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   36317篇
  免费   316篇
  国内免费   383篇
安全科学   933篇
废物处理   1665篇
环保管理   4250篇
综合类   7720篇
基础理论   8517篇
环境理论   7篇
污染及防治   9294篇
评价与监测   2479篇
社会与环境   1962篇
灾害及防治   189篇
  2022年   317篇
  2021年   313篇
  2020年   206篇
  2019年   296篇
  2018年   550篇
  2017年   529篇
  2016年   827篇
  2015年   577篇
  2014年   872篇
  2013年   2822篇
  2012年   1064篇
  2011年   1403篇
  2010年   1266篇
  2009年   1325篇
  2008年   1450篇
  2007年   1565篇
  2006年   1388篇
  2005年   1176篇
  2004年   1188篇
  2003年   1118篇
  2002年   1070篇
  2001年   1391篇
  2000年   941篇
  1999年   610篇
  1998年   441篇
  1997年   413篇
  1996年   452篇
  1995年   475篇
  1994年   463篇
  1993年   411篇
  1992年   425篇
  1991年   409篇
  1990年   440篇
  1989年   418篇
  1988年   349篇
  1987年   319篇
  1986年   292篇
  1985年   309篇
  1984年   344篇
  1983年   326篇
  1982年   357篇
  1981年   318篇
  1980年   279篇
  1979年   299篇
  1978年   250篇
  1977年   229篇
  1976年   222篇
  1974年   212篇
  1973年   212篇
  1967年   222篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Environment, Development and Sustainability - Sugarcane is an industrial crop globally used for producing biofuels and bioproducts and is the only source of white sugar in Bangladesh. However,...  相似文献   
2.
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   
3.
Environmental Science and Pollution Research - The average nutrient concentrations values presented in Table 1 on page 4 in the publication have the unit mg L?1 for the mineral nutrients Fe,...  相似文献   
4.
Environmental Science and Pollution Research - Lake Mariut Main Basin (MB) is not only one of the three basins composing Lake Mariut (LM) but is also the main source of the popular tilapia fish to...  相似文献   
5.
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   
6.
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   
7.
Russian Journal of Ecology - Changes in the distribution of broadleaf tree species—Tilia cordata Mill., Quercus robur L., Acer platanoides L., and Ulmus glabra Huds.—in the central part...  相似文献   
8.
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   
9.
Flares are important safety devices for pressure relief; at the same time, flares are a significant point source for soot and highly reactive volatile organic compounds (HRVOCs). Currently, simple guidelines for flare operations to maintain high combustion efficiency (CE) remain elusive. This paper fills the gap by investigating the characteristics of the incipient smoke point (ISP), which is widely recognized as the condition for good combustion. This study characterizes the ISP in terms of 100–% combustion inefficiency (CE), percent opacity, absorbance, air assist, steam assist, air equivalence ratio, steam equivalence ratio, exit velocity, vent gas net heating value, and combustion zone net heating value. Flame lengths were calculated for buoyant and momentum-dominated plumes under calm and windy conditions at stable and neutral atmosphere. Opacity was calculated using the Beer–Lambert law based on soot concentration, flame diameter, and mass-specific extinction cross section of soot. The calculated opacity and absorbance were found to be lognormally distributed. Linear relations were established for soot yield versus absorptivity with R2 > 0.99 and power-law relations for opacity versus soot emission rate with R2 ≥ 0.97 for steam-assisted, air-assisted, and nonassisted flares. The characterized steam/air assists, combustion zone/vent gas heating values, exit velocity, steam, and air equivalence ratios for the incipient smoke point will serve as a useful guideline for efficient flare operations.

Implications: A Recent EPA rule requires an evaluation of visible emissions in terms of opacity in compliance with the standards. In this paper, visible emissions such as soot particles are characterized in terms of opacity at ISP. Since ISP is widely recognized as most efficient flare operation for high combustion efficiency (CE)/destruction efficiency (DE) with initial soot particles formed in the flame, this characterization provides a useful guideline for flare operators in the refinery, oil and gas, and chemical industries to sustain smokeless and high combustion efficiency flaring in compliance with recent EPA regulations, in addition to protecting the environment.  相似文献   

10.
Environmental Science and Pollution Research - Aedes aegypti and Culex quinquefasciatus are vectors of diseases that constitute public health problems. The discovery of products capable of...  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