全文获取类型
收费全文 | 681篇 |
免费 | 11篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 34篇 |
地球物理 | 358篇 |
地质学 | 114篇 |
海洋学 | 4篇 |
天文学 | 138篇 |
综合类 | 3篇 |
自然地理 | 29篇 |
出版年
2018年 | 8篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 22篇 |
2012年 | 13篇 |
2011年 | 20篇 |
2010年 | 22篇 |
2009年 | 25篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1997年 | 12篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 17篇 |
1989年 | 20篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1971年 | 14篇 |
1970年 | 12篇 |
1969年 | 9篇 |
1968年 | 8篇 |
1966年 | 7篇 |
1963年 | 7篇 |
1960年 | 7篇 |
1959年 | 9篇 |
1958年 | 7篇 |
排序方式: 共有692条查询结果,搜索用时 296 毫秒
21.
22.
23.
24.
Flow dynamics,sedimentation and erosion of glacial lake outburst floods along the Middle Pleistocene Scandinavian Ice Sheet (northern central Europe) 下载免费PDF全文
Jutta Winsemann Petteri Alho Leena Laamanen Nils Goseberg Jörg Lang Josef Klostermann 《Boreas: An International Journal of Quaternary Research》2016,45(2):260-283
During the Middle Pleistocene late Saalian glaciation of northern central Europe numerous pro‐glacial lakes formed along the southwestern margin of the Scandinavian Ice Sheet. Little is known about the drainage history of these lakes, the pathways of glacial lake outburst floods and their impacts on erosion, sedimentation and landscape evolution. This study investigated the impact of the late Saalian Weser and Münsterland Lake (Germany) outburst floods. In particular, we reconstructed the routing and flow dynamics of the lake outburst flood and analysed the flood related sediments. We employed one‐dimensional hydraulic modelling to calculate glacial lake outburst flood hydrographs. We modelled the flow pathway and local flow conditions along the pathway based on the boundary conditions of two different hydrographs and two different ice‐margin positions. The modelling results were compared with geomorphological and sedimentological field data in order to estimate the magnitude and impact of the flood on erosion and sedimentation. Two major lake drainage events are reconstructed for the study area, during which approximately 90–50 km3 of water was released. Modelling results indicate that the lake outburst floods created a high‐energy flood wave with a height of 35–50 m in confined valley areas that rapidly spread out into the Lower Rhine Embayment eventually flowing into the North Sea basin. The sedimentary record of the outburst floods comprises poorly sorted coarse‐grained gravel bars, long‐wavelength bedforms and sandy bedforms deposited by supercritical and subcritical flows. Some parts of the sandy flood deposits are rich in reworked mammoth bones or mammoth and horse teeth, pointing to reworking of older fluvial sediments, hydraulic concentration and subsequent re‐sedimentation of vertebrate remains. These deposits are preserved in sheltered areas or at high elevations, well above the influence of postglacial fluvial erosion. The flood‐related erosional features include up to 80‐m‐deep scour pools, alluvial channels and streamlined hills. 相似文献
25.
Emil M. Apostolov Vojtěch Letfus Reviewer J. Pýcha 《Studia Geophysica et Geodaetica》1989,33(4):379-390
Summary The time variations of the amplitudes and phases of the semi-annual variation in geomagnetic activity, characterized by the linear planetary index aa, have been analysed for the period 1868–1985. The results provide qualitative confirmation of Murayama's conclusions [13] about the systematic f phase in dependence on the changes in the level of solar activity and give support to Russel-McPherron's mechanism [16] concerning the effect of the predominant polarity of the interplanetary magnetic field. A distinctly expressed variation of the phase differences in the course of the sunspot cycle and of the 22-year cycle, and specific variations related to the sequence of four consecutive cycles have been established, as well as a well-defined 90-year period, all of them as a reflection of analogous variations in solar activity. The variations of the phase differences observed around the equinoxes can be explained by the combined effect of the mechanisms of the axial and equinoctial hypothesis. It is assumed that a displacement of the maxima of the semi-annual variation to dates after the equinoxes will be observed in the ascending parts and a reverse displacement towards the equinoxes and earlier dates in the desccending parts of the following sunspot cycles 22 nad 23.On leave from the Geophysical Institute of the Bulgarian Academy of Sciences, Akad. G. Bonchev Str. bl. 3, Sofia 1113, Bulgaria. 相似文献
26.
Summary We find no effect of the interplanetary magnetic field(IMF) sector boundary crossing in ozone at altitudes ranging from the middle stratosphere(10 hPa) to the lower mesosphere(0.4 hPa) at middle latitudes(40°–60° N), based on winter data over the period of December 1979–December 1982.
Резюме Мы не нaшлu нuкaко о эффекma nересеченuя секmорноŭ рaнuцы межnлaнеmно о мa нumно о nоля в озоне в облaсmu высоm меж?rt;у сре?rt;неŭ сmрamосфероŭ(10 Пa) u нuжнеŭ мезосфероŭ(0,4 Пa) нa сре?rt;нuх шuроmaх(40°–60° с.ш.), nрuменяя зuмнuе ?rt;aнные зa nерuо?rt; ?rt;екaбрь 1979 – ?rt;екaбрь 1982 .相似文献
27.
28.
Zdeněk Šimon Jan Kostelecký Antonín Zeman Reviewer L. Skalský 《Studia Geophysica et Geodaetica》1988,32(1):16-23
Summary It is recommended that the data from measurements with supraconducting gravity meters be also analysed with regard to verifying the gravitation absorption hypothesis. Based on theoretical data from a3-year period, the spectrum of the assumed effect of shielding the gravitational influence of the Sun by the Earth's body on the value of the acceleration of gravity has been calculated for the tidal station Brussels (Figs 2a–e).
¶rt;aam aauuam ¶rt;a uu n¶rt;uaumau ma mu u nuunm n¶rt;auaumauu. a mmuu ¶rt;a a mmu nu¶rt; u nm n¶rt;naa ma auauaumau ¶rt;mu a m a uu u u mmu ¶rt; nuu mauu (u. 2a–).相似文献
29.
30.
Milan Hvoždara Ladislav Brimich Reviewer L. Skalský 《Studia Geophysica et Geodaetica》1988,32(2):129-135
Summary The thermo-elastic deformations due to the annual temperature variation are computed. The time variation of these deformations is compared with the variation of the slow deformations observed at the tidal station in Vyhne.
Dedicated to RNDr Jan Pícha, CSc on his 70th birthday 相似文献
u mnu ¶rt;auu, a¶rt; auau mnam nmu a nnmama. ¶rt; mu ¶rt;au a ¶rt; ¶rt; ¶rt;au, u a nuu mauu ().
Dedicated to RNDr Jan Pícha, CSc on his 70th birthday 相似文献