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排序方式: 共有179条查询结果,搜索用时 31 毫秒
1.
Masayuki Takahashi Sooji Shimura Yukuya Yamaguchi Yoshihiko Fujita 《Journal of Oceanography》1971,27(2):43-50
The photo-inhibition of phytoplankton photosynthesis at higher intensities was examined with a cultured marine diatom,Phaeodactylum tricornutum, and natural samples. The question was to determine whether photo-inhibition results from excretion of photosynthetic products from cell or from an actual decrease in photosynthetic rate.
P. tricornutum cultured at 15 klux showed very little photo-inhibition up to 70 klux, and, in the sample cultured at 1 klux, most marked photo-inhibition was observed in 3 hours experiment. Extracellular release was less than 30% of particulate fixation, and did not show any extreme increase to supplement photosynthesis depression at higher light intensities. When the photosynthesis was measured during 10 minutes, both samples showed no photo-inhibition. The photosynthesis by low light sample lost the linearity of time-course with prolonged exposure at high light intensity. Observed photo-inhibition, therefore, we explained with the actual decrease in photosynthetic rate. Similar photo-inhibition could be seen in marine phytoplankton samples concentrated by filtration. 相似文献
2.
Shin Okamoto Nagahide Kani Masahiko Higashino Norihide Koshika Masayuki Kimizuka Mitsumasa Midorikawa Masanori Iiba 《地震工程与工程振动(英文版)》2002,1(2):213-225
The Building Standard Law of Japan and related Enforcement Order and Notifications have been substantially revised since the
year 2000 to introduce a performance-based regulatory and deregulation system for building control systems. Up to then, time-history
analyses were mandatory for isolated buildings and had to be specially approved by the Minster of the Ministry of Construction
(MOC). Simplified design procedures based on the equivalent linear method for seismically isolated buildings have been issued
as “Notification 2009 — Structural calculation procedure for buildings with seismic isolation” from MOC, and are now integrated
into the Ministry of Land, Infrastructure, and Transportation (MLIT). Along with Notification 2009, “Notification 1446 of
year 2000 — Standard for specifications and test methods for seismic isolation devices” was also issued. Buildings with heights
equal to or less than 60m and that are designed according to these Notifications, including base isolated buildings, only
need approval from local building officials, and no longer require the special approval of the Minister of MLIT. This paper
summarizes: 1) some statistics related to buildings with seismic isolation completed up to the end of 2001; 2) simplified
design procedures required by Notification 2009 of year 2000; and 3) performance of seismic isolation devices required by
Notification 1446 of year 2000. 相似文献
3.
Tetsu Nakamura Masayuki Hara Miki Oshika Yoshihiro Tachibana 《Climate Dynamics》2015,45(11-12):3547-3562
4.
Naoki Shirai Yuzuru Karouji Kazuya Kumagai Masayuki Uesugi Kaori Hirahara Motoo Ito Naotaka Tomioka Kentaro Uesugi Akira Yamaguchi Naoya Imae Takuji Ohigashi Toru Yada Masanao Abe 《Meteoritics & planetary science》2020,55(7):1665-1680
Chemical compositions of materials used for new sample holders (vertically aligned carbon nanotubes [VACNTs] and polyimide film), which were developed for the analysis of Hayabusa2‐return samples, were determined by instrumental neutron activation analysis and/or instrumental photon activation analysis, to estimate contamination effects from the sample holders. The synthetic quartz plate used for the sample holders was also analyzed. Ten elements (Na, Al, Cr, Mn, Fe, Ni, Eu, W, Au, and Th) and 14 elements (Na, Al, K, Sc, Ti, Cr, Zn, Ga, Br, Sb, La, Eu, Ir, and Au) could be detected in the VACNTs and polyimide film, respectively. The VACNT data show that contamination by this material with respect to the Murchison meteorite is negligible in terms of the elemental ratios (e.g., Fe/Mn, Na/Al, and Mn/Cr) used for the classification of meteorites due to the extremely low density of VACNTs. However, for the Au/Cr ratio, even small degrees (1.7 wt%) of contamination by VACNTs will change the Au/Cr ratio. Elemental ratios used for the classification of meteorites are only influenced by large amounts of contamination (>60 wt%) of polyimide film, which is unlikely to occur. In contrast, detectable effects on Ti isotopic compositions are caused by >0.1 and >0.3 wt% contamination by VACNTs and polyimide film, respectively, and Hf isotopic changes are caused by >0.1 wt% contamination by VACNTs. The new sample holders (VACNTs and polyimide film) are suitable for chemical classification of Hayabusa2‐return samples, because of their ease of use, applicability to multiple analytical instruments, and low contamination levels for most elements. 相似文献
5.
Tectonic evolution of lower crustal rocks in an exposed magmatic arc section in the Hidaka metamorphic belt, Hokkaido, northern Japan 总被引:3,自引:0,他引:3
Abstract : The Hidaka metamorphic belt consists of an island-arc assembly of lower to upper crustal rocks formed during early to middle Paleogene time and exhumed during middle Paleogene to Miocene time. The tectonic evolution of the belt is divided into four stages, D0rs, D1, D2rs, and D3, based on their characteristic deformation, metamorphism, and igneous activity. The premetamorphic and igneous stage (D0) involves tectonic thickening of an uppermost Cretaceous and earliest Tertiary accretionary complex, including oceanic materials in the lower part of the complex. D1 is the stage of prograde metamorphism with increasing temperatures at a constant pressure during an early phase, and with a slight decrease of pressure at the peak metamorphic phase, accompanying flattening of metamorphic rocks and intrusions of mafic to intermediate igneous rocks. At the peak, incipient partial melting of pelitic and psammitic gneisses took place in the amphibolite–granulite facies transition zone, the melt and residuals cutting the foliations formed by flattening. In the deep crust, large amounts of S-type tonalite magma formed by crustal anatexis, intruded into the granulite facies gneiss zone and also into the upper levels of the metamorphic sequence during the subsequent stage. During D1 stage, mafic and intermediate magmas supplied and transported heat to form the arc-type crust and at the same time, the magmatic underplating caused extensional doming of the crust, giving rise to flattening and vertical uplifting of the crustal rocks. D2 stage is characterized by subhorizontal top-to-the-south displacement and thrusting of lower to upper crustal rocks, forming a basal detachment surface (décollement) and duplex structures associated with intrusions of S-type tonalite. Deformation structures and textures of high-temperature mylonites formed along the décollement, as well as the duplex structures, show that the D2 stage movement occurred under a N-S trending compressional tectonic regime. The depth of intra-crustal décollement in the Hidaka belt was defined by the effect of multiplication of two factors, the fraction of partial melt which increases downward, and the fluid flux which decreases downward. The crustal décollement, however, might have extended to the crust-mantle boundary and/or to the lithosphere and asthenosphere boundary. The subhorizontal movement was transitional to a dextral-reverse-slip (dextral transpression) movement accompanied by low-temperature mylonitization with retrograde metamorphism, the stage defined as D3. The crustal rocks from the basal décollement to the upper were tilted eastward on the N–S axis and exhumed during the D3 stage. During D2 and D3 stages, the intrusion of crustal acidic magmas enhanced the crustal deformation and exhumation in the compressional and subsequent transpressional tectonic regime. 相似文献
6.
Taku Tada Yoshinobu Tsuji Masahito Tsukamoto Yoshikazu Ueno Masayuki Kawashima Takashi Egawa Yasuhiro Yamazaki 《Pure and Applied Geophysics》1992,138(2):309-322
We carried out observations of sea-level fluctuations simultaneously at three stations on the coast of Heda Bay, Honshu, Japan, using supersonic-type water level gauges controlled by a personal computer. Analyses of the obtained data showed predominant spectral peaks at periods of 7.6, 2.0 and 1.3 minutes for all three stations. Comparison of the observed data with numerically calculated normal oscillation modes of the bay indicates that these three spectral peaks correspond to the theoretical first, third and seventh normal modes of the basin respectively, judging from the results of cross-spectral analyses. The reason for the absence of the remaining normal modes, especially of the second or the lateral first mode of the basin, is briefly considered. 相似文献
7.
Kenji Kashiwaya Masayuki Ryugo Masae Horii Hideo Sakai Toshio Nakamura Takayoshi Kawai 《Journal of Paleolimnology》1999,21(2):143-150
The St.16 core obtained from the Academician Ridge of Lake Baikal in eastern Siberia may span about 260 000 years, and some physical properties of the core samples are closely related to aquatic paleoproductivity and climatic change. The median of grain size, grain density, and water content fluctuate synchronously. They also are connected with change in the abundance of biogenic silica (diatoms). The physical parameters indicate that there were high aquatic productivity periods around interglacial periods (MIS 5 and 7; 70 000-125 000 yr B.P. and 180 000-250 000 yr B.P.). Comparatively large clastics were transported from outside of the lake through various routes (ice rafting, etc.) in addition to fluvial routes during the glacials or 'stadials. There are ca. 20 000 yr, 40 000 yr and 100 000 yr periods in the variations of physical properties. These are related to the three Milankovitch parameters of solar insolation. 相似文献
8.
Masayuki Umemura Jun Fukue & Shin Mineshige 《Monthly notices of the Royal Astronomical Society》1998,299(4):1123-1131
We examine the physical processes of radiatively driven mass accretion on to galactic nuclei, owing to intensive radiation from circumnuclear starbursts. The radiation from a starburst not only causes the inner gas disc to contract via radition flux force, but also extracts angular momentum owing to relativistic radiation drag, thereby inducing an avalanche of the surface layer of the disc. To analyse such a mechanism, the radiation–hydrodynamical equations are solved, including the effects of the radiation drag force as well as the radiation flux force. As a result, it is found that the mass accretion rate owing to the radiative avalanche is given by M ˙ ( r )= η ( L * / c 2 )( r / R )2 (Δ R / R )(1 − e −τ ) at radius r , where the efficiency η ranges from 0.2 up to 1, L * and R are respectively the bolometric luminosity and the radius of the starburst ring, Δ R is the extent of the emission regions, and τ is the face-on optical depth of the disc. In an optically thick regime, the rate depends upon neither the optical depth nor the surface mass density distribution of the disc. The present radiatively driven mass accretion may provide a physical mechanism which enables mass accretion from 100-pc scales down to ∼ parsec scales, and it may eventually be linked to advection-dominated viscous accretion on to a massive black hole. The radiation–hydrodynamical and self-gravitational instabilities of the disc are briefly discussed. In particular, the radiative acceleration possibly builds up a dusty wall, which 'shades' the nucleus in edge-on views. This provides another version of the model for the formation of an obscuring torus. 相似文献
9.
Masayuki Kikuchi 《Physics of the Earth and Planetary Interiors》1981,25(2):159-162
The propagation of elastic waves in a medium containing many inclusions is considered. Under the assumption that the spatial distribution of inclusions is uniform, a general equation is derived for the determination of the velocity dispersion and attenuation coefficient of the effective waves. A simple example is presented where scatterers are infinitesimally thin cracks. The calculated results show that the attenuation coefficient Q?1 takes a peak value for the wavelength nearly equal to twice the crack length. 相似文献
10.
Masayuki Kikuchi 《Physics of the Earth and Planetary Interiors》1979,19(3):255-262
Following Burg's algorithm, we develop a new mathematical method of estimating the impulse response of a linear system. Since no data-invariant time window is used in this method, the estimated impulse response gives us reliable information on both the amplitude and the phase spectra of the system.The method is applied to laboratory data to investigate the dynamical response of rock specimens. The experimental results show that the waveform distortion with travel distance may well be described by a standard viscoelastic solid model. However, they also show that there is an additional factor of attenuation which is independent of the frequency and therefore not accompanied by any velocity dispersion. 相似文献