全文获取类型
收费全文 | 1996篇 |
免费 | 68篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 44篇 |
大气科学 | 135篇 |
地球物理 | 965篇 |
地质学 | 491篇 |
海洋学 | 35篇 |
天文学 | 356篇 |
综合类 | 5篇 |
自然地理 | 39篇 |
出版年
2021年 | 25篇 |
2020年 | 28篇 |
2018年 | 52篇 |
2017年 | 65篇 |
2016年 | 93篇 |
2015年 | 74篇 |
2014年 | 90篇 |
2013年 | 96篇 |
2012年 | 38篇 |
2011年 | 53篇 |
2010年 | 74篇 |
2009年 | 63篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 37篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 33篇 |
2002年 | 36篇 |
2001年 | 24篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 32篇 |
1997年 | 20篇 |
1996年 | 40篇 |
1995年 | 24篇 |
1994年 | 31篇 |
1993年 | 34篇 |
1992年 | 31篇 |
1991年 | 26篇 |
1990年 | 31篇 |
1989年 | 26篇 |
1988年 | 31篇 |
1987年 | 25篇 |
1986年 | 34篇 |
1985年 | 19篇 |
1984年 | 34篇 |
1983年 | 31篇 |
1982年 | 34篇 |
1981年 | 25篇 |
1980年 | 22篇 |
1979年 | 37篇 |
1978年 | 29篇 |
1977年 | 26篇 |
1975年 | 21篇 |
1974年 | 25篇 |
1973年 | 26篇 |
1972年 | 27篇 |
1971年 | 29篇 |
1970年 | 18篇 |
排序方式: 共有2070条查询结果,搜索用时 31 毫秒
191.
Kalvová Jaroslava Halenka Tomáš Bezpalcová Klára Nemešová Ivana 《Studia Geophysica et Geodaetica》2003,47(1):185-202
The Köppen climate classification was applied to the observed gridded climatological sets and the outputs of four general circulation models (GCMs) over the continents of the Earth. All data had been acquired via the Data Distribution Centre established by the Intergovernmental Panel on Climate Change. The ability of the GCMs to simulate the Köppen climate zones identified in the real data was explored and possible future (global warming) changes in the climate types' distribution for each GCM were assessed. Differences in the area distributions derived from the GCMs' recent climate simulations give evidence about uncertainties generally involved in climate models. As to the global warming simulations, all GCM projections of warming climate (horizon 2050) show that the zones representing tropical rain climates and dry climates become larger, and the zones identified with boreal forest and snow climates together with the polar climates are smaller. 相似文献
192.
Huth Radan Mládek Richard Metelka Ladislav Sedlák Pavel Huthová Zuzana Kliegrová Stanislava Kyselý Jan Pokorná Lucie Halenka Tomáš Janoušek Martin 《Studia Geophysica et Geodaetica》2003,47(4):863-873
This note summarizes results of the first integration of regional numerical weather prediction model ALADIN in a climate mode. The ALADIN model, developed in an international cooperation led by Météo France, is operationally used for weather prediction. The grid step of the model is 12 km; the integration domain covers a major part of Europe. A one-month-long run has been performed with this model on observed boundary conditions (represented by assimilations by the global model ARPEGE). It is demonstrated that no excessive error is generated and accumulated in the model during the integration; hence the model is integrable for extended time periods and may serve a basis for a development towards a regional climate model. 相似文献
193.
Boška J. Šauli P. Altadill D. German Solé J. Alberca L.F. 《Studia Geophysica et Geodaetica》2003,47(3):579-586
We investigate the short-term fluctuations in the period range from 15 to 180 minutes in the electron density variations of the F region ionosphere. Electron density profiles obtained at the ionospheric stations of Pruhonice (49.9° N, 14.5° E) and Ebro (40.8° N, 0.5° E) at five minute time sampling have been used for this analysis. The diurnal changes of the activity of the acoustic gravity wave fluctuations (AGW) show a clear enhancement during and several hours after sunrise. The periods of such AGW's are about 60 to 75 minutes and these waves propagates vertically through the ionosphere from a source located at an altitude of 180-220 km. The most likely source for these events seems to be passage of the Solar terminator. 相似文献
194.
Studia Geophysica et Geodaetica - 相似文献
195.
The formation and evolution of a large amplitude MHD perturbation propagating perpendicular to the magnetic field in a perfectly conducting low plasma is studied. The perturbation is generated by an abrupt expansion of the source region. Explicit expressions for the time and the distance needed for the transformation of the perturbation's leading edge into a shock wave are derived. The results are applied to coronal conditions and the dynamic spectra of the radio emission excited by the shock are synthesized, reproducing metric and kilometric type II bursts. The features corresponding to the metric type II burst precursor and the moving type IV burst in the case of kilometric type II bursts are identified. A specific radio signature that is sometimes observed at the onset of a metric type II burst is found to appear immediately before the shock wave formation due to the associated growth of the magnetic field gradient. Time delays and starting frequencies of bursts' onsets are calculated and presented as a function of the impulsiveness of the source-region expansion, using different values of the ambient Alfvén velocity and various time profiles of the expansion velocity. The results are confronted with the observations of metric and kilometric type II solar radio bursts. 相似文献
196.
Milan Burša Jan Kouba Viliam Vatrt Vojtěch Vítek Marie Vojtíšková 《Studia Geophysica et Geodaetica》2000,44(1):1-12
The T/P altimeter data 1993 – 1997 (cycles 11 – 194) has been analyzed with emphases on seasonal variations in sea surface topography (SST). The amplitude of the annual variations amounted to (5.9±0.3) mm when inverted barometer (IB) corrections were applied and (2.0±0.4) mm without any IB corrections. The amplitude of the semi-annual variations in SST was small with IB corrections applied: (0.6±0.3) mm. However, when no IB corrections were applied, it was (1.8±0.4) mm, i.e. the semiannual variations are at the same level as the annual variations with no IB corrections. The phase angle offset of the annual term has shifted by about 180° when IB correction was applied. The dynamics of the ocean-atmosphere system is discussed and it is concluded that it could, at least partly, be responsible for the above observed effects. 相似文献
197.
Summary The three-dimensional mesoscale cloud-resolving model ARPS (Advanced Regional Prediction System) was used to investigate the
dispersal of an inert seeding agent within a cumulonimbus (Cb) cloud developing from two different initial states. In this
paper, we stress the influence vortices in the cloud have on seeding agent dispersion. If a strong directional ambient wind
shear is present in the lowest layer, a vortex pair formed at the flanks of the simulated cloud. Following the velocity field,
a considerable amount of the injected seeding agent would be thrown out to the rear of the cloud, where both updrafts associated
with vortices and downdrafts occurred. After a short time the agent was present only in the cloud periphery. If the Cb cloud
developed under conditions where directional ambient wind shear did not exist, seeding agent dispersion would be quite different.
In this case, almost all the seeding agent was transported into the main updraft, while the residence time of the agent within
the cloud was longer due to the weaker cloud dynamics. Therefore, we must pay attention to whether or not the cloud contains
vortices when we make the decision where to seed. This is necessary in order to minimize the loss of seeding material. 相似文献
198.
K. Pandžić I. Šimunić F. Tomić S. Husnjak T. Likso D. Petošić 《Theoretical and Applied Climatology》2006,85(1-2):107-115
Summary This paper presents an the evaluation of three mathematical models for the estimation of 10-day drain discharge using weather, pedological and phenological parameters. One model uses modified Palmer’s procedure for the calculation of
water balance components and the second two use empirical multiple linear regression. The models have been applied to data
of an amelioration experimental field in central Croatia (south-western part of the Pannonian Lowland), where a set of average
10-day air temperature and relative humidity data, average wind speed, cumulative precipitation and drain discharge amounts,
insolation and soil moisture data and vegetation indices have been collected. The experiment has been performed during the
period 1990–1992. The models have been tested by comparing estimated and observed 10-day drain discharge amounts. All models
mainly give acceptable cumulative results although their accuracy depends on the season. 相似文献
199.
This paper presents the development and utilisation of an automated image processing algorithm for detection and analysis
of grains. Using optical polarising microscopy, a set of colored images are collected from an area on a thin section. A filtering
operation, using rotation of a morphological alternating sequence filter (based on a structuring element), is used to remove
twinning features within individual grains. Filtering is followed by the watershed segmentation technique to determine grain
boundaries. The method is used for the identification of calcite grains in marble and the subsequent analysis of morphological
anisotropy. 相似文献
200.
Sea/land breeze climatological characteristics along the northern Croatian Adriatic coast 总被引:1,自引:0,他引:1
Summary Climatological characteristics along the northern Croatian Adriatic coast have been examined for nine meteorological stations
for the summertime sea/land breeze circulation. The stations considered are Pula-airport, Opatija, Rijeka, Senj, Malinska,
Rijeka-airport, Mali Lošinj, Rab and Zadar. The hourly surface measurements at each station from June to September for the
period 1991–2004 as well as the radiosoundings in Zadar (from 2002 to 2004) were used for the analysis. A dataset with the
sea/land breeze days was formed according to the several criteria.
The mean daily maxima of both air and sea surface temperatures were more influenced by the large scale disturbances toward
north (e.g. in Rijeka or Opatija) compared to the values for e.g. Zadar. Furthermore, the influence of the large scale disturbances
diminished toward the south concerning the sea–land temperature difference only at the stations placed at Rijeka Bay and Velebit
channel. The strongest sea breeze was found at Pula-airport and the most frequent ones at Opatija and Zadar. At Senj the rarest,
the weakest and the shortest sea breeze was observed. The climatological records of wind speed and air-sea temperature difference
(ΔT) showed for Opatija, Malinska and Zadar that the maximum measured wind speed is around 4.5 °C confirming the nonlinear relationship
between the sea breeze speeds and the ΔT during the day.
At most stations, the clockwise rotation of the hodographs prevails which is typical for the Northern hemisphere due to Coriolis
force, with the exception at Senj and Malinska. While the hodographs for Pula, Rijeka-airport and Mali Lošinj display a later
onset of the prevailing sea breeze because of the interaction among several sea breeze circulations, the results for Opatija,
Zadar and Senj show considerably distorted hodographs because of the nearby channeling of the air flow. 相似文献