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111.
112.
热带西南季风对0214号热带气旋“黄蜂”的影响 总被引:13,自引:1,他引:12
采用中国数值预报创新基地最新开发的三维变分同化系统(Grapes 3DVAR)的分析场为模式初值场,利用广州热带海洋气象研究所开发的南海热带气旋业务预报模式,在模拟试验(控制试验)的基础上,对强、弱热带西南季风作对比试验(异常试验)研究.试验结果表明除环境引导气流外,"黄蜂"偏心结构变化引起的偏心运动变化对热带气旋移向、移速的变化起了一定的作用;西南季风对热带气旋"黄蜂"的动力结构、热力结构和移动路径都有一定的影响;热带西南季风通过改变热带气旋的不对称结构和削弱副热带高压西侧这两个途径,造成热带气旋路径右偏. 相似文献
113.
THE STRUCTURE OF TROPICAL CYCLONE BY TOVS AND ITS APPLICATION IN NUMERICAL WEATHER PREDICTION 总被引:1,自引:2,他引:1
The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000.
Differences are found to some extent between what is found and classic conceptual models in that (1) the
horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential
height field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of
the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the
geopotential height field between low values at low levels and high values at high levels. It is especially noted
that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the
tropical cyclone. The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS
performs better in coordinating with the environment and predicting the track of the tropical cyclone. The
demonstration is two-fold — the structure of the typhoon BOGUS is such that it means much in the track
prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the
foundation for modification and evolution of typhoon BOGUS. 相似文献
114.
In a limited number of ensembles, some samples do not
adequately reflect the true atmospheric state and can in turn affect
forecast performance. This study explored the feasibility of sample
optimization using the ensemble Kalman filter (EnKF) for a simulation
of the 2014 Super Typhoon Rammasun, which made landfall in southern
China in July 2014. Under the premise of sufficient ensemble spread,
keeping samples with a good fit to observations and eliminating those
with poor fit can affect the performance of EnKF. In the sample
optimization, states were selected based on the sample spatial
correlation between the ensemble state and observations. The method
discarded ensemble states that were less representative and, to
maintain the overall ensemble size, generated new ensemble states by
reproducing them from ensemble states with a good fit by adding random
noise. Sample selection was performed based on radar echo data. Results
showed that applying EnKF with optimized samples improved the estimated
track, intensity, precipitation distribution, and inner-core structure
of Typhoon Rammasun. Therefore, the authors proposed that
distinguishing between samples with good and poor fits is vital for
ensemble prediction, suggesting that sample optimization is necessary
to the effective use of EnKF. 相似文献
115.
116.
Particle number size distribution(PNSD) between 10 nm and 20 μm were measured in the Pearl River Delta(PRD) region in winter 2011.The average particle number concentration of the nucleation mode(10-20 nm),Aitken mode(20-100 nm),accumulation mode(100 nm-1μm) and coarse mode(1-20 μm) particles were 1 552,7 470,4 012,and 19 cm-3,respectively.The volume concentration of accumulation mode particles with peak at 300 nm accounted for over 70% of the total volume concentration.Diurnal variations and dependencies on meteorological parameters of PNSD were investigated.The diurnal variation of nucleation mode particles was mainly influenced by new particle formation events,while the diurnal variation of Aitken mode particles correlated to the traffic emission and the growth process of nucleation mode particles.When the PRD region was controlled by a cold high pressure,conditions of low relative humidity,high wind speed and strong radiation are favorable for the occurrence of new particle formation(NPF) events.The frequency of occurrence of NPF events was 21.3% during the whole measurement period.Parameters describing NPF events,including growth rate(GR) and source rate of condensable vapor(Q),were slightly larger than those in previous literature.This suggests that intense photochemical and biological activities may be the source of condensable vapor for particle growth,even during winter in the PRD. 相似文献
117.
118.
本文采用方差极大正交旋转的因子分析方法,对南海SST场进行分析研究,并进行客观区划。结果表明,南海SST场可划分为七个区域,它们具有自身特定的变化规律,反映了不同的海洋动力学特征,这些具有不同特征的海区的形成可能分别与季风、南海海流、上升流、海洋涡旋、地理特征等因素有关,文中还对各主因子(对应于不同的海区)进行最大熵谱和交叉谱分析,得到各海区的显著周期和它们之间的显著耦合振荡周期,说明各海区除具有各自的特征外,它们之间还存在一定的内在联系。 相似文献
119.
120.
地铁施工中广州中信广场沉降监测 总被引:1,自引:0,他引:1
地铁施工中,高层建筑物都存在一定程度的下沉;结合中信广场的场地条件,介绍了在地铁施工期间的沉降监测实施方法,对沉降监测数据进行了分析,并得出施工阶段沉降变化的规律。其结果对保证建筑物的安全和保障地铁施工具有重要意义。 相似文献