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11.
本文利用历史天气图资料,对1973—1988年中国东部和沿海地区的温带气旋及其爆发性发展情况进行了统计,共有1014个温带气旋发生,其中有1/5达到了爆发性发展的强度,构成了西太平洋爆发性海洋气旋的一部分.它占整个西太平洋爆发性气旋总频数(包括不同来源)的51%.进而对这类爆发性气旋的活动规律进行了分析,概括出了它们的气候学特征.比较亚洲大陆、中国近海及西太平洋地区的爆发性温带气旋表明,西太平洋地区不仅频繁而且强烈.而东、西太平洋地区发生海洋爆发性气旋的对比表明,二者存在着明显的差异.同时也指出,东太平洋地区爆发性气旋的发生并不是一种少见的现象. 相似文献
12.
13.
T. S. V. Vijaya Kumar J. Sanjay B. K. Basu A. K. Mitra D. V. Bhaskar Rao O. P. Sharma P. K. Pal T. N. Krishnamurti 《Natural Hazards》2007,41(3):471-485
This study entails the implementation of an experimental real time forecast capability for tropical cyclones over the Bay
of Bengal basin of North Indian Ocean. This work is being built on the experience gained from a number of recent studies using
the concept of superensemble developed at the Florida State University (FSU). Real time hurricane forecasts are one of the
major components of superensemble modeling at FSU. The superensemble approach of training followed by real time forecasts
produces the best forecasts for tracks and intensity (up to 5 days) of Atlantic hurricanes and Pacific typhoons. Improvements
in track forecasts of about 25–35% compared to current operational forecast models has been noted over the Atlantic Ocean
basin. The intensity forecasts for hurricanes are only marginally better than the best models. In this paper, we address tropical
cyclone forecasts over the Bay of Bengal for the years 1996–2000. The main result from this study is that the position and
intensity errors for tropical cyclone forecasts over the Bay of Bengal from the multimodel superensemble are generally less
than those of all of the participating models during 1- to 3-day forecasts. Some of the major tropical cyclones, such as the
November 1996 Andhra Pradesh cyclone and October 1999 Orissa super cyclone were well handled by this superensemble approach.
A conclusion from this study is that the proposed approach may be a viable way to construct improved forecasts of Bay of Bengal
tropical cyclone positions and intensity. 相似文献
14.
2000年我国主要天气气候特点为:全国大部地区降水偏少或接近常年,出现全国性干旱,特别是北方地区春夏季遭遇多年来罕见的特大干旱,汛期未发生大范围的暴雨洪涝灾害,秋季黄淮以南地区出现持续连阴雨天气,全国大部分气温接近常年成偏高,持续暖冬态势发生转折,夏季高温酷热,春季北方扬沙和沙尘暴天气异常频繁,登陆我国台风个数偏少,风雹等强对流天气明显偏少。 相似文献
15.
The trigonometric relationship between slope inclination, the horizontally acting time‐averaged traction force and the vertical depth of transport allows the estimation of one factor, when both others are known. Depth–transport functions can be deduced by comparing the depth distributions of living organisms and their skeletal remains, and this paper simplifies this comparison using foraminifera in which a single test represents an individual. Differences in distribution parameters between living individuals and empty tests allow depth–transport functions to be determined; these functions differ between species at a single transect according to the varying buoyancies of the tests. Within a single species, differences in depth–transport functions between locations are based on either slope inclination or traction intensities. After establishing a mean depth–transport function by averaging species‐characteristic functions, the time‐averaged traction force acting on the studied transect can be calculated. Transport intensities are also estimated using an erosion–deposition diagram that combines the relative frequency distributions of living individuals and empty tests. The proportion of ‘eroded’, ‘parautochthonous’ and ‘allochthonous’ tests mirrors the influence of both slope inclination and traction force for the deposition of empty tests. To test the model, six species of symbiont‐bearing benthic foraminifers were investigated at two transects in front of a NW Pacific coral reef. One transect is distinguished by a strong slope flattening below the steep reef slope (30 m), whereas further steepening characterizes the equivalent part in the other transect. These differences are mirrored in the depth–transport functions as well as in the erosion–deposition diagrams of all species. The time‐averaged traction forces differ in intensities between transects, because of the position of the reef front with respect to the predominant wind direction. However, the form of the functions is identical and distinguished by an increase from the surface to 35 m depth, followed by a decrease down to 105 m. This can be explained by successive onshore and offshore forces acting on the shallow slope, such as the tropical cyclones that cross the region every summer. 相似文献
16.
根据我国近海热带气旋发生、发展的气候特点,规定12小时热带气旋中心附近最大风速增值≥10 m/s为迅速加强。通过1949~1990年近海发生迅速加强的84个热带气旋个例分析,阐述了迅速加强时段的时间分布、地区分布及迅速加强前后气象要素变化的气候特征。 相似文献
17.
I.horoductionPleNorthwestPacificOceanisti1elnostfrequentlyaffeCtedareaoftropicalcyclone(TC).AboLIt36percentTCoftheworldoccurinffosarea[2],andthenumberofTCWhichlandedonChinawiti1n1akimumwindforcescalesoverlOisabout35percentofti1atintheeastemcoastalcoLUitriesofAsia[l].BothrainstormsandfloodsMide,theidriuenceofTCareheaVyinChina,suchastherainfalldePthof2749mm/3datXinliao,Taiwanandpeakdischargeof44,6oOm'/satHuanggo(55,42okn'),YalujiangRjver.Therefore,TCisanimportantfaCtorforflooddisas… 相似文献
18.
1 INTRODUCTIONWith the methods of correlation and compositeanalyses,Ju et al.[1] discussed the relationship betweenlow-frequency oscillation in the summer monsoonregion in East Asia and droughts/floods in the middleand lower reaches of the Yangtze River and found thatstrong monsoon years usually cause more rain in theregion. Studying the interdecadal variation ofprecipitation in three rain zones over south China,thevalley of Yangtze River and north China,Tan et al.[2]showed that mid- a… 相似文献
19.
Steven L. Morey Mark A. Bourassa Dmitry S. Dukhovskoy James J. O’Brien 《Ocean Dynamics》2006,56(5-6):594-606
A coupled ocean and boundary layer flux numerical modeling system is used to study the upper ocean response to surface heat
and momentum fluxes associated with a major hurricane, namely, Hurricane Dennis (July 2005) in the Gulf of Mexico. A suite
of experiments is run using this modeling system, constructed by coupling a Navy Coastal Ocean Model simulation of the Gulf
of Mexico to an atmospheric flux model. The modeling system is forced by wind fields produced from satellite scatterometer
and atmospheric model wind data, and by numerical weather prediction air temperature data. The experiments are initialized
from a data assimilative hindcast model run and then forced by surface fluxes with no assimilation for the time during which
Hurricane Dennis impacted the region. Four experiments are run to aid in the analysis: one is forced by heat and momentum
fluxes, one by only momentum fluxes, one by only heat fluxes, and one with no surface forcing. An equation describing the
change in the upper ocean hurricane heat potential due to the storm is developed. Analysis of the model results show that
surface heat fluxes are primarily responsible for widespread reduction (0.5°–1.5°C) of sea surface temperature over the inner
West Florida Shelf 100–300 km away from the storm center. Momentum fluxes are responsible for stronger surface cooling (2°C)
near the center of the storm. The upper ocean heat loss near the storm center of more than 200 MJ/m2 is primarily due to the vertical flux of thermal energy between the surface layer and deep ocean. Heat loss to the atmosphere
during the storm’s passage is approximately 100–150 MJ/m2. The upper ocean cooling is enhanced where the preexisting mixed layer is shallow, e.g., within a cyclonic circulation feature,
although the heat flux to the atmosphere in these locations is markedly reduced. 相似文献
20.
55-year (1949 - 2003) data sets are used to study the statistical characteristics in intensity change of the tropical cyclones (TC) over the western North Pacific. According to the mathematical meaning of average value and standard deviation, the abruptly intensifying, gradually intensifying, stable intensity, gradually weakening and abruptly weakening of TC intensity are defined and the statistical characteristics, such as inter-decadal variation, inter-annual variation, inter-monthly variation, and regional distribution, etc. are analyzed. Main results are as follows: (1) From 1949 to 2003, there were 1886 TCs, averaging at 34.29 TCs per year. After 1995, the number of TCs dropped dramatically with less than 30 per year. 3.56% of the total were abruptly intensifying samples, and 3.31% were weakening samples. (2) For the annual mean, all but the stable group tend to decrease with the shift of decades as far as the overall change of the 6-h isallobaric process is concerned. (3) The abruptly intensifying TC seldom occurs over mid- and high-latitude area (north of 30°N) and low-latitude area and sometimes occurs around the islands and continent. Basically there is no gradually intensifying of TC over mid- and high- latitude area (north of 30°N and west of 125°E), in offshore Chinese waters. The gradually weakening and abruptly weakening TCs usually occur offshore China, west of 125 °E, but seldom over low-latitude area (0 - 5°N). 相似文献