全文获取类型
收费全文 | 2939篇 |
免费 | 139篇 |
国内免费 | 13篇 |
专业分类
测绘学 | 92篇 |
大气科学 | 245篇 |
地球物理 | 878篇 |
地质学 | 1015篇 |
海洋学 | 205篇 |
天文学 | 483篇 |
综合类 | 22篇 |
自然地理 | 151篇 |
出版年
2023年 | 9篇 |
2022年 | 22篇 |
2021年 | 59篇 |
2020年 | 58篇 |
2019年 | 56篇 |
2018年 | 118篇 |
2017年 | 119篇 |
2016年 | 159篇 |
2015年 | 140篇 |
2014年 | 156篇 |
2013年 | 232篇 |
2012年 | 203篇 |
2011年 | 192篇 |
2010年 | 146篇 |
2009年 | 169篇 |
2008年 | 127篇 |
2007年 | 114篇 |
2006年 | 111篇 |
2005年 | 91篇 |
2004年 | 83篇 |
2003年 | 76篇 |
2002年 | 90篇 |
2001年 | 58篇 |
2000年 | 39篇 |
1999年 | 31篇 |
1998年 | 35篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 26篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 29篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 17篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 15篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 8篇 |
1973年 | 12篇 |
1969年 | 7篇 |
排序方式: 共有3091条查询结果,搜索用时 15 毫秒
101.
Alberto José Bié Ricardo de Camargo Alberto Francisco Mavume Joseph Harari 《Ocean Dynamics》2017,67(11):1443-1459
The coast of Mozambique is often affected by storms, particularly tropical cyclones during summer or sometimes midlatitude systems in the southern part. Storm surges combined with high freshwater discharge can drive huge coastal floods, affecting both urban and rural areas. To improve the knowledge about the impact of storm surges in the coast of Mozambique, this study presents the first attempt to model this phenomenon through the implementation of the Princeton Ocean Model (POM) in the Southwestern Indian Ocean domain (SWIO; 2–32°S, 28–85°E) using a regular grid with 1/6° of spatial resolution and 36 sigma levels. The simulation was performed for the period 1979–2010, and the most interesting events of surges were related to tropical cyclones Bonita (1996) and Lisette (1997) that occurred in the Mozambique Channel. The results showed that the model represented well the amplitude and phase of principal lunar and solar tidal constituents, as well as it captured the spatial pattern and magnitudes of SST with slight positive bias in summer and negative bias in winter months. In terms of SSH, the model underestimated the presence of mesoscale eddies, mainly in the Mozambique Channel. Our results also showed that the atmospheric sea level pressure had a significant contribution to storm heights during the landfall of the tropical cyclones Bonita (1996) and Lisette (1997) in the coast of Mozambique contributing with about 20 and 16% of the total surge height for each case, respectively, surpassing the contribution of the tide-surge nonlinear interactions by a factor of 2. 相似文献
102.
Russell Cannon Michael Drinkwater Alastair Edge Daniel Eisenstein Robert Nichol Phillip Outram Kevin Pimbblet Roberto De Propris Isaac Roseboom David Wake Paul Allen Joss Bland-Hawthorn Terry Bridges Daniel Carson Kuenley Chiu Matthew Colless Warrick Couch Scott Croom Simon Driver Stephen Fine Paul Hewett Jon Loveday Nicholas Ross Elaine M. Sadler Tom Shanks Robert Sharp J. Allyn Smith Chris Stoughton Peter Weilbacher Robert J. Brunner Avery Meiksin Donald P. Schneider 《Monthly notices of the Royal Astronomical Society》2006,372(1):425-442
103.
104.
Samuel Teissier Sabine Sauvage Philippe Vervier Frédéric Garabétian José‐Miguel Sánchez‐Pérez 《水文研究》2008,22(3):420-428
A mass‐balance approach was used to estimate in‐stream processes related to inorganic nitrogen species (NH4+, NO2? and NO3?) in a large river characterized by highly variable hydrological conditions, the Garonne River (south‐west France). Studies were conducted in two consecutive reaches of 30 km located downstream of the Toulouse agglomeration (population 760 000, seventh order), impacted by modification of discharge regime and high nitrogen concentrations. The mass‐balance was calculated by two methods: the first is based on a variable residence time (VRT) simulated by a one‐dimensional (1‐D) hydraulic model; the second is a based on a calculation using constant residence time (CRT) evaluated according to hydrographic peaks. In the context of the study, removal of dissolved inorganic nitrogen (DIN) for a reach of 30 km is underestimated by 11% with the CRT method. In sub‐reaches, the discrepancy between the two methods led to a 50% overestimation of DIN removal in the upper reach (13 km) and a 43% underestimation in the lower reach (17 km) using the CRT method. The study highlights the importance of residence time determination when using modelling approaches in the assessment of whole stream processes in short‐duration mass‐balance for a large river under variable hydrological conditions. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
105.
Roberto Fusco-Femiano 《Astrophysics and Space Science》2004,294(1-2):37-43
The most evident signature for the presence of non-thermal elements (magnetic fields and relativistic electrons) in clusters
of galaxies is given by the presence of diffuse radio regionspresent so far in a limited number of objects. We review the
recent discoveries of new spectral components by EUVE and BeppoSAX in the spectra of some clusters of galaxies that allow to better determine the non-thermalquantities by relating radio and
X-ray data.
In collaboration with: M. Orlandini, G. Brunetti, L. Feretti, G. Giovannini, P. Grandi, & G. Setti. 相似文献
106.
Tommaso Maccacaro Roberto Della Ceca Valentina Braito Alessandro Caccianiga Paola Severgnini Anna Wolter 《Astrophysics and Space Science》2004,294(1-2):89-94
We present here some initial results from the ongoing XMM-Newton bright serendipitous survey. The survey is aimed at selecting
and spectroscopically identifying a large and statistically representative sample of bright (f
x ≳ 7× 10−14 c.g.s) serendipitous X-ray sources in the 0.5–4.5 keV energy band (BSS) and a complementary (smaller) sample in the 4.5–7.5
keV energy band (HBSS).
The work is partly based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributors directly founded by ESA member states and the USA(NASA) and on
observations collected at TNG. The TNG telescope is operated on the island of La Palma by the Centro Galileo Galilei of the
INAF in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias.
On behalf of the XMM-Newton Survey Science Center. 相似文献
107.
Jerry Edelstein Stuart Bowyer Eric J. Korpela Michael Lampton JoaquÍn Trapero José F. Gómez Carmen Morales Veronica Orozco 《Astrophysics and Space Science》2001,276(1):177-185
The hot interstellar medium (ISM) has far-reaching effect upon thestructure of galaxies. Although ISM heating processes are fairly wellunderstood, after decades of study, the processes that cool the hotinterstellar medium remain obscure. The EURD spectrograph was designed tomeasure the diffuse cosmic background from 350 to 1100 Å in order tostudy the hot ISM and the mechanisms by which it sheds its energy. Wepresent the first analysis of EURD observations of the cosmic background.These EURD observations have proven to be far more sensitive than previouswork; compared to previous results, we have improved the limits to theintensity of 450 to 900 Å line emission from the ISM by one to twoorders of magnitude. Our limit to OVI 1032 Å / 1038 Å doublet of 7900ph s-1 cm-2 str-1 is the lowest yet reported. The EURDlimits to line emission are less intense than predicted by a varietytheoretical models of the local ISM. 相似文献
108.
Guillermo Bosch † Elena Terlevich ‡ Roberto Terlevich § 《Monthly notices of the Royal Astronomical Society》2002,329(3):481-496
We have obtained accurate CCD narrow-band Hβ and Hα photometry of giant H ii regions (GEHRs) in M33, NGC 6822 and M101. Comparison with previous determinations of emission-line fluxes shows large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion ( σ ) derived from emission linewidths, we review the relation. A re-analysis of the properties of the GEHRs included in our sample shows that age spread and the superposition of components in multiple regions introduce a considerable spread in the regression. Combining the information available in the literature regarding ages of the associated clusters, evolutionary footprints on the interstellar medium, and kinematical properties of the knots that build up the multiple GEHRs, we find that a subsample – which we refer to as young and single GEHRs – do follow a tight relation in the plane. 相似文献
109.
An extended version of the classical Generalized Backward Euler (GBE) algorithm is proposed for the numerical integration of a three‐invariant isotropic‐hardening elastoplastic model for cemented soils or weak rocks undergoing mechanical and non‐mechanical degradation processes. The restriction to isotropy allows to formulate the return mapping algorithm in the space of principal elastic strains. In this way, an efficient and robust integration scheme is developed which can be applied to relatively complex yield surface and plastic potential functions. Moreover, the proposed algorithm can be linearized in closed form, thus allowing for quadratic convergence in the global Newton iteration. A series of numerical experiments are performed to illustrate the accuracy and convergence properties of the algorithm. Selected results from a finite element analysis of a circular footing on a soft rock layer undergoing chemical weathering are then presented to illustrate the algorithm performance at the boundary value problem level. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
110.
Abrahan Mora Juan A. Alfonso Luzmila Sánchez Malvis Calzadilla Soraya Silva John J. LaBrecque José A. Azócar 《水文研究》2009,23(3):476-485
Monthly analyses of pH, conductance, alkalinity, total suspended solids, dissolved major cations (Na, K, Ca and Mg), and selected dissolved trace elements (Fe, Al, Mn, Cu, Zn and Cr) were conducted on waters of the lower Orinoco River from February 2004 to May 2006. The data show strong seasonal variability. Major cations had maximum concentrations at low water, and were correlated with pH, conductance and alkalinity because of the tributaries coming from the Andean zones, where the weathering of evaporites and carbonate shales controls water chemistry. K concentrations did not show any relation with evaporite weathering, probably because large amounts of K come from the Guayana Shield rivers as a consequence of feldspar weathering. The concentrations of dissolved Fe, Mn and Cu were highest during the high water stage. Concentrations of the elements K, Cr, Zn and Cu are correlated with each other but not with dissolved Fe and Al, which probably are complexed with humic and fulvic substances. Mn concentrations did not show relationships with other variables. Inter‐annual variability of dissolved elements is explained by temporal changes in precipitation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献