全文获取类型
收费全文 | 3470篇 |
免费 | 316篇 |
国内免费 | 391篇 |
专业分类
测绘学 | 22篇 |
大气科学 | 284篇 |
地球物理 | 1071篇 |
地质学 | 325篇 |
海洋学 | 1056篇 |
天文学 | 692篇 |
综合类 | 62篇 |
自然地理 | 665篇 |
出版年
2024年 | 9篇 |
2023年 | 24篇 |
2022年 | 36篇 |
2021年 | 33篇 |
2020年 | 53篇 |
2019年 | 85篇 |
2018年 | 63篇 |
2017年 | 72篇 |
2016年 | 68篇 |
2015年 | 80篇 |
2014年 | 100篇 |
2013年 | 187篇 |
2012年 | 49篇 |
2011年 | 121篇 |
2010年 | 112篇 |
2009年 | 213篇 |
2008年 | 259篇 |
2007年 | 305篇 |
2006年 | 229篇 |
2005年 | 179篇 |
2004年 | 190篇 |
2003年 | 208篇 |
2002年 | 175篇 |
2001年 | 127篇 |
2000年 | 146篇 |
1999年 | 160篇 |
1998年 | 152篇 |
1997年 | 73篇 |
1996年 | 103篇 |
1995年 | 77篇 |
1994年 | 75篇 |
1993年 | 70篇 |
1992年 | 58篇 |
1991年 | 54篇 |
1990年 | 50篇 |
1989年 | 40篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 19篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1954年 | 4篇 |
排序方式: 共有4177条查询结果,搜索用时 312 毫秒
911.
912.
For more and more applications in coastal and offshore engineering, numerical simulations of waves and surges are required. An important input parameter for such simulations are wind fields. They represent one of the major sources for uncertainties in wave and surge simulations. Wind fields for such simulations are frequently obtained from numerical hindcasts with regional atmospheric models (RAMs). The skill of these atmospheric hindcasts depends, among others, on the quality of the forcing at the boundaries. Furthermore, results may vary due to uncertainties in the initial conditions. By comparing different existing approaches for forcing a regional atmospheric model, it is shown that the models' sensitivity to uncertainties in the initial conditions may be reduced when a more sophisticated approach is used that has been suggested recently. For a specific, although somewhat brief test period, it is demonstrated that an improved hindcast skill for near surface wind fields is obtained when this approach is adopted. Consequences of the reduced uncertainty in wield fields for the hindcast skill of subsequent wave modelling studies are demonstrated. Recently, this new approach has been used together with a regional atmosphere model to produce a 40-year wind hindcast for the Northeast Atlantic, the North Sea and the Baltic Sea. The hindcast is presently extended to other areas and the wind fields are used to produce 40-year high-resolution hindcasts of waves and surges for various European coastal areas. 相似文献
913.
Yu Yuxiu Liu Shuxue
Professor State Key Laboratory of Coastal Offshore Engineering Dalian University of Technology 《中国海洋工程》1994,(1)
-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model test for a port. The test results show that a deep navigation channel has a large effect on the waves in front of the breakwater near the port entrance and on the wave condition in the port. 相似文献
914.
1 .IntroductionAsavividtheoryofwaterwaveswithfiniteamplitudes ,StokeswaveshasbeenstudiedthoroughlyandappliedwidelyinmarinescienceandengineeringsinceStokesproposeditin 1 84 7.Rayleigh(1 876 )developedthetheoryinasimplifiedway .Michell (1 893)deducedlimitingStokeswav… 相似文献
915.
Chuankun Wang 《Marine Georesources & Geotechnology》2004,22(3):133-150
For Future cross-sea passage spanning the Taiwan Strait, no matter what kind of scheme is adopted, its design, construction, and administration are closely related to marine hydrological and meteorological environmental elements. In this article, based on a great number of observed data, analyses for wave, typhoon, and monsoon conditions in the Taiwan strait region are made and their distributional features and character values are given. Especially, the wave height and occurrence frequencies of disastrous waves are analyzed, and the values of design wave parameters (wave height and period with a given return period) are estimated to use for the reference of the scheme optimization and project preliminary program of cross-sea passage spanning the strait. 相似文献
916.
A novel automated trinocular stereo imaging system (ATSIS) is developed for non-intrusively measuring the temporal evolution of three-dimensional wave characteristics. The system consists of three progressive digital cameras to provide three independent stereo-pairs, i.e. left–right, left–center, and center–right, for accurately estimating depth of a scene. A third camera assists to resolve correspondence problems due to specular reflection on the water surface and provides additional constraints on image matching, dramatically reducing the chance of a mismatch. An oblique configuration for the trinocular system effectively increases spatial coverage, allowing observations of wave phenomena over a broad range of spatial scales. The height resolution is increased with the optical axes of the cameras pointed at an oblique angle with respect to vertical surface wave displacements. A new exterior calibration procedure is developed in this paper to determine the orientation of cameras in the field. Field experiments demonstrate that ATSIS can robustly measure hundreds of matched image points in seconds, allowing fast extraction of the temporal evolution of a three-dimensional surface wave field. 相似文献
917.
Experimental and Numerical Study of Wave-Induced Long-Shore Currents on A Mild Slope Beach 总被引:4,自引:0,他引:4
1.Introduction Long shorecurrenthasbecomethesubjectofextensiveworldwideresearchformanyyears.The purposeofthestudyistounderstandandpredicttheprocessesofsedimenttransport,shorelineevolu tionandpollutanttransportinthenear shorezoneundertheactionofwaves.Goda(2001)regarded thesuspendedsedimentastheprincipalloadinsedimenttransportandtheeffectoflong shorecurrents wasemphasized.Theeffectofwavesonpollutanttransportwasstudiedbynumericalmodelandfield experiment(TaoandHan,2002;Rodriguezetal.,1995),andth… 相似文献
918.
Numerical study of the storm-induced circulation on the Scotian Shelf during Hurricane Juan using a nested-grid ocean model 总被引:2,自引:0,他引:2
A nested-grid ocean circulation modelling system is used to assess the upper ocean response of the Scotian Shelf and adjacent slope to Hurricane Juan in September 2003. The nested-grid system consists of a fine-grid inner model covering the Scotian Shelf/slope and a coarse-grid outer model covering the northwest Atlantic Ocean. The model-calculated upper ocean response to Hurricane Juan is characterized by large divergent surface currents forced by the local wind forcing under the storm, and intense near-inertial currents in the wake of the storm. The sea surface temperature (SST) cooling produced by the model is biased to the right of the storm track and agrees well with a satellite-derived analysis. Over the deep water, off the Scotian Shelf, some of the near-inertial energy input by the storm is advected eastward by the Gulf Stream away from the storm track. The hurricane also generates shelf waves that propagate equatorward with the coastline on their right. In comparison with the outer model results, the inner model captures more meso-scale structures, greater SST cooling and stronger near-inertial currents in the study region. 相似文献
919.
Anisotropy of wind and wave regimes in the Baltic proper 总被引:1,自引:0,他引:1
Tarmo Soomere 《Journal of Sea Research》2003,49(4):305
The directional distribution of moderate and strong winds in the Baltic Sea region is shown to be strongly anisotropic. The dominating wind direction is south-west and a secondary peak corresponds to north winds. North-west storms are relatively infrequent and north-east storms are extremely rare. Angular distribution of extreme wind speed also has a two-peaked shape with maxima corresponding to south-west and north winds, and a deep minimum for easterly winds. The primary properties of the anisotropy such as prevailing winds, frequency of their occurrence, directional distribution of mean and maximum wind speeds coincide on both sides of the Baltic proper. The specific wind regime penetrates neither into the mainland nor into the Gulf of Finland or the Gulf of Riga.Properties of the saturated wave field in the neighbourhood of proposed sites of the Saaremaa (Ösel) deep harbour are analysed on the basis of the wave model WAM forced by steady winds. The directional distribution of wave heights in typical and extreme storms is highly anisotropic. Remarkable wave height anomalies may occur in the neighbourhood of the harbour sites. 相似文献
920.