全文获取类型
收费全文 | 8100篇 |
免费 | 1748篇 |
国内免费 | 1694篇 |
专业分类
测绘学 | 577篇 |
大气科学 | 1665篇 |
地球物理 | 4521篇 |
地质学 | 2852篇 |
海洋学 | 730篇 |
天文学 | 297篇 |
综合类 | 508篇 |
自然地理 | 392篇 |
出版年
2024年 | 45篇 |
2023年 | 118篇 |
2022年 | 229篇 |
2021年 | 322篇 |
2020年 | 296篇 |
2019年 | 349篇 |
2018年 | 282篇 |
2017年 | 298篇 |
2016年 | 321篇 |
2015年 | 347篇 |
2014年 | 403篇 |
2013年 | 409篇 |
2012年 | 438篇 |
2011年 | 448篇 |
2010年 | 420篇 |
2009年 | 447篇 |
2008年 | 432篇 |
2007年 | 534篇 |
2006年 | 526篇 |
2005年 | 512篇 |
2004年 | 445篇 |
2003年 | 447篇 |
2002年 | 375篇 |
2001年 | 353篇 |
2000年 | 334篇 |
1999年 | 354篇 |
1998年 | 342篇 |
1997年 | 286篇 |
1996年 | 298篇 |
1995年 | 320篇 |
1994年 | 221篇 |
1993年 | 152篇 |
1992年 | 106篇 |
1991年 | 85篇 |
1990年 | 64篇 |
1989年 | 53篇 |
1988年 | 56篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 4篇 |
1984年 | 18篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1954年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
长江口拦门沙地区的泥沙运动规律 总被引:12,自引:0,他引:12
依据1988年7月和12月水文观测资料,通过流,盐,沙的综合分析,认识到长江口拦门沙地区的泥沙运动有与河口其他地区不同的特点,泥沙输移在水平面上和垂直面上存在着多种循环,潮流和盐水截留大量泥沙积聚的拦门沙地区,河口在盐淡水交锋地带,除了涨,落急时段外,发现在转流时期泥沙也可能产生再悬浮,从而形成一个潮周期中出现3次或4次再悬浮的特殊规律。 相似文献
53.
The effects of free-surface waves on the floating structures are of great importance in the offshore industry. Among the six degrees of motions of a surface ship the absence of restoring forces in surge, sway and yaw led to critical situations for moored ships in the recent times. The order of forces in horizontal plane and their exciting frequencies are matters of interest. The resonance with the presence of moored chains led to many accidents in the recent past. The lines in dry conditions may not give good damping and in wet condition they may trigger the system to chaotic motions and jumps. Two different loading conditions of a container ship model are tested with waves in laboratory conditions in two different drafts. The mooring lines are chosen as per scale law and the energy under the response spectrum is determined from the plots. The results give new insights into the movement of a berthed ships subjected to waves. Response of the moored ship to different loading conditions in different water depths are discussed in this paper. The paper gives the order of energy due to first-order and slowly varying movement of a berthed container model in a towing tank. 相似文献
54.
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
55.
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
56.
A comparison of two three-dimensional numerical modeling systems for tidal elevations and velocities in the coastal waters is presented. The two modeling systems are: (1) the Princeton Ocean Model (POM) and (2) the MIKE 3 flow model. The model performance results for Singapore's coastal waters show that the predicted tidal elevations from the two hydrodynamic modeling systems are almost identical and are in very good agreement with field measurement data. The simulated tidal current velocities match well with field measurement data at the selected stations, but it seems that the POM provides the slightly better simulation, compared to the MIKE 3 flow model. The depth profiles of the velocities obtained from the two modeling systems may be greatly different at some time, due to the vertical diffusion coefficient calculated from different turbulent sub-models in the two modeling systems. The POM generally predicts larger peak tidal velocities. The maximum speed differences for the model results from the two modeling systems occur in the top and differ from time to time and from location to location, reaching up to 20%. 相似文献
57.
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
58.
59.
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
60.