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271.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》2009,105(4):261-274
We calculate the so-called convective term, which shows up in the expression for the angular velocity of the elastic Earth,
within the Andoyer formalism. The term emerges due to the fact that the elasticity-caused perturbation depends not only on
the instantaneous orientation of the Earth but also on its instantaneous angular velocity. We demonstrate that this term makes
a considerable contribution into the overall angular velocity. At the same time the convective term turns out to be automatically
included into the correction to the nutation series due to the elasticity, if the series is defined by the perturbation of
the figure axis (and not of the rotational axis) in accordance with the current IAU resolution. Hence it is not necessary
to take the effect of the convective term into consideration in the perturbation of the elastic Earth as far as the nutation
is related to the motion of the figure axis. 相似文献
272.
Takeshi Inoue 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):185-191
The convergence property is examined for the series which appear in the theory of the planetary motions. With another point of view, we obtain a result different from that already given by Gyldén: The almost divergency in the meaning of category is concluded when the ratio of the mean motions is irrational using as Gyldén the continuous fractions. The author explains the reason why the series are always useful in practical applications: Because the long evolution of the system of interest under the influence of the small irreversible effects has led to many resonances or quasi-resonances, i.e. conditions favorable to a good convergence of suitable series. 相似文献
273.
Asbjrn Johan Breivik Rolf Mjelde Paul Grogan Hideki Shimamura Yoshio Murai Yuichi Nishimura Asako Kuwano 《Tectonophysics》2002,355(1-4)
The assembly of the crystalline basement of the western Barents Sea is related to the Caledonian orogeny during the Silurian. However, the development southeast of Svalbard is not well understood, as conventional seismic reflection data does not provide reliable mapping below the Permian sequence. A wide-angle seismic survey from 1998, conducted with ocean bottom seismometers in the northwestern Barents Sea, provides data that enables the identification and mapping of the depths to crystalline basement and Moho by ray tracing and inversion. The four profiles modeled show pre-Permian basins and highs with a configuration distinct from later Mesozoic structural elements. Several strong reflections from within the crystalline crust indicate an inhomogeneous basement terrain. Refractions from the top of the basement together with reflections from the Moho constrain the basement velocity to increase from 6.3 km s−1 at the top to 6.6 km s−1 at the base of the crust. On two profiles, the Moho deepens locally into root structures, which are associated with high top mantle velocities of 8.5 km s−1. Combined P- and S-wave data indicate a mixed sand/clay/carbonate lithology for the sedimentary section, and a predominantly felsic to intermediate crystalline crust. In general, the top basement and Moho surfaces exhibit poor correlation with the observed gravity field, and the gravity models required high-density bodies in the basement and upper mantle to account for the positive gravity anomalies in the area. Comparisons with the Ural suture zone suggest that the Barents Sea data may be interpreted in terms of a proto-Caledonian subduction zone dipping to the southeast, with a crustal root representing remnant of the continental collision, and high mantle velocities and densities representing eclogitized oceanic crust. High-density bodies within the crystalline crust may be accreted island arc or oceanic terrain. The mapped trend of the suture resembles a previously published model of the Caledonian orogeny. This model postulates a separate branch extending into central parts of the Barents Sea coupled with the northerly trending Svalbard Caledonides, and a microcontinent consisting of Svalbard and northern parts of the Barents Sea independent of Laurentia and Baltica at the time. Later, compressional faulting within the suture zone apparently formed the Sentralbanken High. 相似文献
274.
To understand the characteristics of winter monsoon clouds, dual-polarization Doppler radar observations were carried out at Mihama, Hokuriku, Japan. A series of organized disturbances associated with the passage of a cyclonic circulation was analyzed. The following scenario was proposed. Environmental circumstances, for example, temperature and wind profiles, surface heat and moisture fluxes, etc., determine the organizational style of mesoscale convections. This organization regulates the convection interior flow pattern including the location and intensity of updrafts. Subsequently, it influences interior microphysical properties, for example, the types of precipitation particles, their growth and distributions, their electrification, etc. In this paper, an observational example following this scenario is presented. 相似文献
275.
Vertical distributions of phyllosoma larvae were examined in waters east of the Philippines or west of the Mariana Islands
(18°56′ N to 19°04′ N; 129°10′ E to 129°35′ E) based on zooplankton samples collected with an Isaacs-Kidd Midwater Trawl on
September 22–24, 1986. Phyllosoma larvae belonged to the two families Scyllaridae and Palinuridae comprising 4 genera and
9 species. Of the collected phyllosoma larvae, those of Scyllarus cultrifer and Panulirus longipes were most abundant and showed similar vertical distributions: (1) both species were collected from the mixed layer at night
but not in the day, (2) their vertical distributions did not change with their stages, and (3) the upper limit of their vertical
distributions during the day accorded with the base of mixed layer. Furthermore, their vertical distributions were similar
to those of lepthocephalus larvae which were collected using the same sampling stations and gear in the present study. Vertical
distributions of phyllosoma larvae were discussed in relation to their horizontal distributions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
276.
Since April 1986, measurements of the CO2 concentration in the surface air have been conducted at the Meteorological Research Institure (MRI, 36°04 N, 140°07 E, 25 m above sea level) in Tsukuba, located 50 km northeast of Tokyo, Japan. The CO2 data measured over times between 11:00 Japan Standard Time (JST) and 16:00 JST (C
N
) were considered to be representative of the air (within a few ppmv) in the planetary boundary layer. To evaluate the representative CO2 level on a spatial scale larger than that of the C
N
record, the CO2 data with hour-to-hour variation less than 1 ppmv were selected (C
P
). Comparison of these data with those of Ryori (39°02 N, 141°50 E), a continental station operated by the Japan Meteorological Agency, indicates that the C
P
record provides a representative CO2 level in the air on spatial scales of at least a few hundred kilometers.The C
N
record allows an investigation of the internanual changes in photosynthesis/respiration against changes in climatological parameters. Within a small temperature anomaly (ca.±1 °C) respiration is sensitive to the temperature change, while photosynthesis is less sensitive. When the temperature anomaly is large, however, photosynthesis and respiration tend to be competitive. 相似文献
277.
278.
Physicochemical, mineralogical, and geochemical characteristics of 279 highly calcareous lacustrine sediment samples obtained from a 30 m drilling core in the western part of the Great Konya Basin, Turkey were studied. The sediments have a predominance of silt and clay fractions with a median diameter of 3–5 μm. Vertical changes of the amounts of water soluble components, gypsum, carbonates, and non-salt minerals such as quartz, feldspars, and layer silicates in the sediments suggest that there were climatic changes in the Konya Basin. The dominant clay mineral is smectite followed by kaolinite, illite, and palygorskite. The oxygen isotopic (δ18O) ratios of six quartz samples from the Konya sediments, a terra rossa soil beside Lake Bey
ehir gölü and paleosols at the foot of Mt. Erciyes Da
ranged from +18.1 to +20.6‰. The dominant clay minerals and δ18O ratios suggest that part of quartz and coexisting layer silicates is of long-range transported and/or local aeolian dust origin from arid and semi-arid regions such as North Africa, Israel, and the surroundings. The relatively high deposition rate might be due to aeolian dust input and/or the sediment input introduced by the rivers such as the Çar
amba river from the Toros (Taurus) mountains. The vertical distributions of electro-conductivity, amounts of water soluble and non-salt components, and the gypsum content of the sediments suggest that gypsum-rich layers were formed under shallow, saline waters, possibly associated with warm to hot and dry environments such as the Last Interglacial epoch and the Early Holocene. The sediments characterized by relatively high amounts of non-salt sediments, in which gypsum did not accumulate, could be deeper water phases formed under the cold and/or wet environments such as the Glacial epochs. 相似文献
279.
Ilvaite samples from six different localities in Japan are found to be members of a solid-solution series varying from Ca(Fe2+,Fe3+)2Fe2+(OH)O Si2O7 to approaximately Ca(Fe2+,Fe3+)2Fe 0.5 2+ Mn 0.5 2+ (OH)O Si2O7, and have been studied by Mössbauer spectrometry and magnetic measurements. The variation in intensity of Mössbauer doublets confirms that Mn substitutes for Fe2+ in the M(B) cation site. An temperatures decreasing from 300 K to 4K, an abrupt change in the reciprocal mass magnetic susceptibility, 1/x g, occurs about 120 K; 1/x g depends linearly upon temperature above 120 K. This change, which is characterized by an unusual mode of decrease in 1/x g, has been interpreted based on Mössbauer spectra at 80 K: the spectra of Fe2+ and Fe3+ in the M(A) site show Zeeman splitting, whereas those of Fe2+ in the M(B) site do not show the effect. This Mössbauer evidence suggests that magnetic spins of Fe in M(A) are in an ordered state, very likely of antiparallel coupling, whereas those of Fe in M(B) are randomly oriented, showing that below 120 K ilvaite has two different magnetic states for Fe ions. As there is a line of evidence that the spins of Fe in M(B) would take an ordered state at extremely low temperatures, ilvaite magnetism may be regarded as basically antiferromagnetic. The magnetic spins of Fe in M(A) and M(B) undergo magnetic transitions at different specific temperatures, thus giving as a whole unusual features of magnetism. 相似文献
280.