全文获取类型
收费全文 | 259篇 |
免费 | 18篇 |
国内免费 | 32篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 41篇 |
地球物理 | 64篇 |
地质学 | 167篇 |
海洋学 | 6篇 |
天文学 | 2篇 |
综合类 | 1篇 |
自然地理 | 23篇 |
出版年
2021年 | 4篇 |
2019年 | 2篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 28篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 12篇 |
1996年 | 22篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1965年 | 2篇 |
1937年 | 1篇 |
1934年 | 2篇 |
1933年 | 4篇 |
1931年 | 1篇 |
1927年 | 3篇 |
1926年 | 7篇 |
1925年 | 2篇 |
1924年 | 6篇 |
排序方式: 共有309条查询结果,搜索用时 31 毫秒
31.
32.
Twenty-four geochemical reference samples have been analysed far barium using the stable isotope dilution technique. These include five CRPG, ten ANRT, six Nimroc and two CCRMP samples together with the Tonalite from Tanzania, Duplicate analyses have been made in each case and our values for barium are believed to be accurate to approximately 3 %. In general, our results are in good agreement with the published data except for Nimroc samples where our data are consistently lower than the presently accepted values. No evidence of sample inhomogeneities was observed in the present work. 相似文献
33.
DANIEL VERES SIWAN M. DAVIES BARBARA WOHLFARTH FRANK PREUSSER STEFAN WASTEGÅRD LINDA AMPEL ANNE HORMES GÖRAN POSSNERT JEAN-PAUL RAYNAL GÉRARD VERNET 《Boreas: An International Journal of Quaternary Research》2008,37(3):434-443
A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c . 2 000–45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel; however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard–Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords. 相似文献
34.
C. VAN CROMPHAUT V. G. DE RESENDE E. DE GRAVE R. E. VANDENBERGHE 《Meteoritics & planetary science》2007,42(12):2119-2123
Abstract— –Meridiani Planum is the first iron meteorite found on Mars. It was discovered in 2005 by the Mars Exploration Rover Opportunity (MER‐B). Mössbauer spectra (MS) of the unbrushed and brushed meteorite species were acquired in 10 degrees temperature windows in the range of 210–260 K. Earlier examinations of these MS have led to the conclusion that the meteorite, which contains ~~7 wt% Ni, belongs to the IAB meteorite group. Here, making use of a recently developed calibration/folding procedure for MER MS, we report the results of the MS analyses for the single temperature windows m5 (210–220 K), m6 (220–230 K), m7 (230–240 K), and m89 (240–260 K). All spectra consist of a sextet and a ferric doublet. The hyperfine field of the sextet, extrapolated to room temperature, is ~~34.5 T, which is, based on Mössbauer studies of meteorites found on Earth, indeed consistent with the presence of kamacite. The fractional spectral area of the sextet is ~~0.96 of the total spectrum. The ferric doublet has an average quadrupole splitting of 0.70 mm/s and is not diagnostic of any specific Fe mineral. 相似文献
35.
A. K. ENGVIK E. TVETEN B. BINGEN G. VIOLA M. ERAMBERT P. FEITO S. DE AZAVEDO 《Journal of Metamorphic Geology》2007,25(9):935-952
Pan‐African high‐pressure granulites occur as boudins and layers in the Lurio Belt in north‐eastern Mozambique, eastern Africa. Mafic granulites contain the mineral assemblage garnet + clinopyroxene + plagioclase + quartz ± magnesiohastingsite. Garnet porphyroblasts are zoned with increasing almandine and spessartine contents and decreasing grossular and pyrope contents from core (Alm46Prp32Grs21Sps2) to rim (Alm52Prp26Grs19Sps3). This pattern is interpreted as a retrograde diffusion zoning with the preserved core chemistry representing the peak metamorphic composition. Mineral reaction textures occur in the form of monomineralic and composite plagioclase ± orthopyroxene ± amphibole ± biotite ± magnetite coronas around garnet porphyroblasts. Thermobarometry indicates peak metamorphic conditions of up to 1.57 ± 0.14 GPa and 949 ± 92 °C (stage I), corresponding to crustal depths of ~55 km. Zircon yielded an U–Pb age of 557 ± 16 Ma, inferred to date crystallization of zircon during peak or immediately post‐peak metamorphism. Formation of plagioclase + orthopyroxene‐bearing coronas surrounding garnet indicates a near‐isothermal decompression of the high‐pressure granulites to lower pressure granulite facies conditions (stage II). Development of plagioclase + amphibole‐coronas enclosing the same garnet porphyroblasts shows subsequent cooling into amphibolite facies conditions (stage III). Symplectitic textures of the corona assemblages indicate rapid decompression. The high‐pressure granulite facies metamorphism of the Lurio Belt, followed by near‐isothermal decompression and subsequent cooling, is in accordance with a long‐lived tectonic history accompanied by high magmatic activity in the Lurio Belt during the late Neoproterozoic–early Palaeozoic East‐African–Antarctic orogeny. 相似文献
36.
利用NCEP/NCAR(2.5°×2.5°)再分析资料和常规、非常规观测资料,通过环境场和中尺度特征较全面细致地分析了孟加拉湾风暴费林(Phailin)对西藏特大暴雪的影响。研究表明:“费林”对强降水的影响主要是登陆减弱为低压后,低压云系分两个阶段形成三个中尺度对流云团,对流云团在南支槽的作用下上高原。而强降水的发生和南风风速的大小有直接的对应关系,西南低空急流建立后西藏南部才出现强降水,而低空急流的建立是靠南支槽的贡献。南风风速和强降水的这一重要关系为此类天气提供了预报着眼点。 相似文献
37.
KROON NORRIS KLAUS IAN T. ALEXANDER LEON PAUL BARDOT CHARLES E. BARKER JEAN-PIERRE BELLIER CHARLES D. BLOME LEON J. CLARKE JOCHEN ERBACHER KRISTINA L. FAUL MARY ANNE HOLMES BRIAN T. HUBER MIRIAM E. KATZ KENNETH G. MACLEOD SANDRA MARCA FRANCISA C. MARTINEZ-RUIZ ISAO MITA MUTSUMI NAKAI JAMES G. OGG DOROTHY K. PAK THOMAS K. PLETSCH JEAN M. SELF-TRIAL NICHOLAS J. SHACKLETON JAN SMIT WILLIAM USSLERIII DAVID K. WATKINS JOEN WIDMARK & PAUL A. WILSON 《Geology Today》1998,14(6):222-226
38.
HEIKKI SEPPÄ H. JOHN B. BIRKS ANNE E. BJUNE ATLE NESJE 《Boreas: An International Journal of Quaternary Research》2010,39(4):649-654
Seppä, H., Birks, H. J. B., Bjune, A. E. & Nesje, A. 2010: Current continental palaeoclimatic research in the Nordic region (100 years since Gunnar Andersson 1909) – Introduction. Boreas, Vol. 39, pp. 649‐654. 10.1111/j.1502‐3885.2010.00170.x. ISSN 0300‐9483. 相似文献
39.
40.
C R DE FREITAS 《New Zealand geographer》1994,50(1):30-32
Major changes are occurring in the global warming debate. Popular alarmist views are giving way to more balanced assessments of the situation. There is now greater emphasis on the lack of consensus among climatologists on fundamental scientific issues related to climate change. 相似文献