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   687篇
  免费   32篇
  国内免费   9篇
安全科学   30篇
废物处理   19篇
环保管理   160篇
综合类   107篇
基础理论   229篇
污染及防治   124篇
评价与监测   33篇
社会与环境   16篇
灾害及防治   10篇
  2023年   5篇
  2022年   17篇
  2021年   13篇
  2020年   23篇
  2019年   18篇
  2018年   21篇
  2017年   38篇
  2016年   25篇
  2015年   23篇
  2014年   29篇
  2013年   49篇
  2012年   42篇
  2011年   51篇
  2010年   38篇
  2009年   31篇
  2008年   37篇
  2007年   37篇
  2006年   28篇
  2005年   21篇
  2004年   21篇
  2003年   24篇
  2002年   20篇
  2001年   13篇
  2000年   7篇
  1999年   10篇
  1998年   9篇
  1997年   10篇
  1996年   3篇
  1995年   9篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   4篇
  1990年   7篇
  1989年   8篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   5篇
  1982年   3篇
  1980年   1篇
  1979年   2篇
  1977年   1篇
  1976年   2篇
  1971年   1篇
排序方式: 共有728条查询结果,搜索用时 453 毫秒
471.
A multi-regional integrated energy systems model is developed to assess the economic impact of hydrogen fuel cell, hydrogen internal combustion, and battery electric technologies on the economy of New Zealand. Base case results suggest that a hydrogen fuel dominant vehicle fleet offers economic savings over a conventional fleet but requires the largest sequestration capacity as 75% of hydrogen fuel production is derived from fossil fuel. When the oil price is varied from US$120 to US$240 per barrel in 2030, and the carbon tax varied from US$30 to US$90 per tonne of CO2 equivalent, the change in savings ranges from ?65% to +25%.  相似文献   
472.
473.
474.
475.
476.
477.
Objective: The aim of this study was to (1) examine the psychological impact of non-invasive prenatal testing (NIPT) in women with a high-risk (≥1 : 300) and low-risk (≤1 : 301) result on combined first trimester screening (cFTS) and (2) to examine factors influencing anxiety and decision-making in both risk populations. Method: Questionnaires and structured interviews were administered to low (n = 50) and high (n = 63) risk women at the time of NIPT blood draw (point A) and again at least 1 week after receiving their NIPT result (point B). Anxiety levels were measured at these two time points using the State–Trait Anxiety Inventory. Results: Both high-risk and low-risk cFTS groups demonstrated similar intrinsic (trait) anxiety levels (36 ± 10 vs 35 ± 10; p = 0.70). High-risk women had significantly higher levels of state anxiety at point A than low-risk women (42 ± 11 vs 36 ± 11; p < 0.01). Both groups had a statistically significant reduction (p < 0.01), to similar final levels of state anxiety at point B (30 ± 11 vs 29 ± 8; p = 0.61). Conclusion: Women receiving a high-risk result on cFTS have higher levels of state anxiety than their low-risk counterparts. Following a low-risk NIPT result, the anxiety levels in both populations are reduced to similar levels. © 2017 John Wiley & Sons, Ltd.  相似文献   
478.
479.
480.
At many sites, long‐term monitoring (LTM) programs include metals as chemicals of concern, although they may not be site‐related contaminants and their detected concentrations may be natural. At other sites, active remediation of organic contaminants in groundwater results in changes to local geochemical conditions that affect metal concentrations. Metals should be carefully considered at both types of sites, even if they are not primary contaminants of concern. Geochemical evaluation can be performed at LTM sites to determine if the monitored metals reflect naturally high background and, hence, can be removed from the analytical program. Geochemical evaluation can also be performed pre‐ and post‐treatment at active remediation sites to document the effects of organics remediation on metals and identify the processes controlling metal concentrations. Examples from both types of sites are presented in this article. © 2008 Wiley Periodicals, Inc.  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