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   90801篇
  免费   1231篇
  国内免费   1093篇
安全科学   3531篇
废物处理   3338篇
环保管理   13810篇
综合类   21183篇
基础理论   26372篇
环境理论   73篇
污染及防治   14805篇
评价与监测   5456篇
社会与环境   4022篇
灾害及防治   535篇
  2022年   755篇
  2021年   817篇
  2020年   651篇
  2019年   865篇
  2018年   1189篇
  2017年   1240篇
  2016年   2188篇
  2015年   1848篇
  2014年   2602篇
  2013年   9261篇
  2012年   2222篇
  2011年   2495篇
  2010年   3315篇
  2009年   3424篇
  2008年   2017篇
  2007年   1875篇
  2006年   2282篇
  2005年   2320篇
  2004年   2571篇
  2003年   2420篇
  2002年   1969篇
  2001年   2319篇
  2000年   1911篇
  1999年   1489篇
  1998年   1344篇
  1997年   1328篇
  1996年   1451篇
  1995年   1575篇
  1994年   1484篇
  1993年   1310篇
  1992年   1322篇
  1991年   1293篇
  1990年   1246篇
  1989年   1208篇
  1988年   1057篇
  1987年   974篇
  1986年   997篇
  1985年   1064篇
  1984年   1156篇
  1983年   1165篇
  1982年   1172篇
  1981年   1092篇
  1980年   945篇
  1979年   925篇
  1978年   817篇
  1977年   712篇
  1976年   639篇
  1975年   602篇
  1973年   628篇
  1972年   625篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
21.
Russian Journal of Ecology - Changes in the distribution of broadleaf tree species—Tilia cordata Mill., Quercus robur L., Acer platanoides L., and Ulmus glabra Huds.—in the central part...  相似文献   
22.
Environment, Development and Sustainability - The current study explores the role of green trust, green perceived risk and green perceived quality in changing green purchase intention....  相似文献   
23.
Environmental Science and Pollution Research - Nutrient source and transport study in tropical creeks adjacent to megacities are sparse on a regional and global scale. High-frequency chemical data...  相似文献   
24.
Russian Journal of Ecology - A study of the anthropogenic impacts on the on-shore aggregation of true seals was carried out at a haul-out located at the mouth of Piltun Bay (the northeastern part...  相似文献   
25.
Catalytic activity of spinel ferrite in breaking down toxic dye materials are promising due to their uniqueness. In this study, aluminum-doped copper zinc ferrite, Cu0.4Zn0.6-xAlxFe2O4 (x = 0.0, 0.2, 0.4, 0.6), a catalyst for toxic dye degradation is synthesized through chemical co-precipitation route. The formation of the spinel ferrite catalyst is initially confirmed by Fourier transform infrared spectra, which shows the frequency of metal-oxygen bond vibration at 539 and 427 cm−1 attributed to the tetrahedral and octahedral sites respectively. Higher intensity sharp peak of X-ray diffraction for (311) plane is the evidence for the phase purity and the formation of spinel ferrite. The crystallite size is found to decrease with the increase of Al3+ ion. The surface structure of the obtained particles is investigated using a scanning electron microscope. Analyses of the material's magnetic characteristics using a vibrating sample magnetometer (VSM) revealed that it is, in fact, a soft magnet, as evidenced by the loop of its hysteresis, which is narrow. The catalytic degradation of methylene blue dye under the mechanism of the photo-Fenton process is studied with the obtained spinel ferrites and the result is found to be as high as 96.5%. The process follows pseudo-second order kinetics and the Langmuir isotherm.  相似文献   
26.
The High Plains aquifer (HPA) is the primary water source for agricultural irrigation in the US Great Plains. The water levels in many locations of the aquifer have declined steadily over the past several decades because the rate of water withdrawals exceeds recharge, which has been a serious concern to the water resources management in the region. We evaluated temporal trends and variations in agricultural water use and hydroclimatic variables including precipitation, air temperature, reference evapotranspiration, runoff, groundwater level, and terrestrial water storage across the HPA region for different periods from 1985 to 2020 at the grid, county, or region scale. The results showed that water withdrawals decreased from 21.3 km3/year in 1985 to 18.2 km3/year in 2015, while irrigated croplands increased from 71,928 km2 in 1985 to 78,464 km2 in 2015 in the entire HPA. The hydroclimatic time-series showed wetting trends in most of the northern HPA, but drying and warming trends in the southern region from 1985 to 2020. The groundwater level time-series indicated flat trends in the north, but significant declining in the central and southern HPA. Trends in irrigation water withdrawals and irrigation area across the HPA were controlled by the advancement of irrigation systems and technologies and the management of sustainable water use, but also were affected by dynamical changes in the hydroclimatic conditions.  相似文献   
27.
Russian Journal of Ecology - The dynamics of the species richness, breeding density, and structure of the community of birds occupying nest-boxes upon a 50-fold reduction of atmospheric emissions...  相似文献   
28.
Environmental Science and Pollution Research - The southwest coast of India along the Cochin region is seriously affected by metal contamination from increasing industrial activities. This...  相似文献   
29.
Environment, Development and Sustainability - Good air quality is highly essential to the well-being of mankind, all living organisms and the environment. The quality of air is degrading at a...  相似文献   
30.
Environmental Science and Pollution Research - With the use of different multivariate statistical analysis methods, spatio-temporal fluctuations in the water parameters of Tiru reservoir located at...  相似文献   
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