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   30914篇
  免费   254篇
  国内免费   260篇
安全科学   713篇
废物处理   1241篇
环保管理   3344篇
综合类   7266篇
基础理论   7205篇
环境理论   18篇
污染及防治   7715篇
评价与监测   2057篇
社会与环境   1752篇
灾害及防治   117篇
  2022年   241篇
  2021年   231篇
  2019年   220篇
  2018年   434篇
  2017年   442篇
  2016年   639篇
  2015年   501篇
  2014年   773篇
  2013年   2109篇
  2012年   869篇
  2011年   1264篇
  2010年   965篇
  2009年   1068篇
  2008年   1253篇
  2007年   1296篇
  2006年   1161篇
  2005年   1001篇
  2004年   970篇
  2003年   977篇
  2002年   932篇
  2001年   1179篇
  2000年   751篇
  1999年   539篇
  1998年   336篇
  1997年   373篇
  1996年   393篇
  1995年   415篇
  1994年   417篇
  1993年   353篇
  1992年   367篇
  1991年   383篇
  1990年   364篇
  1989年   311篇
  1988年   316篇
  1987年   254篇
  1986年   271篇
  1985年   270篇
  1984年   280篇
  1983年   279篇
  1982年   294篇
  1981年   262篇
  1980年   215篇
  1979年   211篇
  1978年   225篇
  1977年   203篇
  1976年   197篇
  1975年   185篇
  1974年   213篇
  1967年   212篇
  1964年   189篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Catastrophic disasters like earthquake and flood cause widespread destruction and financial devastation. This has brought disaster management into limelight making it a burgeoning academic research field. The remarkable rise of ICT (Information and Communication Technology) has instigated the scientific world to incorporate these technologies in disaster management. This study presents scientometric analysis to identify the status quo of research on the management of various disasters and role of ICT in it. This paper uses bibliographic data retrieved from Scopus for the observation period from 2011 to 2018. We provide extensive insights into growth of publications, citation pattern and their connectedness with other subject disciplines. Furthermore, we identify most productive and influential countries, institutes and journals. Our study analyses co-occurrence of keywords using Visualization of Similarities (VOS) Viewer. This structured overview will enhance the understanding of this field leading to more focussed and purposeful research.  相似文献   
13.
Journal of Material Cycles and Waste Management - The present research work focused on fabricating Biodegradable Plate (BD plate) composed of rice husk ash, bagasse and corn starch which is...  相似文献   
14.
Quantitative methods have been applied to the study of floristic structure and diversity in Samarskaya Luka. The results show that Samarskaya Luka is a floristically heterogeneous area in which six elementary floras can be distinguished. This area has been assessed as a floristically autonomous formation, and its floristic representativeness was estimated.  相似文献   
15.
During the artificial reproduction of salmonides, the fecundity can be increased either by improving the viability of spermatozoa, or by extending the time period during which a roe micropile remains open, thus allowing its fecundation. Practically, this can be achieved by the use of some fertilising techniques suitable for fish species. Here, we show that the reproduction of rainbow trout in a 1:1 solution of deuterium-depleted water and distilled water led to a significant increase in survival of roes during their embryonic development. Moreover, the addition of glucose and fructose into the deuterium-depleted fertilising solutions led to a further increase in roe survival during embryonic development. The increase in survival is mainly explained by an increase in the motility of spermatozoa.  相似文献   
16.
17.
Elevated concentrations of arsenic, nickel, and molybdenum in aquatic systems around northern Saskatchewan uranium mines are an environmental concern. Early life stage fathead minnows were used to assess toxicity from several aquatic systems near the Key Lake and Rabbit Lake uranium operations. Hatching success of fish embryos exposed to waters receiving contaminants associated with uranium ore milling was reduced by 32-61% relative to controls. Mortality differed in two lakes receiving mill effluents because of opposing factors influencing metal toxicity (i.e. low pH and high hardness). In one mill receiving water (Fox Lake), larval mortality was 0%, whereas mortality was 85% in water collected from a downstream location (Unknown Lake). Fish embryos exposed to open-pit dewatering effluent receiving waters, or water from a flooded open pit (i.e. pit waters), hatched 26-39% earlier than those exposed to reference or control water. The combination of low water hardness and elevated nickel concentrations in pit waters contributed to the early hatching. Egg hatchability and hatching time were more sensitive indicators of toxicity than 'standard' endpoints, like larval mortality and growth. Current regulatory emphasis on single contaminants and standard toxicological endpoints should be re-evaluated in light of the complex interaction among confounding variables such as pH, hardness. conductivity, and multi-metal mixtures.  相似文献   
18.
19.
The periodicity of fires in larch forests of Evenkia and their relationship with landscape elements have been studied. Cross-sections with “burns” in them caused by past fires have been analyzed in 72 test plots; the fire chronology encompassed the period from the 15th to the 20th century. The between-fire intervals (BFIs) have been calculated by two methods: (I) on the basis of burns alone and (II) on the basis of burns and the start of growth of the new generation of larch after the earliest fire. The BFI depends on local orographic features; it is 86 ± 11 (105 ± 12), 61 ± 8 (73 ± 8), 139 ± 17 (138 ± 18), and 68 ± 14 (70 ± 13) years for northeastern slopes, southwestern slopes, bogs, and flatlands, respectively. The mean BFIs calculated by methods I and II are 82 ± 7 and 95 ± 7 years, respectively. The permafrost horizon rises at a mean rate of 0.3 cm per year after a forest fire. It has been shown that the number of fires regularly peaks at periods of 36 and 82 years. There is also a temporal trend in fire frequency: the mean BFI was approximately 100 years in the 19th century and 65 years in the 20th century.  相似文献   
20.
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