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   1829篇
  免费   16篇
  国内免费   59篇
安全科学   174篇
废物处理   34篇
环保管理   502篇
综合类   548篇
基础理论   186篇
环境理论   1篇
污染及防治   157篇
评价与监测   68篇
社会与环境   82篇
灾害及防治   152篇
  2023年   13篇
  2022年   11篇
  2021年   24篇
  2020年   44篇
  2019年   14篇
  2018年   23篇
  2017年   43篇
  2016年   53篇
  2015年   49篇
  2014年   62篇
  2013年   86篇
  2012年   46篇
  2011年   121篇
  2010年   63篇
  2009年   96篇
  2008年   97篇
  2007年   84篇
  2006年   81篇
  2005年   58篇
  2004年   67篇
  2003年   96篇
  2002年   69篇
  2001年   57篇
  2000年   64篇
  1999年   53篇
  1998年   60篇
  1997年   54篇
  1996年   56篇
  1995年   47篇
  1994年   29篇
  1993年   33篇
  1992年   20篇
  1991年   14篇
  1990年   14篇
  1989年   6篇
  1988年   9篇
  1987年   12篇
  1986年   7篇
  1985年   8篇
  1984年   10篇
  1983年   9篇
  1982年   11篇
  1981年   3篇
  1980年   7篇
  1979年   9篇
  1978年   4篇
  1977年   4篇
  1974年   1篇
  1973年   1篇
  1968年   1篇
排序方式: 共有1904条查询结果,搜索用时 62 毫秒
621.
水足迹强度是可以量化水资源利用效率的指标,文章在计算江苏省水足迹的基础上,选取6项水足迹强度指标,分部门比较各地市水资源利用效率的差异,并基于ESDA研究水足迹强度的空间自相关性,构建空间集聚图。研究表明:2002~2014年江苏省各市水足迹总体呈现上升趋势,水资源压力增大;总体上苏南和苏北地区的农业水足迹强度都偏高,农业水资源利用效率低;苏南地区工业产值高但耗水量大,因此工业水足迹强度也偏高;苏北地区的灰水足迹强度偏高,水资源压力较大;江苏省水足迹强度具有不断增强的全局自相关性,地市出现集聚现象,不同地市的集聚分布也日益明显;大部分苏北地区属于高高集聚并且向外扩张,低低集聚主要分布在苏南地区。研究结果为政府部门分析地市间水资源利用效率差异,制定高效的水资源利用政策等提供依据。  相似文献   
622.
白塔堡河不同粒级有机物的三维荧光特征解析   总被引:2,自引:1,他引:1  
利用三维荧光扫描(3DEEM)和体积积分法(FRI),分析了辽河流域白塔堡河在春汛期水中溶解性有机物(DOM)、小粒径有机物(0.22~0.7μm)和大粒径有机物(>0.7μm)的分布。结果显示:白塔堡河中有机物以芳香类蛋白质和溶解性微生物代谢产物为主,腐植酸类物质含量极少;5类组分在不同粒径有机物中分布相似,在0.22μm以下的DOM中分布最多;溯源分析显示,DOM来源较单一,表现出较强的内源生物降解特性,而颗粒状有机物则表现出内源和陆源的双重特性;多元统计分析显示,白塔堡河点位有机物分布基本上呈现区域性分布特征。  相似文献   
623.
生态环境空间分级管控是为了确保各级尺度下的生态环境空间充分发挥其生态服务功能所采取的管理控制手段与途径,同时给城市生态环境空间的管控提供依据,在不同尺度下,生态环境空间需按照不同精细度的管控方法和不同的土地空间单位进行分级,生态环境空间分级管控主要包括:省域尺度生态环境空间的管控、市域尺度生态环境空间管控和在主城区尺度下生态环境空间管控。通过3种尺度不同管控方法和策略的有效衔接,从宏观、中观和微观3个层次保证了生态规划的完整性和连续性,使生态系统服务真正发挥其价值。  相似文献   
624.
制定适合企业自身发展的职业安全健康方针至关重要,然而目前这方面的研究相对较少。本文收集了国内27家、国外10家知名企业的职业安全健康方针,统计分析了国内外职业安全健康方针在形式和内容上的区别与联系。通过定性分析和定量研究,得出国外企业职业安全健康方针的共性特点和国内企业职业安全健康方针的最常见组合模式。理论联系实际,将我国《职业安全健康管理体系规范(》GB/T28001-2004)中方针的编写要求与研究结论相结合,探讨在新形势下,如何制定企业职业安全健康方针的方法。  相似文献   
625.
Phytophthora ramorum, cause of sudden oak death, is a quarantined, non-native, invasive forest pathogen resulting in substantial mortality in coastal live oak (Quercus agrifolia) and several other related tree species on the Pacific Coast of the United States. We estimate the discounted cost of oak treatment, removal, and replacement on developed land in California communities using simulations of P. ramorum spread and infection risk over the next decade (2010-2020). An estimated 734 thousand oak trees occur on developed land in communities in the analysis area. The simulations predict an expanding sudden oak death (SOD) infestation that will likely encompass most of northwestern California and warrant treatment, removal, and replacement of more than 10 thousand oak trees with discounted cost of $7.5 million. In addition, we estimate the discounted property losses to single family homes of $135 million. Expanding the land base to include developed land outside as well as inside communities doubles the estimates of the number of oak trees killed and the associated costs and losses. The predicted costs and property value losses are substantial, but many of the damages in urban areas (e.g. potential losses from increased fire and safety risks of the dead trees and the loss of ecosystem service values) are not included.  相似文献   
626.
In recent years, significant advances have been made in business organization and management. The growing demands of clients as well as the globalization of world markets are among the many factors that have led to the establishment of systems of quality control and environmental management as a competitive strategy for businesses. When compared to other professional sectors, the construction sector has been slower to respond to environmental problems and to adopt Environmental Management Systems (EMS). In the world today the ISO 14001 standard is currently the main frame of reference used by construction companies to implement this type of management system. This article presents the results of a general study regarding the evaluation of the application of the ISO 14001 standard at civil engineering construction worksites in the Community of Madrid (Spain), specifically pertaining to requirement 4.4.1, Resources, roles, responsibilities, and authority. According to requirement 4.4.1, company executives should appoint people responsible for implementing the EMS and also specify their responsibilities and functions. The personnel designated for supervising environmental work should also have sufficient authority to establish and maintain the EMS. The results obtained were the following: - EMS supervisors did not generally possess adequate training and solid experience in construction work and in the environment. Furthermore, supervisors were usually forced to combine their environmental work with other tasks, which made their job even more difficult. - Generally speaking, supervisors were not given sufficient authority and autonomy because productivity at the construction site had priority over environmental management. This was due to the fact that the company management did not have a respectful attitude toward the environment, nor was the management actively involved in the establishment of the EMS. - Insufficient resources were allocated to the Environmental Management Unit. As a result, the application of EMSs in construction projects often appeared to be more of a formality, which was merely a way of maintaining the certification of the Environmental Management System. It was more a means of meeting the requirements for submitting a tender to contracting organisms rather than an indicator of any real commitment to improving the environmental performance of construction companies.  相似文献   
627.
In this paper, we show that the potential for endogenous technological change in alternative energy sources may alter the behaviour of resource-owning firms. When technological progress in an alternative energy source can occur through learning-by-doing, resource owners face competing incentives to extract rents from the resource and to prevent expansion of the new technology. We show that in such a context, it is not necessarily the case that scarcity-driven higher traditional energy prices over time will induce alternative energy supply as resources are exhausted. Rather, we show that as we increase the learning potential in the substitute technology, lower equilibrium energy prices prevail and there may be increased resource extraction and greenhouse gas emissions. We show that the effectiveness and the incidence of emissions reduction policies may be altered by increased potential for technological change. Our results suggest that treating finite resource rents as endogenous consequences of both technological progress and policy changes will be important for the accurate assessment of climate change policy.  相似文献   
628.
629.
630.
测定自来水中铀浓度及其变化规律,对评估饮用水质量及公众接受的铀放射水平有较大意义。该文介绍了经过一年连续监测所获得的上海市自来水中铀浓度及其变化。结果表明,上海市自来水中铀浓度在0.025 ̄0.28μg/L之间,年均值为0.112μg/L;一年中的12月-15月浓度较高,6-11月浓度略低,其中3月份浓度最高,8月份深度最低,上海市自来水中铀浓度较低,比全国平均浓度低一个数量级。  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