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451.
古风暴学是始于20世纪90年代的一门新兴学科,通过研究风暴活动的地质记录和历史文献资料,恢复器测之前几百年至数千年前的热带气旋活动规律。经过十几年的发展,逐渐形成一套包括研究领域、方法、技术与手段等比较完整的理论体系,成为第四纪古气候研究和过去全球变化的重要组成部分。古风暴学研究的替代指标包括:文字记载、特征的风暴事件沉积、海相化石组合、同位素地球化学组成等。这些指标单独使用时都有一定局限性。寻找新的替代指标,并运用多种指标综合分析方法提高古风暴事件的分辨率和可信度,是今后该学科发展的重要方向。已有的研究多侧重于古风暴频数的研究,今后应充分利用现代风暴潮理论的新进展,通过数值模拟与替代指标研究相结合,更准确地恢复古风暴强度。同时,应加强古风暴活动的全球对比研究,以揭示风暴活动与全球气候变化的关系,为在全球不断变暖背景下台风活动的情景预测提供依据。 相似文献
452.
本文应用1976年提出的登陆浙、闽的热带气旋造成华北暴雨的天气预报指标对近12年登陆浙、闽的热带气旋对华北暴雨的影响进行了考察分析,指出30年前的研究成果目前仍然适用,同时根据30年来的天气变化提出了预报指标的调整方案。 相似文献
453.
A brief summary of Dr. G. V. Rao's research interests is presented. Many of his earlier studies were in conjunction with the
summer Monsoon Experiment of 1979 (MONEX-79). These included: 1) the structure of the Somali jet based on aerial observations;
2) sea-level air trajectories over the equatorial Indian Ocean; 3) structural features of the east African low-level flow;
4) effects of Indian Ocean surface temperature anomaly patterns on the summer monsoon circulations; 5) structures of the monsoon
low-level flow over the Arabian Sea; 6) characteristics and momentum-flux budgets of the Arabian Sea convective bands; and
7) evaporation and precipitation over the Arabian Sea during the monsoon seasons. Dr. Rao's research efforts in recent years
had focused on case studies of mesocyclones spawned by tropical cyclones (TCs) in Florida using Doppler radar data and a mesoscale
numerical model. These included: 1) research on tornadic mesocyclones spawned by TC Earl in 1998; 2) documentation of subtle
differences between tornadic and non-tornadic mesocyclones in TC Floyd in 1999; and 3) numerical simulation of the tornadic
environment observed in peninsular Florida during TC Earl in 1998. Preliminary findings show that the supercells' cold pools
interacted with an existing boundary resulting in increased baroclinicity and horizontal vorticity, and a maximization of
the tornado production potential by the updrafts. The model successfully simulated the mesoscale features of the mesocyclones
and the tornadic environment observed during TC Earl. A 24 h simulation of accumulated rainfall within the inner domain agreed
well with the observed precipitation pattern over the region. 相似文献
454.
Indu Jain P. Chittibabu Neetu Agnihotri S. K. Dube P. C. Sinha A. D. Rao 《Natural Hazards》2007,42(1):67-73
The northeastern sector of the Arabian Sea, which covers the Gujarat coast of India and western coast of Pakistan, is a region
vulnerable to extreme sea levels associated with tropical cyclones (TCs). Although the frequency of tropical cyclones in the
Arabian Sea is not high, the coastal regions of India and Pakistan suffer in terms of loss of life and property caused by
the surges. In view of this a location-specific fine resolution model is developed for the Gujarat coast of India and adjoining
Pakistan coast. The east–west and north–south grid distance is about 3.0 km. Using this model, numerical experiments are carried
out to simulate the surges generated by 1999 and 2001 cyclones which struck the Pakistan coast. The model computed surges
are in agreement with the available observational estimates. 相似文献
455.
Sensitivity of tropical cyclone intensification to boundary layer and convective processes 总被引:1,自引:1,他引:1
This study examines the role of the parameterization of convection, planetary boundary layer (PBL) and explicit moisture processes
on tropical cyclone intensification. A high-resolution mesoscale model, National Center for Atmospheric Research (NCAR) model MM5,
with two interactive nested domains at resolutions 90 km and 30 km was used to simulate the Orissa Super cyclone, the most
intense Indian cyclone of the past century. The initial fields and time-varying boundary variables and sea surface temperatures
were taken from the National Centers for Environmental Prediction (NCEP) (FNL) one-degree data set. Three categories of sensitivity
experiments were conducted to examine the various schemes of PBL, convection and explicit moisture processes. The results
show that the PBL processes play crucial roles in determining the intensity of the cyclone and that the scheme of Mellor-Yamada
(MY) produces the strongest cyclone. The combination of the parameterization schemes of MY for planetary boundary layer, Kain-Fritsch2
for convection and Mixed-Phase for explicit moisture produced the best simulation in terms of intensity and track. The simulated
cyclone produced a minimum sea level pressure of 930 hPa and a maximum wind of 65 m s−1 as well as all of the characteristics of a mature tropical cyclone with an eye and eye-wall along with a warm core structure.
The model-simulated precipitation intensity and distribution were in good agreement with the observations. The ensemble mean
of all 12 experiments produced reasonable intensity and the best track. 相似文献
456.
采用位涡理论对1998年7月4—7日的一次河套气旋强烈发展中的暴雨过程进行分析。结果表明:此次夏季河套气旋的强烈发展是在高层正位涡平流和低层暖平流的共同作用下产生的。高空双急流结构产生的强烈辐散加强了低层辐合,有利于气旋的加强。强降水出现在河套气旋强烈发展过程中,是由高层冷空气与季风涌带来的西南暖湿气流辐合而引起的大尺度降水过程。在这次气旋强烈发展过程中,对流层低层到中上层均出现强的上升气流,使得南方深厚的暖湿空气不断随西南风流入暴雨区上空。暴雨发生时,华北地区处于地面Ω型的θse高能舌之中,其上空500 hPa存在一个由大尺度动力强迫形成的东北—西南向的非地转湿 Q 矢量辐合带,对流云带与 Q 矢量辐合中心有非常好的对应关系。 相似文献
457.
458.
1. IntroductionMuch attention has been paid to the role playedby diabatic heating in the genesis and intensificationof tropical cyclone (TC). Based on a two-dimensionalprimitive equation model, Li (1984) proposed that theevolution of TC should be different if the maximumheating appears at different height. Yang et al. (1995)found that abrupt intensification of TC at the mid-latitudes is closely related to the vertical structure ofconvective heating. May and Holland (1998) suggestedthat the… 相似文献
459.
一类奇异孤波解及其在高原低涡结构分析中的应用 总被引:5,自引:0,他引:5
文中利用相平面分析法 ,由非绝热大气运动方程组导出了与非线性重力内波有关的 Kd V方程 ,然后用直接积分法得到两类有意义的孤立波解 ,重点分析了一类具有间断点的奇异孤立波解的特征 ,初步建立了此波解与一类青藏高原暖性低涡的联系 ,讨论了高原加热和层结稳定度对高原低涡生成和移动的影响 ,并且从理论上论证了高原低涡具有与热带气旋类低涡( Tropical cyclone- like vortices)类似的涡眼和暖心结构 相似文献
460.