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81.
徐文金 《南京气象学院学报》1995,18(2):242-247
分析了8807号台风所引发的局地特大暴雨成因:(1)台风提供了足够的水汽;(2)台风螺旋状云雨区和太阳辐射不均匀,形成了低层中尺度锋区,为暴雨发生提供极不稳定能量和触发条件;(3)局地地形和摩擦因子使湖北省宜昌地区成为这次对流云发展较有利的地点;(4)高空的中尺度降压系统和涡度因子加强了对流云团的发展。 相似文献
82.
North Pacific sea ice cover, a predictor for the Western North Pacific typhoon frequency? 总被引:13,自引:0,他引:13
Fan Ke 《中国科学D辑(英文版)》2007,50(8):1251-1257
The relationship between the sea ice cover in the North Pacific and the typhoon frequency has been studied in this paper. It follows that the index for the sea ice cover in the North Pacific (ISA) both in December-January-February (DJF) and in March-April-May (MAM) is negatively correlated with annual typhoon number over the western North Pacific (TNWNP) during 1965―2004, with correlation coeffi-cients of -0.42 and -0.49 respectively (above 99% significant level). Large sea ice cover in the North Pacific tends to decrease TNWNP. Positive ISA (MAM) is associated with the tropical circulation and SST anomalies in the North Pacific, which may lead to unfavorable dynamic and thermal conditions for typhoon genesis over WNP from June to October (JJASO). The variability of the atmospheric circula-tion over the North Pacific, associated with the ISA anomaly in MAM is connected to the tropical at-mospheric circulation variability in MAM via the teleconnection wave train. Besides, as the tropical circulation has strong seasonal persistency from the MAM to JJASO, thus, the ISA in MAM-related variability of the tropical atmospheric circulation as well as the SST can affect the typhoon activity over the western North Pacific. 相似文献
83.
84.
湛江港邻近海域台风浪的模拟研究 总被引:3,自引:0,他引:3
对第三代近岸海浪数值模式SWAN及包含的物理过程进行了简要介绍,利用该模式对影响南海湛江港海域的二次台风浪过程进行了模拟研究:由藤田台风风场模型同化相应时刻的台风要素、NCAR/NCEP网格点资料、单站观测资料后,提供模式所需风场;利用自嵌套的方式,提供模式波谱边界条件;两次模拟结果与实际海浪观测资料相符较好,可以为该海域台风浪的模拟预报提供较为重要的参考。 相似文献
85.
Wang Pengyun 《Acta Meteorologica Sinica》1999,13(4):474-493
The track,landfall,dynamic and thermodynamic and cloud-rain physical mesoscale structures and their evolution of typhoon HERB 1996 in 36 h from 0000 UTC 31 July to 1200 UTC 1 August 1996 were simulated by using the non-hydrostatic mesoscale model MM5.This period covered the process of typhoon HERB landfall at Taiwan and Fujian Provinces.Results show that the model successfully simulated the landfall process of typhoon HERB,revealed the most important characteristics of the mesoscale dynamic and thermodynamic and cloud-rain physical structure during its landfall.The simulated typhoon track was close to the observation.The center of cyclonic circulation simulated at 0000 UTC on 1 August 1996 (24 h integration) was located in shore near Fuqing,Fujian Province at which the typhoon was reported to landfall two hours later.It shows that strong upward motion formed by low level convergence existed in the eye-wall and subsidence at the eye.The wind field shows clear asymmetrical structure near the typhoon center.The cloud and rainband was screw-typed distributed around typhoon center,and consisted of meso-β scale rain cores.During the period of typhoon HERB staying near and passing over Taiwan,the lower cloud was developed in the eye region so that the previous clear typhoon eye on the satellite pictures became fuzzy.Observation shows that the typhoon center was "warm",but the model simulations with higher space resolution show that in the mid-troposphere the region of eye-wall with stronger upward motion and more cloud-and rain-water was warmer than the eye.During the period of typhoon passing over Taiwan and its following landfall at Fujian,the track of model typhoon deviated about 30 km northward (i.e.,rightward) because of the orographic effects of Taiwan Island,but the strength of the typhoon was not affected remarkably.The amount of rainfall on Taiwan in the 36 h simulations was enhanced more than six times by the orographic lifting of Taiwan Mountain. 相似文献
86.
Statistic and typical-year composition methods are used to study the northwest Pacific typhoon activities in relation with the EI Niño and La Niña events. The result indicates that the typhoon tends to be inactive in the EI Niño years and active in the La Niña years and it is also dependent on the onset and ending time and intensity of the events and areas of genesis of typhoons. With statistic features of the frequency of typhoon activity in the EI Niño and La Niña years and the time-lag correlation between the frequency and sea surface temperature(SST), useful information is provided for the prediction of typhoon occurrence. In addition, the singular values disassemble(SVD)method is applied to study the correlation between the geopotential field and SST field. The result shows that the air-sea coupling in the EI Niño years is unfavorable for the typhoon to develop. Which take place with a smaller number. Opposite situations are found with the La Niña years. 相似文献
87.
88.
分析 2 0 0 1年 7月 2 - 3日台风“榴莲”暴雨过程中湿位涡及其各分量的变化 ,发现对流层低层 85 0 h Pa湿位涡的负值中心、 70 0 h Pa湿位涡的正值区与强降水中心相对应 ;急流与层结稳定度的变化 ,影响着湿位涡的变化 相似文献
89.
台风路径可视为二维平面上的一段曲线,根据两条台风路径曲线的相似离度可以判断其数值相似和形态相似的程度。由于直接应用台风基本资料进行相似离度计算有一定的难度和局限性,需要研究利用相似离度原理判断两条台风路径曲线相似程度的计算方法。按照设计的算法处理台风基本资料,可以确定两条台风路径曲线上的对应控制点,得到两条曲线对应控制点之间的距离和距离偏差的方向,最终只需在一个方向计算相似离度就能直接分析两条曲线的相似性。对相似台风进行检索的实例表明,该算法是可行的,能够从台风基本资料库中检索出与当前台风路径最相似的台风个例。 相似文献
90.
“96·8”华北暴雨数值模拟与稳定性分析 总被引:3,自引:3,他引:3
分析1996年8月发生在华北地区的台风暴雨过程的环流形势,发现:副热带高压与台风低压之间的气压梯度很大,宽广的偏南急流源源不断地向北输送水汽和能量,而太行山一带正处于汇合区,构成十分有利的暴雨天气形势。应用MM5数值预报方法对1996年8月4—5日的降雨天气过程进行数值模拟,并依据天气学原理和位涡理论对此过程的稳定性进行分析认为:(1)MM5数值预报模式较好地模拟出了台风暴雨的物理过程。(2)此次降雨的不稳定层结有南高北低现象,同时有对称不稳定和对流不稳定存在;条件性对称不稳定可使环流加速,对降水有一定的增幅作用。 相似文献