全文获取类型
收费全文 | 101225篇 |
免费 | 1239篇 |
国内免费 | 1155篇 |
专业分类
安全科学 | 3996篇 |
废物处理 | 3795篇 |
环保管理 | 15289篇 |
综合类 | 21515篇 |
基础理论 | 27884篇 |
环境理论 | 74篇 |
污染及防治 | 19708篇 |
评价与监测 | 6068篇 |
社会与环境 | 4618篇 |
灾害及防治 | 672篇 |
出版年
2022年 | 848篇 |
2021年 | 850篇 |
2020年 | 669篇 |
2019年 | 884篇 |
2018年 | 1346篇 |
2017年 | 1390篇 |
2016年 | 2293篇 |
2015年 | 1870篇 |
2014年 | 2601篇 |
2013年 | 9268篇 |
2012年 | 2668篇 |
2011年 | 3377篇 |
2010年 | 3506篇 |
2009年 | 3667篇 |
2008年 | 3027篇 |
2007年 | 2931篇 |
2006年 | 3050篇 |
2005年 | 2882篇 |
2004年 | 3152篇 |
2003年 | 2987篇 |
2002年 | 2570篇 |
2001年 | 3019篇 |
2000年 | 2336篇 |
1999年 | 1675篇 |
1998年 | 1427篇 |
1997年 | 1427篇 |
1996年 | 1562篇 |
1995年 | 1655篇 |
1994年 | 1530篇 |
1993年 | 1380篇 |
1992年 | 1385篇 |
1991年 | 1353篇 |
1990年 | 1304篇 |
1989年 | 1272篇 |
1988年 | 1120篇 |
1987年 | 1041篇 |
1986年 | 1014篇 |
1985年 | 1092篇 |
1984年 | 1192篇 |
1983年 | 1193篇 |
1982年 | 1190篇 |
1981年 | 1113篇 |
1980年 | 956篇 |
1979年 | 965篇 |
1978年 | 848篇 |
1977年 | 738篇 |
1976年 | 666篇 |
1974年 | 655篇 |
1973年 | 687篇 |
1972年 | 691篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
New birds on the block: new neighbors increase defensive costs for territorial male willow ptarmigan 总被引:4,自引:0,他引:4
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
122.
Brent M. Matsuda 《Conservation biology》1997,11(6):1449-1450
123.
Paul C. James 《Conservation biology》1994,8(4):1161-1162
124.
Yaping Zhong Michael R. Overcash Arnold L. McPeters 《Environmental geochemistry and health》1994,16(3-4):235-240
Studies were conducted to understand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) behaviour in the near surface zone in relation to the operating conditions: UV-intensity, temperature and exposure modes. Comparisons have been made between Oriel lamp exposure tests and sunlight exposure tests. Under Oriel lamp exposure, the convective transport of TCDD, which depends on operating temperature, was the limiting factor in the cleanup process. The product differences between Oriel exposure tests and sunlight exposure tests probably result from the difference of UV-intensities. 相似文献
125.
126.
127.
128.
129.
130.