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   94篇
  免费   6篇
  国内免费   8篇
安全科学   7篇
废物处理   1篇
环保管理   9篇
综合类   22篇
基础理论   47篇
污染及防治   13篇
评价与监测   3篇
社会与环境   2篇
灾害及防治   4篇
  2022年   3篇
  2021年   2篇
  2020年   2篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   5篇
  2015年   2篇
  2014年   2篇
  2013年   4篇
  2012年   2篇
  2011年   13篇
  2010年   7篇
  2009年   20篇
  2008年   10篇
  2007年   4篇
  2006年   10篇
  2005年   2篇
  2004年   3篇
  2003年   4篇
  2002年   1篇
  2000年   1篇
  1998年   1篇
  1995年   1篇
排序方式: 共有108条查询结果,搜索用时 15 毫秒
91.
Gastrointestinal tract atresia has an incidence of 1 in 10 000 live-births, while gastric outlet obstruction comprises only approximately 1 per cent of these malformations. A prenatally diagnosed case is described, followed by a discussion regarding the diagnosis and possible associated abnormalities.  相似文献   
92.
介绍了国内外利用Internet网进行大气污染监测的状况,提出了基于Intemet的大气污染监测的在线系统,设计了监测系统的功能,选择了系统实现环境。设计了数据库的结构。  相似文献   
93.
Abstract:  Coastal marine ecosystems worldwide have undergone such profound transformations from overfishing that trophic interactions observed today might be artifacts of these changes. We determined whether the trophic level of an endangered seabird, the Marbled Murrelet ( Brachyramphus marmoratus ), has declined over the past 100 years after the collapse of Pacific sardine ( Sardinops sadax ) fisheries in the late 1940s and the recent declines of similar fisheries in central California. We compared stable-isotope signatures of δ15N and δ13C in feathers of museum specimens collected before fisheries decline with values in murrelet feathers collected recently. Values of δ15N in prebreeding diets declined significantly, 1.4‰ or 38% of a trophic level, over the past century during cool ocean conditions and by 0.5‰ during warm conditions, whereas postbreeding values of δ15N were nearly constant. The δ13C values in prebreeding diets declined by 0.8‰, suggesting an increased importance of krill in modern compared with historic prebreeding diets, but postbreeding diets did not change. Stable-isotope mixing models indicated that the proportion of energetically superior, high-trophic-level prey declined strongly whereas energetically poor, low-trophic-level and midtrophic-level prey increased in the prebreeding diet in cool years when murrelet reproduction was likely to be high. Decreased prey resources have caused murrelets to fish further down on the food web, appear partly responsible for poor murrelet reproduction, and may have contributed to its listing under the U.S. Endangered Species Act.  相似文献   
94.
本文调查了我国官方环保网站的现状和存在的问题,提出了互联网环境管理的定义、功能、运作机制和官方环保网站的基本要求。  相似文献   
95.
研究了基于ArcSDE的防震减灾遥感数据库系统的框架结构、建库过程及利用ArclMS建立海量遥感影像网络发布系统的体系结构.分析了遥感影像网络发布系统中自动创建地图服务、不同坐标系统的矢量和影像数据的叠加显示、远程图像处理等关键技术.同时,介绍了系统的功能和目前系统包含的主要遥感影像库和矢量库.该遥感影像网络发布系统实现了遥感技术、数据库技术以及网络地理信息系统技术在防震减灾工作中的综合应用.  相似文献   
96.
以有毒有害危险气体突发性泄漏扩散事故为研究对象,对基于网络地理信息系统(WebGIS)的危险气体泄漏扩散预警信息平台进行研究,根据需求,对平台的总体结构设计、功能设计、数据库设计和技术实现等方面进行了深入的探讨;采用B/S模式,利用ArcGIS,ASP.NET和VB.NET开发出预警信息平台,并通过Internet发布相关信息。该研究项目为环境管理部门对突发性气体泄漏事故的预警、指挥、调度以及对事故的控制提供了准确的预测信息和及时的技术支持,对提高事故应急救援指挥和救援行动的效率有重要的意义。  相似文献   
97.
Projecting the consequences of warming and sea-ice loss for Arctic marine food web and fisheries is challenging due to the intricate relationships between biology and ice. We used StrathE2EPolar, an end-to-end (microbes-to-megafauna) food web model incorporating ice-dependencies to simulate climate-fisheries interactions in the Barents Sea. The model was driven by output from the NEMO-MEDUSA earth system model, assuming RCP 8.5 atmospheric forcing. The Barents Sea was projected to be > 95% ice-free all year-round by the 2040s compared to > 50% in the 2010s, and approximately 2 °C warmer. Fisheries management reference points (FMSY and BMSY) for demersal fish (cod, haddock) were projected to increase by around 6%, indicating higher productivity. However, planktivorous fish (capelin, herring) reference points were projected to decrease by 15%, and upper trophic levels (birds, mammals) were strongly sensitive to planktivorous fish harvesting. The results indicate difficult trade-offs ahead, between harvesting and conservation of ecosystem structure and function.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01616-9.  相似文献   
98.
基于Web Services的重大危险源管理平台实践   总被引:1,自引:1,他引:0  
重大危险源的监督管理是安全生产需要解决的问题之一。随着计算机技术的快速发展,信息化的手段已经在安全生产领域广泛应用。本文通过对Web Services技术的研究,详细分析了Web Services的体系结构,讨论了WSDL、SOAP、UDDI三个关键对象的构建。基于Web Services体系架构,根据对重大危险源的监管需求,本文实现了一个重大危险源管理平台,该平台是一个中心、多个部门、多个节点的B/S系统,通过该管理平台,可以有效的实现重大危险源的登记、查询、统计、应急管理等功能,为重大危险源的监管提供了信息化手段,有效提升了管理效率。  相似文献   
99.
Based on a review of available models for ecological risk estimation, most are site-specific and their applications are limited. However, general models, which can be easily adapted to other sites, remain few, in addition, they are simple and associated with significant uncertainties. In this paper, an approach is introduced for an ecological risk assessment (ERA) model that can be modified for site-specific conditions. Using computer simulation as a screening tool for ecological risk assessment can assist environmental managers and policy decision-makers in the planning and implementation of potentially highly focused assessments and remediation, should the ERA dictate the need. The model was integrated with a Windows-based interface and interactive database management system (DBMS) as a user-friendly software package. In addition, based on trophic sources, a food web has been integrated into the framework of the DBMS. In an effort to evaluate the model, a case study was implemented to characterize the effects on an ecosystem of replacing electroplated chromium coatings with sputtered tantalum at U.S. Army Yuma and Aberdeen Proving Grounds. Potential exposure pathways included ingestion, inhalation, and dermal absorption for terrestrial animals; root and foliar uptake for plants; and direct absorption for aquatic species. Overall, results showed that the most significant exposure resulted from molybdenum and hexavalent chromium, which posed higher risks to select aquatic and terrestrial species at both sites. On the other hand, tantalum (with vanadium as the surrogate) resulted in the least risk to all receptors within the studied areas. A sensitivity analysis demonstrated that soil-water distribution coefficients have a significant impact on the results. Based on the results, neither molybdenum nor chromium are recommended as a coating in gun barrels, and further study would be essential to address any affected firing range area. Tantalum is recommended for use, although for those species receiving a slight adverse risk, field investigations that include receptor sampling maybe necessary once soil/sediment and water sampling validates projected concentrations.  相似文献   
100.
基于我国平腹杆双肢柱厂房的实际情况,分析了钢筋混凝土平腹杆双肢柱的破损机理,并提出了加固处理方法。  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