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11.
Carbon and water cycling in a Bornean tropical rainforest under current and future climate scenarios
Tomoomi Kumagai Gabriel G. Katul Amilcare Porporato Taku M. Saitoh Mizue Ohashi Tomoaki Ichie Masakazu Suzuki 《Advances in water resources》2004,27(12):1844
We examined how the projected increase in atmospheric CO2 and concomitant shifts in air temperature and precipitation affect water and carbon fluxes in an Asian tropical rainforest, using a combination of field measurements, simplified hydrological and carbon models, and Global Climate Model (GCM) projections. The model links the canopy photosynthetic flux with transpiration via a bulk canopy conductance and semi-empirical models of intercellular CO2 concentration, with the transpiration rate determined from a hydrologic balance model. The primary forcing to the hydrologic model are current and projected rainfall statistics. A main novelty in this analysis is that the effect of increased air temperature on vapor pressure deficit (D) and the effects of shifts in precipitation statistics on net radiation are explicitly considered. The model is validated against field measurements conducted in a tropical rainforest in Sarawak, Malaysia under current climate conditions. On the basis of this model and projected shifts in climatic statistics by GCM, we compute the probability distribution of soil moisture and other hydrologic fluxes. Regardless of projected and computed shifts in soil moisture, radiation and mean air temperature, transpiration was not appreciably altered. Despite increases in atmospheric CO2 concentration (Ca) and unchanged transpiration, canopy photosynthesis does not significantly increase if Ci/Ca is assumed constant independent of D (where Ci is the bulk canopy intercellular CO2 concentration). However, photosynthesis increased by a factor of 1.5 if Ci/Ca decreased linearly with D as derived from Leuning stomatal conductance formulation [R. Leuning. Plant Cell Environ 1995;18:339–55]. How elevated atmospheric CO2 alters the relationship between Ci/Ca and D needs to be further investigated under elevated atmospheric CO2 given its consequence on photosynthesis (and concomitant carbon sink) projections. 相似文献
12.
Physics and Chemistry of Minerals - The X-ray emission spectra were measured for tetrahedrally coordinated Zn ion in several synthetic compounds. Intensity ratios of L β and L α spectral... 相似文献
13.
Hiroshi Satake Masahiko Ohashi Yoshimitsu Hayashi 《Pure and Applied Geophysics》1984,122(2-4):185-193
The concentration of H2 in soil gases has been measured weekly at five stations on the Atotsugawa and Ushikubi faults in northern central Main Island, Japan, since 1981 in search of possible relationship with earthquakes. The observed H2 concentration varies from lower than 1 ppm to 7.8% in time and place. When a large earthquake (M: 7.7, epicenter distance: 486 km) occurred on 26 May 1983, an outstanding discharge of H2 was observed at all five stations, preseismically at three of them, and coseismically at the other two. Simultaneous H2 emission was also observed at some stations in seven other occasions. These periods of unusual H2 discharge nearly coincided with occurrences of major earthquakes in Japan, but not of local minor earthquakes along the Atotsugawa fault. This fault, being a deep fracture zone, may be sensitive to large-scale crustal stress changes which incidentally cause the major earthquakes. Increased H2 may be produced by rock fracture caused by the increased stresses on the fault and by the earthquakes themselves. Local minor earthquakes along Atotsugawa fault with magnitude lower than 3 may be unable to cause sufficient rock fracture to produce significant H2. 相似文献
14.
R. Bianchi A. Forni F. Cámara R. Oberti H. Ohashi 《Physics and Chemistry of Minerals》2007,34(8):519-527
The synthetic LiGaSi2O6 clinopyroxene is monoclinic C2/c at room-T. Its experimental electron density, ρ(r), has been derived starting from accurate room-T single-crystal diffraction data. Topological analysis confirms an intermediate ionic-covalent character for Si–O bonding,
as found by previous electron-density studies on other silicates such as diopside, coesite and stishovite. The non-bridging
Si–O bonds have more covalent character than the bridging ones. The Ga–O bonds have different bonding characters, the Ga–O2
bond being more covalent than the two Ga–O1 bonds. Li–O bonds are classified as pure closed-shell ionic interactions. Similar
to spodumene (LiAlSi2O6), Li has sixfold coordination, but the bond critical points associated to the two longest bonds are characterized by very
low electron density values. Similar to what previously found in spodumene and diopside, O···O interactions were detected
from the topological analysis of ρ(r), and indicate a cooperative interaction among the lone pairs of neighbouring oxygen atoms. In particular, this kind of interaction
has been obtained for the O1···O1 edge shared between two Ga octahedra. Integration over the atomic basins gives net charges
of −1.39(10), 2.82(10), 1.91(10) and 0.82(8) e for O (averaged), Si, Ga and Li atoms, respectively. Periodic Hartree–Fock
and DFT calculations confirm the results obtained by multipole refinement of the experimental data. Moreover, the theoretical
topological properties of the electron density distribution on the Si2O6 group are very similar to those calculated for spodumene.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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16.
S. Takechi T. Miyachi M. Fujii N. Hasebe K. Nogami H. Ohashi S. Sasaki H. Shibata T. Iwai E. Grün R. Srama N. Okada 《Journal of Atmospheric and Solar》2009,71(2):191-193
A cosmic dust detector for installation on a satellite is currently being developed using piezoelectric lead zirconate titanate (PZT), which can possess both functions of the collector and the transducer. The characteristics of the PZT detector have been studied by bombarding it with hypervelocity particles supplied by a Van de Graaff accelerator. The front surface of the detector used in this study was covered with a white paint to reduce any increase in the temperature due to the solar radiation. There was a linear relationship between the rise time of the signal produced by the detector and the particle's velocities, which were above 10 km/s on impact. This implies that individual particle velocities on impact can be inferred through the empirical formula derived from the data obtained from the PZT detector. 相似文献
17.
Aoki Koji Sakamaki Tatsuya Ohashi Tomonori Ikeda Osamu Suzuki Akio 《Physics and Chemistry of Minerals》2020,47(6):1-9
Physics and Chemistry of Minerals - A black tourmaline sample from Seagull batholith (Yukon Territory, Canada) was established to be a schorl with concentrations of Fe2+ among the highest currently... 相似文献
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19.
Y. Ezoe R. Fujimoto N.Y. Yamasaki K. Mitsuda T. Ohashi K. Ishikawa S. Oishi Y. Miyoshi N. Terada Y. Futaana F.S. Porter G.V. Brown 《Astronomische Nachrichten》2012,333(4):319-323
Recent results of charge exchange emission from solar system objects observed with the Japanese Suzaku satellite are reviewed. Suzaku is of great importance to investigate diffuse X‐ray emission like the charge exchange from planetary exospheres and comets. The Suzaku studies of Earth's exosphere, Martian exosphere, Jupiter's aurorae, and comets are overviewed (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
Toshio Kataoka Eiji Yunoki Mitsuo Shimizu Tadashige Mori Osamu Tsukamoto Yukitaka Ohashi Ken Sahashi Toshihiko Maitani Koh’ichi Miyashita Toru Iwata Yoko Fujikawa Akira Kudo Roger H. Shaw 《Boundary-Layer Meteorology》2001,101(2):131-156
Concentrations of radon 222Rn andair pollutants, meteorological parametersnear the surface and vertical profiles of meteorological elements were measured atUchio (Okayama City, Okayama Prefecture, Japan) 12 km north from the coast ofthe Inland Sea of Japan. In the nighttime, the 222Rn concentration increased in the case of weak winds, but did not increase as much in the case of moderate or strong winds, as had been expected. In the daytime, the 222Rn concentrationheld at a slightly higher than average level for the period from sunrise to about 1100 JST. It is considered that this phenomenon is due to a period of morning calm, that is, a transition period from land breeze to sea breeze.NO, which is sensitive to traffic volume,brought information concerning advection.Oxidant concentrations,which reflect the availability of sunlight,acted in the reverse manner to 222Rnconcentrations. Thus, a set of 222Rn and air pollutants could provide useful information regarding the local conditions of the atmospheric boundary layer. 相似文献