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   138篇
  免费   35篇
  国内免费   12篇
安全科学   16篇
废物处理   3篇
环保管理   22篇
综合类   56篇
基础理论   46篇
污染及防治   25篇
评价与监测   2篇
社会与环境   13篇
灾害及防治   2篇
  2024年   5篇
  2023年   3篇
  2022年   5篇
  2021年   7篇
  2020年   4篇
  2019年   9篇
  2018年   5篇
  2017年   11篇
  2016年   7篇
  2015年   3篇
  2014年   8篇
  2013年   26篇
  2012年   7篇
  2011年   14篇
  2010年   5篇
  2009年   8篇
  2008年   6篇
  2007年   5篇
  2006年   6篇
  2005年   9篇
  2004年   2篇
  2003年   5篇
  2002年   6篇
  2001年   4篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1997年   2篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
排序方式: 共有185条查询结果,搜索用时 15 毫秒
121.
This study explores the implications of improved access to national rail and road infrastructure for urban planning and land use in two small Swedish towns. The promotion of sustainable mobility is considered a strategic objective at the municipal level, yet the study questions the extent to which national investments, and increased access to regional labour markets, support local efforts to increase sustainable mobility. The results indicate that municipalities struggle to adopt coherent approaches to increasing sustainable mobility and continue to develop physical plans that induce use of motor vehicles, a trend reinforced by national investments in road infrastructure in peri-urban areas.  相似文献   
122.

Introduction

Self-screening by older drivers has shown considerable promise for increasing self-awareness about functional abilities associated with safe driving. The purpose of this study was to improve upon existing self-screening instruments by focusing entirely on “health concerns” that affect driving - that is, the symptoms that people experience due to medical conditions and the medications used to treat them - rather than the medical conditions or medications themselves.

Method

A computer-based, easy-to-use self-screening instrument for older drivers was developed to provide individualized feedback intended to increase self-awareness about declines in driving-related abilities, as well as suggestions for behavioral changes or safety tips to maintain safe driving, further evaluation from a physician/health professional, and vehicle modifications to help compensate for driving-related declines.

Results

This paper describes the development of the self-screening instrument and summarizes findings relative to increasing self-awareness among older drivers. This research represents an important first step in improving self-awareness among older drivers through self-screening.  相似文献   
123.
重金属化学活性评估方法准确性质疑--以煤矸石样品为例   总被引:5,自引:0,他引:5  
重金属元素化学活性的大小是决定它们环境行为最主要的因素之一,我们曾分别用总量法,实验模拟法,环境地球化学法和化学形态分析法对煤矸石样品所含的重金属元素进行过环境影响分析,试图了解自然风化条件下这些有害元素潜在的生态环境效应,结果发现重金属元素的化学活性除了与它们在样品中含量的高低,赋存状态和化学形态等因素有关外,更主要地是取决于样品基质的组成和结构,由于大量有机质的络合和风化过程中生成的铁的胶体的吸附,从煤矸石释放出的重金属元素的化学活性受到明显限制,它们对环境的污染可能仅限于煤矸石堆周围有限的范围。  相似文献   
124.
    
1 IntroductionChinaisundergoingsubstantialandrapidchangesinitssocietyanditseconomicpolicies.Amongvariousenvironmentalproblems,waterpollutionisoneofthemostcriticalissuesfacingChinatoday.Thesepollutantspoisonaquaticorganismsandaccumulateinfishandothere…  相似文献   
125.
    
Through a batch experiment, the mobility and speciation of heavy metals(Cd, Cu, Zn) in two acidic forest soils from Hunan Province were studied. The results showed that the release and potential active speciation of Cd, Cu, and Zn in the tested contaminated red soil(CRS) and yellow red soil(CYRS) increased significantly with pH decreasing and ion concentrations increasing of simulated acid rain, and these effects were mainly decided by the pH value of simulated acid rain. Cd had the highest potential nsk on the environment compared with Cu and Zn. Cd existed mainly in exchangeable form in residual CRS and CYRS, Cu in organically bound and Mn-oxide occluded forms, and Zn in mineral forms due to the high background values.  相似文献   
126.
A Pb-Zn tailings pond, abandoned for approximately 90 years, has been naturally colonized by Glyceria fluitans and is an excellent example of long-term metal retention in tailings ponds under various water cover and vegetation conditions. Shallow/intermittently flooded areas (dry zone) were unvegetated and low in organic matter (OM) content. Permanently flooded areas were either unvegetated with low OM, contained dead vegetation and high OM, or living plants and high OM. It was expected that either water cover or high OM would result in enhanced reducing conditions and lower metal mobility, but live plants would increase metal mobility due to root radial oxygen loss. The flooded low OM tailings showed higher As and Fe mobility compared with dry low OM tailings. In the permanently flooded areas without live vegetation, the high OM content decreased Zn mobility and caused extremely high concentrations of acid-volatile sulfides (AVS). In areas with high OM, living plants significantly increased Zn mobility and decreased concentrations of AVS, indicating root induced sediment oxidation or decreased sulfate-reduction. This is the first study reporting the ability of wetland plants to affect the metal mobility and AVS in long-term (decades), unmanaged tailings ponds.  相似文献   
127.
    
Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.  相似文献   
128.
为改善气溶胶静电分级器分级测量性能,建立了其传递函数和积分响应理论模型.通过对关键参数理论模拟,设置了静电分级器样气流速、鞘气和样气流速比例等关键参数,并且通过试验对理论模型进行了验证,评价了该静电分级器分级测量性能.模拟结果表明,提高气流流速可以改善静电分级器的分级性能,而鞘气和样气流速比例过大会降低其传输效率,过小则会影响分辨率,流速比例可以设定为5~25.试验结果表明,积分响应理论计算的粒子数浓度与该静电分级器试验测量结果呈线性相关(R2=0.98).研究显示,该静电分级器测量粒径与预测粒径的误差在5.0%以内,线性相关(R2=0.99),且测量多个单分散和多分散粒径浓度谱型与商业化SMPS(scanning mobility particle sizer,扫描电迁移颗粒物粒径谱仪)基本一致,该传递函数和积分响应模型显著提高了静电分级器分级测量性能.   相似文献   
129.
恶唑菌酮的土壤薄层层析迁移特性   总被引:1,自引:0,他引:1  
在室内模拟条件下研究了农药恶唑菌酮在不同土壤薄板上的移动性能,以及阴离子、阳离子和非离子表面活性剂对恶唑菌酮土壤中的迁移影响。结果表明:恶唑菌酮在土壤中的移动性能主要受土壤有机质和粘粒含量影响,它们之间呈显著的负相关性;在低于表面活性剂临界胶束浓度中恶唑菌酮的移动性受到抑制,而在高于临界胶束浓度下恶唑菌酮的移动性明显增大,恶唑菌酮在表面活性剂中移动性的变化是恶唑菌酮和土壤表面吸附位、表面活性剂分子、胶束之间相互作用的结果。  相似文献   
130.
目的降低外界环境对离子迁移率的影响。方法讨论用标校物的IMS信号迁移时间对待测物质的IMS信号迁移时间进行校正的算法,通过对待测物质IMS信号进行修正,来减少外界环境的变化对IMS信号迁移时间的影响,提高探测的准确性,最后通过用空气作为标校物进行试验验证。结果迁移区电压的变化对IMS信号的影响降低了96%,迁移区温度的变化对IMS信号的影响降低了53%。结论该方法有效,为该校正技术在IMS信号处理中的应用奠定了基础。  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