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81.
Channel braiding and stability of the Brahmaputra River, Bangladesh, since 1967: GIS and remote sensing analyses 总被引:1,自引:1,他引:1
T. Takagi T. Oguchi J. Matsumoto M.J. Grossman M.H. Sarker M.A. Matin 《Geomorphology》2007,85(3-4):294
Spatial and temporal changes in channel distribution in the large, sandy, braided system of the Brahmaputra River, Bangladesh, were analyzed using satellite images and GIS. Supervised classification of the images within the braided belt, i.e., channels and bars between the bank-lines, provided raster land cover data for 14 different years between 1967 and 2002. The width of the braided-belt, the number and width of channels, the distribution of land cover attributes and land stability change were examined from the data. The results indicate that the recent history of the dynamics of the Brahmaputra can be divided into four phases: 1) the late 1960s to early 1970s, 2) the mid-1970s to early 1980s, 3) the mid-1980s to early 1990s, and 4) the mid-1990s to early 2000s. Spatial distributions of the land cover and channels in Phase 4 were the least complex suggesting a state of dynamic equilibrium. Land cover and channel distributions during Phase 2 were partly less complex indicating quasi-dynamic equilibrium. Phases 1 and 3 can be regarded as transitional phases with more complex conditions. Frequent large floods may have triggered significant changes in the river system during Phases 1 and 3. 相似文献
82.
The Jinnosuke-dani landslide is a giant landslide 2,000 m long and 500 m wide in the Haku-san Mountain area, Japan. It was
also the first landslide to be designated as a “Landslide Prevention Area” according to the “Japan Landslide Prevention Law.”
This landslide consists of alternating layers of sandstone and shale in the Tedori Formation, which was deposited from the
Jurassic period to the Early Cretaceous. Based on deformation monitoring results for more than 7 years, the landslide is divided
into upper and lower blocks. The upper block has moved at a speed of 80 to 170 mm/year, while the lower block has moved more
slowly (3 to 15 mm/year). Monitoring data show that the variation of the groundwater level has a great influence on the landslide
movement. The deteriorating effect of the weathering of the alternating layers of sandstone and shale on the landslide deformation
has been confirmed by borehole exploration and monitoring. 相似文献
83.
Shusaku Inoue Anil C. Wijeyewickrema Hiroyuki Matsumoto Hiroyuki Miura Priyantha Gunaratna Manoj Madurapperuma Toru Sekiguchi 《Pure and Applied Geophysics》2007,164(2-3):395-411
The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (Mw) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake
caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously
affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes
two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first
field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities
of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the
first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival
times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee,
Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness
information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments. 相似文献
84.
To obtain the profile of excess 210Pb in sediment column, it is necessary to section the collected core to date. Sectioning thickness is generally not explicit. An approach when sedimentation rate is constant has been suggested by Lu and Matsumoto (Environ Geol 47:804–810, 2005). This paper addresses the case when sedimentation rate is variable. Actually, it is possible to assume that sedimentation rate is constant within the sectioning thickness and based on this concept, a tentative approach for determining reasonable sectioning thickness is proposed. 相似文献
85.
Lake sediment records on climate change and human activities since the Holocene in Erhai catchment,Yunnan Province,China 总被引:16,自引:1,他引:15
R. Matsumoto 《中国科学D辑(英文版)》2005,48(3):353-363
Climate of Yunnan Plateau is mainly controlledby the system of southwest Asian monsoon, and alsoaffected by westerlies and local climate of the Qing-hai-Tibet Plateau. Since the Cenozoic, a large numberof structural lake basins have formed with the uplift ofthe Qinghai-Tibet Plateau[1]. As the information aboutthe climate and environment change was faithfullydocumented in lake sediments, which have the char-acteristics of continuity, high resolution, abundant in-formation, lake sediments p… 相似文献
86.
Astrophysics and Space Science - Starting with the equation of transfer in a plane-parallel inhomogeneous atmosphere which emits and scatters radiation anisotropically, we obtain a set of... 相似文献
87.
S. Nishida T. Tanabé Y. Nakada S. Matsumoto K. Sekiguchi I. S. Glass 《Monthly notices of the Royal Astronomical Society》2000,313(1):136-140
We report on the light variations of the infrared stars that were discovered recently in the Magellanic clusters NGC 419, 1783 and 1978. Their periods, of 528, 458 and 491 days, are among the longest known for carbon-rich Mira variables in the Clouds. All three IR stars were found to lie on the extension of the period– M bol relation derived from the shorter-period C-rich Miras while they were 0.45–0.70 mag fainter than the extension of the period– M K relation. Their main sequence masses were determined by isochrone fitting to be 1.5–1.6 M⊙ , consistent with the prediction of the evolutionary models of Vassiliadis & Wood. 相似文献
88.
Yuma Enokido Tomoki Nakamura Megumi Matsumoto Akira Miyake Takazo Shibuya Changkun Park Mike Zolensky 《Meteoritics & planetary science》2023,58(3):405-420
Dmisteinbergite, a hexagonal form of CaAl2Si2O8, was found in a compact type A Ca-Al-rich inclusion (CAI) in the Allende CV3 chondrite. Scanning and transmission electron microscopic observations show that dmisteinbergite was always in contact with grossular and grossular was in contact with melilite. In addition, there is a crystallographic relationship between dmisteinbergite and anorthite. Based on the textural and crystallographic evidence, the following mineralogical alteration processes are proposed to have occurred in the CAI. (1) Melilite was replaced by grossular. High densities of vesicles in the grossular indicate that hydrogrossular might have been the primary alteration phase and dehydrated by later metamorphism. (2) Dmisteinbergite formed from (hydro)grossular through a reaction with Si-rich fluid. (3) Nano-sized minerals are formed within dmisteinbergite. (4) Dmisteinbergite was transformed to anorthite. (5) Both anorthite and dmisteinbergite were altered to nepheline. (6) Hydrogrossular was dehydrated to grossular. (Hydro)grossular, dmisteinbergite, anorthite, and nepheline in the CAI seem to have formed in the course of metasomatism that occurred in the Allende parent body. Except for the hydrogrossular dehydration, these reactions could have occurred at moderate temperature (200–250°C) in high pH fluids (pH 13–14) according to past experimental studies. Episodic changes in fluid composition seem to have occurred before reactions (2), (4), and (5), because these reactions were not completed before the next reaction started. Higher temperature is required for reactions (5) and (6) to occur. Our observation of the CAI suggests that it experienced multiple episodes of metasomatism as temperatures were rising in the Allende parent asteroid. 相似文献
89.
Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models 总被引:1,自引:0,他引:1
S. Goossens K. Matsumoto D. D. Rowlands F. G. Lemoine H. Noda H. Araki 《Journal of Geodesy》2011,85(8):487-504
The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents
a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking
data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far
side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit
determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis.
It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values
in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter
data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an
average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed
through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be
mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the
SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used. 相似文献
90.
Toshihiko Masui Kenichi Matsumoto Yasuaki Hijioka Tsuguki Kinoshita Toru Nozawa Sawako Ishiwatari Etsushi Kato P. R. Shukla Yoshiki Yamagata Mikiko Kainuma 《Climatic change》2011,109(1-2):59-76
Representative Concentration Pathway 6.0 (RCP6) is a pathway that describes trends in long-term, global emissions of greenhouse gases (GHGs), short-lived species, and land-use/land-cover change leading to a stabilisation of radiative forcing at 6.0 Watts per square meter (Wm?2) in the year 2100 without exceeding that value in prior years. Simulated with the Asia-Pacific Integrated Model (AIM), GHG emissions of RCP6 peak around 2060 and then decline through the rest of the century. The energy intensity improvement rates changes from 0.9% per year to 1.5% per year around 2060. Emissions are assumed to be reduced cost-effectively in any period through a global market for emissions permits. The exchange of CO2 between the atmosphere and terrestrial ecosystem through photosynthesis and respiration are estimated with the ecosystem model. The regional emissions, except CO2 and N2O, are downscaled to facilitate transfer to climate models. 相似文献