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101.
Phase relations in the system CaTiO3-CaSiO3 were experimentally examined at 5.3–14.7 GPa and 1200–1600 °C with a 6–8 type multianvil apparatus. As pressure increases, stability field of perovskite solid solution extends from CaTiO3 to CaSiO3, and the perovskite becomes stable for the entire composition range above about 12.3 GPa. The stability field of Ca(Ti1?X, SiX)2O5 (0.78<x≦1) titanite solid solution +Ca2SiO4 larnite exists in the CaSiO3-rich composition range at 9.3–12.3 GPa and 1200 °C. Perovskite solid solutions containing CaSiO3 component of 0 to 66 mol% could be quenched to 1 atm. The composition-molar volume relationship of perovskite solid solution showed that molar volume of perovskite solid solution linearly reduces from the value of CaTiO3 to that of CaSiO3. 相似文献
102.
Martin G. LOCKLEY LI Jianjun LI Rihui Masaki MATSUKAWA Jerald D. HARRIS XING Lida 《《地质学报》英文版》2013,87(1):1-20
<正>"Splitting" and "lumping" are perpetual problems in vertebrate,especially dinosaur, ichnotaxonomy.Chinese dinosaur ichnotaxonomy,which began in 1940,provides a series of interesting case studies,highlighting the dual problems of historical and dubious ichnotaxonomy. Chinese Mesozoic tetrapod track types have been placed into 63 ichnospecies(one Triassic,28 Jurassic,and 34 Cretaceous),exclusive of other,non-type ichnospecies or ichnotaxa identified from China.Fifty-two(~83%) of these 63 tetrapod ichnospecies were placed in monospecific ichnogenera. At the ichnogenus level,we prune—either by recognizing nomina dubia or by synonymy—17 from the list of 53 dinosaurian ichnogenera(a 32%reduction),leaving 36 ichnotaxa that we consider valid. Most of the cuts affect Jurassic theropod ichnotaxa,which are reduced from 23 to only nine because most ichnogenera are subjective junior synonyms of Grallator and Eubrontes.Fewer Chinese Cretaceous ichnotaxa(only six of 21 ichnogenera) are obvious nomina dubia or subjective synonyms, suggesting greater east Asian endemism during this time.Because ichnospecies differences are subtle, we provisionally retain ichnospecies as valid pending detailed comparative analyses of congeneric ichnospecies.This synthesis is long overdue and is necessary to address problems of historical and provincial ichnotaxonomy,which severely hamper comparisons of tetrapod ichnofaunas in space and time. 相似文献
103.
Measuring saturated hydraulic conductivity and anisotropy of peat by a modified split-container method 总被引:1,自引:0,他引:1
Ranjeet M. Nagare Robert A. Schincariol Aaron A. Mohammed William L. Quinton Masaki Hayashi 《Hydrogeology Journal》2013,21(2):515-520
Long-term changes in the physical and hydraulic properties of peat result from the decomposition and consolidation processes. The saturated hydraulic conductivity (K s) of peat is depth-dependent and could increase or decrease with depth; therefore, K s determination on a large number of samples is required to more accurately assess field variability. The cube method is a popular laboratory procedure to determine K s because it allows use of smaller sample dimensions, while minimizing edge effects. This article describes the design and use of an alternate split container to enclose undisturbed peat cubes during measurement of K s and the application of this method to a field site in Northwest Territories, Canada. The method allows for simpler and more controlled K s measurements while also permitting anisotropy measurements. Matched tests on identical samples (K s range 21–314 m/d), using the split-container and wax methods, showed a good agreement for intermediate K s values; however, significant deviations occurred for low and high K s values. Hydraulic-conductivity measurements taken on field samples showed a decrease with depth and exhibited anisotropic hydraulic conductivity as expected based on previous studies. 相似文献
104.
Masaki Nemoto Takeshi Sato Kenji Kosugi Shigeto Mochizuki 《Boundary-Layer Meteorology》2014,152(3):395-410
Wind-tunnel and numerical experiments were performed to investigate the effects of snowfall on the wind profile and the development of drifting snow. Wind profiles and mass-flux profiles of drifting snow were measured with and without artificial snowfall over a snow surface within the tunnel. Wind and shear-stress profiles and the impact speeds of the snowflakes during snowfall were also investigated numerically. During snowfall, snowflakes transfer part of their horizontal momentum to the air, which increases the stress close to the snow surface; however, the resultant modifications of the wind profiles are small. Because snowflakes have large momentum, the decomposed snow crystals that result from their collision with a surface can form a saltation layer, even over a hard snow surface where entrainment of the grains from the surface does not occur. Additionally, during snowfall, the threshold friction velocity can be lower than the impact threshold because snowflake fragmentation facilitates snow drifting. The broken crystals contribute to the increase in the number of drifting snow grains, even below the impact threshold. 相似文献
105.
Shin-ichi Takehiro Masaki Ishiwatari Kensuke Nakajima Yoshi-Yuki Hayashi 《地球物理与天体物理流体动力学》2013,107(6):439-459
Linear stability of rotating thermal convection in a horizontal layer of Boussinesq fluid under the fixed heat flux boundary condition is examined by the use of a vertically truncated system up to wavenumber one. When the rotation axis is in the vertical direction, the asymptotic behavior of the critical convection for large rotation rates is almost the same as that under the fixed temperature boundary condition. However, when the rotation axis is horizontal and the lateral boundaries are inclined, the mode with zero horizontal wavenumber remains as the critical mode regardless of the rotation rate. The neutral curve has another local minimum at a nonzero horizontal wavenumber, whose asymptotic behavior coincides with the critical mode under the fixed temperature condition. The difference of the critical horizontal wavenumber between those two geometries is qualitatively understood by the difference of wave characteristics; inertial waves and Rossby waves, respectively. 相似文献
106.
Water level monitoring provides essential information about the condition of aquifers and their responses to water extraction, land‐use change, and climatic variability. It is important to have a spatially distributed, long‐term monitoring well network for sustainable groundwater resource management. Community‐based monitoring involving citizen scientists provides an approach to complement existing government‐run monitoring programs. This article demonstrates the feasibility of establishing a large‐scale water level monitoring network of private water supply wells using an example from Rocky View County (3900 km2) in Alberta, Canada. In this network, community volunteers measure the water level in their wells, and enter these data through a web‐based data portal, which allows the public to view and download these data. The close collaboration among the university researchers, county staff members, and community volunteers enabled the successful implementation and operation of the network for a 5‐year pilot period, which generated valuable data sets. The monitoring program was accompanied by education and outreach programs, in which the educational materials on groundwater were developed in collaboration with science teachers from local schools. The methodology used in this study can be easily adopted by other municipalities and watershed stewardship groups interested in groundwater monitoring. As governments are starting to rely increasingly on local municipalities and conservation authorities for watershed management and planning, community‐based groundwater monitoring provides an effective and affordable tool for sustainable water resources management. 相似文献
107.
Masahiro Sakata Masaki Yamada Satoshi Mitsunobu Yasuhiro Senga 《Journal of Oceanography》2012,68(5):807-813
The contribution of abiogenic and biogenic particles to trace-metal (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Ti, V, and Zn) composition was investigated for phytoplankton (primarily diatoms) collected in Shimizu Port, a coastal seawater region. Except for Cd, the trace metals occurred predominantly in lithogenic or nonlithogenic abiogenic particles associated with plankton. In contrast, it is likely that Cd in seawater is taken up intracellularly, and not adsorbed extracellularly by phytoplankton. The lower P-normalized quotas of Cd in Shimizu Port than in offshore regions may be because plankton are dominated by diatoms. 相似文献
108.
Yoshimitsu Masaki Tsuneo Kuwagata Yasushi Ishigooka 《Theoretical and Applied Climatology》2010,100(3-4):283-297
We have developed a method for estimating hourly global solar radiation (GSR) from hourly sunshine duration data. This procedure requires only hourly sunshine duration as the input data and utilizes hourly precipitation and daily snow cover as auxiliary data to classify time intervals into six cases according to weather conditions. To obtain hourly GSR using a simple algebraic form, a quadratic function of the solar elevation angle and the sunshine duration ratio is used. Daily GSR is given by a sum of hourly GSRs. We evaluated the performance of the newly developed method using data obtained at 67 meteorological stations and found that the estimated GSR is highly consistent with that observed. Hourly and daily root-mean-square misfits are approximately 0.2 MJ/m2/h (~55 W/m2) and 1.4 to 1.5 MJ/m2/day (~16 to 17 W/m2), respectively. Our classification of weather conditions is effective for reducing estimation errors, especially under cloudy skies. Since the sunshine duration is observed at more meteorological stations than GSR, the proposed new method is a powerful tool for obtaining solar radiation with hourly resolution and a dense geographical distribution. One of the proposed methods, GSRgrn, can be applicable to hourly GSR estimations at different observation sites by setting local parameters (the precipitable water, surface albedo, and atmospheric turbidity) suitable to the sites. The hourly GSR can be applied for various micrometeorological studies, such as the heat budget of crop fields. 相似文献
109.
Keigo Yamamoto Hirotaka Tsujimura Masaki Nakajima Paul J. Harrison 《Journal of Oceanography》2013,69(6):727-736
The first observation of a red tide of the toxic dinoflagellate Alexandrium tamarense in the Yodo River estuary, Osaka Bay, Japan was in the spring of 2007. To clarify which environmental factors controlled the abundance of A. tamarense, field surveys were conducted in 2008 and 2009. In 2008, the increase of A. tamarense occurred from early to mid-March and temperatures ranged from 9 to 13 °C. In contrast, in 2009, the increase was 1 month later, from early to mid-April and therefore temperatures were higher. In both years, A. tamarense was most abundant when salinities were relatively high (15–25), river discharge was low, and the water column was stable. There were no cells during periods of low salinity (<10), high discharge. In 2008, possibly silicate and phosphate were limiting during the simultaneous diatom and A. tamarense bloom in early March with silicate restricting the further growth of diatoms. In this estuarine basin, freshwater discharge from the weir increased the flow rate at stations downstream of the weir and deterred bloom formation by A. tamarense. Conversely, the lack of discharge increased the salinity and stability of the water column and decreased in the flow rate in the river/estuary. This process promoted the initiation of the bloom of A. tamarense and the subsequent accumulation of paralytic shellfish toxin in the brackish water clam Corbicula japonica. It is recommended that a constant discharge from the weir is maintained in order to prevent blooms of A. tamarense and subsequent paralytic shellfish poisoning (PSP) incidents in this area. 相似文献
110.
Calorimetric measurements of fusion enthalpies for Ni2SiO4 and Co2SiO4 olivines were carried out using a high-temperature calorimeter, and Ni and Co partitioning between olivine and silicate liquid was analyzed using the measured heats of fusion. The fusion enthalpy of Co2SiO4 olivine measured by transposed-temperature drop calorimetry was 103 ± 15 kJ/mol at melting point (1688 K). The fusion enthalpy of Ni2SiO4 olivine was calculated based on the enthalpies of liquids in the system An50Di50-Ni2SiO4 measured by transposed-temperature drop calorimetry at 1773 K, and was 221 ± 26 kJ/mol at its metastable melting point (1923 K). The fusion enthalpy of Ni2SiO4 is the largest among those of olivine group, this is caused by the large crystal field stabilization energy of six-coordinated Ni2+ in olivine. The larger fusion enthalpy of Ni2SiO4 can account for the large and variable partition coefficient of Ni between olivine and silicate liquid. Based on the comparison between partition coefficients calculated from thermodynamic data and those observed in partition experiments, it is considered that the magnitude of partition coefficients is primarily dependent on the heats of fusion of the components. Furthermore, the activity coefficients for Ni-, Co- and Mn-bearing components in magmatic liquid are nearly of the same magnitude. 相似文献