全文获取类型
收费全文 | 427篇 |
免费 | 42篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 10篇 |
大气科学 | 33篇 |
地球物理 | 145篇 |
地质学 | 182篇 |
海洋学 | 36篇 |
天文学 | 31篇 |
综合类 | 3篇 |
自然地理 | 31篇 |
出版年
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 20篇 |
2019年 | 7篇 |
2018年 | 31篇 |
2017年 | 22篇 |
2016年 | 54篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 37篇 |
2012年 | 24篇 |
2011年 | 36篇 |
2010年 | 23篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有471条查询结果,搜索用时 15 毫秒
431.
Josep M. TRIGO‐RODRÍGUEZ Jordi LLORCA Alan E. RUBIN Jeffrey N. GROSSMAN Derek W. G. SEARS Mateo NARANJO Stacy BRETZIUS Mar TAPIA Marino H. GUARÍN SEPÚLVEDA 《Meteoritics & planetary science》2009,44(2):211-220
Abstract— The fall of the Cali meteorite took place on 6 July 2007 at 16 h 32 ± 1 min local time (21 h 32 ± 1 min UTC). A daylight fireball was witnessed by hundreds of people in the Cauca Valley in Colombia from which 10 meteorite samples with a total mass of 478 g were recovered near 3°24.3′N, 76°30.6′W. The fireball trajectory and radiant have been reconstructed with moderate accuracy. From the computed radiant and from considering various plausible velocities, we obtained a range of orbital solutions that suggest that the Cali progenitor meteoroid probably originated in the main asteroid belt. Based on petrography, mineral chemistry, magnetic susceptibility, thermoluminescence, and bulk chemistry, the Cali meteorite is classified as an H/L4 ordinary chondrite breccia. 相似文献
432.
Víctor M. Muñoz Marín Rosa M. González Delgado Henrique R. Schmitt Roberto Cid Fernandes Enrique Pérez 《Astrophysics and Space Science》2009,324(2-4):253-258
We explore the role of star clusters in the nuclear regions of galaxies through their connection with active galactic nuclei (AGN). Nuclear star clusters (NCs) are conspicuous in the centers of most nearby galaxies, all along the Hubble sequence. These clusters are probably the faint-end distribution of the central supermassive black holes (SMBHs) in massive bulges. On the other hand, star formation is known to be ongoing in the majority of Seyfert nuclei and in many low-luminosity active galactic nuclei (LLAGN). We study two samples of AGN galaxies (75 Seyferts and 26 LLAGN) in the near-ultraviolet with the Hubble Space Telescope’s Advanced Camera for Surveys. We aim to better understand the connection between the growing of the SMBH and the build-up of the bulge, and we also intend to make statistical progress and determine the properties of the population of NCs coexisting with growing SMBHs. 相似文献
433.
De Lacy M.C. Rodríguez-Caderot G. Marín E. Ruiz A. Borque M.J. Gil A.J. Biagi L. 《Studia Geophysica et Geodaetica》2001,45(1):55-66
Two new GPS surveys have been carried out to check the accuracy of an existing gravimetric geoid in a test area located in northern Andalusia (Spain). The fast collocation method and the remove-restore procedure have been used for the computation of the quasigeoid model. The Spanish height system is based on orthometric heights, so the gravimetrically determined quasigeoid has been transformed to a geoid model and then compared to geoid undulations provided by GPS and levelling at benchmarks belonging to the Spanish first-order levelling network. The discrepancies between the gravimetric solution and GPS/levelling undulations amount to ±2 cm for one survey and ±5 cm for another after fitting a plane to the geoid model. 相似文献
434.
Vera Ẑutić Boẑena Ćosović Elena Marčenko Nevenka Bihari Frano Kršinić 《Marine Chemistry》1981,10(6):505-520
Electrochemical methods based on adsorption of organic molecules at the mercury electrode-solution interface were used to investigate surfactant production by marine phytoplankton. Six species of marine phytoplankton, representing the classes of Bacillariophyceae, Haeptophyceae, Chlorophyceae and Cryptophyceae, were studied in batch cultures.Our experimental results showed that surfactants were produced in culture media by healthy exponential growing cells. The measured response was found to depend on the particular species and the age of the culture.Total surfactant content in culture media generally increased with cell density, while surfactants per cell showed an inverse relation to cell density. However, we found that in Cryptomonas culture medium, during the exponential growth, excretion of the insoluble surfactant material per cell was independent of cell concentration.In addition to culture experiments, surfactant activity at several northern Adriatic stations was measured during various stages of phytoplankton bloom. It was concluded that a significant part of surfactant activity in a seawater column is due to phytoplankton production. 相似文献
435.
Based on analysis techniques including homogeneity testsand anomalies and trend analysis, a methodology was developed and applied to nine long monthlyrainfall series of the Peninsular Spain (1859–1997). Lying on the basis of a previousspatial regionalization, these series are considered to be representative for this area. Afterstudying the main features of their temporal evolution on a regional scale, results have been comparedto those procured by other studies within the AMHY/FRIEND project of UNESCO for otherMediterranean regions. The conclusions show that there is no significant trendin the series. On the contrary, a common dry period for whole Spain between 1935 and 1955 thatcoincides with a negative anomaly affecting the Western Mediterranean has been found. 相似文献
436.
Carlos Marı́n Jesús Galindo-Zaldı́var Luı́s Roberto Rodrı́guez-Fernández 《Comptes Rendus Geoscience》2003,335(2):255-264
The Campo de Dal??as, located between the central and eastern Betic Cordilleras, shows an evolution determined by the overprinting of two main stress fields since Pliocene times. The first of these develops hybrid and tensional joint sets up to Pleistocene (100 000 yr) and is characterized by NNW–SSE horizontal trend of compression and an ENE–WSW horizontal extension. The second stress field has prolate to triaxial extensional ellipsoids, also with ENE–WSW horizontal extension, and continues to be active today. The most recent stresses produce the reactivation of previous joints as faults whose trends are comprised mainly from N120°E to N170°E and have a normal and transtensional regime, with dextral or sinistral components. The palaeostress evolution of this region is similar to that undergone by other basins of the Eastern Betic Cordilleras, although the Pliocene–Pleistocene transcurrent deformations in the Campo de Dal??as only develop joints and not strike-slip faults. 相似文献
437.
438.
439.
440.
Galliski Miguel Ángel Márquez-Zavalía María Florencia Škoda Radek Novák Milan Čopjaková Renata Pagano Diego Sebastián 《Mineralogy and Petrology》2019,113(5):687-701
Mineralogy and Petrology - An assemblage of tantalite-(Mn), tantalian rutile, tapiolite-(Fe), titanowodginite, ferrotitanowodginite, and hydroxycalciomicrolite occurs in the Nancy granitic... 相似文献