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   5187篇
  免费   523篇
  国内免费   310篇
测绘学   1061篇
大气科学   285篇
地球物理   788篇
地质学   1433篇
海洋学   1103篇
天文学   13篇
综合类   476篇
自然地理   861篇
  2024年   10篇
  2023年   21篇
  2022年   74篇
  2021年   125篇
  2020年   161篇
  2019年   155篇
  2018年   134篇
  2017年   254篇
  2016年   199篇
  2015年   239篇
  2014年   301篇
  2013年   386篇
  2012年   309篇
  2011年   342篇
  2010年   305篇
  2009年   305篇
  2008年   355篇
  2007年   339篇
  2006年   337篇
  2005年   278篇
  2004年   234篇
  2003年   172篇
  2002年   190篇
  2001年   150篇
  2000年   111篇
  1999年   131篇
  1998年   77篇
  1997年   72篇
  1996年   39篇
  1995年   44篇
  1994年   33篇
  1993年   29篇
  1992年   17篇
  1991年   13篇
  1990年   15篇
  1989年   11篇
  1988年   16篇
  1987年   9篇
  1986年   4篇
  1985年   7篇
  1984年   9篇
  1983年   3篇
  1982年   3篇
  1981年   1篇
  1971年   1篇
排序方式: 共有6020条查询结果,搜索用时 15 毫秒
151.
第二松花江干流区地下水信息管理数据库系统开发与研制   总被引:1,自引:0,他引:1  
介绍了第二松花江干流区地下水信息管理数据库系统的开发环境及总体设计。在分析与地下水有关的数据信息的基础上,提出了较为合理的地下水信息管理数据库系统的结构。将该系统按其功能分为5个子系统基础子系统、数据信息管理子系统、区域信息管理子系统、动态绘图子系统、水资源评价子系统,并对5个子系统的功能进行了详细阐述。  相似文献   
152.
As one of the most powerful tools to reduce the earthquake loss, the Earthquake Disaster Management [EDM] and Insurance [EI] have been highlighted and have had a great progress in many countries in recent years. Earthquake disaster management includes a series of contents, such as earthquake hazard and risk analysis, vulnerability analysis of building and infrastructure, earthquake aware training, and building the emergency response system. EI, which has been included in EDM after this practice has been done for many years, include these contents: insurance model, financing. This paper presents the development of china in EDM and EI. The main contents include: (1) the statue and trend of earthquake disaster management and insurance in china; (2) the progresses and new methods about the seismic risk zonation and vulnerability analysis, and the future developing trend, the application of GIS in earthquake disaster assessment is introduced; (3) the way and illustration in building the earthquake disaster e  相似文献   
153.
郭发明 《中国煤田地质》2004,16(3):66-67,70
现代企业必须建立严密的、完善的控制系统,严格的、科学的管理制度,有效的、畅通的运行机制,才能保证经营目标的实现。内部审计可以及时发现经营管理中的薄弱环节和存在的漏洞,及时、准确提醒企业决策者采取措施加以改进,有利于企业不断发展壮大。  相似文献   
154.
21世纪中国地质灾害防治形势与减灾战略思考   总被引:9,自引:0,他引:9  
文章论述了21世纪中国地质灾害减灾面临的形势是既存在许多有利条件又存在多方面困难而面临严重挑战。提出21世纪地质灾害减灾战略:1.建立地质灾害防治安全维护体系;2.优先安排西部地区地质灾害防治工程,实施地质灾害风险管理;3.建立矿山地质灾害防治监督管理体系;4.城市地质灾害防治与土地利用相结合;5.加强我国地质环境监测与网站建设;6.针对地质灾害区域分布规律,采取分区减灾对策;7.加大地质灾害防治投入力度。  相似文献   
155.
根据MapInfo在其它领域应用的原理,利用其包含图形信息对象的数据表是图形和数据之间有机结合的概念,从矿山生产勘探的管理特点出发,论述MapInfo在矿山生产勘探过程中对勘探资料图和储量计算表的对应管理,探讨了矿山生产勘探的管理过程数字化的一种新方法。  相似文献   
156.
库区塌岸空间信息管理系统构建   总被引:3,自引:1,他引:3  
以ArcGIS为平台,扩展其专业功能,建立一套集库区塌岸预测与防治有关的基本信息采集、信息管理、预测评价,以及塌岸防治工程决策于一体的“库区塌岸信息管理系统及防治决策支持系统”。建立起库区各数据库和各库岸段的塌岸模式数据库,结合典型塌岸防治实例、专家经验、专家知识,建立塌岸防治决策支持系统,为库区塌岸防治工程的宏观决策提供技术支撑,同时也可对重大灾情进行及时预警预报提供数据支撑。  相似文献   
157.
J. S. Mani 《Natural Hazards》2004,31(2):523-536
Chennai coast, right from the inception of Madras harbourin the year 1876, has been experiencinghostile conditions such as (i) coastal erosion, (ii) sandbar formation at the entrance to inlets, (iii) sea water ingression and (iv) change insea bed elevation, etc. In addition, construction of a new satellite harbour, about18 km north of Madras harbour has produced a negative impact on the delicatecoastal features such as (i) Pulicat lake, (ii) Ennore shoals, etc. Construction ofthis satellite harbour has led to the accumulation of sand south of the southbreakwater of the harbour and its accelerated growth is of concern to an inletlocated 2.6~km south of the harbour. `Coastal erosion', a perennial problemassociated with north Chennai sea front for the past 100 years has been addressedin this paper. The paper discusses on a long term solution and details of themethodologies to be adopted for effective management of the coast. Thesolution presented in this paper is based on numerical model study consideringthe nearshore currents and wave induced sediment transports.  相似文献   
158.
This paper examines the melding of two discourses in southeastern Zimbabwe: land reform and wildlife management. The former seeks to redistribute large, ‘under-utilized’ landholdings to smallholders whilst the latter needs extensive land holdings to be viable. These two discourses are rooted in very different models of development. The land reform exercise emphasizes direct redistribution, equity and land for crops; whilst the wildlife management discourse tends to stress maximizing foreign exchange earnings, encouraging public-private partnerships and trickle down. Yet there has been a recent flurry of interest in the development of ‘wildlife models’ for land reform which would combine the two. This paper investigates whether the competing discourses about land for smallholders and wildlife-based land reform are compatible or can be successfully reconciled. It traces the ways they have come together in Zimbabwe’s southeast lowveld and examines the ‘science’ and politics underlying their melding. Finally it explores the potential implications for rural people’s livelihoods of this development. It concludes that land reform and wildlife management can be reconciled, but probably not in a particularly equitable way: it is more likely to provide an opening for an equitable land reform agenda to be usurped by local and non-local elites with wildlife interests.  相似文献   
159.
S. O. Asamu 《GeoJournal》2004,61(2):183-189
There is a general shortage of potable water in Nigeria, partly through the lack of natural provision and partly because of rapid urban growth that has largely been unplanned. The paper describes the recent redevelopment of a public water facility in a run-down area of Ibadan which is part of the Sustainable Ibadan Project. Despite funding from national and international bodies, the development is strongly based at community level. The local inhabitants feel they have control over their own water supply through their representatives on the various planning and managing committees. This aims to reduce vandalism and to increase pride and involvement in the community. The project is a pilot for other projects around Ibadan, some of which have begun and others are being planned. This paper describes the administrative structures and management principles that have been employed. It forcefully advocates community-based planning and management which respects both the environment and the water-users, and involves a major “bottom-up” element. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
160.
Bakir  P.G. 《Natural Hazards》2004,33(3):405-425
While laboratory and analytical studies can provide valuable information about earthquake hazard mitigation, the most effective educator is the impact of a full-scale earthquake on a full-scale city. The recent earthquakes in Turkey showed that the governmental as well as individual attitudes towards earthquakes did not represent proportionate responses to the risk levels concerned. Turkey had weaknesses in preparing, planning, mitigating and responding to disasters in spite of the known seismic vulnerability of the country. Many steps have been taken after 1999 earthquakes in Turkey, however, the preparations largely concentrate on the response and recovery phases and a fundamental step to reform the current disaster management system and steps to rehabilitate the vulnerable building stock has not been undertaken until today. This would involve changing the present laws and regulations and de-centralising the disaster management system. The aim of this paper is to propose a national mitigation strategy for Turkey for a time-frame of 10 years. The model proposed is a very comprehensive model for earthquake risk reduction in Turkey and within this context, the legislative and technical aspects of mitigation will be discussed in detail. Strategies for mitigating and retrofitting the existing building stock will also be proposed.  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