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151.
The Fuscaldo assemblages show that in metabasites suitable for the production of glaucophane at higher pressures, amphibole poor(er) in Gl-molecule + albite + Al-rich chlorite is formed at lower pressure. Blue amphibole formed together with albite, chlorite and a Ca-silicate appears to have a fixed content of the Gl-molecule and of Ca2+, apart from the Fe2+/ R2+ ratio, which varies with host rock chemistry. The constant Gl-content indicates attainment of equilibrium, and is a function of T and especially P, so it may be used as a geobarometer. Glaucophane generally forms at the cost of albite+chlorite. In a P-T diagram the reaction is probably situated somewhat below the reaction albitejadeite+quartz, and has a smaller slope than the latter. The concomitant high-pressure character of glaucophane justifies reintroduction of Eskola's glaucophane-schist facies, of which glaucophane is critical. 相似文献
152.
Ge Verver Frank Raes Daan Vogelezang Doug Johnson 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):126-140
A review is given of the climatological and actual meteorological conditions in the sub‐tropical northeast Atlantic, during June–July 1997, when the 2nd Aerosol Characterization Experiment (ACE‐2) took place. Surface pressure maps, trajectory calculations and in‐situ measurements show how the outflow of European pollution into the marine boundary layer of this area is determined by the location of the Azores high pressure cell. Observations during ACE‐2 and 3 preceding summers show that pollution outbreaks both from the Iberian peninsula and from northern or central Europe can occur during such situations. During ACE‐2, an unusually low number of strong North African dust outbreaks were recorded at the free tropospheric station of Izaña (Tenerife, 2360 m asl), although dust was recorded aloft the station. 相似文献
153.
David J. Ampleford Andrea Ciardi Sergey V. Lebedev Simon N. Bland Simon C. Bott Jeremy P. Chittenden Gareth N. Hall Adam Frank Eric Blackman 《Astrophysics and Space Science》2007,307(1-3):29-34
We present experimental data on the steady state deflection of a highly supersonic jet by a side-wind in the laboratory. The
use of a long interaction region enables internal shocks to fully cross the jet, leading to the development of significantly
more structure in the jet than in previous work with a similar setup (Lebedev et al., 2004). The ability to control the length
of the interaction region in the laboratory allows the switch between a regime representing a clumpy jet or wind and a regime
similar to a slowly varying mass loss rate. The results indicate that multiple internal oblique shocks develop in the jet
and the possible formation of a second working surface as the jet attempts to tunnel through the ambient medium. 相似文献
154.
Frank Press 《地震地质》2000,22(2):103
我想根据自己的经历回顾过去 4 0年来美国科学的发展 ,我有幸在这个时期中成长为一名地球物理学家。这个时期被称为科学的黄金时代 ,因为在基础科学和工程科学中有大量发现和进展。在这个时期 ,不仅有伟大的创造和充足的资金支持 ,还获得了很多新知识 ,正是这些知识产生了新的工业并使我们增加了对环境的理解。对于地球物理学 ,正是在这个时期使用现代技术对海底进行了勘测 ,建立了全球地震台网 ,用实验室实验模拟深部地球环境 ,将示踪元素化学应用于岩石系统。也是在这个时期 ,对其它行星做了探测并从月球取回了岩样 ,创立了板块构造理论。在其它领域也有巨大进展 ,如分子生物学与疾病性质研究 ,以及农业绿色革命等。许多科学家在开始自己的研究时 ,并未想到后来会有那么多的创效益应用。许多年轻的科学家不珍惜美国科学尤其是地球物理学的繁荣。在四十年代以前 ,美国有较强的技术和工业生产优势 ,但在科学方面不如西欧 ,类似于现在的日本。那时基础研究主要在得到私人慈善机构支持的大学以及少数政府机构和工业实验室中进行。例如州立大学和地质调查局承担了地质填图 ,一些石油公司实验室开拓了勘探地球物理。除了地学外 ,政府对基础科学的资助很少。那时世 相似文献
155.
Axel D. Schwope Valeri Hambaryan Frank Haberl Christian Motch 《Astrophysics and Space Science》2007,308(1-4):619-623
We present a first analysis of a deep X-ray spectrum of the isolated neutron star RBS1223 obtained with XMM-Newton. Spectral
data from four new monitoring observations in 2005/2006 were combined with archival observations obtained in 2003 and 2004
to form a spin-phase averaged spectrum containing 290 000 EPIC-pn photons. This spectrum shows higher complexity than its
predecessors, and can be parameterised with two Gaussian absorption lines superimposed on a blackbody. The line centers, E
2≃2E
1, could be regarded as supporting the cyclotron interpretation of the absorption features in a field B∼4×1013 G. The flux ratio of those lines does not support this interpretation. Hence, either feature might be of truly atomic origin.
相似文献
156.
Ourania Tzoraki Nikolaos P. Nikolaidis Anna Rosa Trancoso Frank Braunschweig Ramiro Neves 《水文研究》2009,23(2):272-283
The RS‐tempQ Model ( r each– s cale t emporary flow biogeochemical model) is a conceptual model that can describe the hydrologic, sediment transport and biogeochemical processes of temporary rivers at the reach scale. The model takes into account the expansion–contraction of the inundated area of the river. It simulates the sediment transport and the nutrient fluxes that are transferred to the coastal area due to the first flash flood and during extreme rain events. The RS‐tempQ Model simulates the in‐stream processes during the wet and dry cycles as the river corridor expands and contracts. The model was used to assess and quantify the hydrologic and geochemical processes occurring in a temporary river reach (Krathis River) in Greece. Since the conventional gauging techniques cannot measure the flow in rivers that are split into small braided streams, discharge measurements could not be obtained in order to calibrate and verify the model. Other field measurements such as infiltration losses and sediment accumulation were used for model calibration. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
157.
158.
J. Nordhaus E. G. Blackman A. Frank 《Monthly notices of the Royal Astronomical Society》2007,376(2):599-608
The origin, evolution and role of magnetic fields in the production and shaping of proto-planetary nebulae (PPNe) and planetary nebulae (PNe) are a subject of active research. Most PNe and PPNe are axisymmetric with many exhibiting highly collimated outflows; however, it is important to understand whether such structures can be generated by isolated stars or require the presence of a binary companion. Towards this end, we study a dynamical, large-scale α−Ω interface dynamo operating in a 3.0 M⊙ Asymptotic Giant Branch (AGB) star in both an isolated setting and a setting in which a low-mass companion is embedded inside the envelope. The back reaction of the fields on the shear is included and differential rotation and rotation deplete via turbulent dissipation and Poynting flux. For the isolated star, the shear must be resupplied in order to sufficiently sustain the dynamo. Furthermore, we investigate the energy requirements that convection must satisfy to accomplish this by analogy to the Sun. For the common envelope case, a robust dynamo results, unbinding the envelope under a range of conditions. Two qualitatively different types of explosion may arise: (i) magnetically induced, possibly resulting in collimated bipolar outflows and (ii) thermally induced from turbulent dissipation, possibly resulting in quasi-spherical outflows. A range of models is presented for a variety of companion masses. 相似文献
159.
Frank Haberl 《Astrophysics and Space Science》2007,308(1-4):181-190
Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name “The Magnificent Seven”. Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which are interpreted as cyclotron resonance absorption lines by protons or heavy ions and/or atomic transitions shifted to X-ray energies by strong magnetic fields of the order of 1013 G. New XMM-Newton observations indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals variations in derived emission temperature and absorption line depth with pulse phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are interpreted as due to free precession of the neutron star. Modeling of the pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the surface temperature distribution of the neutron stars indicating hot polar caps which have different temperatures, different sizes and are probably not located in antipodal positions. 相似文献
160.