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   94105篇
  免费   1229篇
  国内免费   1107篇
安全科学   3854篇
废物处理   3514篇
环保管理   14426篇
综合类   21129篇
基础理论   26782篇
环境理论   72篇
污染及防治   16228篇
评价与监测   5696篇
社会与环境   4150篇
灾害及防治   590篇
  2022年   824篇
  2021年   831篇
  2020年   656篇
  2019年   865篇
  2018年   1233篇
  2017年   1264篇
  2016年   2208篇
  2015年   1838篇
  2014年   2567篇
  2013年   9213篇
  2012年   2380篇
  2011年   2833篇
  2010年   3356篇
  2009年   3505篇
  2008年   2440篇
  2007年   2242篇
  2006年   2553篇
  2005年   2506篇
  2004年   2780篇
  2003年   2621篇
  2002年   2173篇
  2001年   2451篇
  2000年   2042篇
  1999年   1554篇
  1998年   1378篇
  1997年   1373篇
  1996年   1506篇
  1995年   1606篇
  1994年   1487篇
  1993年   1338篇
  1992年   1336篇
  1991年   1311篇
  1990年   1254篇
  1989年   1220篇
  1988年   1065篇
  1987年   1001篇
  1986年   998篇
  1985年   1067篇
  1984年   1163篇
  1983年   1170篇
  1982年   1178篇
  1981年   1101篇
  1980年   939篇
  1979年   935篇
  1978年   830篇
  1977年   722篇
  1976年   640篇
  1975年   610篇
  1973年   652篇
  1972年   648篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
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   
33.
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   
34.
35.
36.
37.
38.
39.
40.
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