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71.
Observations at 44 GHz in the 70−61
A
+ methanol line have been carried out on the 20-m telescope of the Onsala Space Observatory (Sweden) in the directions of the
poorly studied region G27.4–0.2 and of several supernova remnants, at the coordinates of the OH(1720) maser satellite emission,
with the aim of searching for Class I methanol maser emission in these sources. The region G27.4–0.2 has beenmapped, and contains
maser sources and two supernova remnants with similar coordinates and radial velocities, which may accelerate condensation
of the ambient gas-dust medium. This may play a role in enhancing the probability of methanol formation and maser emission.
This is the first detection of 44 GHz maser emission in this source, and this maser is among the 10% of the strongest Class
I methanol masers, within the uncertainties in the integrated flux (of a total of 198 currently knownmasers). A 27′ × 27′
region around the maser has been mapped at 44 GHz in steps of 1′. The 44-GHz emission forms only within the previously known
maser region. Further studies in water lines are needed to estimate the influence of shocks from supernovae. No 44-GHz Class
I methanol maser emission was detected at the 3σ level at the coordinates of the OH(1720) satellite emission in six supernova remnants; i.e., the presence of OH(1720) emission
is not a sufficient condition for the detection of Class I methanol masers. 相似文献
72.
G. A. Shul’man 《Astronomy Reports》2011,55(8):718-723
The quantum motion of non-relativistic and relativistic electrons in the presence of constant magnetic fields at the surfaces of magnetic stars, magnetic white dwarfs, and pulsars is considered. The quantizing magnetic-field strengths for charged particles with specified energies are determined. The quantum motion of these particles in a plane perpendicular to the magnetic field is accompanied by spontaneous radiation due to electron transitions from higher to lower discrete energy levels, right down to the ground state. In the non-relativistic case, this emission is monochromatic. In the non-relativistic case, various frequencies are emitted, but lie within an order of magnitude of each other. The electron kinetic energy along the magnetic field varies from zero to a maximum value, due to the one-dimensional character of the motion along the field, between each pair of potential barriers corresponding to the discrete energy levels. The results may be relevant to describing gamma-ray flares of pulsars. 相似文献
73.
A. V. Volkov N. E. Savva A. A. Sidorov V. Yu. Prokof’ev N. A. Goryachev S. D. Voznesensky A. V. Al’shevsky A. D. Chernova 《Geology of Ore Deposits》2011,53(1):1-26
The Shkol’noe deposit is localized in a small granitoid stock, the root portion of which is traced using geophysical data
to a depth of 5–8 km. The high-grade gold ore (33 gpt Au) is enriched in silver and principally differs in ore composition
from the previously studied mesothermal gold-quartz and epithermal gold-silver deposits in the Russian Northeast. The main
reserves of the Shkol’noe deposit concentrate in bonanzas (20% of the total volume of orebodies). The internal deformation
is related to the rearrangement of matter in freibergite; exsolution structures in fahlore and native gold are related to
postmineral metamorphism. It is suggested that the ore of the Shkol’noe deposit occupies a transitional position between porphyrytype
and epithermal levels of ore deposition. 相似文献
74.
The first findings of Au and Ag tellurides (sylvanite and petzite) in sulfide-quartz ore of the Shirokinsky ore and placer
cluster located in the Sette-Daban Horst-Anticlinorium are described. These minerals were found for the first time at the
gold deposits of East Yakutia. The chemical compositions (wt %) of sylvanite (23.65–24.61 Au, 12.7–13.13 Ag, 59.3–59.97 Te,
96.26–97.97 in total) and petzite (23.17–25.24 Au, 42.27–44.40 Ag, 31.26–33.37 Te, 98.19–102.55 in total) are reported. Galena
as a host mineral is associated with native gold, electrum, hessite, and stützite. The finding of Au-Ag and Ag tellurides
provides evidence for the development of Au-telluride mineralization in the Sette-Daban Horst-Anticlinorium. 相似文献
75.
The emergence of photospheric magnetic fields and the dynamics of the associated pattern of vertical motions in a developing active region are studied based on SOHO/MDI data. Objects were selected for which complete time series of data were available, so as to make it possible to determine the onset time of the magnetic-field emergence at the surface and tracing the formation of the first pores. The active regions studied originated near the central meridian. The total area of sunspots in these regions exceeded 100 millionths of the hemisphere at the maximum of active region evolution. A generalized evolutionary scenario is constructed for the magnetic field and vertical motions in the emerging active region. An asymmetry in the Doppler velocities is noted at an early stage of the active-region development, which corresponds to a matter flow from the leading to the trailing end of the emerging Ω-shaped tube. A direct relationship is found between the matter-downflow velocity in the area of the pore development and the growth in the strength of the longitudinal magnetic field. 相似文献
76.
A. M. Zubareva E. P. Pavlenko M. V. Andreev S. V. Antipin N. N. Samus’ A. V. Sergeev 《Astronomy Reports》2011,55(3):224-229
We have obtained data on various brightness states of the polar MT Dra over five years of observations, including the first
multicolor photometry for this close binary. We confirm the known orbital period, which has remained constant over 17 years,
which is unusual for cataclysmic binaries. Our observations in October 2006 demonstrated a transition of the polar to its
low brightness state within one day. 相似文献
77.
The ion composition of fluxes of charged particles in interplanetary space with energies ∼0.03–10 MeV/nucleon are studied
during quiet periods in the 23rd solar-activity cycle using data from the ACE spacecraft. Apart from the activity minimum,
the Fe/O ratio during such periods corresponds to either the relative abundances of ions in particle fluxes accelerated in
solar flares or the mean abundances of elements in the solar corona. At the cycle minimum, this ratio takes on values characteristic
for the solar wind. These results indicate that the background fluxes of low-energy particles in the phases of the growth,
maximum, and decay of the solar cycle include significant contributions from both coronal particles accelerated to suprathermal
energies and particles accelerated in small impulsive solar flares. The particle fluxes from such flares are distinguished
by an enhanced abundance of iron ions. 相似文献
78.
Paolo D’Adda Andrea Zanchi Maria Bergomi Fabrizio Berra Marco G. Malusà Annalisa Tunesi Stefano Zanchetta 《International Journal of Earth Sciences》2011,100(5):1095-1113
The Triassic succession of the central Southern Alps (Italy) is stacked into several units bounded by south-verging low-angle
thrust faults, which are related to two successive steps of crustal shortening. The thrust surfaces are cut by high-angle
extensional and strike-slip faults, which controlled the emplacement of hypabissal magmatic intrusions that post-date thrusts
motions. Intrusion ages based on SHRIMP U–Pb zircon dating span between 42 ± 1 and 39 ± 1 Ma, suggesting close time relationships
with the earliest Adamello intrusion stages and, more in general, with the widespread calc-alkaline magmatism described in
the Southern Alps. Fission-track ages of magmatic apatites are indistinguishable from U–Pb crystallization ages of zircons,
suggesting that the intrusion occurred in country rocks already exhumed above the partial annealing zone of apatite (depth < 2–4 km).
These data indicate that the central Southern Alps were already structured and largely exhumed in the Middle Eocene. Although
we describe minor faults affecting magmatic bodies and local reactivations of older structures, no major internal deformations
have occurred in the area after the Bartonian. Neogene deformations were instead concentrated farther south, along the frontal
part of the belt. 相似文献
79.
在近年来中亚造山带东段多金属矿床研究取得新进展的基础上,选择铀、钼两类矿床,结合铀、钼元素的地球化学行为探讨成矿物质来源的多样性和成矿的多阶段演化。此外,从构造研究角度,结合中亚造山带东段中大量中间地块存在的构造现象,讨论中间地块与成矿作用的关系:中间地块经历了从大陆边缘的裂解、漂移和板块碰撞造山作用,在漫长而复杂的地质过程中遭受的多次改造,有利成矿物质的反复被萃取和聚集。最后提出印支期华北克拉通北缘和北部造山带的成矿作用与底侵背景下的伸展作用密切相关。 相似文献
80.
V. Yu. Timofeev A. Yu. Kazansky D. G. Ardyukov D. V. Metelkin P. Yu. Gornov N. V. Shestakov A. V. Timofeev G. Z. Gil’manova 《Russian Journal of Pacific Geology》2011,5(4):288-297
The motion of lithospheric blocks was analyzed in the junction zone between the Eurasian Plate and its surrounding structures.
Its present-day stage was considered using GPS and seismologic data. Models of the movement of a rigid plate are considered
for Eurasia. A model of Eurasia (northern part of Asia) was used to determine the rotation parameters of its southern periphery
(Amur Plate) based on GPS data for the Far East (Sikhote Alin profile), and Transbaikal regions are shown as an example. A
model of the Amur Plate was used to illustrate the behavior of the extension zone on its western boundary represented by the
Lake Baikal depression during the Kultuk earthquake (M = 6.3, August, 27, 2008). Paleomagnetic data made it possible to determine
the rotation pole of the Siberian Craton relative to its surrounding folded structures during the Mesozoic and to estimate
its kinematic parameters. The permanent position of the rotation pole in the relative coordinate system since the terminal
Paleozoic until the Recent indicates a constant rotation velocity of the Siberian domain within the Eurasian Plate structure. 相似文献