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   252953篇
  免费   16951篇
  国内免费   35882篇
安全科学   23709篇
废物处理   11681篇
环保管理   29282篇
综合类   103748篇
基础理论   47852篇
环境理论   211篇
污染及防治   50398篇
评价与监测   16698篇
社会与环境   15157篇
灾害及防治   7050篇
  2023年   3282篇
  2022年   8929篇
  2021年   9039篇
  2020年   8708篇
  2019年   6823篇
  2018年   7890篇
  2017年   9283篇
  2016年   9307篇
  2015年   9364篇
  2014年   11487篇
  2013年   21063篇
  2012年   16215篇
  2011年   18191篇
  2010年   15906篇
  2009年   15684篇
  2008年   16078篇
  2007年   15752篇
  2006年   14726篇
  2005年   11393篇
  2004年   8842篇
  2003年   7787篇
  2002年   6922篇
  2001年   6276篇
  2000年   5317篇
  1999年   3638篇
  1998年   2401篇
  1997年   2181篇
  1996年   2195篇
  1995年   2305篇
  1994年   2039篇
  1993年   1492篇
  1992年   1508篇
  1991年   1371篇
  1990年   1254篇
  1989年   1145篇
  1988年   1014篇
  1987年   906篇
  1986年   859篇
  1985年   871篇
  1984年   897篇
  1983年   824篇
  1982年   919篇
  1981年   817篇
  1980年   627篇
  1979年   686篇
  1978年   585篇
  1977年   513篇
  1976年   439篇
  1975年   467篇
  1974年   461篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
通过对湖北九宫山国家级自然保护区甜槠群落建立的1ha固定森林样地进行植物群落调查,分析了样地内木本植物物种组成、区系成分、种群径级结构和空间分布格局,结果表明:(1)样地内木本植物(DBH≥1 cm)共有132种,隶属于42科78属,其中,杜鹃花科、壳斗科、樟科、蔷薇科、冬青科等是优势科,短柄袍、鹿角杜鹃、青冈、长叶石栎、甜槠等是优势种.(2)样地内植物科、属的分布类型均以泛热带分布类型为主,分别为30.95%和20.51%.(3)样地内所有木本植物个体的径级结构均呈倒"J"型,幼龄个体数量大,森林群落更新状况良好.(4)样地内木本植物个体的空间分布格局以聚集分布为主,部分优势物种在小尺度上呈聚集分布,而在较大尺度上则为随机分布.  相似文献   
32.
Environmental Science and Pollution Research - Growing environmental pressure urges China to develop in a sustainable and low carbon way, and thus China strives to achieve a carbon peak by 2030 and...  相似文献   
33.
Environmental Science and Pollution Research - The aim of this study is to examine the trophic state of three reservoirs located in the northwest of Algeria based on the physicochemistry of water...  相似文献   
34.

Landslide poses severe threats to the natural landscape of the Lesser Himalayas and the lives and economy of the communities residing in that mountainous topography. This study aims to investigate whether the landscape change has any impact on landslide occurrences in the Kalsi-Chakrata road corridor by detailed investigation through correlation of the landslide susceptibility zones and the landscape change, and finally to demarcate the hotspot villages where influence of landscape on landslide occurrence may be more in future. The rational of this work is to delineate the areas with higher landslide susceptibility using the ensemble model of GIS-based multi-criteria decision making through fuzzy landslide numerical risk factor model along the Kalsi-Chakrata road corridor of Uttarakhand where no previous detailed investigation was carried out applying any contemporary statistical techniques. The approach includes the correlation of the landslide conditioning factors in the study area with the changes in land use and land cover (LULC) over the past decade to understand whether frequent landslides have any link with the physical and hydro-meteorological or, infrastructure, and socioeconomic activities. It was performed through LULC change detection and landslide susceptibility mapping (LSM), and spatial overlay analysis to establish statistical correlation between the said parameters. The LULC change detection was performed using the object-oriented classification of satellite images acquired in 2010 and 2019. The inventory of the past landslides was formed by visual interpretation of high-resolution satellite images supported by an intensive field survey of each landslide area. To assess the landslide susceptibility zones for 2010 and 2019 scenarios, the geo-environmental or conditioning factors such as slope, rainfall, lithology, normalized differential vegetation index (NDVI), proximity to road and land use and land cover (LULC) were considered, and the fuzzy LNRF technique was applied. The results indicated that the LULC in the study area was primarily transformed from forest cover and sparse vegetation to open areas and arable land, which is increased by 6.7% in a decade. The increase in built-up areas and agricultural land by 2.3% indicates increasing human interference that is continuously transforming the natural landscape. The landslide susceptibility map of 2019 shows that about 25% of the total area falls under high and very high susceptibility classes. The result shows that 80% of the high landslide susceptible class is contained by LULC classes of open areas, scrubland, and sparse vegetation, which point out the profound impact of landscape change that aggravate landslide occurrence in that area. The result acclaims that specific LULC classes, such as open areas, barren-rocky lands, are more prone to landslides in this Lesser Himalayan road corridor, and the LULC-LSM correlation can be instrumental for landslide probability assessment concerning the changing landscape. The fuzzy LNRF model applied has 89.6% prediction accuracy at 95% confidence level which is highly satisfactory. The present study of the connection of LULC change with the landslide probability and identification of the most fragile landscape at the village level has been instrumental in delineation of landslide susceptible areas, and such studies may help the decision-makers adopt appropriate mitigation measures in those villages where the landscape changes have mainly resulted in increased landslide occurrences and formulate strategic plans to promote ecologically sustainable development of the mountainous communities in India's Lesser Himalayas.

  相似文献   
35.
Environmental Science and Pollution Research - At present, the contradiction between survival and ecology necessitates the integration of crop planting, chemical fertilizer application, and...  相似文献   
36.
Environmental Science and Pollution Research - The present study focuses on extract-mediated Ag nanoparticles (NPs), AgCl-NPs, and Ag/AgCl nanocomposites (NCs) as photocatalysts along with its...  相似文献   
37.
This article postulates strong endogenous relationships in lower income countries between institutional quality, financial development and sustained economic growth. These associations were investigated using the vector-error correction model (VECM) and Granger causality method for a sample of 79 countries from 2005 to 2022. The findings show that (1) these variables reinforce each other in the short run. (2) In the long run, both institutional quality and financial development can fuel economic growth. (3) The positive effect of institutional quality on economic growth is greater than that of financial development. Policy implications of these findings are that careful attention should be paid to co-development policies to enhance the institutional quality and the financial system in these economies. Policies should also consider economic growth strategies to enable sustainable economic growth rates.  相似文献   
38.
Environmental Science and Pollution Research - The surface areas of lakes alter constantly due to many factors such as climate change, land use policies, and human interventions, and their surface...  相似文献   
39.
Environment, Development and Sustainability - Literature indicates that littering is a social environmental issue resulting from people’s actions towards the environment. This study was...  相似文献   
40.
Environmental Science and Pollution Research - Increasing business organizations are also damaging the natural infrastructure, and researchers are pressing hard on this issue since several decades....  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