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   2444篇
  免费   243篇
  国内免费   349篇
安全科学   199篇
废物处理   29篇
环保管理   526篇
综合类   1252篇
基础理论   306篇
污染及防治   74篇
评价与监测   141篇
社会与环境   431篇
灾害及防治   78篇
  2024年   12篇
  2023年   31篇
  2022年   78篇
  2021年   88篇
  2020年   64篇
  2019年   70篇
  2018年   80篇
  2017年   104篇
  2016年   102篇
  2015年   121篇
  2014年   86篇
  2013年   152篇
  2012年   175篇
  2011年   193篇
  2010年   161篇
  2009年   143篇
  2008年   118篇
  2007年   193篇
  2006年   166篇
  2005年   104篇
  2004年   99篇
  2003年   90篇
  2002年   79篇
  2001年   53篇
  2000年   81篇
  1999年   67篇
  1998年   36篇
  1997年   43篇
  1996年   42篇
  1995年   33篇
  1994年   33篇
  1993年   26篇
  1992年   24篇
  1991年   9篇
  1990年   10篇
  1989年   8篇
  1988年   5篇
  1987年   8篇
  1986年   3篇
  1985年   4篇
  1983年   6篇
  1982年   3篇
  1980年   8篇
  1979年   4篇
  1978年   3篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1972年   4篇
  1971年   2篇
排序方式: 共有3036条查询结果,搜索用时 375 毫秒
211.
生态系统服务价值的变化决定着区域的可持续发展,其评估已成为生态学研究的热点之一,其研究结果对维持地区生态平衡、合理利用土地资源、建立可持续的土地利用模式等具有重要意义。本文在综合已有研究的基础上,通过估算万源市太平镇不同海拔高度土地生态服务价值量,探讨经济发展与生态服务价值变化的关系。结果表明,城市规划区的自然生态系统服务功能的价值是不可忽视的,自然生态系统无论是从物质上还是经济上,都为万源市太平镇的国民经济和社会可持续发展提供者重要支撑。从生态系统服务功能角度,海拔750 m高程是太平镇城市用地扩张的控制线。  相似文献   
212.
Carbon emission is the current hot issue of global concern. How to assess various contributing factors for carbon emission is of great importance to find out the key factors and promote carbon emission reduction. In this paper, the author constructs an identical equation for carbon emission, based on the economic aggregate, the economic structure, the efficiency of energy utilization, the structure of energy consumption, and the coefficient of carbon emission; by applying to LMDI decomposition technology, the author analyzes the carbon emission of China from 1995 to 2007 at industrial level and regional level. The results show that the expansion of economic aggregate is the main reason for China’ s rapidly increasing carbon emission and the increase of energy utilization efficiency is the key factor that can hold back the increase of carbon emission. In addition, the change of industrial structure or regional structure and the change of traditional energy structure have limited influence on the carbon emission, and their potentials have not yet been exploited. At the end of this paper, the author proposes the efforts that China should make to reduce carbon emission.  相似文献   
213.
农地资源不仅具有经济生产功能,还具有大气调节、涵养水源、保持土壤成分、休闲娱乐等多种生态功能,而在非农化过程中这些功能在市场中没有以价格的形式体现出来,没有包含在农地的现实价值中。因而,有必要对农地的非市场功能进行详尽的分类及价值估算。同时,将由于市场失灵而没能包含到农地总价值中的生态环境等非市场价值纳入到成本效益决策中,来减少市场失灵所造成的农地非农化的效率损失。通过对农地非市场功能的具体分类及量化,测算我国不同经济区域因市场失灵导致的农地非农化过度损失,结果显示,代表东、中、西部地区的江苏、湖北和甘肃省的农地非农化过度损失Ⅰ分别为31.58%、38.13%和43.85%,这为我国农地非农化的行为调控及相应公共政策措施的制订和实施提供了理论依据。  相似文献   
214.
高铁时代到来的区域影响和意义   总被引:2,自引:0,他引:2  
近年来,全国范围内的高铁网络建设成为全社会关注的焦点之一。高铁之所以倍受青睐,是在于其显著优点:速度快、输送能力大、安全性好、舒适方便、能耗低、经济效益好。伴随着“四纵四横”客运专线建设的全面展开,我国将步入高铁时代。高铁缩短了人流、物流、信息流的时空距离,开启了一个新经济时代的来临。因此,高铁时代的到来势必将具有深远的区域影响和意义。高铁将加速和放大都市经济圈同城效应,改变人们的生产、生活方式;高铁将加快中心城市引领的大区域板块的融合和共促共赢;高铁将促进旅游、房地产等沿线产业的升级,推进沿线城市规划的重新布局;高铁将引发空、陆、水三大现代交通运输方式的重组,带来人们出行方式的多样化  相似文献   
215.
During the 11th Five Year Plan period,China improved its policy system for the overall strategy of regional development,and established and completed the policies intended for the promotion of regional cooperation and interaction.Thereupon,regional development in China took on a series of positive changes such as the enhancement of coordination.During the 12th Five Year Plan period,China will fully implement and continuously improve the policy measures for development in its four major regions,strengthen differentiated guidance to different regions in line with the planning for major function-oriented zones,and accelerate the establishment of basic systems that facilitate coordinated regional development.  相似文献   
216.
During the 11^th Five Year Plan period, China improved its policy system for the overall strategy of regional development, and established and completed the policies intended for the promotion of regional cooperation and interaction. Thereupon, regional development in China took on a series of positive changes such as the enhancement of coordination. During the 12^th Five Year Plan period, China will fully implement and continuously improve the policy measures for development in its four major regions, strengthen differentiated guidance to different regions in line with the planning for major function-oriented zones, and accelerate the establishment of basic systems that facilitate coordinated regional development.  相似文献   
217.
以宝天高速公路为背景,讨论了公路建设对水体环境的主要影响,并利用改进的密切值法对公路沿线地表水进行水环境质量现状评价.通过评价表明:沿线地表水质量良好,基本达到地表水环境Ⅰ级标准;评价结果真实地反映了天宝高速公路沿线水体水质的基本情况,说明采用密切值法对水体进行评价是可行的;该方法概念清晰、计算简便实用,能较好地反映区域内各水体水环境质量的相对优劣,可为制定环境规划、进行环境决策、实施环境综合整治提供科学依据.  相似文献   
218.
我国经济高速发展的同时,出现了矿产资源大量消耗和环境严重污染的问题。许多学者认为是矿产资源国家所有权惹的祸,极力倡导所有权改制。从理性的角度出发分析,出现这种现象并不是国家所有权惹的祸,而是国家所有权的管理体制不再适应今天市场化的要求,应从管理体制和竞争方面来加强矿产资源的管理。  相似文献   
219.
The management of endangered species under climate change is a challenging and often controversial task that incorporates input from a variety of different environmental, economic, social, and political interests. Yet many listing and recovery decisions for endangered species unfold on an ad hoc basis without reference to decision‐aiding approaches that can improve the quality of management choices. Unlike many treatments of this issue, which consider endangered species management a science‐based problem, we suggest that a clear decision‐making process is equally necessary. In the face of new threats due to climate change, managers’ choices about endangered species require closely linked analyses and deliberations that identify key objectives and develop measurable attributes, generate and compare management alternatives, estimate expected consequences and key sources of uncertainty, and clarify trade‐offs across different dimensions of value. Several recent cases of endangered species conservation decisions illustrate our proposed decision‐focused approach, including Gulf of Maine Atlantic salmon (Salmo salar) recovery framework development, Cultus Lake sockeye salmon (Oncorhynchus nerka) management, and Upper Columbia River white sturgeon (Acipenser transmontanus) recovery planning. Estructuración de Decisiones para Manejar Especies Amenazadas y en Peligro en un Clima Cambiante  相似文献   
220.
There is a widespread recognition of the need for better information sharing and provision to improve the viability of end-of-life (EOL) product recovery operations. The emergence of automated data capture and sharing technologies such as RFID, sensors and networked databases has enhanced the ability to make product information; available to recoverers, which will help them make better decisions regarding the choice of recovery option for EOL products. However, these technologies come with a cost attached to it, and hence the question ‘what is its value?’ is critical. This paper presents a probabilistic approach to model product recovery decisions and extends the concept of Bayes' factor for quantifying the impact of product information on the effectiveness of these decisions. Further, we provide a quantitative examination of the factors that influence the value of product information, this value depends on three factors: (i) penalties for Type I and Type II errors of judgement regarding product quality; (ii) prevalent uncertainty regarding product quality and (iii) the strength of the information to support/contradict the belief. Furthermore, we show that information is not valuable under all circumstances and derive conditions for achieving a positive value of information.  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