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   23094篇
  免费   117篇
  国内免费   100篇
安全科学   389篇
废物处理   1277篇
环保管理   3049篇
综合类   3207篇
基础理论   6679篇
环境理论   7篇
污染及防治   4771篇
评价与监测   1788篇
社会与环境   2056篇
灾害及防治   88篇
  2023年   68篇
  2022年   106篇
  2021年   109篇
  2020年   91篇
  2019年   100篇
  2018年   1722篇
  2017年   1606篇
  2016年   1481篇
  2015年   332篇
  2014年   298篇
  2013年   928篇
  2012年   857篇
  2011年   1959篇
  2010年   1219篇
  2009年   1167篇
  2008年   1537篇
  2007年   1933篇
  2006年   479篇
  2005年   539篇
  2004年   411篇
  2003年   521篇
  2002年   547篇
  2001年   506篇
  2000年   377篇
  1999年   220篇
  1998年   159篇
  1997年   162篇
  1996年   172篇
  1995年   201篇
  1994年   201篇
  1993年   165篇
  1992年   141篇
  1991年   175篇
  1990年   167篇
  1989年   158篇
  1988年   123篇
  1987年   118篇
  1986年   121篇
  1985年   94篇
  1984年   128篇
  1983年   124篇
  1982年   123篇
  1981年   117篇
  1980年   102篇
  1979年   114篇
  1978年   74篇
  1977年   78篇
  1975年   76篇
  1973年   73篇
  1967年   66篇
排序方式: 共有10000条查询结果,搜索用时 843 毫秒
191.
192.
193.
194.
195.
196.
Mitigation and adaptation synergy in forest sector   总被引:1,自引:1,他引:1  
Mitigation and adaptation are the two main strategies to address climate change. Mitigation and adaptation have been considered separately in the global negotiations as well as literature. There is a realization on the need to explore and promote synergy between mitigation and adaptation while addressing climate change. In this paper, an attempt is made to explore the synergy between mitigation and adaptation by considering forest sector, which on the one hand is projected to be adversely impacted under the projected climate change scenarios and on the other provide opportunities to mitigate climate change. Thus, the potential and need for incorporating adaptation strategies and practices in mitigation projects is presented with a few examples. Firstly, there is a need to ensure that mitigation programs or projects do not increase the vulnerability of forest ecosystems and plantations. Secondly, several adaptation practices could be incorporated into mitigation projects to reduce vulnerability. Further, many of the mitigation projects indeed reduce vulnerability and promote adaptation, for example; forest and biodiversity conservation, protected area management and sustainable forestry. Also, many adaptation options such as urban forestry, soil and water conservation and drought resistant varieties also contribute to mitigation of climate change. Thus, there is need for research and field demonstration of synergy between mitigation and adaptation, so that the cost of addressing climate change impacts can be reduced and co-benefits increased.  相似文献   
197.
IntroductionBecauseofthelowefficiencyoftheelectrostaticprecipitator (ESP)forcollectingthesubmicronparticles ,theelectricalagglomerationmethodhasledtoanincreasinginterestinreducingtheemissionofthefineparticles .Manyauthorshavestudiedelectricalagglomerati…  相似文献   
198.
Sustainable resource management is the critical agricultural research and development challenge in sub-Saharan Africa. The accumulated knowledge on soil management gathered over the last 10 years, combined with solid crop improvement and plant health research at farmers’ level, has brought us to a stage where we can now address with confidence the intensification of cereal–grain–legume-based cropping systems in the dry savanna of West Africa in a sustainable and environmentally positive manner.Two sustainable farming systems that greatly enhance the productivity and sustainability of integrated livestock systems have been developed and implemented in the dry savanna of Nigeria. These are: (i) maize (Zea mays L.)–promiscuous soybean [Glycine max (L.) Merr.] rotations that combine high nitrogen fixation and the ability to kill large numbers of Striga hermonthica seeds in the soil; and (ii) miflet [Eleusine coracana (L.) Gaerth] and dual-purpose cowpea [Vigna unguiculata (L.) Walp.]. Improvement of the cropping systems in the dry savanna has been driven by the adoption of promiscuously nodulating soybean varieties (in particular TGx 1448-2E) and dual-purpose cowpea. The rate of adoption is very high, even in the absence of an efficient seed distribution system. The number of farmers cultivating the improved varieties increased by 228% during the last 3 years. Increased production of promiscuous soybean has been stimulated by increased demand from industries and home utilization. Production in Nigeria was estimated at 405,000 t in 1999 compared to less than 60,000 t in 1984. Economic analysis of these systems shows already an increase of 50–70% in the gross incomes of adopting farmers compared to those still following the current practices, mainly continuous maize cultivation. Furthermore, increases in legume areas of 10% in Nigeria (about 30,000 ha in the northern Guinea savanna) and increases of 20% in yield have translated into additional fixed nitrogen valued annually at US$ 44 million. This reflects, at the same time, an equivalent increase in land-use productivity, and with further spread of the improved crops, there are excellent prospects for additional economic and environmental benefits from a very large recommendation domain across West Africa.  相似文献   
199.
Population differences in anti-predator behaviour have been demonstrated in several species, although less is known about the genetic basis of these traits. To determine the extent of genetic differences in boldness (defined as exploration of a novel object) and shoaling within and between zebrafish (Danio rerio) populations, and to examine the genetic basis of shoaling behaviour in general, we carried out a study that involved laboratory-raised fish derived from four wild-caught populations. Controlling for differences in rearing environment, significant inter-population differences were found in boldness but not shoaling. A larger shoaling experiment was also performed using one of the populations as the basis of a North Carolina type II breeding design (174 fish in total) to estimate heritability of shoaling tendency. A narrow-sense heritability estimate of 0.40 was obtained, with no apparent dominance effects.  相似文献   
200.
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