全文获取类型
收费全文 | 9405篇 |
免费 | 2016篇 |
国内免费 | 2118篇 |
专业分类
测绘学 | 494篇 |
大气科学 | 1661篇 |
地球物理 | 5503篇 |
地质学 | 3631篇 |
海洋学 | 1028篇 |
天文学 | 46篇 |
综合类 | 571篇 |
自然地理 | 605篇 |
出版年
2024年 | 54篇 |
2023年 | 149篇 |
2022年 | 301篇 |
2021年 | 383篇 |
2020年 | 407篇 |
2019年 | 461篇 |
2018年 | 366篇 |
2017年 | 394篇 |
2016年 | 419篇 |
2015年 | 465篇 |
2014年 | 572篇 |
2013年 | 534篇 |
2012年 | 578篇 |
2011年 | 583篇 |
2010年 | 540篇 |
2009年 | 565篇 |
2008年 | 537篇 |
2007年 | 640篇 |
2006年 | 605篇 |
2005年 | 559篇 |
2004年 | 482篇 |
2003年 | 456篇 |
2002年 | 398篇 |
2001年 | 367篇 |
2000年 | 349篇 |
1999年 | 365篇 |
1998年 | 357篇 |
1997年 | 303篇 |
1996年 | 307篇 |
1995年 | 300篇 |
1994年 | 216篇 |
1993年 | 139篇 |
1992年 | 94篇 |
1991年 | 76篇 |
1990年 | 57篇 |
1989年 | 40篇 |
1988年 | 47篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 16篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1979年 | 10篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1954年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 173 毫秒
61.
A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach, in a TLP is assumed to be flexible instead of rigid, is based on a combination of the three dimensional source distribution method and the finite-element method. The hydrodynamic interactions among TLP members, such as columns and pontoons, are included in the motion and structural response analysis. Numerical results are compared with the experimental and numerical ones. The results of comparison confirmed the validity of the proposed approach. 相似文献
62.
63.
Wei Rulong Prof. Senior Engineer Geotechnical Engineering Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1994,(1)
-The shear strength and deformation properties of soft clay are discussed first. Then some methods for predicting the performance of soft clay foundation are proposed. Finally, case histories are presented to illustrate some discussed aspects of soft clay. 相似文献
64.
台湾海峡及其西边地区正常地震动态及危险性特征 总被引:1,自引:2,他引:1
本文从地震的时,空分布特征,区域应力场动态,能量释放方式,b值及震群特征6个方面研究了台湾海峡及其西边地区地震活动的正常动态及异常特征。结果表明,具有前兆意义的变化模式表现为区域地震活动在时间,空间及功能方面的有序性变化,即:(a)地震空间分布由分散转为集中,形成条带或空区;(b)断裂活动由多组转为单一,应力场趋向一致;(display status 相似文献
65.
The Effect of Internal Fluid on the Response of Vortex-Induced Vibration of Marine Risers 总被引:5,自引:1,他引:5
Based on Iwan‘s wake oseillator model developed with the classical van der Pol equalion, the differential equation for the response of the vortex-induced vihration (VIV) of the riser considering the effect of the internal flowing fluid and the external marine environmental condition is derived. The effect of the intermal flowing fluid on the response of VIV of the riser is studied by means of the Finite Element Method. The results show that the effect of the internal fluid velocity on the VIV of the riser is strong when the natural frequency of the riser is close to the vortex shedding frequency. In addition, the increase of the top tension can decrease the sensitivity of the riser to the internal fluid velocity. 相似文献
66.
The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long 相似文献
67.
68.
针对常垂直湍流系数和变垂直湍流系数两种情况,给出了开阔静止海面对风应力的非定常响应的解析表达式,并讨论了水深,风应力强弱对响应过程的影响,尽管没有考虑风场的非定常性,但本文的结果对理解海洋对风应力的非定常响应过程具有一定的帮助,对分析海面停风后的消衰过程也具有实际意义。通过与实测资料比较,认为垂直湍流系数模式要比常垂直湍流系数模式更为合理。 相似文献
69.
一个基于TOPEX卫星极端海面风速预测的海洋地理信息系统 总被引:4,自引:1,他引:4
在基于 TOPEX卫星数据建立全球极端海面风速预测模型的基础上 ,开发出用于极端海面风速预测和可视化预测结果的海洋地理信息系统 (MGIS)。并论述全球极端海面风速预测的意义和 MGIS在预测过程中的重要性及必要性 ;给出全球极端海面风速预测的统计模型 ;简述极端海面风速预测海洋地理信息系统的结构、工作流程和功能 ;同时 ,对系统的预测结果进行初步分析 相似文献
70.
- The dynamic response behaviors of upright breakwaters under broken wave impact are analysed based on the mass-damper-spring dynamic system model. The effects of the mass, damping, stiffness, natural period, and impulse duration (or oscillation period) on the translation, rotation, sliding force, overturning moment, and corresponding dynamic amplifying factors are studied. It is concluded that the ampli-ying factors only depend on the ratio of the system natural period to impulse duration (or oscillation period) under a certain damping ratio. Moreover, the equivalent static approach to breakwater design is also discussed. 相似文献