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   61篇
  免费   3篇
  国内免费   4篇
安全科学   8篇
废物处理   2篇
环保管理   16篇
综合类   32篇
基础理论   3篇
污染及防治   5篇
评价与监测   1篇
灾害及防治   1篇
  2021年   3篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   3篇
  2016年   1篇
  2015年   3篇
  2013年   3篇
  2012年   1篇
  2011年   10篇
  2010年   5篇
  2009年   6篇
  2008年   5篇
  2007年   4篇
  2006年   3篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  2001年   1篇
  1998年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1991年   1篇
  1987年   2篇
  1986年   1篇
  1984年   1篇
  1980年   1篇
排序方式: 共有68条查询结果,搜索用时 15 毫秒
51.
The paper is concerned with the impact of small business advice agencies on their clients. The work of two agencies (an Enterprise Agency and a local authority Development Unit) operating in the same geographical area (Swale in Kent) is evaluated using a survey of clients as evidence. It is concluded that both agencies are meeting real and distinctive needs among start‐up and established small businesses in the area, and have established effective systems for the delivery of their services. Quality of staff is confirmed as a key factor influencing client satisfaction with the agencies. The impact of the agencies on busines efficiency is ambiguous; it is suggested that major beneficiaries of the work of the agencies are the banks.  相似文献   
52.
ABSTRACT: The dam impounding White Rock Lake was completed in 1910 to provide water for the City of Dallas. Since then, land use on the watershed has changed from entirely rural to over 77 percent urban. A model called SWRRB (Simulator for Water Resources in Rural Basins) was utilized to determine the effect of urbanization on water and sediment entering the lake. The simulation results show that, if urbanization had not occurred, then the annual surface runoff would be 135 mm rather than 151 mm and the annual sediment yield would be 4.4 t/ha rather than 4.1 t/ha. Also, the effect of urbanization on delivery ratios was shown and a positive linear correlation was found. Finally, the weather generator in SWRRB was utilized to estimate the loss of reservoir capacity until 2050 for three different land use management scenarios.  相似文献   
53.
The very potent greenhouse gas nitrous oxide (N2O) is widely used as a mild anaesthetic for mothers in delivery work in Sweden. As a part of the Stockholm County Council environmental program it was decided in 2002 that the emissions should be drastically reduced. Different ways were theoretically evaluated, and catalytic splitting to nitrogen and oxygen gas (N2 and O2) was chosen for a demonstration installation. A Japanese commercial unit for treatment of mixed anaesthetic gases (Anesclean® from Showa Denko K.K.) was thoroughly modified and installed at the Karolinska University Hospital at Huddinge in Stockholm in 2004. The destruction of N2O was optimised and studied for 2 years. Data from both collection and destruction are given in the article. Of the collected N2O more than 95% was split to N2 and O2 in the very stable system. The overall emission decrease was mainly dependent on the share that could be collected in the specific exhaustion system as compared to the normal room ventilation. Life cycle assessment (LCA) and life cycle costing (LCC) were used to evaluate the actual environmental value and economical cost for the process. Important factors are pointed out.  相似文献   
54.
塔里木河下游地下水化学特征对输水响应的阶段性研究   总被引:2,自引:1,他引:2  
通过对塔里木河下游英苏断面地下水化学特征在生态输水作用下变化的观测资料研究发现,地下水化学特征对间歇性输水的响应表现出阶段性的特点:在受输水影响的初期地下水中矿化度和主要离子含量呈现上升变化,随着输水的进行,矿化度和主要离子的含量逐步下降,最后又表现出上升态势.根据地下水盐变化特点可将地下水化学对输水的响应划分为3个阶段:初期阶段(盐分横向累积阶段)、中期阶段(淡化压盐阶段)和后期阶段(蒸发溶盐阶段);输水间歇地下水化学特征的变化与地下水化学对输水响应表现出的阶段性特征相一致的特点.在“盐随水来,盐随水去”规律作用下,地下水化学特征的阶段性变化受土壤盐分含量、与河道距离、输水水质、水量的影响,其中土壤盐分、输送水的水质与地下水位的抬升是主导因素,而距河道远近与水量的多寡则是导致与河道不同距离处阶段性变化时间差异的重要原因.从水盐运移规律的角度考虑,河道输水方式比面上输水方式更利于生态恢复.  相似文献   
55.
56.
57.
通过问卷调查研究外卖配送公共交通违法行为影响因素,将外卖配送员分为曾经发生过和未发生过公共交通违法行为2组样本。通过Logistic回归对比分析,发现影响外卖配送员是否会发生公共交通违法行为的因素为平均每月送餐收入和平均每单配送距离;接着对其中发生过公共交通违法行为的1组样本,运用灰色关联分析法判断外卖配送员发生公共交通违法行为的主要驱动因素是平均每日接单数量、平均每月送餐收入以及平均每单配送时长,并根据影响因素提出了解决该问题的针对性长期建议。  相似文献   
58.
介绍了车辆装备海上投送的重要现实意义及其面临的严峻腐蚀环境,分析了车辆装备海上投送腐蚀与防护及其相关领域的研究现状,指出了车辆装备海上投送存在的问题。结合具体的投送工具及装卸方式,对影响车辆装备腐蚀的因素进行了分析,并提出了相应的防腐蚀对策。  相似文献   
59.
60.
Although there are many reports on the dangers posed by glyphosate, this herbicide is still one of the most popular and widely used total weed killers. Therefore, great effort should be made to minimize exposure to this herbicide and limit its losses into the environment. The aim of this study was to prepare a new formulation consisted of various molecular weight chitosans with glyphosate and their evaluation toward active substance release, phytotoxicity, and preliminary herbicidal efficiency. The phytotoxicity study of the obtained chitosan/glyphosate formulations was determined based on the Organisation for Economic Co-operation and Development 208 guideline. Among all tested formulations evaluated for phytotoxicity, that containing the highest molecular weight of chitosan was found to be the least toxic, showing simultaneously the most effective herbicidal activity against selected weeds. The release rate of glyphosate from the obtained formulations was dependent on the molecular weight and viscosity of chitosan.  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