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   53147篇
  免费   462篇
  国内免费   408篇
安全科学   1409篇
废物处理   2811篇
环保管理   6844篇
综合类   7243篇
基础理论   14403篇
环境理论   13篇
污染及防治   12870篇
评价与监测   4173篇
社会与环境   3970篇
灾害及防治   281篇
  2023年   205篇
  2022年   416篇
  2021年   471篇
  2020年   294篇
  2019年   377篇
  2018年   1994篇
  2017年   1932篇
  2016年   2169篇
  2015年   893篇
  2014年   1231篇
  2013年   3724篇
  2012年   1911篇
  2011年   3142篇
  2010年   2301篇
  2009年   2212篇
  2008年   2799篇
  2007年   3127篇
  2006年   1809篇
  2005年   1625篇
  2004年   1578篇
  2003年   1587篇
  2002年   1538篇
  2001年   1752篇
  2000年   1227篇
  1999年   787篇
  1998年   585篇
  1997年   567篇
  1996年   622篇
  1995年   653篇
  1994年   577篇
  1993年   516篇
  1992年   534篇
  1991年   503篇
  1990年   475篇
  1989年   487篇
  1988年   446篇
  1987年   360篇
  1986年   331篇
  1985年   342篇
  1984年   405篇
  1983年   381篇
  1982年   415篇
  1981年   331篇
  1980年   259篇
  1979年   299篇
  1978年   257篇
  1977年   213篇
  1976年   201篇
  1975年   203篇
  1973年   233篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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   
2.
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   
3.
Environmental Science and Pollution Research - A current environmental problem is the uncontrolled use of various pesticides that are harmful to the environment and public health. The herbicide...  相似文献   
4.
Russian Journal of Ecology - Climate change entails shifts in the ranges of woody plants along both latitudinal and altitudinal gradients in the boreal forest biome. In this study,...  相似文献   
5.
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   
6.
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   
7.
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   
8.
9.
This paper investigates the effects of the incorporation of lignin and small quantities of epoxidized natural rubber (ENR) as an impact modifying agent on blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL). The addition of lignin resulted in a slight improvement of flexural strength and modulus of the ternary blending system. Incorporation of ENR into the blend resulted in an increase in notched Izod impact strength from 40 to 135% depending on the concentration of ENR. The addition of lignin into the blend resulted in an improvement of thermal stability of the ternary blend system. Morphological analysis showed a good dispersion of PHBV phases and lignin within the PCL matrix. Rheological characterization revealed that the presence of lignin resulted in increased storage modulus of the bioblend.  相似文献   
10.
Nano-ZnO-chitosan bio-composite beads were prepared for the sorption of \({\text{UO}}_{2}^{{2+}}\) from aqueous media. The resulting nano-ZnO/CTS bio-composite beads were characterized by TEM, XRD etc. The sorption of \({\text{UO}}_{2}^{{2+}}\) by bio-composite beads was optimized using RSM. The correlation between four variables was modelled and studied. According to RSM data, correlation coefficients (R2?=?0.99) and probability F-values (F?=?2.24?×?10??10) show that the model fits the experimental data well. Adsorption capacity for nano-ZnO/CTS bio-composite beads was obtained at 148.7 mg/g under optimum conditions. The results indicate that nano-ZnO/CTS bio-composite beads are appropriate for the adsorption of \({\text{UO}}_{2}^{{2+}}\) ions from aqueous media. Also, the suitability of adsorption values to adsorption isotherms was researched and thermodynamic data were calculated.  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