全文获取类型
收费全文 | 8375篇 |
免费 | 1131篇 |
国内免费 | 1053篇 |
专业分类
测绘学 | 1326篇 |
大气科学 | 708篇 |
地球物理 | 1657篇 |
地质学 | 3031篇 |
海洋学 | 1666篇 |
天文学 | 41篇 |
综合类 | 726篇 |
自然地理 | 1404篇 |
出版年
2024年 | 19篇 |
2023年 | 54篇 |
2022年 | 241篇 |
2021年 | 318篇 |
2020年 | 357篇 |
2019年 | 341篇 |
2018年 | 251篇 |
2017年 | 423篇 |
2016年 | 369篇 |
2015年 | 401篇 |
2014年 | 489篇 |
2013年 | 609篇 |
2012年 | 553篇 |
2011年 | 547篇 |
2010年 | 520篇 |
2009年 | 493篇 |
2008年 | 547篇 |
2007年 | 539篇 |
2006年 | 528篇 |
2005年 | 444篇 |
2004年 | 407篇 |
2003年 | 302篇 |
2002年 | 302篇 |
2001年 | 264篇 |
2000年 | 210篇 |
1999年 | 230篇 |
1998年 | 137篇 |
1997年 | 127篇 |
1996年 | 90篇 |
1995年 | 87篇 |
1994年 | 74篇 |
1993年 | 74篇 |
1992年 | 41篇 |
1991年 | 46篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1971年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
海洋作业渔船管理系统的设计与运行试验 总被引:1,自引:0,他引:1
对渔政管理指挥系统建设项日中的业务软件部分渔船管理系统的设计方案进行了介绍。根据我国渔洋作业渔船的实际管理模式,提出了渔船管理系统设计方案。系统通过网络化的业务处理和管理流程,规范渔船建造、审批、登记以及捕捞许可证发放等管理业务,实现渔船控制指标的统一分配,以控制捕捞业发展规模和保护我国的渔业资源。系统以Microsoft VB6.0,Delphi6.0开发,在Window98/2000/XP环境下运行。通过运行试验,对系统运行环境进行了评估,为渔政管理信息化的建设、系统升级提供了经验和技术依据。 相似文献
122.
Access to information about past states of the environment and social systems is fundamental to understand, and cope with, the challenges of climate change and over-exploitation of natural resources at the onset of the 21st century. The loss of (old) data is a major threat to understanding better and mitigating long-term effects of human activities and anthropogenic changes to the environment. Although this is intuitively evident for old and local literature of any kind, even present-day international publishing of papers without the underlying raw data makes access to basic information a crucial issue. Here, we summarise experience resulting from a EU-funded International Science & Technology Cooperation (INCO) project (CENSOR) addressing Coastal Ecosystem Research and Management in the El Niño Southern Oscillation (ENSO) context. We show that indeed “Grey Literature” is still one of the most important sources of knowledge about natural science research and management of natural resource systems in Latin American countries. We argue that public archiving of original data of present-day research and old (Grey) Literature and easy public access are important for appreciating today's global environmental challenges caused by human activities, both past and present. 相似文献
123.
124.
李柱臣 《中国地理科学(英文版)》1992,2(1):56-63
The Loess Plateau is one of China s developing areas where socio-econ-omy is backward, ecological environment deteriorated and people's life difficult.The purpose of carrying out comprehensive development of the area's agriculture is, in essence, to open up new fields of agro-production, to intensify the utilization of related resources, to raise productivity and to win bigger output. The decision is important, as by so doing, the physical landscape could be tranformed, the local economy could be flourished, and the people's standard of living could be improved, and moreover the national development strategy of "depending on the East and shifting to the West" and building Shanxi Province into an energy and chemical industrial base could be realized.Based on field investigations in recent years, the auther proposed the purpose, target, principles, steps, tactics and strategies for the comprehensive development of the are's agriculture. 相似文献
125.
126.
127.
利用雷电定位系统进行电网雷击故障快速查询(英文) 总被引:1,自引:0,他引:1
At present, lightning is one of the 10 natural disasters, and it is also the top environmental factor of power interruption. It often causes huge losses to the electric system. The Wuhan High Voltage Institute of the State Grid Corporation of China and Huazhong University of Science and Technology have been researching and developing lightning location systems (LLSs) since the late 1980s. In the mid-1990s, a lightning detection network was created in 29 provinces and cities in China. It is primarily applied to rapidly find lightning accidents, which greatly reduces power interruption. Also, it ensures high efficiency and safe operation of the electricity system. Remarkable benefit is achieved. China's LLS went through an "orientation positioning - time difference positioning - integrated positioning" development process. The positioning precision, detection efficiency, degree of automation, practicability and applied range are improved. Also, a lightning information system plan of the national network has been implemented, which services the whole society. 相似文献
128.
129.
城市公共卫生安全应急管理系统技术集成研究 总被引:2,自引:1,他引:1
从国内城市公共卫生安全应急管理系统的研究和应用现状出发,指出城市公共卫生安全应急管理系统建设的核心要务是集成现有的卫生信息系统、消除卫生信息孤岛、实现数据共享与交换;并提出了城市公共卫生安全应急管理系统数据采集类型和业务支持部门。在此基础上,构建了一个基于数据仓库、以GIS为应急响应支持平台、能统一管理信息、可与其他电子政务系统互连互通的城市公共卫生安全应急管理系统框架结构,并详细阐述了各业务模块的基本功能和系统实现的关键技术方法。 相似文献
130.