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391.
The nature of OH species in natural clear quartz was investigated by means of in-situ IR measurements over the temperature
range –185 to 1000 °C. Reversible thermal behavior of OH species was examined for a sample pre-heated to 1000 °C for 1 hour.
At room temperature, the IR spectrum of the quartz sample examined includes an intense absorption peak at 3379 cm–1 which has been assigned to an OH stretching vibration associated with Al substituting for Si (OH(Al)). The major spectral
changes of the OH(Al) bond involve a systematic shift of its peak position and a decrease in its integral absorbance with
temperature. A quasi-linear increase of the peak position from –185 to 400 °C is interpreted to be due to the change in the
vibrational frequency of OH(Al) with hydrogen bond (H bond) distance. At higher temperatures, the IR frequency shows only
a slight change, indicating a small influence of the H bond. On the other hand, the gradual decrease of the integral absorbance
of OH(Al) with temperature indicates a decrease of this defect’s molar absorptivity without any reduction in defect concentration.
This is interpreted to result from a decrease in dipole moment of OH(Al) with temperature. A sudden shift of the vibrational
frequency from 3396 to 3386 cm–1 between 550 and 560 °C and a constant value of the integral absorbance from 535 to 570 °C were considered to be related to
the change in H bond distance during the structural transformation of α-quartz to its β-form. The local environment of OH(Al)
begins to change at temperatures below 570 °C, where the crystallographic α–β transition occurs.
Received: 18 February 1998/ Accepted: 10 July 1998 相似文献
392.
H. Morishima E. Ohtani T. Kato T. Kubo A. Suzuki T. Kikegawa O. Shimomura 《Physics and Chemistry of Minerals》1999,27(1):3-10
The high-pressure and temperature equation of state of majorite solid solution, Mj0.8Py0.2, was determined up to 23 GPa and 773 K with energy-dispersive synchrotron X-ray diffraction at high pressure and high temperature
using the single- and double-stage configurations of the multianvil apparatuses, MAX80 and 90. The X-ray diffraction data
of the majorite sample were analyzed using the WPPD (whole-powder-pattern decomposition) method to obtain the lattice parameters. A least-squares fitting using the third-order Birch-Murnaghan equation
of state yields the isothermal bulk modulus, K
T0
= 156 GPa, its pressure derivative, K′ = 4.4(±0.3), and temperature derivative (∂K
T
/∂T)
P
= −1.9(±0.3)× 10−2 GPa/K, assuming that the thermal expansion coefficient is similar to that of pyrope-almandine solid solution.
Received: 5 October 1998 / Revised, accepted: 24 June 1999 相似文献
393.
Mg-Fe partitioning experiments between (Mg,Fe)2SiO4 spinel and (Mg,Fe)O magnesiowüstite were carried out at pressures of 17–21.3 GPa at temperatures of 1400 and 1600 °C, using
a multi-anvil apparatus, in order to determine interaction parameters of spinel and magnesiowüstite solid solutions and also
to constrain the equilibrium boundaries of the postspinel transition in the Fe-rich side in the system Mg2SiO4-Fe2SiO4. The obtained values of the interaction parameters were 3.4 ± 1.5 and 13.9 ± 1.4 kJ mol−1, respectively, for spinel and magnesiowüstite solid solutions at 19 GPa and 1600 °C. The partitioning data in the system
Mg2SiO4-Fe2SiO4 at 1400 and 1600 °C showed that the transition boundary between spinel and the mixture of magnesiowüstite and stishovite
has a negative dP/dT slope. Using the above interaction parameters and available thermodynamic data of the Mg2SiO4 and Fe2SiO4 end members, the transition boundaries of spinel to the mixture of magnesiowüstite and stishovite were calculated. Within
the uncertainties of the data used, the calculated boundaries are in good agreement with the boundaries at 1400 and 1600 °C
experimentally determined in this study. The dissociation boundary of Fe2SiO4 spinel to wüstite and stishovite, calculated from the thermodynamic data, has a negative slope of −1.5 ± 0.6 MPa K−1.
Received: 18 February 1998 / Revised, accepted: 18 October 1999 相似文献
394.
A simple trap model of solar hard X-ray bursts is discussed in which nonthermal electrons trapped in a magnetic bottle precipitate into the lower chromosphere through the resonant scattering by whistlers. In such a model, the X-ray spectra produced from trapped and precipitating electrons have different spectral shape, and both of the spectra will initially soften with time, provided the precipitation dominates over collisional degradation. 相似文献
395.
Tomonori Kume Koichiro Kuraji Natsuko Yoshifuji Toshiyuki Morooka Shinji Sawano Lucy Chong Masakazu Suzuki 《水文研究》2006,20(3):565-578
This study emphasizes the importance of canopy drying time (CDT) after rainfall in a lowland tropical rain forest. In this study, we estimate CDT using sap flow velocities measured by a heat‐pulse method in an emergent tree in a lowland mixed‐dipterocarp forest. Estimated CDT (ECDT) for each rain event has been defined as the time from rainfall cessation to the specific time derived from the difference between diurnal courses of sap flow velocities on a rainy day versus bright days. ECDT could be derived for 22 rain events that were grouped into two types, depending on whether rainfall ceased before or after noon. The ECDTs were distributed more widely and with greater values when rainfall ceased before noon (Type 1) than after noon (Type 2). The ECDTs of both Type 1 and Type 2 decreased with increases in net radiation (Rn) and vapour pressure deficit (VPD) after rainfall. This result shows that ECDT is determined mainly by post‐rainfall evaporation rates. The sap flow velocity as a detector of canopy wetness worked out well because of the specific rainfall characteristics at this site. The practical limitations of the method using sap flow velocities are discussed in relation to rainfall characteristics and time lags between transpirations and sap flow velocities. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
396.
397.
The temperature dependence of carbon isotopic fractionations between calcite and graphite, and between dolomite and graphite are calibrated by the calcite-dolomite solvus geothermometry using marbles collected from the contact metamorphic aureole in the Kasuga area, central Japan. The carbon isotopic fractionations (Δ13CCc-Gr and Δ13CDoGr) systematically decrease with increasing metamorphic temperature. The concordant relationships between the fractionations and solvus temperatures are approximately linear with T?2 over the temperature range. 400° to 680°C: Δ13CCcGr (%.) = 5.6 × 106 × T?2 (K) ? 2.4 Δ13CDoGr (%.) = 5.9 × 106 × T?2 (K) ? 1.9 These systematic relationships between fractionation and temperature suggest that carbon isotopic equilibria between carbonates and graphite were attained in many cases. The equation for the calcite-graphite system has a slope steeper than Bottinga's (1969) results. It is, however, in good agreement with that of Valley and O'Neil (1981) in the temperature range from 600° to 800°C.Because of the relatively high sensitivity to temperature, these isotopic geothermometers are useful for determining the temperatures in moderate- to high-grade metamorphosed carbonate rocks. 相似文献
398.
Toshihiro Suzuki Syun-iti Akimoto Yuh Fukai 《Physics of the Earth and Planetary Interiors》1984,36(2):135-144
The system iron-enstatite-water was investigated at pressures around 5 GPa and at temperatures ranging from 1000 to 1200°C, using several different kinds of starting materials. Quenched samples showed the coexistence of iron, olivine and pyroxene. Synthesis of the Fe-containing olivine in the run products proves that a series of reactions, Fe + H2O → FeHx + FeO and FeO + MgSiO3 → (Mg, Fe)2SiO4, have taken place. Spherical “balls of iron” were observed in the 1200°C run. This strongly indicates that the melting temperature of iron decreased by ~ 500 K by the possible dissolution of hydrogen. Following geophysical implications are derived from these experimental results. If water was retained in the hydrous minerals in the primordial material, the iron-water reaction is expected to occur throughout the core-formation process. The reaction product FeHx will melt and then sink to form a proto-core and iron oxide will be dissolved in the Earth's mantle. The dissolution of hydrogen in the Earth's core is a natural consequence of the core-formation process. 相似文献
399.
Jingzhe Zheng Kiichi Suzuki Naoto Ohbo J.H. Prevost 《Soil Dynamics and Earthquake Engineering》1996,15(6):369-379
The evaluation of a countermeasure against liquefaction which uses a sheet pilering for oil tank sites is presented. The simulation of earthquake responses observed at tank sites with and without sheet pile-ring is first performed to validate the three-dimensional finite element numerical model. Using the numerical model, liquefaction analysis is performed and the excess pore water pressure generated in the soil and the settlement of tank are investigated. The comparison of two- and three-dimensional models is also conducted to assess the applicability of two-dimensional analysis. The results show that the numerical model could simulate the observed earthquake responses of tank-ring-soil system, and that the excess pore water pressure and the settlement of the tank could be significantly reduced using a sheet pile-ring. The two-dimensional analysis proves to be capable of representing the main features of the dynamic response of the three-dimensional tank-ring-soil system. 相似文献
400.
Alexander Chakhmakhchev Masaru Suzuki Amane Waseda Kuniaki Takayama 《Organic Geochemistry》1997,27(7-8)
Siliceous sourced Tertiary oils from the Circum-Pacific area of Japan, Russia and the U.S.A. have a heavy carbon isotope composition, monomodal n-alkane distributions, and nearly identical regular sterane compositions with a predominance of C27 homologues. These are consistent with open marine depositional environments dominated by diatomaceous organic matter. However, a number of alkane and biomarker parameters such as Pr/Ph, CPI, relative concentration of 28,30-bisnorhopane, and the C35/C34 homohopane ratio indicate more oxic depositional environments for the source rocks of Japan and Russia. In contrast to the California Monterey Formation sourced oils, petroleums with low maturity levels from the North Sakhalin basin, Russia and the Akita basin, Japan have lower concentrations of asphaltenes and sulphur and are characterized by higher API gravities. A correlation of extractable organic matter from source rocks vs the least matured petroleums demonstrates that oil expulsion in siliceous shales of the Akita basin occurs at a maturity level corresponding to Ro≥0.65%, which is in the range of the conventional oil window (Ro = 0.6−1.1%). 相似文献