全文获取类型
| 收费全文 | 62篇 |
| 免费 | 7篇 |
| 国内免费 | 7篇 |
专业分类
| 测绘学 | 12篇 |
| 大气科学 | 9篇 |
| 地球物理 | 3篇 |
| 地质学 | 9篇 |
| 海洋学 | 30篇 |
| 综合类 | 5篇 |
| 自然地理 | 8篇 |
出版年
| 2023年 | 1篇 |
| 2021年 | 2篇 |
| 2020年 | 2篇 |
| 2019年 | 3篇 |
| 2018年 | 4篇 |
| 2017年 | 2篇 |
| 2016年 | 3篇 |
| 2015年 | 4篇 |
| 2014年 | 4篇 |
| 2013年 | 5篇 |
| 2012年 | 2篇 |
| 2011年 | 5篇 |
| 2010年 | 5篇 |
| 2009年 | 4篇 |
| 2008年 | 3篇 |
| 2007年 | 3篇 |
| 2006年 | 3篇 |
| 2005年 | 3篇 |
| 2004年 | 2篇 |
| 2002年 | 2篇 |
| 2001年 | 4篇 |
| 2000年 | 1篇 |
| 1999年 | 1篇 |
| 1996年 | 1篇 |
| 1995年 | 1篇 |
| 1994年 | 1篇 |
| 1992年 | 3篇 |
| 1991年 | 1篇 |
| 1982年 | 1篇 |
排序方式： 共有76条查询结果，搜索用时 15 毫秒
41.
42.
利用包含Argo和WOD05的历史现场观测数据集,分析研究了全球历史海温观测的三维时宅分布特征,并对观测数据的偏度特征进行研究.研究结果表明:1)海温观测数据在全球许多海域(特别是南大洋和北冰洋)较为稀少,大多数观测集中在北欧沿海、北美的东西部沿海和西北太平洋区域以及其他少数区域;北半球观测数据明显多于南半球;2)海温具有明显的非对称性分布特征,其非正态分布和有偏现象是一个全球的普遍现象,且随着海区和深度而变化;非正态分布网格数量在任意给定的深度层次上占总网格数的比率超过80%:3)海温观测在各水平层次总体上具有正偏的特性,但在黑潮、湾流、南极绕极流等区域呈现出负偏的特征;具有正偏分布特征的区域网格数量占全球网格总数的比例随着深度的增加而增加,至600 m时达到75%左右. 相似文献
43.
本文基于Amarouche的二阶理论回波模型,导出了带有偏度系数的二阶理论回波模型;针对HY-2A卫星高度计波形特点,引入了奇异值分解滤波,并根据最大似然估计算法反演参数的不同得到6种重跟踪方案;利用其中的五参数方案处理该波形数据,获得海面散射点高度概率密度函数中偏度的合理取值为0.15;将结果分别与浮标、Jason-1和HY-2AIDR有效波高对比,分析6种方案反演有效波高的准确度,确定了MLE4_SVD(波形重跟踪之前进行滤波)对HY-2A高度计重跟踪更适合反演有效波高。 相似文献
44.
A simple conceptual formulation to compute seabed shear stress due to asymmetric and skewed waves is presented. This formulation generalizes the sinusoidal wave case and uses a variable friction factor to describe the physics of the boundary layer and to parameterize the effects of wave shape. Predictions of bed shear stresses agree with numerical computations using a standard boundary layer model with a k–ε turbulence closure. The bed shear stress formulation is combined with a Meyer-Peter and Müller-type formula to predict sheet flow bedload transport under asymmetric and skewed waves for a horizontal or sloping bed. The predictions agree with oscillatory water tunnel measurements from the literature. 相似文献
45.
Postal probability surveys were used to estimate the angler catch of salmon, and the number of anglers fishing for salmon, on the Rakaia River, Canterbury, New Zealand, for the seasons 1973/74 and 1974/75. Response levels of over 97% were obtained. An estimated 3531 fish were caught by an estimated 4405 anglers in 1973/74 and 4875 fish by 5332 anglers in 1974/75. The sample catch frequency distributions returned were highly positively skewed with few anglers catching most of the fish. The effect of this skewness on the estimate of total catch was investigated by bootstrapping and confidence intervals thus set were compared to those derived from the Gaussian assumption. Confidence limits were obtained for the estimate of number of anglers. 相似文献
46.
Skewness(S) and kurtosis(K) of temperature in the surface layer over a grassland are investigated under unstable thermal stratifications. We find that both skewness and kurtosis generally obey Monin–Obukhov similarity theory and tend to be constant values(1.5 and 5.3, respectively) when the stability parameter z/L -2. Quantitative formulas of the similarity functions are proposed. The temperature probability density function(PDF) is close to Gaussian in near neutral stratification and non-Gaussian in unstable stratification. The influence of coherent motions on the PDF behavior is analyzed using the quadrant analysis technique. It shows that PDF behaviors are controlled by ejections and sweeps. The results also indicate that the PDF type of the ejections always follows a Gaussian distribution, while the PDF of the sweeps changes with stability. 相似文献
47.
The temporal and spatial evolutions of nonlinear wave group with an initial Gaussian envelope are theoretically studied under the governing of MNLS equations, demonstrating that the temporal and spatial versions of numerical model are not always consistent in the whole evolution process, particularly in the presence of strong nonlinearity. Moreover, a large set of numerical simulations, performed respectively by these two versions of numerical model, are systematically compared to mechanically generated waves with different initial directional spreading and Benjamin–Feir Index, mainly focusing on the evolution properties of surface elevations such as the coefficients of skewness and kurtosis, the probability density function, and the maximal surface elevation. On the whole, it can be argued that the statistical properties of both numerically simulated wave fields are basically consistent with the laboratory observations. 相似文献
48.
49.
选取河北省西部地区30个国家基本站30年年平均气温作为样本，通过对总体样本、分区样本的偏度系数、峰度系数的分析，研究了各站点组成的空间序列，年平均气温以及地理参数(海拔高度、经度、纬度)的正态性。研究发现：总体样本的年平均气温、海拔高度不遵从正态分布，而经度、纬度能较好的遵从正态分布；按照经纬度跨度不大于1．5，尽量多选取山区站；或既要多选山区站，又要使同一分区的站点具有相同的气候特点两种原则，对站点进行分区，能使分区样本的年平均气温和地理参数均遵从正态分布。 相似文献
50.