全文获取类型
收费全文 | 308篇 |
免费 | 37篇 |
国内免费 | 28篇 |
专业分类
测绘学 | 50篇 |
大气科学 | 15篇 |
地球物理 | 15篇 |
地质学 | 30篇 |
海洋学 | 217篇 |
综合类 | 19篇 |
自然地理 | 27篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 23篇 |
2019年 | 19篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 22篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 3篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1985年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有373条查询结果,搜索用时 31 毫秒
101.
针对十万吨级深远海养殖工船在波浪中的阻力和运动响应开展了船模试验与模拟计算,并对其最小推进功率进行了校核。以试验流体力学(EFD)模型试验与模型尺度计算流体力学(CFD)模拟计算的结果进行对比作为方法验证,将实尺度CFD模拟计算的结果直接用于最小推进功率的校核。结果显示,EFD模型试验结果与模型尺度CFD计算结果误差在10%左右,计算精度满足工程要求。在规定的恶劣海况下该船型波浪增阻占总阻力的比例最高可达56.3%,螺旋桨转矩可达最大转矩的63.9%。等级2简化评估法得到的最小推进功率为等级1线评估法给出的最小功率线值的58.9%。研究表明实尺度CFD模拟计算可直接用于船舶最小推进功率的校核,此深远海养殖工船使用等级2简化评估方法进行校核更容易满足规范要求,其最小推进功率应不小于6 833 kW。 相似文献
102.
103.
104.
105.
Investigation of hydroelastic ship responses has been brought to the attention of the scientific and engineering world for several decades. There are two kinds of high-frequency vibrations in general ship responses to a large ocean-going ship in its shipping line, so-called springing and whipping, which are important for the determination of design wave load and fatigue damage as well. Because of the huge scale of an ultra large ore carrier (ULOC), it will suffer seldom slamming events in the ocean. The resonance vibration with high frequency is springing, which is caused by continuous wave excitation. In this paper, the wave-induced vibrations of the ULOC are addressed by experimental and numerical methods according to 2D and 3D hydroelasticity theories and an elastic model under full-load and ballast conditions. The influence of loading conditions on high-frequency vibration is studied both by numerical and experimental results. Wave-induced vibrations are higher under ballast condition including the wave frequency part, the multiple frequencies part, the 2-node and the 3-node vertical bending parts of the hydroelastic responses. The predicted results from the 2D method have less accuracy than the 3D method especially under ballast condition because of the slender-body assumption in the former method. The applicability of the 2D method and the further development of nonlinear effects to 3D method in the prediction of hydroelastic responses of the ULOC are discussed. 相似文献
106.
107.
L. A. De Bock P. E. Joos K. J. Noone R. A. Pockalny R. E. Van Grieken 《Journal of Atmospheric Chemistry》2000,37(3):299-329
The chemical composition of individual particles >0.2 m sampled duringthe MAST-experiment wereanalysed by SEM-EDX, in combination with multivariatetechniques. The objective of this experiment was toidentify the mechanisms responsible for themodification of marine stratocumulus clouds byemissions from ships and in a wider sense to provideinformation on the global processes involved inatmospheric modification of cloud albedo. Aerosolswere examined under different MBL pollution levels(clean, intermediately polluted and moderatelypolluted) in five different reservoirs: backgroundbelow-cloud and above-cloud aerosol; background clouddroplet residual particles; below-cloud ship plumeaerosol and ship track cloud droplet residualparticles.In this study a relation was provided between theaerosol emitted from the ship's stack to an effect incloud. Additionally, a large fraction of the ambientaerosol was found to be composed of organic materialor other compounds, consisting of low Z-elements,associated with chlorine. Their number fraction waslargest in clean marine boundary layers, and decreasedwith increasing pollution levels. The fraction of`transformed sea salt' (Na, Cl, S), on the other hand,increased with the pollution level in the MBL. Only20% of the particles fell within the detectable rangeof the analysis. 相似文献
108.
商业性地质工作是和公益性地质工作相对应提出的。在公益性地质工作得到初步加强的同时,如何认识商业性地质工作风险管理的问题,是当前政府部门和地勘单位值得关注的一个重要问题。 相似文献
109.
An investigation has been conducted to quantify the effect of waterway geometry on the form and magnitude of forces and moment experienced by a berthed ship due to a passing ship. By using the dynamic mesh technique and solving the unsteady RANS equations in conjunction with a RNG k?ε turbulence model, numerical simulation of the three-dimensional unsteady viscous flow around a passing ship and a berthed ship in different waterway geometries is conducted, and the hydrodynamic forces and moment acting on the berthed ship are calculated. The proposed method is verified by comparing the numerical results with existing empirical curves and a selection of results from model scale experiments. The calculated interaction forces and moment are presented for six different waterway geometries. The magnitude of the peak values and the form of the forces and moment on the berthed ship for different cases are investigated to assess the effect of the waterway geometry. The results of present study can provide certain guidance on safe maneuvering of a ship passing by a berthed ship. 相似文献
110.