全文获取类型
收费全文 | 1242篇 |
免费 | 63篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 50篇 |
大气科学 | 106篇 |
地球物理 | 334篇 |
地质学 | 391篇 |
海洋学 | 126篇 |
天文学 | 192篇 |
综合类 | 16篇 |
自然地理 | 97篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 26篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 50篇 |
2017年 | 55篇 |
2016年 | 85篇 |
2015年 | 64篇 |
2014年 | 63篇 |
2013年 | 91篇 |
2012年 | 50篇 |
2011年 | 79篇 |
2010年 | 58篇 |
2009年 | 68篇 |
2008年 | 59篇 |
2007年 | 51篇 |
2006年 | 56篇 |
2005年 | 30篇 |
2004年 | 33篇 |
2003年 | 23篇 |
2002年 | 30篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 21篇 |
1998年 | 17篇 |
1997年 | 24篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有1312条查询结果,搜索用时 31 毫秒
181.
182.
183.
Jorge Del Río Vera Francisco Criado-Aldeanueva Jesús García-Lafuente F. Javier Soto-Navarro 《Global and Planetary Change》2009,68(3):232-235
Altimetry measurements over the Ionian region and tide gauge records along the southern Italian coasts have been combined to analyse the negative sea level trend over the Ionian basin in the last decades. The apparent decreasing trend should be better understood as an abrupt sea level drop in 1998 probably linked to changes in the surface circulation in the Ionian basin induced by the Eastern Mediterranean Transient, which changed from anticyclonic to cyclonic about March 1998. From then onwards, a rising rate of 7.9 ± 0.9 mm/year is observed over the basin. 相似文献
184.
S. N. Charan E. V. S. S. K. Babu S. M. Naqvi J. G. Rana Prathap M. Ram Mohan D. Srinivasa Sarma 《Journal of the Geological Society of India》2009,73(3):371-378
The major part of the Peninsular Gneiss in Dharwar craton is made up of Trondjhemite-Tonalite-Granodiorite (TTG) emplaced
at different periods ranging from 3.60 to 2.50 Ga. The sodic-silicic magma precursors of these rocks have geochemical features
characteristic of partial melting of hydrated basalt. In these TTGs, enclaves of amphibolites (± garnet) are abundant. These
restites are considered to be the residue of a basaltic crust after its partial melting. A detailed study of these (residue)
enclaves reveals textures formed due to the process of partial melting. Major, trace and REE analysis of these residue enclaves
and the melt TTGs and microprobe analysis of the coexisting minerals show partitioning of REE and HFSE between the precursor
melt of TTGs and the upper amphibolite facies residues. Formation of garnetiferous amphibolites with biotite, Cpx and plagioclase
consequent to melting, has squeezed the original MORB type of basaltic crust and given rise to the TTGs, depleted in Y, Yb,
K2O, MgO, FeO, TiO2 and enriched in La, Th, U, Zr and Hf. Coevally during the process of melting, the hydrated basalt was depleted in Na2O, Al2O3, LREE, Th, U and enriched in K2O, MgO, Nb, Ti, Yb, Y, Sc, Ni, Cr and Co. Mineral chemistry of co-existing garnet-biotite and amphibole-plagioclase in these
amphibolitic (restite) enclaves indicates an average temperature of 700 ± 50° C and pressure of 5 ± 1 Kbar. These data are
inferred to indicate that during the garnet stability field metamorphism, effective fractionation of HREE and HFSE has taken
place between the restites having Fe-Mg silicates, ilmenites and the extracted melt generated from the MORB type of hydrated
basalt. These results are strongly substantiated by the reported melting experiments on hydrated basalts. 相似文献
185.
Francisco González-Sánchez Antoni Camprubí Eduardo González-Partida Rafael Puente-Solís Carles Canet Elena Centeno-García Viorel Atudorei 《Mineralium Deposita》2009,44(3):343-361
Northeastern Mexico hosts numerous epigenetic stratabound carbonate-hosted low-temperature hydrothermal deposits of celestine,
fluorite, barite and zinc-lead, which formed by replacement of Mesozoic evaporites or carbonate rocks. Such deposits can be
permissively catalogued as Mississippi Valley-type (MVT) deposits. The deposits studied in the state of Coahuila are associated
with granitic and metasedimentary basement highs (horsts) marginal or central to the Mesozoic Sabinas Basin. These horsts
controlled the stratigraphy of the Mesozoic basins and subsequently influenced the Laramide structural pattern. The Sabinas
Basin consists of ~6,000-m-thick Jurassic to Cretaceous siliciclastic, carbonate and evaporitic series. The MVT deposits are
mostly in Barremian and in Aptian-Albian to Cenomanian formations and likely formed from basinal brines that were mobilized
during the Laramide orogeny, although earlier diagenetic replacement of evaporite layers (barite and celestine deposits) and
lining of paleokarstic cavities in reef carbonates (Zn–Pb deposits) is observed. Fluid inclusion microthermometry and isotopic
studies suggest ore formation due to mixing of basinal brines and meteoric water. Homogenization temperatures of fluid inclusions
range from 45°C to 210°C; salinities range from 0 to 26 wt.% NaCl equiv., and some inclusions contain hydrocarbons or bitumen.
Sulfur isotope data suggest that most of the sulfur in barite and celestine is derived from Barremian to Cenomanian evaporites.
Regional geology and a compilation of metallogenic features define the new MVT province of northeastern Mexico, which comprises
most of the state of Coahuila and portions of the neighboring states of Nuevo León, Durango and, perhaps extends into Zacatecas
and southern Texas. This province exhibits a regional metal zonation, with celestine deposits to the south, fluorite deposits
to the north and barite and Zn–Pb deposits mostly in the central part. 相似文献
186.
187.
Ram Gopal Vishwakarma 《Astrophysics and Space Science》2012,340(2):373-379
A critical analysis of the relativistic formulation of matter reveals some surprising inconsistencies and paradoxes. Corrections are discovered which lead to the long-sought-after equality of the gravitational and inertial masses, which are otherwise different in general relativity. 相似文献
188.
Robles-Diaz Lucia Ocampo-Torres Francisco J. Branger Hubert Garcia-Nava Hector Osuna Pedro Rascle Nicolas 《Ocean Dynamics》2021,71(10):981-992
Ocean Dynamics - A comprehensive analysis of the wavefield evolution under accelerated wind conditions provides an essential contribution to understanding the wind-wave generation process. A set of... 相似文献
189.
Adolfo L. Méndez Berhondo Ramón E. Rodríguez Taboada Paolo Zlobec 《Astrophysics and Space Science》2008,318(1-2):73-78
Pulsating structures recorded at 237 MHz that are associated to decimetric continuum enhancement during the September 9, 2001 solar radio burst are described. We analyzed the radiopolarimetric data recorded at the Trieste Solar Radio System (INAF—Trieste Astronomical Observatory—Basovizza Observing Station) with very high time resolution (1 ms) at metric frequencies. Two different types of pulsations that occur in about 4 minutes at the same frequency are described. The possible mechanisms are analyzed and some parameters of the associated magnetic structure are estimated. 相似文献
190.
We study the magnetic and velocity field evolution in the two magnetically complex active regions NOAA 10486 and NOAA 10488 observed during October–November 2003. We have used the available data to examine net flux and Doppler velocity time profiles to identify changes associated with evolutionary and transient phenomena. In particular, we report detection of rapid moving features observed in NOAA 10486 during the maximum phase of the X17.2/4B superflare of October 28, 2003. The velocity of this moving feature is estimated around 40 km/s, i.e., much greater than the usual Hα flare-ribbons’ separation speed of 3–10 km/s, but similar to the velocity of seismic waves, i.e., ~ 45 km/s reported earlier by Kosovichev & Zharkova (1998). 相似文献