全文获取类型
收费全文 | 426篇 |
免费 | 1篇 |
国内免费 | 11篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 12篇 |
地球物理 | 58篇 |
地质学 | 90篇 |
海洋学 | 254篇 |
天文学 | 1篇 |
自然地理 | 6篇 |
出版年
2013年 | 4篇 |
2007年 | 3篇 |
2004年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 37篇 |
1998年 | 41篇 |
1997年 | 39篇 |
1996年 | 30篇 |
1995年 | 29篇 |
1994年 | 32篇 |
1993年 | 30篇 |
1992年 | 20篇 |
1991年 | 30篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1966年 | 6篇 |
1965年 | 16篇 |
1962年 | 2篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1956年 | 1篇 |
1955年 | 4篇 |
1954年 | 3篇 |
1953年 | 1篇 |
1952年 | 2篇 |
1950年 | 1篇 |
1949年 | 5篇 |
1948年 | 2篇 |
1942年 | 1篇 |
1939年 | 1篇 |
1937年 | 2篇 |
1936年 | 1篇 |
1933年 | 7篇 |
1931年 | 1篇 |
1924年 | 2篇 |
1923年 | 2篇 |
排序方式: 共有438条查询结果,搜索用时 343 毫秒
71.
72.
73.
Professor Dr. Werner Borchert 《Contributions to Mineralogy and Petrology》1952,3(2):124-130
Ohne ZusammenfassungHerrn Professor Dr. O. H.Erdmannsdörffer zur Vollendung seines 75. Lebensjahres in Dankbarkeit gewidmet. 相似文献
74.
Mr.T.F.Hou,geologist of the National Geological Survey of Chinabrought back in 1931 from Liaoning province,a specimen of subbituminous coalin which are included patches or aggregates of small oolites.This interestingspecimen was given to the writer for microscopical investigation.Both polished 相似文献
75.
76.
—In the designing of the flexible fender pile,M-method is usually adopted.But M-method isusable only in the case that the value of the force(moment M and shear force Q)exerted on the pile abovethe soil is known.In practical cases,only the percussive energy of the ship can be found,while the exactvalue of the percussive force cannot be computed directly.In this paper,a method is introduced which canbe used to calculate the inner force of flexible fender piles by a computer in these cases.First,according tothe known docking dynamic energy of a ship,the absorbed energy can be found from the deformation ofthe pile and the rubber fender respectively,at the same time the value of the force acting on the fender pilesand the reaction of fenders can be calculated.Then the inner force and displacement of the fender piles canalso be calculated further by M-method.The whole computing process is realized by a computer programand the results obtained are reasonable.In this paper,the computation,the iteration method a 相似文献
77.
Zhang Yonggang Li Yucheng Associate Professor Dept. of Mechanic Engineering Shanghai Jiao Tong University Shanghai Professor Dept. of Civil Engineering Dalian University of Technology Dalian 《中国海洋工程》1998,(1)
A nonlinear numerical model has been set up by use of Boussinesq Equation with finite differ-ence method,and has been applied to the simulation of the abnormal change of wave height induced by ex-cavated waterway.Numerical results demonstrate that the abnormal change of wave height is due to theadding of the reflected wave height induced by excavated waterway to the incident wave height.Becausethe angle between the incident wave and the axis of the waterway is smaller than the critical angle,the re-flected wave produced by the waterway may propagate to the breakwater and may be added with the inci-dent wave,then the abnormal change of wave height before the breakwater may be caused.So the wave re-flection caused by the change of water depth cannot be neglected. 相似文献
78.
GUAN Changlong Professor 《中国海洋工程》1998,(3)
On the basis of the linear model of random sea waves presented by Longuet-Higgins,the statis-tical distribution of the horizontal velocities of water particles at wave surface maxima is derivedtheoretically.The derived distribution is similar to that of wave surface maxima,and a new spectral widthε_u,which is defined as(1-(m_3~2/m_2m_4))~(1/2),is introduced in the distribution.When ε_u tends to zero,the distribu-tion is reduced to Rayleigh distribution and it is reduced to the normal distribution when ε_u tends to unity.For a narrow spectrum,it is proved that ε is equal to 1/2ε,where ε is(1-(m_2~2/m_0m_4))~(1/2)and is the commonlyused spectral width.. 相似文献
79.
—The forces of random wave plus current acting on a simplified offshore platform(jacket)mod-el have been studied numerically and experimentally.The numerical results are in good agreement withexperiments.The mean force can be approximated as a function of equivalent velocity parameter and theroot-mean-square force as a function of equivalent significant wave height parameter. 相似文献
80.
—The nonlinear behaviors of plane coupled motions for a given two-point tension mooring sys-tem,are discussed in the present paper.For a cylinder moored by two taut lines under the action ofgravity,buoyance and forces due to wave-current and mooring lines,a mathematical model of motionswith three degrees of freedom is established.The steady solution and stability are analyzed.By integratingthe equations of motions,history,phase map and Poincare map are obtained.The Liapunov exponentsare also computed.The numerical results show that:the horizontal movement will increase,and stabilitywill also increase as the steady force increases.The amplitude of responses will decrease as time-dependentforces decrease.Because of the geometric nonlinearity,there exist many windows bifurcating to pseudo-pe-riodic or multi-periodic solution.The bifurcating patterns may be different.The behaviors are very com-plex.Under wave excitation alone,the motions are nonsymmetrical but still symmetrical statistically. 相似文献