全文获取类型
收费全文 | 34602篇 |
免费 | 357篇 |
国内免费 | 251篇 |
专业分类
安全科学 | 946篇 |
废物处理 | 1275篇 |
环保管理 | 4455篇 |
综合类 | 5415篇 |
基础理论 | 9587篇 |
环境理论 | 24篇 |
污染及防治 | 8847篇 |
评价与监测 | 2143篇 |
社会与环境 | 2304篇 |
灾害及防治 | 214篇 |
出版年
2022年 | 227篇 |
2021年 | 253篇 |
2019年 | 261篇 |
2018年 | 496篇 |
2017年 | 504篇 |
2016年 | 690篇 |
2015年 | 569篇 |
2014年 | 858篇 |
2013年 | 2541篇 |
2012年 | 1049篇 |
2011年 | 1480篇 |
2010年 | 1212篇 |
2009年 | 1237篇 |
2008年 | 1482篇 |
2007年 | 1608篇 |
2006年 | 1387篇 |
2005年 | 1208篇 |
2004年 | 1197篇 |
2003年 | 1118篇 |
2002年 | 1091篇 |
2001年 | 1428篇 |
2000年 | 1019篇 |
1999年 | 614篇 |
1998年 | 475篇 |
1997年 | 487篇 |
1996年 | 484篇 |
1995年 | 533篇 |
1994年 | 482篇 |
1993年 | 434篇 |
1992年 | 454篇 |
1991年 | 413篇 |
1990年 | 428篇 |
1989年 | 446篇 |
1988年 | 374篇 |
1987年 | 332篇 |
1986年 | 315篇 |
1985年 | 339篇 |
1984年 | 328篇 |
1983年 | 345篇 |
1982年 | 361篇 |
1981年 | 304篇 |
1980年 | 279篇 |
1979年 | 307篇 |
1978年 | 250篇 |
1977年 | 220篇 |
1976年 | 220篇 |
1975年 | 213篇 |
1974年 | 195篇 |
1973年 | 199篇 |
1972年 | 229篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
V. Thomas Parker 《Conservation biology》2002,16(5):1444-1446
83.
Jürgen Heinze Bernhard Stengl Matthew F. Sledge 《Behavioral ecology and sociobiology》2002,52(1):59-65
Workers in de-queened colonies of the neotropical ant, Pachycondyla cf. inversa, form linear or near-linear dominance hierarchies by violent antennation and biting. In these rank orders, social status and ovarian activity are on average highly correlated. Whereas the presence of a fertile queen appears to be sufficient to prevent workers from laying eggs, fertile workers do not completely control reproduction by their nestmates, suggesting that workers are able to differentiate between an egg-laying queen and an egg-laying worker. Here we show that the composition of cuticular hydrocarbons of egg-laying workers is quantitatively and qualitatively different from that of non-laying workers and resembles the hydrocarbon blend of the queen but does not completely match it. Furthermore, using discriminant analysis, it was possible to distinguish workers with four different classes of ovarian development based only on their cuticular hydrocarbon profiles. Fertility-associated changes in cuticular hydrocarbons may play an important role in the behavioural regulation of reproduction in this ant. 相似文献
84.
85.
86.
Lim KJ Engel BA Tang Z Muthukrishnan S Choi J Kim K 《Journal of environmental management》2006,78(1):35-43
Urbanization can result in alteration of a watershed's hydrologic response and water quality. To simulate hydrologic and water quality impacts of land use changes, the Long-Term Hydrologic Impact Assessment (L-THIA) system has been used. The L-THIA system estimates pollutant loading based on direct runoff quantity and land use based pollutant coefficients. The accurate estimation of direct runoff is important in assessing water quality impacts of land use changes. An automated program was developed to calibrate the L-THIA model using the millions of curve number (CN) combinations associated with land uses and hydrologic soil groups. L-THIA calibration for the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana was performed using land use data for 1991 and daily rainfall data for six months of 1991 (January 1-June 30) to minimize errors associated with use of different temporal land use data and rainfall data. For the calibration period, the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The calibrated CN values were used for validation of the model for the same year (July 1-December 31), and the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The Nash-Sutcliffe coefficient was 0.52 for January 1, 1991 to December 31, 1991 using uncalibrated CN values. As shown in this study, the use of better input parameters for the L-THIA model can improve accuracy. The effects on direct runoff and pollutant estimation of the calibrated CN values in the L-THIA model were investigated for the LEC. Following calibration, the estimated average annual direct runoff for the LEC watershed increased by 34%, total nitrogen by 24%, total phosphorus by 22%, and total lead by 43%. This study demonstrates that the L-THIA model should be calibrated and validated prior to application in a particular watershed to more accurately assess the effects of land use changes on hydrology and water quality. 相似文献
87.
88.
Russian Journal of Ecology - 相似文献
89.
90.