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   457篇
  免费   11篇
  国内免费   1篇
安全科学   39篇
废物处理   22篇
环保管理   82篇
综合类   103篇
基础理论   90篇
环境理论   2篇
污染及防治   79篇
评价与监测   25篇
社会与环境   16篇
灾害及防治   11篇
  2023年   10篇
  2021年   10篇
  2020年   17篇
  2019年   6篇
  2018年   17篇
  2017年   11篇
  2016年   18篇
  2015年   23篇
  2014年   13篇
  2013年   27篇
  2012年   37篇
  2011年   39篇
  2010年   21篇
  2009年   28篇
  2008年   28篇
  2007年   24篇
  2006年   23篇
  2005年   14篇
  2004年   11篇
  2003年   17篇
  2002年   15篇
  2001年   8篇
  2000年   5篇
  1999年   4篇
  1998年   6篇
  1997年   6篇
  1996年   2篇
  1995年   6篇
  1994年   10篇
  1993年   1篇
  1992年   2篇
  1991年   7篇
  1989年   1篇
  1988年   1篇
  1983年   1篇
排序方式: 共有469条查询结果,搜索用时 203 毫秒
41.
PURPOSE: This study aims to assess whether the Driving Decisions Workbook, a self-assessment instrument for older drivers, increased self-awareness and general knowledge. This study also assessed perceptions regarding its usefulness, particularly as a tool for facilitating discussions within families of older drivers. A secondary purpose of the study was to determine if problems identified by drivers in the workbook related to problems they had with actual driving. DESIGN AND METHODS: The Driving Decisions Workbook was administered along with a questionnaire and a road test. A convenience sample of 99 licensed drivers aged 65 and above was used. RESULTS: After completing the workbook, about three fourths of the participants reported being more aware of changes that could affect driving. Fourteen percent reported that they had discovered a change in themselves of which they had not been previously aware. All respondents found the workbook to be at least a little useful and thought the workbook could help facilitate family discussions. Workbook responses were positively correlated with overall road test scores. Significant correlations were also noted between the road test and a majority of workbook subsection responses. IMPLICATIONS: This study indicates that the workbook may be a useful first-tier assessment instrument and educational tool for the older driver. It may encourage an older driver to drive more safely and/or to seek clinical assessment, and help in facilitating discussions about driving within their families.  相似文献   
42.
Prenatal screening for sex chromosome aneuploidies (SCAs) is increasingly available through expanded non-invasive prenatal testing (NIPT). NIPT for SCAs raises complex ethical issues for clinical providers, prospective parents and future children. This paper discusses the ethical issues that arise around NIPT for SCAs and current guidelines and protocols for management. The first section outlines current practice and the limitations of NIPT for SCAs. It then outlines key guidelines before discussing the ethical issues raised by this use of NIPT. We conclude that while screening for SCAs should be made available for people seeking to use NIPT, its implementation requires careful consideration of what, when and how information is provided to users.  相似文献   
43.
44.
45.
46.
47.
48.
49.
针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。  相似文献   
50.
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