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41.
A series of studies was conducted on three buildings of steel reinforced concrete structures with RC shear walls damaged in the 1995 Hyogo-ken Nanbu earthquake. These buildings are located in an area where structural damage centred around. Two of these buildings suffered severe damage, while the third was not structurally damaged. Our studies deal with site inspections, including micro-tremor measurement of buildings, the evaluation of input motions, and the response analyses considering soil–structure interaction. The results of simulation analyses of the two severely damaged buildings correspond to their actual damage state. From the response analyses of the one slender building with no structural damage, it was concluded that uplifting is the main reason it did not suffer any structural damage. Through these studies, the importance of soil–structure interaction and effective input motion is fully understood. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
42.
Richard D. Brodeur Joseph P. Fisher Yasuhiro Ueno Kazuya Nagasawa William G. Pearcy 《Journal of Oceanography》2003,59(4):415-434
During the 1980s and 1990s, scientific research cruises were conducted in both the eastern and western boundary regions of
the North Pacific Ocean. The main purpose of these cruises was to examine the abundance and distribution patterns of juvenile
salmon in coastal waters. These studies created one of the most extensive databases ever collected on the species composition
of coastal Transition Zone epipelagic nekton in the North Pacific Ocean. Catch data from two purse seine and two surface trawl
surveys (one each from off northern Japan and eastern Russia and off the West Coast of the U.S.) were examined using multivariate
techniques to analyze the community structure of nektonic cephalopods, elasmobranchs, and teleosts in the coastal zone during
the summer and autumn months. Juvenile salmonids are generally among the most common species caught, but in terms of overall
abundance, other potential competitors with juvenile salmon, such as small squids and clupeoid fishes predominated the catches.
Species diversity and dominance varied among areas and gear types. Distinct assemblages were found in each area, but the two
regions had closely related species occupying similar ecological positions in each habitat.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
43.
An Ecosystem Model Including Nitrogen Isotopes: Perspectives on a Study of the Marine Nitrogen Cycle
Chisato?YoshikawaEmail author Yasuhiro?Yamanaka Takeshi?Nakatsuka 《Journal of Oceanography》2005,61(5):921-942
We have developed an ecosystem model including two nitrogen isotopes (14N and 15N), and validated this model using an actual data set. A study of nitrogen isotopic ratios (δ15N) using a marine ecosystem model is thought to be most helpful in quantitatively understanding the marine nitrogen cycle.
Moreover, the model study may indicate a new potential of δ15N as a tracer. This model has six compartments: phytoplankton, zooplankton, particulate organic nitrogen, dissolved organic
nitrogen, nitrate and ammonium in a two-box model, and has biological processes with/without isotopic fractionation. We have
applied this model to the Sea of Okhotsk and successfully reproduced the δ15N of nitrate measured in seawater and the seasonal variations in δ15N of sinking particles obtained from sediment trap experiments. Simulated δ15N of phytoplankton are determined by δ 15N of nitrate and ammonium, and the nitrogen f-ratio, defined as the ratio of nitrate assimilation by phytoplankton to total nitrogenous nutrient assimilation. Detailed
considerations of biological processes in the spring and autumn blooms have demonstrated that there is a significant difference
between simulated δ15N values of phytoplankton, which assimilates only nitrate, and only ammonium, respectively. We suggest that observations of
δ 15N values of phytoplankton, nitrate and ammonium in the spring and autumn blooms may indicate the ratios of nutrient selectivity
by phytoplankton. In winter, most of the simulated biogeochemical fluxes decrease rapidly, but nitrification flux decreases
much more slowly than the other biogeochemical fluxes. Therefore, simulated δ15N values and concentrations of ammonium reflect almost only nitrification. We suggest that the nitrification rate can be parameterized
with observations of δ15N of ammonium in winter and a sensitive study varying the parameter of nitrification rate. 相似文献
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Self-sustained oscillations at Volcán de Colima (México) inferred by Independent Component Analysis 总被引:2,自引:1,他引:1
We have analyzed Long-Period (LP) seismic events of Volcán de Colima (Mexico) recorded by four three-component broad-band
seismometers during January 2006. Frequency-domain analysis shows spectra mainly peaked in the range 0.3–2 Hz and characterized
by a monotonic decreasing envelope, as those produced in a cylindrically-symmetric self-oscillating cavity interacting with
a confined jet. Independent Component Analysis, a time-series decomposition method, extracts two or three nonlinear oscillation
modes depending on the station, with the fundamental one peaked at 0.4–0.5 Hz. These decomposed waves have a well defined
spectral content and are self-sustained oscillations with low dimensionality, as shown by dynamic system reconstruction methods.
Moreover, they show radial polarization in near field and transverse polarization in far field in North-West South-East direction.
Finally, we hypothesize a branched plumbing system with two principal conduits having alignments orthogonal to one another. 相似文献
47.
Philip Lah Jayaram N. Chengalur Frank H. Briggs Matthew Colless Roberto De Propris Michael B. Pracy W. J. G. de Blok Shinobu S. Fujita Masaru Ajiki Yasuhiro Shioya Tohru Nagao Takashi Murayama Yoshiaki Taniguchi Masafumi Yagi Sadanori Okamura 《Monthly notices of the Royal Astronomical Society》2007,376(3):1357-1366
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Masahito Shigemitsu Yutaka W. Watanabe Yasuhiro Yamanaka Hajime Kawakami Makio C. Honda 《Journal of Oceanography》2010,66(5):697-708
We used time-series sediment trap data for four major components, organic matter and ballast minerals (CaCO3, opal, and lithogenic matter) from 150, 540, and 1000 m in the western subarctic Pacific (WSAP), where opal is the predominant
mineral in sinking particles, to develop four simple models for settling particles, including the “ballast model”. The ballast
model is based on the concept that most of the organic matter “rain” in the deep sea is carried by the minerals. These four
models are designed to simultaneously reproduce the flux of each major component of settling particles at 540 and 1000 m by
using the data for each component at 150 m as initial values. Among the four models, the ballast model, which considers the
sinking velocity increase with depth, was identified as the best using the Akaike information criterion as a measure of the
model fit to data. This model successfully reproduced the flux of organic matter at 540 and 1000 m, indicating that the ballast
model concept works well in the shallow zone of the WSAP on a seasonal timescale. This also suggests that ballast minerals
not only physically protect the organic matter from degradation during the settling process but also enhance the sinking velocity
and reduce the degree of decomposition. 相似文献