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91.
Atsushi Toramaru Akira Ishiwatari Maki Matsuzawa Masaru Nakamura Shoji Arai 《Bulletin of Volcanology》1996,58(5):393-400
We report a novel type of layering structure in igneous rocks. The layering structure in the Ogi picrite sill in Sado Island,
Japan, is spatially periodic, and appears to be caused by the variation in vesicle volume fraction. The gas phase forming
the vesicles apparently exsolved from the interstitial melt at the final stage of solidification of the magma body. We call
this type of layering caused by periodic vesiculation in the solidifying magma body "vesicle layering." The presence of vesicle
layering in other basic igneous bodies (pillow lava at Ogi and dolerite sill at Atsumi, Japan) implies that it may be a fairly
common igneous feature. The width of individual layers slightly, but regularly, increases with distance from the upper contact.
The layering plane is perpendicular to the long axes of columnar joints, regardless of gravitational direction, suggesting
that the formation of vesicles is mainly controlled by the temperature distribution in the cooling magma body. We propose
a model of formation of vesicle layering which is basically the same as that for Liesegang rings. The interplay between the
diffusion of heat and magmatic volatiles in melt, and the sudden vesiculation upon supersaturation, both play important roles.
Received: 15 February 1996 / Accepted: 24 June 1996 相似文献
92.
Masaru Yoshida 《Gondwana Research》1998,1(3-4):433-434
93.
Japanese seaperch Lateolabrax japonicus migrate from Ariake Bay to the estuarine turbidity maximum (ETM) zone of the Chikugo River and inhabit there through the post-migration period (15–20 mm in standard length). The feeding, growth and mortality during the post-migration period of Japanese seaperch were analyzed in relation to seasonal changes in temperature and prey concentration. Larvae and juveniles were collected from ten sampling stations at 4–7 day intervals from 24 February to 24 April 2005 in the Chikugo estuary. Based on the otolith microstructure analysis the sampled fish were divided into nine cohorts, each cohort covering a 5 day hatch date period (22 December 2004 to 4 February 2005). The growth coefficient (G, day−1) was higher and the mortality coefficient (M, day−1) was lower in the later cohorts. The ratio of G to M as an index of stage-specific survival during the post-migration period significantly increased as the season progressed and exceeded 1.0 in the last cohort examined. Variability in abundance of the major prey organism, Sinocalanus sinensis, had a significant effect on the Japanese seaperch ingestion rate. Increase in temperature and spring bloom of S. sinensis is concluded to provide the later cohorts with a higher survival probability through increasing ingestion and growth rates during their post-migration period in spring 2005. 相似文献
94.
Yoshihiro Fujiwara Masaru Kawato Tomoko Yamamoto Toshiro Yamanaka Waka Sato-Okoshi Chikayo Noda Shinji Tsuchida Tomoyuki Komai Sherine Sonia Cubelio Takenori Sasaki Karen Jacobsen Kaoru Kubokawa Katsunori Fujikura Tadashi Maruyama Yasuo Furushima Kenji Okoshi Hiroshi Miyake Masayuki Miyazaki Yuichi Nogi Akiko Yatabe & Takashi Okutani 《Marine Ecology》2007,28(1):219-232
We report the first study of sperm whale‐fall ecosystems, based on mass sinking of whale carcasses at shelf depths in the northwest Pacific. We conducted three observations over a 2‐year period on replicate sperm‐whale carcasses implanted at depths of 219–254 m off the southern part of Japan from July 2003 to August 2005. The study was made possible by a mass stranding of sperm whales in January 2002, and the subsequent sinking of 12 carcasses in the waters off Cape Nomamisaki. Dense aggregations of unique chemosynthesis‐based fauna had formed around the whale carcasses after 18 months (July 2003). The mytilid mussel Adipicola pacifica was the most abundant macrofaunal species and covered most of the exposed bone surfaces. The general composition of the fauna was similar to that of deep‐water reducing habitats, but none of the species appearing in this study has been found at hydrothermal vents, cold seeps or deep‐water whale falls. A new species of lancelet, which was the first record of the subphylum Cephalochordata from reducing environments, a new species of Osedax; a rarely encountered benthic ctenophore, and a rare gastropod species were discovered at this sperm whale‐fall site. Benthic communities were similar across all the carcasses studied, although the body sizes of the whales were very different. The succession of epifaunal communities was relatively rapid and the sulphophilic stage was considerably shorter than that of other known whale falls. 相似文献
95.
Relationships between biotic and abiotic factors and the ecological performance of late larval and juvenile flatfish in nursery grounds are examined from ecophysiological viewpoints. The first events in the nursery are metamorphosis and settlement. Development of organs, osmoregulation and behavioural changes during metamorphosis, and size at metamorphosis are regulated by environmental factors. Various hormones play critical roles in this regulation. Effects of environmental conditions on individual growth in the nursery grounds are described on the basis of Fry's five environmental factors: limiting, controlling, masking, directive and lethal factors. The main limiting factors are food and dissolved oxygen; controlling factors are temperature and body size; masking factors are salinity and pollutants; lethal factors are extreme environments; and directive factors are food, predators and dissolved oxygen. In addition to temperature, it has been indicated that dissolved oxygen seems to be relatively important for flatfish of the eastern US and northern European countries, while food abundance appears to be more critical for Japanese flounder. The feasibility is discussed of ecophysiological modelling to predict individual growth and subpopulation production based on the assessment of the role of environmental variability using the above classification, which organises and integrates environmental effects. 相似文献
96.
The local ensemble transform Kalman filter (LETKF) is implemented with the Weather Research and Forecasting (WRF) model, and
real observations are assimilated to assess the newly-developed WRF-LETKF system. The WRF model is a widely-used mesoscale
numerical weather prediction model, and the LETKF is an ensemble Kalman filter (EnKF) algorithm particularly efficient in
parallel computer architecture. This study aims to provide the basis of future research on mesoscale data assimilation using
the WRF-LETKF system, an additional testbed to the existing EnKF systems with the WRF model used in the previous studies.
The particular LETKF system adopted in this study is based on the system initially developed in 2004 and has been continuously
improved through theoretical studies and wide applications to many kinds of dynamical models including realistic geophysical
models. Most recent and important improvements include an adaptive covariance inflation scheme which considers the spatial
and temporal inhomogeneity of inflation parameters. Experiments show that the LETKF successfully assimilates real observations
and that adaptive inflation is advantageous. Additional experiments with various ensemble sizes show that using more ensemble
members improves the analyses consistently. 相似文献
97.
98.
Coupling behavior of shear deformation and end rotation of elastomeric seismic isolation bearings 下载免费PDF全文
This paper presents a mechanical model for predicting the behavior of elastomeric seismic isolation bearings subject to combined end rotations and shear deformation. The mechanical model consists of a series of axial springs at the top, mid‐height and bottom of the bearing to vertically reproduce asymmetric bending moment distribution in the bearings. The model can take into account end rotations of the bearing, and the overall rotational stiffness includes the effect of the variation of vertical load on the bearing and the imposed shear deformation. Static bending tests under various combinations of vertical load and shear deformation were performed to identify the mechanical characteristics of bearings. The test results indicate that bearing rotational stiffness increases with increasing vertical load but decreases with increasing shear deformation. Simulation analyses were conducted to validate the new mechanical model. The results of analyses using the new model show very good agreement with experimental observations. A series of seismic response analyses were performed to demonstrate the dynamic behavior of top‐of‐column isolated structures, a configuration where the end rotations of isolation bearings are typically expected to be larger. The results suggest that the end rotations of elastomeric bearings used in practical top‐of‐column isolated structures do not reduce the stability limit of isolation system. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
99.
Keita W. Suzuki Kouji Nakayama Masaru Tanaka 《Estuarine, Coastal and Shelf Science》2009,83(4):516-528
The estuarine turbidity maximum (ETM) that develops in the lower salinity areas of macrotidal estuaries has been considered as an important nursery for many fish species. Mysids are one of the dominant organisms in the ETM, serving as a key food source for juvenile fish. To investigate the horizontal distribution and population dynamics of dominant mysids in relation to the fluctuation of physical conditions (temperature, salinity, turbidity, and freshwater discharge), we conducted monthly sampling (hauls of a ring net in the surface water) along the macrotidal Chikugo River estuary in Japan from May 2005 to December 2006. Hyperacanthomysis longirostris was the dominant mysid in the estuary, usually showing peaks of density and biomass in or close to the ETM (salinity 1–10). In addition, intra-specific differences (life-cycle stage, sex, and size) in horizontal distribution were found along the estuary. Larger males and females, particularly gravid females, were distributed upstream from the center of distribution where juveniles were overwhelmingly dominant. Juveniles increased in size toward the sea in marked contrast with males and females. The findings suggest a possible system of population maintenance within the estuary; gravid females release juveniles in the upper estuary, juveniles grow during downstream transport, young males and females mature during the upstream migration. Density and biomass were primarily controlled by seasonal changes of temperature, being high at intermediate temperatures (ca. 15–25 °C in late spring and fall) and being low at the extreme temperatures (ca. 10 °C in midwinter and 30 °C in midsummer). High density (up to 666 ind. m−3) and biomass (up to 168 mg dry weight m−3) of H. longirostris were considered to be comparable with those of copepods in the estuary. 相似文献
100.