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   6966篇
  免费   62篇
  国内免费   35篇
安全科学   148篇
废物处理   280篇
环保管理   653篇
综合类   1020篇
基础理论   1490篇
环境理论   6篇
污染及防治   1690篇
评价与监测   558篇
社会与环境   1178篇
灾害及防治   40篇
  2022年   73篇
  2021年   92篇
  2020年   50篇
  2019年   60篇
  2018年   130篇
  2017年   159篇
  2016年   188篇
  2015年   121篇
  2014年   232篇
  2013年   574篇
  2012年   255篇
  2011年   314篇
  2010年   247篇
  2009年   274篇
  2008年   338篇
  2007年   373篇
  2006年   291篇
  2005年   285篇
  2004年   253篇
  2003年   234篇
  2002年   221篇
  2001年   252篇
  2000年   205篇
  1999年   94篇
  1998年   74篇
  1997年   78篇
  1996年   68篇
  1995年   83篇
  1994年   67篇
  1993年   60篇
  1992年   59篇
  1991年   62篇
  1990年   73篇
  1989年   56篇
  1988年   46篇
  1987年   44篇
  1986年   52篇
  1985年   50篇
  1984年   51篇
  1983年   40篇
  1982年   47篇
  1981年   38篇
  1980年   47篇
  1979年   45篇
  1975年   32篇
  1974年   34篇
  1973年   34篇
  1972年   40篇
  1971年   32篇
  1969年   31篇
排序方式: 共有7063条查询结果,搜索用时 15 毫秒
831.
There currently exists a need for better characterization and simulation of the processes that occur during the incineration of hazardous wastes in the environment of a rotary kiln. Addressing this need, a comprehensive research program was formed with the goal of developing a rudimentary predictive capability for rotary kiln incineration of hazardous wastes. This comprehensive program is headed by Louisiana State University and includes interaction with the University of Utah and also various industrial participants. Such cooperation allows use of laboratory, pilot, and field scale equipment. While laboratory scale experiments provide the necessary decoupling of complex phenomena and a high degree of experimental control, and pilot scale studies provide more realism at the expense of experimental control, the problems of scale-up make generalization of results to field scale units very tenuous. The unique aspect of the LSU program is the coupling of the laboratory and pilot scale units with afield scale unit in order to overcome these generalizations. In this study, plastic packs containing a mixture of toluene and sorbent were fed to a field-scale rotary kiln incinerator at a rate of one pack every 10 minutes. Selected continuous gas samples and temperatures were obtained from the exit of the rotary kiln, from the afterburner, and from the stack. These measurements were obtained during various operating conditions. These data provide, for the first time, an ability to compare conditions in the kiln to simultaneous conditions in the afterburner and stack. This paper outlines several new experimental features of our field-scale tests conducted in October 1990. Oxygen responses from the kiln, the afterburner, and the stack are compared during various operating conditions.  相似文献   
832.
The strain differences in the neurotoxic potential of monocrotophos (MCP) were assessed by determining the inhibition of brain acetylcholinesterase (AChE) in BALB/cAnN, DBA/2J and C57BL/6J in vitro. MCP being a competitive inhibitor for AChE, alters the Km values widely among these inbred strains. Comparatively least alterations in Km were found in BALB/cAnN and maximum in DBA/2J. Based on the Ki values DBA/2J was found to be the most sensitive strain to MCP inhibition followed by C57BL/6J and BALB/cAnN.  相似文献   
833.
Sequence functions were used to construct a simulation model of the long-term population dynamics of the bank vole in Karelia. The mechanisms of population reproduction control affect the population size if it is greater than 1 and 4 ind./100 trap-days in spring and autumn, respectively.  相似文献   
834.
An easy and reproducible technique for direct fetal chromosome analysis after chorionic biopsy is described. Very high colchicine concentration and rehydratation of the fixed villi are the two original points of this method.  相似文献   
835.
The design of efficient water allocation systems depends, among other factors, on economic issues and, above all, on a reliable estimate of the economic value of water. In this paper the hedonic price method is utilized to reveal the implicit value of irrigation water by analyzing agricultural land values in Chalkidiki, a typical rural area in Greece. The method was applied to a sample of both irrigated and nonirrigated properties and the value of irrigation water was estimated by disaggregating the total price of each parcel of land, obtained through a local survey. Results show that, apart from typical value attributes, the agricultural characteristics of the land, including irrigation water availability, have a significant influence on land prices.  相似文献   
836.
837.
Development of new economically feasible ecofriendly products from agricultural wastes or byproducts for shrimp farm wastewater treatment is the objective of our continued research. Ammonia is a nitrogenous toxicant, which is commonly found in wastewater from shrimp farms. In the present study, we explored the possibility of the use of simply and inexpensively prepared bagasse products so that this abundant crop byproduct could be used to remove ammonia from shrimp farm wastewater. Bagasse, a natural highly fibrous lignocellulosic byproduct of sugarcane, was converted into five different products. Experimental results have shown that ammonia is efficiently removed from wastewater by four bagasse products with a dose of 1 to 6 g/L within 24 hours. The effect of bagasse products on other water quality parameters and growth kinetics of biofilm bacteria onto bagasse fiber have also been studied. Efficacies of products were compared by using statistical analysis. Products developed from bagasse are useful and economical.  相似文献   
838.
New principles of the assessment of soil cover degradation and desertification, the scale and intensity of destructive processes manifestation are determined.  相似文献   
839.
840.
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