, of which 38.9% were needlestick injuries, 32.7% were cutaneous exposures and 28.4% sharps-related injuries. Nurses were the most commonly affected staff members, accounting for 63.5% of the total, followed by doctors (18.8%) and other staff (17.7%). Needlestick injuries were responsible for the majority of nurses' PEI (44.7%). Sharps injuries constituted the major category for doctors (44.3%). Most needlestick injuries (67.6%) were caused by hollow-bore needles, while the majority of cutaneous exposures involved blood or serum (55.8%). Most sharps injures were caused by unknown devices (35.9%) or suture needles (34.9%). Overall, our investigation suggests that PEI is a considerable burden for health care workers in Australia. Further research is now required to determine the relationships, if any, between workers who suffer PEI and those who do not.  相似文献   
202.
203.
The runoff of pesticides (insecticides, herbicides and fungicides) from agricultural lands is a key concern for the health of the iconic Great Barrier Reef, Australia. Relatively low levels of herbicide residues can reduce the productivity of marine plants and corals. However, the risk of these residues to Great Barrier Reef ecosystems has been poorly quantified due to a lack of large-scale datasets. Here we present results of a study tracing pesticide residues from rivers and creeks in three catchment regions to the adjacent marine environment. Several pesticides (mainly herbicides) were detected in both freshwater and coastal marine waters and were attributed to specific land uses in the catchment. Elevated herbicide concentrations were particularly associated with sugar cane cultivation in the adjacent catchment. We demonstrate that herbicides reach the Great Barrier Reef lagoon and may disturb sensitive marine ecosystems already affected by other pressures such as climate change.  相似文献   
204.
205.
/ This paper describes a framework for estimating the economic value of outdoor recreation across different ecoregions. Ten ecoregions in the continental United States were defined based on similarly functioning ecosystem characters. The individual travel cost method was employed to estimate recreation demand functions for activities such as motor boating and waterskiing, developed and primitive camping, coldwater fishing, sightseeing and pleasure driving, and big game hunting for each ecoregion. While our ecoregional approach differs conceptually from previous work, our results appear consistent with the previous travel cost method valuation studies.KEY WORDS: Recreation; Ecoregion; Travel cost method; Truncated Poisson model  相似文献   
206.
This special edition of the Journal of Cleaner Production celebrates the twentieth anniversary of a piece of legislation that has special significance to the environmental movement - the Massachusetts Toxics Use Reduction Act of 1989 (TURA). Most of the papers in this issue were presented at a symposium to commemorate the twentieth anniversary that was held on November 4, 2009.Much has been written about the Massachusetts Toxics Use Reduction Program. It has been heralded as a major pollution prevention success story. It has been lauded as a premier American example of the precautionary principle in action. It has been condemned by the American chemical industry trade association as “bad for the chemical industry”. And it has been praised by the Ford Foundation and Harvard’s Kennedy School of Government as an award-receiving example of innovation in government (Harvard Kennedy School, 2005).Looking back now to some twenty years ago—back to the early origins of the program concept—it can be seen both as a landmark breakthrough in international chemicals policy, and as a fairly conventional next step in the political evolution of Massachusetts environmental policy.Where did this idea come from? How did it develop? How were pieces put together? Why did Massachusetts adopt such an idea into law? And how did the idea change during the early years of implementation? This paper provides a brief history of the development of the concept of toxics use reduction and the process by which it was drafted into law in Massachusetts, followed by an introduction to the articles included in this special edition and their assessment of TURA - past, present, and future.  相似文献   
207.
208.
209.
Effects of diurnal variation in phytoplankton photosynthesis on estimating daily primary production (DPP) were examined using field data from Sagami Bay, Japan. DPP at 5 m depth was calculated from the continuous data of chlorophyll a (Chl a) and light intensity monitored by a natural fluorescence sensor with and without considering time-dependent changes in the photosynthesis–irradiance (P–E) relationship. Chl a could be estimated from natural fluorescence examining the variations in the quantum yield of fluorescence (φ f) and Chl a-specific light absorption coefficient (a*ph), and relating them to Chl a. The P–E relationship was determined by water sampling three times daily. A distinct diurnal pattern was observed for the maximum photosynthetic rate (P*max), being maximal at noon, while periodicity of the maximum light utilization coefficient (α*) was less obvious. The actual DPP was calculated by interpolating the P–E parameters from those obtained at dawn, noon, and dusk. For comparison, DPP was calculated by fixing the P–E parameters as the constants measured at dawn, noon or dusk for a day. The difference from the actual DPP was small when the P–E parameters measured at dawn (3% on average) and noon (5%) were used as the constants for a day. The difference was largest when the values at dusk were used (−43%). The medium values of P*max at dawn, its low values at dusk, and the fact that a major part of the DPP was produced around noon were responsible for these results. The present study demonstrates that measurement of the P–E parameters at dawn or noon can give a good estimation of DPP from natural fluorescence.  相似文献   
210.
Abstract: A nontraditional application of the Hydrological Simulation Program – FORTRAN (HSPF) model to simulate freshwater discharge to upper Charlotte Harbor along Florida’s west coast was performed. This application was different from traditional HSPF applications in three ways. First, the domain of the model was defined based on the hydraulic characteristics of the landforms using small distributed parameter discretization. Second, broad wetland land forms, representing more than 20% of this area, were simulated as reaches with storage‐attenuation characteristics and not as pervious land segments (PERLNDs). Finally, the reach flow‐tables (F‐Tables) were configured in a unique way to be calibrated representing the uncertainty of the storage‐attenuation process. Characterizing wetlands as hydrography elements allows flow from the wetlands to be treated as a stage‐dependent flux. The study was conducted for the un‐gauged portion of the Peace and Myakka rivers in west‐central Florida. Due to low gradient tidal influences, a large portion of the basin is un‐gauged. The objective of this study was to simulate stream flow discharges and to estimate freshwater inflow from these un‐gauged areas to upper Charlotte Harbor. Two local gauging stations were located within the model domain and were used for calibration. Another gauge with a shorter period of record was used for verification. A set of global hydrologic parameters were selected and tested using the parameter optimization software (PEST) during the calibration. Model results were evaluated using PEST and well‐known statistical indices. The correlation coefficients were very high (0.899 and 0.825) for the two calibration stations. Further testing of this approach appears warranted for watersheds with significant wetlands coverage.  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