全文获取类型
收费全文 | 5526篇 |
免费 | 1067篇 |
国内免费 | 713篇 |
专业分类
测绘学 | 899篇 |
大气科学 | 938篇 |
地球物理 | 1828篇 |
地质学 | 2107篇 |
海洋学 | 565篇 |
天文学 | 38篇 |
综合类 | 301篇 |
自然地理 | 630篇 |
出版年
2024年 | 14篇 |
2023年 | 44篇 |
2022年 | 108篇 |
2021年 | 167篇 |
2020年 | 218篇 |
2019年 | 217篇 |
2018年 | 175篇 |
2017年 | 252篇 |
2016年 | 235篇 |
2015年 | 225篇 |
2014年 | 291篇 |
2013年 | 451篇 |
2012年 | 335篇 |
2011年 | 357篇 |
2010年 | 260篇 |
2009年 | 336篇 |
2008年 | 348篇 |
2007年 | 393篇 |
2006年 | 374篇 |
2005年 | 322篇 |
2004年 | 313篇 |
2003年 | 308篇 |
2002年 | 204篇 |
2001年 | 205篇 |
2000年 | 203篇 |
1999年 | 174篇 |
1998年 | 135篇 |
1997年 | 131篇 |
1996年 | 119篇 |
1995年 | 76篇 |
1994年 | 79篇 |
1993年 | 60篇 |
1992年 | 44篇 |
1991年 | 18篇 |
1990年 | 39篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有7306条查询结果,搜索用时 62 毫秒
41.
气象灾害每年都有,只是轻重程度不同。就全国和全省范围来说,很少有真正风调雨顺的年份。本文根据1951~1988年38年的气象历史资料及有关政府部门的材料、简报、报道,统计出台风、洪涝、海上大风和强对流等几种主要气象灾害对浙江经济造成损失和伤亡人数。文中对主要气象灾害的特点、一般规律和灾情作了概述,并列出一些典型实例,提出了预防气象灾害的意见。 相似文献
42.
Alberto Omar Vazquez-Hernandez Gilberto Bruno Ellwanger Luís Volnei Sudati Sagrilo 《Applied Ocean Research》2006,28(6):398-406
The characteristic environmental load effect for the design of mooring systems of floating units can be defined by means of three procedures: (a) the one associated to an extreme sea state with a given return period, (b) the worst one from a set of sea states on a contour line associated to a return period or (c) the extreme one based on response statistics for a long-term period. This work presents the result of a reliability-based partial safety factor calibration study for a LRFD mooring line design criteria considering the three approaches mentioned above. The calibration exercise is applied to three FPSOs considering North Sea environmental conditions and different water depths: 200, 800 and 3000 m. The mooring systems investigated take into account mooring lines made up of chains and polyester ropes. It is shown that, among all cases investigated, the design procedure based on the long-term response is the one that presents less scattered reliability indices around the target level. 相似文献
43.
The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results show that the mooring system has an annual reliab 相似文献
44.
45.
46.
47.
GIS和RS技术在城市规划设计中的应用探讨 总被引:3,自引:0,他引:3
数字技术时代的到来,城市规划行业面临机遇和挑战。本文针对国内目前3S技术在城市规划管理层次应用较广而在规划设计方面应用薄弱这一现状,结合规划设计相关案例介绍GIS和RS技术在规划设计方面的辅助应用。案例选用ArcGIS软件介入规划设计的全过程,进行现状地形分析、三维模拟等辅助分析,并与Sketchup建模充分结合制作大范围三维漫游动画,辅助推敲规划建筑与周边环境相互关系,同时还充分利用GoogleEarth与Sketchup和ArcGIS之间的接口,将规划方案和建筑模型导入全球卫星影像,从而更好地辅助规划决策和公众参与等。 相似文献
48.
SVLBI (space very long baseline interferometry) has some important potential applications in geodesy and geodynamics, for which one of the most difficult tasks is to precisely determine the orbit of an SVLBI satellite. This work studies several technologies that will possibly be able to determine the orbit of a space VLBI satellite. Then, according to the types and charac- teristics of the satellite and the requirements for geodetic study and the geometry of the GNSS (GPS, GALILEO) satellite to track the space VLBI satellite, the six Keplerian elements of the SVLBI satellite (TEST-SVLBI) are determined. A program is designed to analyze the coverage area of space of different altitudes by the stations of the network, with which the tracking network of TEST-SVLBI is designed. The efficiency of tracking TEST-SVLBI by the network is studied, and the results are presented. 相似文献
49.
50.