全文获取类型
收费全文 | 377篇 |
免费 | 10篇 |
国内免费 | 15篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 40篇 |
地球物理 | 107篇 |
地质学 | 102篇 |
海洋学 | 86篇 |
天文学 | 45篇 |
综合类 | 4篇 |
自然地理 | 17篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 21篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 22篇 |
2010年 | 16篇 |
2009年 | 24篇 |
2008年 | 15篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 16篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有402条查询结果,搜索用时 0 毫秒
41.
42.
Concurrent variations of CNA fluctuations and geomagnetic fluctuations are classified into Type 1 (substorm-type), Type 2 (Pc5-type), and Type 3 which is the object of the present study. Type 3 apparently has peculiar characteristics in that CNA fluctuations at a certain auroral-zone station show a pronounced positive correlation with magnetic fluctuations at distant low-latitude stations. The magnetic fluctuations of this type are identified to generalized Si which tends to take place much more frequently than the so-called Si. The CNA fluctuations of this type are found to take place on the dayside auroral zone only when preceded by a magnetic substorm on the night side. Considering the change of the growth rate of electron cyclotron instability and enhancement of pitch angle diffusion due to the change of magnetic field intensity, the following model is proposed to explain the occurrence mechanism of Type 3 concurrent variations. The CNA fluctuations take place only when two conditions are satisfied; generation of the accelerated electrons in association with substorm onset and modulation of the precipitation of the electrons by compression and expansion of the magnetosphere, in other words, by generalized Si. 相似文献
43.
K.?MinouraEmail author F.?Imamura U.?Kuran T.?Nakamura G. A.?Papadopoulos D.?Sugawara T.?Takahashi A. C.?Yalciner 《Natural Hazards》2005,36(3):297-306
A tsunamigenic sediment layer has been discovered in fluvio-alluvial sequences on the northern coast of the Marmara Sea, northwestern
Turkey. The layer consists of unsorted silty coarse sand including terrestrial molluscs and charcoal fragments. The AMS radiometric
ages of the shells have been estimated at around BC 400, AD 300, AD 400, and AD 1000. We propose that a tsunami occurred in
the Marmara Sea in the middle of 11th century and invaded the fluvial plains. The older fossils were derived from the underlying
horizons, and it is probable that buoyant materials such as terrestrial molluscs and charcoals were isolated from liquefied
sediments during submarine sliding. Slope failure of coastal blocks triggered by fault movement generated tsunamis, which
might have transported floating materials to the backshore. 相似文献
44.
45.
Meddies are warm and saline anticyclonic eddies found at the mid-depth of the Mediterranean Outflow in the Eastern North Atlantic.
They are observed to move almost southward at average speeds as high as 1.3±0.2 cm s−1. This paper examines a mechanism which accelerates this curious translation to a reasonable speed when combined with nonlinearity
and a suitable vertical eddy structure. This mechanism is thepseudo-topographic β effect due to the westward decrease in the thickness of the mid-layer induced by the surface southward mean current. The
linear dispersion relation including this effect is shown to account for a quarter of the surface southward mean current or
a fifth of the observed southward translation of meddies. Three-layer quasi-geostrophic experiments reveal that the surface
southward mean current certainly enhances the southward translation velocity of meddies to a speed in agreement with observation,
if the meddy has a current structure of plausible intensity and vertical coherence. In the light of the current-induced pseudo-topographic
β effect, previous hypotheses are also re-examined through dynamic arguments together with numerical experiments; they are
suggested to have some difficulty either in dynamics or in correspondence with observation. Thus the nonlinear effect due
to secondary eddies combined with thecurrent-induced pseudo-topographic β effect is the most likely mechanism responsible for the rapid southward translation of meddies among those examined in
the paper. 相似文献
46.
47.
Yuhei Yamamoto Yoshio Takahashi Yutaka Kanai Yoshio Watanabe Tomoya Uruga Hajime Tanida Yasuko Terada Hiroshi Shimizu 《Applied Geochemistry》2008,23(8):2452-2461
The uranium LIII-edge XANES spectra for natural rocks at the concentration range of 0.96–124 mg kg−1 were measured using a log spiral bent crystal Laue analyzer (BCLA) combined with a multi-element Ge detector. It was found that the quality of the XANES spectra using the BCLA was greatly improved due to a reduction of interfering fluorescence from major components such as Rb and Sr. The ratio of signal to background intensities in the U LIII-edge XANES spectra increased by a factor of 2.9–17 with the use of the BCLA, which greatly enhanced the detection limit for the speciation of the oxidation states of U or the U(IV)/U(VI) ratio of natural samples. In addition, it was demonstrated that the fluorescence XANES method coupled with the BCLA enable determination of the speciation of U for various natural samples such as acidic igneous rocks, ferromanganese nodules, sediments, and some sedimentary rocks such as shale and limestone. 相似文献
48.
Sébastien Masson Pascal Terray Gurvan Madec Jing-Jia Luo Toshio Yamagata Keiko Takahashi 《Climate Dynamics》2012,39(3-4):681-707
This paper explores the impact of intra-daily Sea Surface Temperature (SST) variability on the tropical large-scale climate variability and differentiates it from the response of the system to the forcing of the solar diurnal cycle. Our methodology is based on a set of numerical experiments based on a fully global coupled ocean–atmosphere general circulation in which we alter (1) the frequency at which the atmosphere sees the SST variations and (2) the amplitude of the SST diurnal cycle. Our results highlight the complexity of the scale interactions existing between the intra-daily and inter-annual variability of the tropical climate system. Neglecting the SST intra-daily variability results, in our CGCM, to a systematic decrease of 15% of El Ni?o—Southern Oscillation (ENSO) amplitude. Furthermore, ENSO frequency and skewness are also significantly modified and are in better agreement with observations when SST intra-daily variability is directly taken into account in the coupling interface of our CGCM. These significant modifications of the SST interannual variability are not associated with any remarkable changes in the mean state or the seasonal variability. They can therefore not be explained by a rectification of the mean state as usually advocated in recent studies focusing on the diurnal cycle and its impact. Furthermore, we demonstrate that SST high frequency coupling is systematically associated with a strengthening of the air-sea feedbacks involved in ENSO physics: SST/sea level pressure (or Bjerknes) feedback, zonal wind/heat content (or Wyrtki) feedback, but also negative surface heat flux feedbacks. In our model, nearly all these results (excepted for SST skewness) are independent of the amplitude of the SST diurnal cycle suggesting that the systematic deterioration of the air-sea coupling by a daily exchange of SST information is cascading toward the major mode of tropical variability, i.e. ENSO. 相似文献
49.
Performance assessment of three convective parameterization schemes in WRF for downscaling summer rainfall over South Africa 总被引:1,自引:1,他引:1
Satyaban B. Ratna J. V. Ratnam S. K. Behera C. J. deW. Rautenbach T. Ndarana K. Takahashi T. Yamagata 《Climate Dynamics》2014,42(11-12):2931-2953
Austral summer rainfall over the period 1991/1992 to 2010/2011 was dynamically downscaled by the weather research and forecasting (WRF) model at 9 km resolution for South Africa. Lateral boundary conditions for WRF were provided from the European Centre for medium-range weather (ECMWF) reanalysis (ERA) interim data. The model biases for the rainfall were evaluated over the South Africa as a whole and its nine provinces separately by employing three different convective parameterization schemes, namely the (1) Kain–Fritsch (KF), (2) Betts–Miller–Janjic (BMJ) and (3) Grell–Devenyi ensemble (GDE) schemes. All three schemes have generated positive rainfall biases over South Africa, with the KF scheme producing the largest biases and mean absolute errors. Only the BMJ scheme could reproduce the intensity of rainfall anomalies, and also exhibited the highest correlation with observed interannual summer rainfall variability. In the KF scheme, a significantly high amount of moisture was transported from the tropics into South Africa. The vertical thermodynamic profiles show that the KF scheme has caused low level moisture convergence, due to the highly unstable atmosphere, and hence contributed to the widespread positive biases of rainfall. The negative bias in moisture, along with a stable atmosphere and negative biases of vertical velocity simulated by the GDE scheme resulted in negative rainfall biases, especially over the Limpopo Province. In terms of rain rate, the KF scheme generated the lowest number of low rain rates and the maximum number of moderate to high rain rates associated with more convective unstable environment. KF and GDE schemes overestimated the convective rain and underestimated the stratiform rain. However, the simulated convective and stratiform rain with BMJ scheme is in more agreement with the observations. This study also documents the performance of regional model in downscaling the large scale climate mode such as El Niño Southern Oscillation (ENSO) and subtropical dipole modes. The correlations between the simulated area averaged rainfalls over South Africa and Nino3.4 index were ?0.66, ?0.69 and ?0.49 with KF, BMJ and GDE scheme respectively as compared to the observed correlation of ?0.57. The model could reproduce the observed ENSO-South Africa rainfall relationship and could successfully simulate three wet (dry) years that are associated with La Niña (El Niño) and the BMJ scheme is closest to the observed variability. Also, the model showed good skill in simulating the excess rainfall over South Africa that is associated with positive subtropical Indian Ocean Dipole for the DJF season 2005/2006. 相似文献
50.
Kim Hanjun Kang Sarah M. Takahashi Ken Donohoe Aaron Pendergrass Angeline G. 《Climate Dynamics》2021,56(1-2):17-27
Climate Dynamics - We investigate the possible causes for inter-model spread in tropical zonal-mean precipitation pattern, which is divided into hemispherically symmetric and anti-symmetric modes... 相似文献