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91.
Yutaka Uchida 《Solar physics》1982,113(1-2):125-129
Loop flares are given a new magnetodynamic interpretation. In this model, the top of the magnetic loop is heated up by a collision of magnetic twist-wave packets (non-linear torsional Alfven wave) which are produced in the process of the loop emergence, and stored and released from the footpoints of the loop with some retardation. The appearance of the blueshifted component in CaXIX and FeXXV lines a minute or so before the impulsive phase, and the so-called instantaneous acceleration of ions deduced from the nearly simultaneous (with a delay of seconds) occurrence of -ray line emission with the impulsive hard X rays, are very naturally explained in the present model which originally aims at providing an explanation of the source of energy, a blackbox located at the top of the loop in the loop flare theories discussed thus far. 相似文献
92.
A model for diurnal variations of neutral and ionic nitrogen compounds in the thermosphere is reconstructed on the basis of a new photochemical aspect on N(2D), together with new observations of the NO density. The NO density so far measured must be reduced by a factor 2, due to a revision of the fluorescence coefficient for the NO γ-band airglow. Incorporating the quenching reaction of N(2D) with O in the model calculation results in a reduction of the NO density at heights as low as 100 km. These two effects are combined to lead to an evaluation that the N(2D) quantum yield for various possible reactions is as large as 0.9. A smaller rate coefficient for the quenching reaction than that measured in the laboratory, i.e. 1.0 × 10?12cm3sec?1 is favourable for the recent NO observation in the early morning, as well as the observed emission rates of the 5200 A airglow from N(2D) The present model predicts a significant day-to-night variation of N and NO densities at heights above 100 km. Below 100 km, the NO density is fairly stable because of its long chemical time constant. Since the rate coefficient for the conversion of N(4S) to NO is highly temperature dependent, the relative population of N(4S) and NO is very sensitive to the thermospheric temperature variation. Large variations of both N(4S) and NO densities due to the temperature change could occur especially at night. The model is in good agreement with the NO observations so far available in low and middle latitudes, as well as the N observation by the use of a rocket in the twilight. 相似文献
93.
Takeyasu Sawa Tatsuya Kurita Akira Sobue Yutaka Sabano 《Astrophysics and Space Science》1983,92(1):181-190
The CO distribution in the Galaxy is investigated through an analysis of longitude-velocity diagrams of CO emission lines for the two longitude ranges 20°<l<80° and 105°<l<140°. For the kinematics of the Galaxy we adopt the three typical models; the circular rotation, the linear density waves, and the galactic shock waves. It is shown that the distributions and kinematics of CO clouds are consistent with the predictions of the density wave model and the galactic shock model, and that the observed data of CO emissions do not contradict with the claim that the CO clouds form spiral arms. 相似文献
94.
95.
To verify the actual usefulness of time-dependent tracer dating techniques in the ocean, we simultaneously obtained two cross
sections of sulfur hexafluoride (SF6) and chlrofluoromethanes (CFC-11, trichlorofluoromethane; CFC-12, dichloro-difluromethane; CFC-113, trichlorotrifluoroethane)
in the western North Pacific in 1998. The vertical distribution patterns of SF6 and CFC-113 were similar in shape to those of CFC-11 and CFC-12. Maximum penetration depths of SF6 and CFC-113 remained around 800 m in the subpolar region and 400 m in the tropical region, while the maximum penetration
depths of CFC-11 and CFC-12 were still found below 1000 m depth. We also found all maximum contents of these tracers around
26.6−26.8σθ with a gradual decrease southward. This suggested that a new subsurface water mass in the subpolar region spread out over
the entire North Pacific, which agrees closely with previous studies based on the salinity minimum. Moreover, we compared
the tracer ages (the elapsed period of a water mass from when the water mass left from the ocean surface) using ten time-dependent
tracer dating techniques, CFC-11, CFC-12, CFC-113, SF6, CFC-11/CFC-12, CFC-113/CFC-11, CFC-113/CFC-12, SF6/CFC-11, SF6/CFC-12 and SF6/CFC-113. This quantitative evaluation of multiple tracer dating techniques in the ocean was the first confirmation of its
usefulness based on the observational data on the ocean basin-wide scale. We conclude that SF6/CFC-11, SF6/CFC-12, SF6/CFC-113 and SF6 dating techniques would be the most promising tools for determining the age of water mass not only just for the past several
decades but for the future, too.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
96.
97.
Tsuneo?OnoEmail author Hiromi?Kasai Takashi?Midorikawa Yusuke?Takatani Kazuhiro?Saito Masao?Ishii Yutaka?W.?Watanabe Katsuyuki?Sasaki 《Journal of Oceanography》2005,61(6):1075-1087
Eight-year observation results of DIC from 1996 to 2003 in the Oyashio region have been analyzed to obtain a climatological
view of its seasonal variation and interannual variation. Data of DIC obtained by several institutes are synthesized to give
a dataset with an uncertainty lower than 5 μmol/kg. The obtained climatology of NDIC seasonal variation in the Oyashio mixed layer shows a seasonal amplitude of 176 μmol/kg, with a maximum in January and a minimum in September. These features closely resemble those observed in the southern
half of the western subarctic North Pacific (WSNP) including Station KNOT, although the timing of the NDIC maximum is slightly
advanced in the case of the Oyashio. Analysis using a quasi-conservative tracer Cp0 (NDIC - 106NP) shows that among 176 μmol/kg of NDIC seasonal variation, only 16 μmol/kg is attributed to hydrographic processes while the remaining 160 μmol/kg is attributed to biological processes. The Cp0 value in the Oyashio mixed layer also resembles that of the WSNP mixed
layer during the months May to November, suggesting further resemblance of the Oyashio water mass to that of WSNP in terms
of carbon dynamics. The present results also suggest that a single data obtained in Oyashio mixed layer contains 30 μmol/kg of potential uncertainty for the representativity of this region, which leads to a note about a need to treat with
caution results obtained by a single observation in this region. 相似文献
98.
A numerical study on the formation and variation of a clockwise-circulation during winter in the Yellow Sea 总被引:1,自引:0,他引:1
In the Yellow Sea, the north-westerly wind dominates in winter and the existence of horizontal clockwise circulation has been suggested (Yanagi and Takahashi, 1993). The formation and variation mechanisms of this clockwise circulation is investigated using the wind forced numerical model which has a simplified basin configuration of the Yellow Sea. The model results show that two vortices (an anticlockwise vortex off Chinese coast and a clockwise vortex off Korean coast) are generated by the uniform north-westerly wind. Both vortices propagate along the shelf slope as the first mode shelf waves. An anti-clockwise vortex can not grow because it does not balance to the wind forcing. On the other hand, a clockwise vortex can grow and it reaches to the equilibrium condition at the northern part of the Yellow Sea, because this circulation can balance to the wind forcing. The time scale to become into the equilibrium condition is about 2 days. From this fact, it is ascertained that a clockwise circulation in the basin is generated periodically according to the variable wind forcing with 4 days period. The steady part of the current field exists with the fluctuating one which is induced by the periodical north-westerly wind. 相似文献
99.
Hiroshi Kuroda Yutaka Isoda Hidetaka Takeoka Satoshi Honda 《Journal of Oceanography》2006,62(5):731-744
In order to examine seasonal variation in a coastal current and the dynamics of the current, we carried out a mooring current
measurement near the coast on the eastern shelf of Hidaka Bay from December 2002 to July 2003. There seemed to be two current
regimes during the observed period; one a southeastward current from December to March, and the other a northwestward current
after April. Arrested topographic wave dynamics was used to understand along-shore steady momentum balance at the mooring
site. It was found that the friction term was negligible during the former regime, that is, the wind stress term roughly counterbalanced
the pressure gradient term. On the other hand, the contribution of each term to the momentum balance was sensitive to the
resistance coefficient value during the latter regime. A numerical study showed that wind forcing alone could not reproduce
the observed current velocity and momentum balance during the former regime. One possible interpretation of the observed results
is superposition of the arrested topographic waves forced by the along-shore wind stress and downstream extension of the Coastal
Oyashio. Numerical experiments using combined forcing of the wind stress and an inflow associated with the Coastal Oyashio
supported the expected dynamics. 相似文献
100.
In the previous paper (Yanget al., 1993), it was shown that there always exists the coastal salinity-minimum-layer (SML) water just off the Boso Peninsula. The coastal SML water is bounded by the current zone of the Kuroshio, and a relatively high salinity domain separates it from the offshore SML water which would be a continum of the North Pacific Intermediate Water. We suggested that the coastal SML water region indicates the pathway along which the Intermediate Oyashio Water intrudes into Sagami Bay. In this paper, by selecting seven cases where we found the coastal SML water having abnormally high oxygen content and low salinity, we try to follow the intrusion manner of the Intermediate Oyashio Water into Sagami Bay by using available hydrographic data taken routinely by various organizations in the period from 1973 to 1986. Some of these water can be traced from the observation line near the cape of Inubo to the central part of Sagami Bay, and its propagation speed along the coast is shown to be of order of 1 cm/s. The intruding intermediate Oyashio water usually has a complicated layered structure in it, and its time scale of persistence is shown to be only a few months. 相似文献