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   99671篇
  免费   1247篇
  国内免费   1341篇
安全科学   3939篇
废物处理   3810篇
环保管理   14969篇
综合类   21698篇
基础理论   27563篇
环境理论   73篇
污染及防治   19058篇
评价与监测   6068篇
社会与环境   4450篇
灾害及防治   631篇
  2022年   855篇
  2021年   901篇
  2020年   706篇
  2019年   916篇
  2018年   1350篇
  2017年   1351篇
  2016年   2348篇
  2015年   1892篇
  2014年   2651篇
  2013年   9364篇
  2012年   2671篇
  2011年   3246篇
  2010年   3500篇
  2009年   3653篇
  2008年   2872篇
  2007年   2805篇
  2006年   2929篇
  2005年   2764篇
  2004年   3016篇
  2003年   2954篇
  2002年   2428篇
  2001年   2911篇
  2000年   2342篇
  1999年   1653篇
  1998年   1402篇
  1997年   1408篇
  1996年   1542篇
  1995年   1625篇
  1994年   1511篇
  1993年   1371篇
  1992年   1376篇
  1991年   1330篇
  1990年   1296篇
  1989年   1245篇
  1988年   1081篇
  1987年   1026篇
  1986年   1001篇
  1985年   1084篇
  1984年   1175篇
  1983年   1183篇
  1982年   1175篇
  1981年   1105篇
  1980年   960篇
  1979年   946篇
  1978年   833篇
  1977年   726篇
  1976年   650篇
  1974年   624篇
  1973年   652篇
  1972年   666篇
排序方式: 共有10000条查询结果,搜索用时 606 毫秒
11.
Russian Journal of Ecology - In this paper, Ellenberg’s indicator values were estimated in order to soil nitrogen (N), pH (R) and soil moisture (M) in different subalpine grassland...  相似文献   
12.
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   
13.
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   
14.
Environmental Science and Pollution Research - This study aims to re-examine the impacts of monetary and fiscal policy on environmental quality in ASEAN countries from 1990 to 2019. We utilized the...  相似文献   
15.
Russian Journal of Ecology - A new method for assessing the response of biota to climatic changes in the ecosystem has been tested. In the Central Forest Natural Biosphere Reserve, the average...  相似文献   
16.
The Science of Nature - We present the first study that compares phenological variation in parasite load and inflammatory response in a lizard with asynchronous male and female gonadal cycles....  相似文献   
17.
18.
Journal of Material Cycles and Waste Management - Power generation from municipal solid waste plays significant role to mitigate the environmental pollution. The power generation potential of...  相似文献   
19.
The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because the intensity of peaks at 1335 and 1111 cm?1 significantly decreased due to the fungal decay. Furthermore, the intensity of O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.  相似文献   
20.
Effective management refers to the ability of a protected area or indigenous territory to meet its objectives, particularly as they relate to the protection of biodiversity and forest cover. Effective management is achieved through a process of consolidation, which among other things requires legally protecting sites, integrating sites into land‐use planning, developing and implementing management and resource‐use plans, and securing long‐term funding to pay for recurrent costs. Effectively managing all protected areas and indigenous territories in the Amazon may be needed to avoid a deforestation tipping point beyond which regional climatic feedbacks and global climate change interact to catalyze irreversible drying and savannization of large areas. At present, protected areas and indigenous territories cover 45.5% (3.55 million km2) of the Amazon, most of the 60–70% forest cover required to maintain hydrologic and climatic function. Three independent evaluations of a long‐term large‐scale philanthropic initiative in the Amazon yielded insights into the challenges and advances toward achieving effective management of protected areas and indigenous territories. Over the life of the initiative, management of sites has improved considerably, particularly with respect to management planning and capacity building, but few sites are effectively managed and many lack sufficient long‐term financing, adequate governance, support of nongovernmental organizations, and the means to withstand economic pressures. The time and money required to complete consolidation is still poorly understood, but it is clear that philanthropic funding is critical so long as essential funding needs are not met by governments and other sources, which could be on the order of decades. Despite challenges, it is encouraging that legal protection has expanded greatly and management of sites is improving steadily. Management of protected areas in other developing countries could be informed by improvements that have occurred in Amazonian countries.  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