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   311篇
  免费   24篇
  国内免费   52篇
安全科学   73篇
废物处理   4篇
环保管理   39篇
综合类   169篇
基础理论   36篇
污染及防治   9篇
评价与监测   22篇
社会与环境   10篇
灾害及防治   25篇
  2024年   3篇
  2023年   3篇
  2022年   6篇
  2021年   11篇
  2020年   5篇
  2019年   11篇
  2018年   7篇
  2017年   8篇
  2016年   11篇
  2015年   6篇
  2014年   17篇
  2013年   20篇
  2012年   13篇
  2011年   29篇
  2010年   17篇
  2009年   11篇
  2008年   17篇
  2007年   38篇
  2006年   25篇
  2005年   14篇
  2004年   16篇
  2003年   17篇
  2002年   17篇
  2001年   9篇
  2000年   18篇
  1999年   6篇
  1998年   5篇
  1997年   4篇
  1996年   5篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1991年   3篇
  1989年   3篇
  1988年   4篇
排序方式: 共有387条查询结果,搜索用时 31 毫秒
81.
上海市在用车监测与维修制度探讨   总被引:1,自引:0,他引:1  
刘昶  屠莹 《上海环境科学》2003,22(6):373-378
根据上海市机动车辆的管理现状,提出上海市在用车I/M制度体系网络、监测方法、数据收集网络与“通过/不通过”排放限值方面的基本设想,为建立一个真正有效的在用车监测与维修制度提供依据。  相似文献   
82.
史云祥  焦峰  顾强 《环境科技》2003,16(3):12-14
在ARCINFO中的GRID模块的支持下,对宜兴市湖滏小流域的土地驱动力进行了研究,建立了以像元为单位的属性数据库,并随机选取了800个样点。采用LOGISTIC模型,探讨了社会经济因子与土地类型转移概率间的关系,揭示了任意两个土地类型相互转换的内在联系。  相似文献   
83.
本文在对内蒙古自治区煤炭行业发展现状分析的基础上,借鉴国内外煤炭行业及其企业推行清洁生产的实践经验,以循环经济"3R"原则,即减量化、再使用、资源化为指导,针对煤炭行业的污染特性,对适合本地区煤炭行业实施清洁生产的主要内容和相关技术进行了研究.  相似文献   
84.
论述了塑料模具标准件、通用件制造工艺数据库的开发过程。利用C++编程实现对数据库的检索、管理及用户界面设计,利用SQLServer建立工艺数据库,运用API编程技术完成工序图生成和编辑,采用ADO技术对数据库进行访问,以及系统的功能。  相似文献   
85.
环境污染事故应急监测技术管理系统开发初探   总被引:2,自引:1,他引:2  
通过实际开发研制突发性环境污染事故应急监测技术管理系统,对其开发思路、研制过程进行了探讨,并对系统的功能、特点及数据库结构进行了简单介绍,总结出此类系统的开发经验及实践应用效果,并对下一步的开发完善进行了展望。  相似文献   
86.
2002年7月美国通过了关于会计和公司治理一系列重大改革的索克斯法案(SOX Act),该法案以加强公司治理、强化信息披露为核心,主要内容是强化对高级管理人员的监管和防止外部审计失败.本文简单系统地介绍和分析了该法案中重要措施的相关内容和出台的原因,以期对我国当前公司治理和审计业发展有所启迪和帮助.  相似文献   
87.
Since 1994 data on fungal fruiting have been gathered in the Dawyck Botanic Garden outside Edinburgh, including that for eight plots within a 7.5 ha wood, which has been left unmanaged in order to investigate relationships amongst fungal succession, habitat characteristics and local weather patterns. The climatic data are provided by a small meteorological station situated on site. To handle nearly 4000 entries of data so far collected a computer database was constructed. This assists querying of the information so that changes in fungal communities and patterns of succession can be observed, and the relevant data extracted for further analysis. To aid in this analysis, and to give the user full control over editing, updating and querying the database, a special computer program was compiled.Analysis of the database records revealed that the currently known Dawyck fungal community comprises over 620 different taxa, and the species list increases every year. Although some species of mycorrhizal fungi showed high specificity towards their preferred host either at species (e.g. Lactarius blennius with beech, Lactarius quietus with oak, Russula fellea and Russula mairei with beech), or at genus level (e.g. Suillus spp. with Pinaceae), some other common fungi (e.g. of the genus Amanita) were found to have very wide host ranges. In addition, unusual mycorrhizal associations have also been recorded. A lime tree (Tilia), which is supposedly primarily endomycorrhizal, has been found regularly associated with Russula cyanoxantha, Russula parazurea, Russula pectinata and Inocybe fastigiata. Many common Scottish fungi were found to be associated with introduced exotic trees, which is illustrated on the example of Pseudotsuga menziesii (Douglas Fir).The software created utilises the Microsoft Office suite of programs. Microsoft Access was used to construct the database, and Microsoft Excel was used for statistical investigations. The software was programmed using Microsoft Visual Basic, and provided a means of extracting the necessary data stored in Access and controlling the formulae used in Excel for their analysis. The recorded seasonal patterns of fungal fruiting was successfully described by a simulation mathematical model comprising differential and algebraic equations. This model may now be used as a submodel within more complex models describing terrestrial ecosystem processes. Examples of model simulations and sensitivity analysis are given and implications for future research discussed.  相似文献   
88.
This paper examines the minimum essential requirements that must be satisfied when a database is established for life cycle inventory calculations. It shows that the format of the database is governed by the physical requirements of the system being examined, by the need to include iterative calculations within the analysis and by the demands of the final data presentation.  相似文献   
89.
炼油企业是用水大户,也是水污染大户,如何降低该类企业的用水量和排污量是当前节水研究的焦点之一,也是环境管理的重要内容.以提高企业节水减排的积极性为目标,本文依据层次分析法原理建立了炼油企业合理用水评价指标体系,分别采用相关系数法、相似系数法来确定指标体系中各层指标的权重,这样即保留了层次分析法分类清楚、解释性强的特点,又发挥了客观赋权法人为因素少的优点.  相似文献   
90.
Earthen embankment dams comprise 85% of all major operational dams in the United States. Assessment of peak flow rates for these earthen dams and the impacts on dam failure are of high interest to engineers and planners. Regression analysis is a frequently used risk assessment approach for earthen dams. In this paper, we present a decision support tool for assessing the applicability of nine regression equations commonly used by practitioners. Using data from 108 case studies, six parameters were observed to be significant factors predicting for peak flow as a metric for risk analysis. We present our work on an expanded earthen dam break database that relates the regression equations and underlying data. A web application, regression selection tool, is also presented to assess the appropriateness of a given model for a given test point. This graphical display allows users to visualize how their data point compares with the data used for the regression equation. These contributions improve estimates and better inform decision makers regarding operational and safety decisions.  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