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   410篇
  免费   28篇
  国内免费   45篇
安全科学   76篇
废物处理   30篇
环保管理   71篇
综合类   199篇
基础理论   32篇
污染及防治   32篇
评价与监测   21篇
社会与环境   7篇
灾害及防治   15篇
  2024年   1篇
  2023年   11篇
  2022年   10篇
  2021年   10篇
  2020年   11篇
  2019年   11篇
  2018年   5篇
  2017年   15篇
  2016年   12篇
  2015年   15篇
  2014年   21篇
  2013年   33篇
  2012年   28篇
  2011年   29篇
  2010年   23篇
  2009年   25篇
  2008年   11篇
  2007年   34篇
  2006年   26篇
  2005年   11篇
  2004年   23篇
  2003年   21篇
  2002年   20篇
  2001年   21篇
  2000年   5篇
  1999年   10篇
  1998年   7篇
  1997年   7篇
  1996年   4篇
  1995年   5篇
  1994年   1篇
  1993年   4篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1988年   1篇
  1980年   2篇
  1978年   1篇
  1975年   1篇
  1972年   1篇
排序方式: 共有483条查询结果,搜索用时 765 毫秒
131.
文章简介了利用鄂东大别山地区的食用菌香菇下脚料(香菇柄)制作几类风味独特、脆嫩鲜香、深受人们喜爱的香菇食品的加工技术和方法。  相似文献   
132.
基于小波分析的声发射信号处理   总被引:4,自引:0,他引:4  
小波分析作为一种新的信号分析处理方法,可对任意信号,信号的任一时刻、任一频段进行时频分析。将小波分析用于声发射信号处理,有助于声发射技术的发展与推广应用。  相似文献   
133.
为解决电网防台抗台过程中缺少应急辅助支持的问题,提出基于现有电网防台抗台系统中的业务数据,采用星型结构分析与设计“台风气象灾情”、“电网因灾(台风)损失”、“电网因灾(台风)应急资源投入”等应急主题数据仓库,充分利用、开发相关的数据探查与ETL工具实现相关的数据集成,构建相关应急主题下的多维数据模型,并开展联机分析处理(OLAP)研究工作,为相关企业和部门开展电网应急管理工作提供应急辅助支持。  相似文献   
134.
Many technologies in precision agriculture (PA) require image analysis and image- processing with weed and background differentiations. The detection of weeds on mulched cropland is one important image-processing task for sensor based precision herbicide applications. The article introduces a special vegetation index, the Difference Index with Red Threshold (DIRT), for the weed detection on mulched croplands. Experimental investigations in weed detection on mulched areas point out that the DIRT performs better than the Normalized Difference Vegetation Index (NDVI). The result of the evaluation with four different decision criteria indicate, that the new DIRT gives the highest reliability in weed/background differentiation on mulched areas. While using the same spectral bands (infrared and red) as the NDVI, the new DIRT is more suitable for weed detection than the other vegetation indices and requires only a small amount of additional calculation power. The new vegetation index DIRT was tested on mulched areas during automatic ratings with a special weed camera system. The test results compare the new DIRT and three other decision criteria: the difference between infrared and red intensity (Diff), the soil-adjusted quotient between infrared and red intensity (Quotient) and the NDVI. The decision criteria were compared with the definition of a worse case decision quality parameter Q, suitable for mulched croplands. Although this new index DIRT needs further testing, the index seems to be a good decision criterion for the weed detection on mulched areas and should also be useful for other image processing applications in precision agriculture. The weed detection hardware and the PC program for the weed image processing were developed with funds from the German Federal Ministry of Education and Research (BMBF).  相似文献   
135.
Waste printed circuit boards contain valuable metals such as Au, Pd, Ag, and Cu that can be reutilized and harmful elements such as Pb, Br, and Cr that must be removed from the viewpoint of environmental conservation. In this research, we examined a method that separates the materials from printed circuit boards contained in discarded personal computers. After cutting the printed circuit boards to a size of 20 × 20 mm, they were heated at 873 K under an Ar atmosphere to remove organic resins containing elements such as C, H, and N. After heat treatment, the printed circuit boards were crushed using a planetary ball mill and the pulverized powders were filtered. The fraction with a granularity of greater than 250 μm was separated into magnetic and nonmagnetic materials by a magnetic field. Because the fraction with a granularity of less than 250 μm contained 39 mass% of C, it was heated at 1273 K in an atmosphere of 95% Ar and 5% O2 to allow carbon combustion to take place, followed by metal reduction processing at the same temperature in an atmosphere of 97% Ar and 3% H2. The basicity of the resulting powder was adjusted and the powder was heated at 1773 K under an Ar atmosphere. The proposed method separated the slag and metal, and 80% of the valuable metals contained in printed circuit boards could be collected.  相似文献   
136.
As biodegradable material represents approximately 70% of household waste in Brazil, any strategy to divert appreciable waste quantities from landfills of necessity has to include valorization and recycling of this material. A societal change of attitude is required to perceive this challenge. Experiments in an urban apartment building are described that produced this change of attitude with a success factor of 80%. Divided waste collection was implemented that separated at the source biodegradable from inert material. Correct collection, handling and display procedures were established. Composting of biodegradable material was carried out under the rooftop of the building as an alternative to using it as animal feed. Half of the inert material entered the reverse logistics chain and was also diverted from the landfill. Waste related material flow through the building is completely quantified, food intake and waste production are related, diversion of both biodegradable and inert waste components from the landfill is measured and the composting process is described. The landfill diversion stands at 61%, mass reduction through the composting process is 80% and matured compost is returned to residents for use in flower cages. The system has been operational for two years and stands out as a precedent in successful decentralized household waste management supported by material flow analysis. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
137.
138.
环境突发事件应急处理要做到“万无一失”,必须动员社会上的一切力量,现有的环保系统处理这一系统工程困难较大。笔者根据多年实践经验,分析了应急处理的系统性,提出了建立环境突发事件应急处理系统的设想,探索了其运行机制。  相似文献   
139.
为加强环境自动监测系统的建设,提供了一个支持多种类型现场信息宽接入的信息采集、支持有线和无线信息传输的开放式在线数据采集传输装置.装置用标准化的工控机作为控制核心,具备模拟信号、LonWorks信号、视频信号、RS-485信号输入接口,网络通信和GPRS远程通信方式,采用Windows操作系统和数据库技术,应用方便灵活,有助于提供有效、客观的现场环境信息,实现环境自动监测与管理.  相似文献   
140.
火灾预测的模糊马尔柯夫模型   总被引:6,自引:0,他引:6  
姜学鹏  徐志胜  冷彬 《灾害学》2006,21(3):27-32
火灾发生并不是一个严格马尔柯夫随机过程,而是一个“近似具有马尔柯夫性”的模糊马尔柯夫过程。本文在对我国55年火灾统计资料“相对化”处理的基础上,根据模糊马尔柯夫理论和方法,建立我国火灾相对变动模糊马尔可夫预测模型。根据隶属度最大原则,确定所属状态,进行火灾预测。2005年我国火灾预测值与实际值的相对误差为0.0148,表明模型具有相当高的预测精度。对我国2006年进行预测,得到火灾相对变动状态等级为微降,我国2006年的火灾发生率与2005年相比降低了0~0.1,火灾频数约为212347~235941起,预测结果可为有关部门的决策提供一定的依据。  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