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   96980篇
  免费   1233篇
  国内免费   1139篇
安全科学   3883篇
废物处理   3531篇
环保管理   14783篇
综合类   21393篇
基础理论   27232篇
环境理论   73篇
污染及防治   17915篇
评价与监测   5798篇
社会与环境   4136篇
灾害及防治   608篇
  2022年   819篇
  2021年   806篇
  2020年   660篇
  2019年   874篇
  2018年   1233篇
  2017年   1270篇
  2016年   2236篇
  2015年   1852篇
  2014年   2600篇
  2013年   9289篇
  2012年   2452篇
  2011年   2964篇
  2010年   3374篇
  2009年   3531篇
  2008年   2576篇
  2007年   2496篇
  2006年   2721篇
  2005年   2614篇
  2004年   2907篇
  2003年   2767篇
  2002年   2320篇
  2001年   2803篇
  2000年   2272篇
  1999年   1625篇
  1998年   1415篇
  1997年   1413篇
  1996年   1538篇
  1995年   1632篇
  1994年   1516篇
  1993年   1359篇
  1992年   1366篇
  1991年   1328篇
  1990年   1291篇
  1989年   1262篇
  1988年   1102篇
  1987年   1014篇
  1986年   1005篇
  1985年   1084篇
  1984年   1175篇
  1983年   1187篇
  1982年   1185篇
  1981年   1105篇
  1980年   955篇
  1979年   945篇
  1978年   835篇
  1977年   732篇
  1976年   663篇
  1974年   646篇
  1973年   664篇
  1972年   680篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
We examined the impact of stressful job demands on employee attitudes and attendance. Using Karasek's (1979) theory of job decision latitude as the conceptual foundation, we hypothesized that mental and physical work demands would interact with employee beliefs of personal control. Survey data from 90 male manufacturing employees regarding their control beliefs were combined with objective job analysis data concerning mental and physical demands and one year's worth of archival data regarding unexcused absences, sick days, and days tardy. There were significant interactions between control and objective psychological demands that indicated that these demands were associated with higher levels of tardiness and sick days only under conditions of low perceived control. In contrast, subjective workload ratings showed no relationship with tardiness and sick days, but, in interaction with control, predicted work satisfaction and voluntary absence. We discussed these results in terms of a stress process that affects health-related attendance independent of employee attitudes.  相似文献   
53.
Previous researchers have hypothesized that site-faithful animals may benefit from the presence of familiar neighbors. This study compares the relative costs of territorial defense against new and former neighbors by male willow ptarmigan (Lagopus lagopus). Territorial defense against new neighbors appeared to require a greater expenditure of both time and effort than did defense against former neighbors. Territorial males that had several new neighbors spent a higher proportion of time fighting than did males with fewer new neighbors, and males with both new and former neighbors spent a greater amount of time fighting with their new neighbors, on average, than with their former neighbors. In addition, fights with new neighbors occurred relatively more frequently and were longer than fights with former neighbors. Finally, fights involving new neighbors tended to escalate to higher levels than fights between former neighbors. Reduced defensive costs for site-faithful, territorial males may provide one explanation for the tendency of males to be more site-faithful than females in many species.  相似文献   
54.
55.
56.
57.
58.
59.
60.
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