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排序方式: 共有373条查询结果,搜索用时 250 毫秒
131.
Y. Ishikawa 《GeoJournal》2000,52(3):189-194
Japanese geography studies are now being greatly affected by the rapid development of geographical information systems (GIS). Unfortunately, there has been little response from Japanese population geographers to this movement. Is GIS a welcome or an unwelcome guest? After discussing the significance of employing GIS, this article introduces some recent papers that used GIS in the field of population geography on such issues as mortality mapping, migration analysis, and household studies. Then, the two promising population-related topics of married one-person households and fertility are discussed. The ability of GIS to greatly facilitate analysis, which previously needed much time and energy, can be an encouraging stimulus of innovation in studies of current population geography. Therefore, GIS is clearly a welcome guest, although it is too wishful to think that its use would lead directly to a revitalization of contemporary population geography studies. 相似文献
132.
133.
This study developed a one‐dimensional model of downslope rain splash transport based on field experiments and previous studies. The developed model considers soil detachment processes, ground cover, probability densities, and the effect of overland run‐off in preventing detachment. Field monitoring was conducted to observe precipitation run‐off, ground cover, and sediment production on steep hillslopes. Field‐observed data were used to develop the splash detachment rate equation, probability densities for splash transport, and the maximum splash transport distance. Observed and estimated splash transport showed overall agreement, with some differences for small storm events or events with relatively low intensity, probably caused by variation of overland run‐off depth and connectivity as well as differences in soil surface cohesion at various degrees of wetness. Our model can provide insights on the interactions among rainfall intensity, soil surface condition, soil wetness, and splash transport on forested hillslopes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
134.
Tsurane Kuragano Yosuke Fujii Takahiro Toyoda Norihisa Usui Koji Ogawa Masafumi Kamachi 《Journal of Oceanography》2014,70(1):45-62
A consistency between seasonal fluctuation of actual sea surface height (SSH) and those caused by mass and density variations in gyre-scale regions is examined. The SSH obtained from satellite altimetry (altimetric SSH) is adopted as the actual SSH. SSH caused by mass variation (mass-related SSH) is simulated using a barotropic global ocean model forced by water flux, wind stress and surface pressure. SSH caused by density variation (steric SSH) is calculated from water density profile, i.e. temperature and salinity profiles. The model SSH well represents mass-related SSH for gyre-scale regional means, and seasonal fluctuation of the altimetric SSH corrected for the model SSH is similar to that of steric SSH above a pressure level larger than 300 dbar. The results indicate that the mass-related SSH does not much respond to the baroclinic adjustment to the seasonally varying wind stress curl. The mass-related SSH forced by wind stress and surface pressure should be accounted for regional evaluation, though it is not necessary for global mean evaluation. Detection of steric SSH from altimetric SSH would be useful for assimilation approaches in which the altimetric SSH is treated as the variable reflecting subsurface temperature and salinity. 相似文献
135.
Hiroyuki Takata Satoshi Tanaka Koji Seto Saburo Sakai Katsumi Takayasu Boo-Keun Khim 《Journal of Paleolimnology》2014,51(3):421-435
We investigated responses of shallow-water benthic foraminifera to changes in climate and ocean conditions, using sediment core ASC2 from Aso-kai lagoon, central Japan. Six AMS 14C dates reveal that the studied interval corresponds to sediments deposited from ~AD 700 to 1600. Sulfur content of the bulk sediment and multi-dimensional scaling (MDS) axis 1 of fossil benthic foraminifera indicate that the composition of the benthic foraminifera community was closely related to dissolved oxygen (DO) concentration in the hypolimnion. The sulfur content and MDS axis 1 also revealed two shifts over the 900-year interval. In the first phase (~AD 700–1250), the Shannon–Wiener Index (H′), E (S200), evenness and rank abundance curve (RAC) kurtosis indicate a gradual deterioration in structure of the benthic foraminifera community. In that period, there are statistically significant correlations between the faunal composition (MDS axis 1) and faunal structure [Shannon–Wiener (H′), E (S200), evenness and RAC kurtosis]. In the second phase (~AD 1250–1600), however, faunal composition and structure show no marked correspondence. Instead, abundance of benthic foraminifera fluctuated on a scale of ~200 years. Thus, a shift in the biotic response of benthic foraminifera in Aso-kai lagoon occurred in ca. AD 1250. Gradual deterioration of benthic foraminifera, with taxonomic losses, is consistent with declining DO in the first phase, possibly associated with the increasing influence of the Tsushima Warm Current. The possibility that closure of Aso-kai lagoon and development of the sand bar affected benthic foraminifera cannot, however, be ruled out. No corresponding response was observed in the second phase, during which there was no distinct taxonomic loss. Large variations in abundance, however, were a consequence of strength of the East Asian summer and winter monsoons. The shift in the biotic response of benthic foraminifera in Aso-kai lagoon during the period AD 700–1600 was apparently a result of changes in climate and ocean conditions on the East Asian continental margin. 相似文献
136.
A rapid change in climate patterns potentially driven by global warming is considered to be greatest threats to agriculture. However, little is known about how the change in climate concretely affects agricultural production especially in Nepal with respect to seasons and regions of different altitudes. To examine this issue, we seek to empirically identify the impact of climatic variation on agricultural yield and its variability by utilizing the data of rice, wheat and climate variables in the central region of Nepal. The main focus is on whether the impacts vary across seasons, altitudes and the types of crops. For this purpose, we employ a stochastic production function approach by controlling a novel set of season-wise climatic and geographical variables. The result shows that an increase in the variance of both temperature and rainfall has adverse effects on crop productions in general. On the other hand, a change in the mean levels of the temperature and rainfall induces heterogeneous impacts, which can be considered beneficial, harmful or negligible, depending on the altitudes and the kinds of crops. These results imply that adaptation strategies must be tailor-made in Nepalese agriculture, considering growing seasons, altitudes and the types of crops. 相似文献
137.
MaoShan Li YaoMing M WeiQiang M Ishikawa Hirohiko FangLin Sun Shinya Ogino 《寒旱区科学》2011,3(6):0509-0516
In this paper, based on in-situ observational data of the Coordinated Enhanced Observing Period (CEOP) Asia-Australia
Monsoon Project (CAMP) on the Tibetan Plateau (CAMP-Tibet), structure of the Atmospheric Boundary Layer (ABL) was
preliminarily studied during the dry and rainy seasons. The main results show: (a) Diurnal variation of the ABL is obvious over
the northern Tibetan Plateau area. The height of the ABL is different with the season change, which ranges from 2,211 m to
4,430 m during the pre-monsoon season and from 1,006 m to 2,212 m during the monsoon season. The ABL height is higher
during the dry period than during the rainy period. (b) The humidity is lower during the dry period than during the rainy period,
and there are reverse humidity during both periods. (c) Horizontal wind direction is mostly west during the dry period, east
under the height of 2,500 m and west above the height of 2,500 m during the rainy period. The wind speed is low during both
the rainy and dry periods in the lower ABL layer. The wind speed is stronger within the upper ABL during the dry period than
during the rainy period. 相似文献
138.
139.
K. D. Litasov A. Ishikawa I. S. Bazhan D. S. Ponomarev T. Hirata N. M. Podgornykh N. P. Pokhilenko 《Doklady Earth Sciences》2018,478(1):62-66
A complete microelement analysis of the Chinga meteorite was performed, and the possibility of attributing it together with a number of other iron meteorites into the IVC subgroup, which is transition between IVA and IVB is proposed. 相似文献
140.