全文获取类型
收费全文 | 200篇 |
免费 | 28篇 |
国内免费 | 52篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 3篇 |
地球物理 | 59篇 |
地质学 | 85篇 |
海洋学 | 111篇 |
天文学 | 1篇 |
综合类 | 17篇 |
自然地理 | 2篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 21篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1981年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 15 毫秒
51.
Mineralization Ages of the Jiapigou Gold Deposits,Jilin 总被引:1,自引:0,他引:1
Li Junjian Shen Baofeng Mao Debao Li Shuangbao Zhou Huifang Cheng Yuming Tianjin Institute of Geology Mineral Resources Chinese Academy of Geological Sciences Tianjin Nonferrous Metal Geological Exploration Bureau Changchun Jilin 《《地质学报》英文版》1997,71(2):180-188
The Jiapigou gold deposits are typical vein type deposits associated withArchaean greenstone belts in China. According to the crosscutting relationships between dykesand auriferous veins, single hydrothermal zircon U-Pb dating and quartz K-Ar,~(40)Ar-~(39)Ar andRb-Sr datings, the main mineralization stage of the Jiapigou deposit has been determined to be2469-2475 Ma, while mineralization superimposition on the gold deposit occurred in1800-2000 Ma and 130-272 Ma. They form a mineralization framework of one oldermetallogenic epoch (Late Archaean-Early Proterozoic) and one younger metallogenic epoch(Mesozoic) of gold deposits in Archaean greenstone belts in China. 相似文献
52.
1 .IntroductionAshiptravelingatseaundergoesundesirablewave inducedmotions ,namely ,surge ,sway ,heav ing ,rolling ,pitchingandyaw .Thesemotionsoftencauseproblemstothecrew ,theonboardequip mentand ,intheworstcase ,thesafetyofthevessel.Tominimizethewave inducedshipmotions ,controlsystemsmaybeapplied .Theaccuratemodelingofshipmotionsisthereforeveryimportantforshipdesignanddesignofmotioncontrolsystems .Manyresearchershavedevelopedshipmotionpredictionmethodsbasedonthepotentialflowtheo ries (Dong ,… 相似文献
53.
An optimization mathematical model of the pile forces for piled breasting dolphins in the open sea under various loading conditions is presented. The optimum layout with the well distributed pile forces and the least number of piles is achieved by the multiplier penalty function method. Several engineering cases have been calculated and compared with the result of the conventional design method. It is shown that the number of piles can be reduced at least by 10%—20% and the piles‘ bearing state is improved greatly. 相似文献
54.
This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University. 相似文献
55.
Fan Yunlin Chang Dezhi Associate Professor Dept. of Ocean Eng. Tianjin University Engineer Construction Committee of Weihai City Shandong Province 《中国海洋工程》1991,(4)
The Wei- Liu water supplying submarine pipeline is at present the longest one of the kind in China. It is about 4 kilometers long from Weihai City to Liugong Island in Shandong province. It took only half a year to design and construct it. The project was of a high economic efficiency and some practical experiences were achieved. In this paper a general introduction to the design and construction of this pipeline is presented and such problems as the stability of the pipeline in very soft clay, design of curved slide for launching and estimation of dragging forces are expounded. 相似文献
56.
Xue Hongchao Su Dehui Xu Fumin
Professor Research Institute of Coastal Ocean Engineering Hohai University Nanjing Doctor Dept. of Navigation Ocean Engineering Hohai University Nanjing Ph. D. Student Dept. of Navigation Ocean Engineering Hohai University Nanjing 《中国海洋工程》1995,(3)
- Combined with irregular wave-maker, the growing process of Wave Energy Spectrum in shallow water can be studied in wind wave channel on different water depth conditions, and its transformation characteristics and rules can be obtained. 相似文献
57.
In order to suit the condition that the wave uplift is correlated with the horizontal wave load acting on a vertical breakwater, a generally used method for determining the reliability index β of the breakwater, i.e. the Hasofer-Lind method, is extended in a generalized stochastic space for correlative variables. The computational results for a caisson breakwater indicate that the value of β for the case of correlated variables is obviously smaller than that for the case of independent variables. 相似文献
58.
CHEN Yang SUN Jingshi
Associate Professor Tianjin Research Institute of Water Transport Engineering Tianjin P. R. China.
Professor Tianjin Research Institute of Water Transport Engineering Tianjin P. R. China. 《中国海洋工程》1999,(2)
-By use of the parabolic equation of numerical simulation of wave which is suitable forlarge-angle propagation and Crank-Nicolson differential method,the wave field at the Kemema Rivermouth has been studied for analysis of sediment movement in the area.In order to reflect wave energy lossaccurately,the Bretchneider-Reid formula is quoted and the friction coefficient in the formula is discussedin this paper.The calculation results indicate that the wave becomes a little damped at the mouth ofKemena River influenced by the topography and bottom friction,and the wave at the east beach is higherthan that at the west beach,because the east beach extends out. 相似文献
59.
Qiu Changlin Yan Shuwang
Ph. D. Student Dept. of Hydraulic Engrg. Tianjin University Tianjin Professor Dept. of Hydraulic Engrg. Tianjin University Tianjin 《中国海洋工程》1997,(1)
Strengthening soft foundation by vacuum loading from lower position is a new method of ac-celerating the consolidation of dredger fill.This paper presents the mechanism of soft foundation strength-ening by vacuum loading from lower position and evaluates the effectiveness of this method under variousboundary conditions by means of finite element method(FEM)on the basis of Biot's consolidationtheory. 相似文献
60.
Zhang Yonggang Li Yucheng Teng Bin
Doctor Degree Candidate The National Key Laboratory of Coastal Offshore Engineering Dalian University of Technology Dalian
Professor The National Key Laboratory of Coastal Offshore Engineering Dalian University of Technology Dalian
Associate Professor The National Key Laboratory of Coastal Offshore Engineering Dalian University of Technology Dalian 《中国海洋工程》1995,(4)
The mild-slope equation derived by Berkhoff (1972), has widely been used in the numerical calculation of refraction and diffraction of regular waves. However, it is well known that the random sea waves has a significant effect in the refraction and diffraction problems. In this paper, a new form of time-dependent mild slope equation for irregular waves was derived with Fade approximation and Kubo's time series concept. The equation was simplified using WKB method, and simple and practical irregular mild slope equation was obtained. Results of numerical calculations are compared with those of laboratory experiments. 相似文献