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291.
The fifth Japaniese X-ray astronomy satellite, Astro-E, following Hakucho, Tenma, Ginga, and ASCA is scheduled for launch in the year 2000 by the Institute of Space and Astronautical Science (ISAS) with an M-V rocket. The satellite will be put into an approximately circular orbit with an altitude of ∽550 km and an inclination of ∽31°. There will be three experiments on board Astro-E: an X-ray micro-calorimeter array, four X-ray CCDs and a hard X-ray detector. All three experiments combined, Astro-E will become a spectrometer facility covering a wide energy band from 0.5 keV to 600 keV. 相似文献
292.
Naoki Niwa Takuji Kobori Motoichi Takahashi Hiroshi Midorikawa Narito Kurata Takayuki Mizuno 《地震工程与结构动力学》2000,29(6):789-812
A semi‐active hydraulic damper (SHD) for a semi‐active damper system, which is useful for practical structural control especially for large earthquakes, has been developed. Its maximum damping force is set to 1 or 2 MN, and it is controlled by only 70 W of electric power. An SHD with a maximum damping force of 1 MN was applied to an actual building in 1998. This paper first presents the results of a dynamic loading test to confirm the control performance of the SHD. Next, an analytical model of SHDs (SHD model) is constructed with the same concept for two kinds of SHDs based on the test results. Through simulation analyses of the test results using the proposed SHD model, the dynamic characteristics of the SHD can be well represented within practical conditions. Simulation analyses are also carried out using a simple structure model with the SHD model. It is shown that this SHD model can be used to precisely evaluate the control effect of the semi‐active damper system and is useful in practical SHD design under the applied conditions. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
293.
Murata S Takahashi S Agusa T Thomas NJ Kannan K Tanabe S 《Marine pollution bulletin》2008,56(4):641-649
Organotin compounds (OTs) including mono- to tri-butyltins, -phenyltins, and -octyltins were determined in the liver of adult sea otters (Enhydra lutris) found dead along the coasts of California, Washington, and Alaska in the USA and Kamchatka, Russia. Total concentrations of OTs in sea otters from California ranged from 34 to 4100ng/g on a wet weight basis. The order of concentrations of OTs in sea otters was total butyltins>total octyltins> or = total phenyltins. Elevated concentrations of butyltins (BTs) were found in some otters classified under 'infectious-disease' mortality category. Concentrations of BTs in few of these otters were close to or above the threshold levels for adverse health effects. Total butyltin concentrations decreased significantly in the livers of California sea otters since the 1990s. Based on the concentrations of organotins in sea otters collected from 1992 to 2002, the half-lives of tributyltin and total butyltins in sea otters were estimated to be approximately three years. 相似文献
294.
Distribution,age, and origin of a submarine landslide deposit in the Pleistocene Kiwada Formation,forearc basin fill on the Boso Peninsula,east‐central Japan: Constraints from tephro‐ and biostratigraphy
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Masayuki Utsunomiya 《Island Arc》2018,27(4)
A mass‐transport deposit named MTD1 (up to 100 m in thickness) is intercalated in the upper Kiwada Formation, a Pleistocene forearc basin fill on the Boso Peninsula, east‐central Japan. The present study aims to examine the origin, age, and distribution of MTD1. MTD1 consists mainly of mudstone blocks containing thin very fine‐ to medium‐grained sandstones, and ranges from tens of centimeters to more than tens of meters in length and thickness. Correlation of marker tuff beds and application of the biostratigraphy of calcareous nannofossils suggest that the blocks in MTD1 were derived from the underlying strata. The total thickness of the stratified blocks from the different stratigraphic horizons exceeds 60 m, implying that MTD1 originated from deeply‐excavated slope failure. The slope failure occurred in a short time interval at ca 1.3 Ma. MTD1 provides an estimate of the height of the escarpment on the basis of the stratigraphic origin of the blocks. 相似文献
295.
U–Pb zircon ages of the Nakanogawa Group in the Hidaka Belt,northern Japan: Implications for its provenance and the protolith of the Hidaka metamorphic rocks
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Futoshi Nanayama Yutaka Takahashi Toru Yamasaki Mitsuru Nakagawa Hideki Iwano Tohru Danhara Takafumi Hirata 《Island Arc》2018,27(2)
Zircon U–Pb ages of two acidic tuff and two turbidite sandstone samples from the Nakanogawa Group, Hidaka Belt, were measured to estimate its depositional age and the development of the Hokkaido Central Belt, northeast Japan. In the northern unit, homogeneous zircons from pelagic acidic tuff from a basal horizon dated to 58–57 Ma, zircons from sandstone from the upper part of the unit dated to 56–54 Ma, and zircons from acidic tuff from the uppermost part dated to 60–56 Ma and 69–63 Ma. Both of the tuff U–Pb ages are significantly older than the youngest radiolarian fossil age (66–48 Ma). Therefore, the maximum depositional age of the turbidite facies in the northern unit is 58 Ma and the younger age limit, estimated from the fossil age, is 48 Ma. In the southern unit, homogeneous zircons from turbidite sandstone dated to 58–57 Ma. Thus the depositional age of this turbidite facies was interpreted to be 66–56 Ma from the fossil age, probably close to 57 Ma. Most of the zircon U–Pb ages from the Nakanogawa Group are younger than 80 Ma, with a major peak at 60 Ma. This result implies that around Hokkaido volcanic activity occurred mainly after 80 Ma. Older zircon ages (120–80 Ma, 180–140 Ma, 340–220 Ma, 1.9 Ga, 2.2 Ga, and 2.7 Ga) give information about the provenance of other rocks in the Hidaka Belt. It is inferred that the Nakanogawa Group comprises protoliths of the upper sequence of the Hidaka Metamorphic Zone, which therefore has the same depositional age as the Nakanogawa Group (66–48 Ma). The depositional ages of the lower sequence of the Hidaka Metamorphic Zone and the Nakanogawa Group are probably the same. 相似文献
296.
Masayuki Uesugi Motoo Ito Hikaru Yabuta Hiroshi Naraoka Fumio Kitajima Yoshinori Takano Hajime Mita Yoko Kebukawa Aiko Nakato Yuzuru Karouji 《Meteoritics & planetary science》2019,54(3):638-666
Carbonaceous materials in the sample catcher of the Hayabusa spacecraft were assigned as category 3 particles. We investigated the category 3 particles with a suite of in situ microanalytical methods. Possible contaminants collected from the cleanrooms of the spacecraft assembly and extraterrestrial sample curation center (ESCuC) were also analyzed in the same manner as category 3 particles for comparison. Our data were integrated with those of the preliminary examination team for category 3 particles. Possible origins for the category 3 particles include contamination before and after the operation of the Hayabusa spacecraft. 相似文献
297.
Queenie H. S. Chan Aiko Nakato Yoko Kebukawa Michael E. Zolensky Tomoki Nakamura Jessica A. Maisano Matthew W. Colbert James E. Martinez A. L. David Kilcoyne Hiroki Suga Yoshio Takahashi Yasuo Takeichi Kazuhiko Mase Ian P. Wright 《Meteoritics & planetary science》2019,54(1):104-125
We present in this study the effects of short‐term heating on organics in the Tagish Lake meteorite and how the difference in the heating conditions can modify the organic matter (OM) in a way that complicates the interpretation of a parent body's heating extent with common cosmothermometers. The kinetics of short‐term heating and its influence on the organic structure are not well understood, and any study of OM is further complicated by the complex alteration processes of the thermally metamorphosed carbonaceous chondrites—potential analogues of the target asteroid Ryugu of the Hayabusa2 mission—which had experienced posthydration, short‐duration local heating. In an attempt to understand the effects of short‐term heating on chondritic OM, we investigated the change in the OM contents of the experimentally heated Tagish Lake meteorite samples using Raman spectroscopy, scanning transmission X‐ray microscopy utilizing X‐ray absorption near edge structure spectroscopy, and ultraperformance liquid chromatography fluorescence detection and quadrupole time of flight hybrid mass spectrometry. Our experiment suggests that graphitization of OM did not take place despite the samples being heated to 900 °C for 96 h, as the OM maturity trend was influenced by the heating conditions, kinetics, and the nature of the OM precursor, such as the presence of abundant oxygenated moieties. Although both the intensity of the 1s?σ* exciton cannot be used to accurately interpret the peak metamorphic temperature of the experimentally heated Tagish Lake sample, the Raman graphite band widths of the heated products significantly differ from that of chondritic OM modified by long‐term internal heating. 相似文献
298.
Simon F. Portegies Zwart Koji Takahashi 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):179-186
Recent N-body simulations have shown that there is a serious discrepancy between the results of N-body simulations and the
results of Fokker-Planck simulations for the evolution of globular and rich open clusters under the influence of the galactic
tidal field. In some cases, the lifetime obtained from Fokker-Planck calculations is more than an order of magnitude smaller
than those from N-body simulations. In this paper we show that the principal cause for this discrepancy is an over-simplified
treatment of the tidal field used in previous Fokker-Planck simulations. We performed new Fokker-Planck calculations using
a more appropriate implementation for the boundary condition of the tidal field. The implementation is only possible with
anisotropic Fokker-Planck models, while all previous Fokker-Planck calculations rely on the assumption of isotropy. Our new
Fokker-Planck results agree well with N-body results. Comparison of the two types of simulations gives a better understanding
of the evolution of such clusters.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
299.
Wuyi Wang Shigeho Sueno Eiichi Takahashi Hisayoshi Yurimoto Tibor Gasparik 《Contributions to Mineralogy and Petrology》2000,139(6):720-733
Trace element concentrations of peridotitic garnet inclusions in diamonds from two Chinese kimberlite pipes were determined
using the ion microprobe. Garnet xenocrysts from the same two kimberlite pipes were also analyzed for comparison. In contrast
to their extremely refractory major element compositions, all harzburgitic garnets showed enrichment in light rare earth elements
(REE) relative to chondrite, resulting in sinuous REE patterns. Both normal and sinuous REE patterns were observed from the
lherzolitic garnets. Concentrations of REE in garnets changed significantly from diamond to diamond and no specific correlations
were observed with their major element compositions. Analyses of randomly selected two to three points within every grain
of a large number of garnet inclusions by the ion microprobe demonstrated that there was no evident compositional heterogeneity,
and multiple grains of one phase from a single diamond host also exhibit very similar compositions. This implies that the
trace element heterogeneity within one grain or among multiple inclusions from the same diamond host, as reported from Siberian
diamonds, is not a common feature for these Chinese diamonds. Concentrations of Na, Ti, and Zr tend to decrease when garnets
become more refractory, but variations of Sr and Li are more complex. Compositions rich in light REE and relatively poor in
high field strength elements (HFSE) of the harzburgitic garnet inclusions in diamonds are generally consistent with metasomatism
by carbonatite melts. The trace element features observed from the garnet inclusions in Chinese diamonds may be caused by
carbonatite melt infiltration and partial melt extraction. Spatial and temporal gradients in melt/rock ratio and temperature
are the main reasons for the large variations of REE patterns and other trace element concentrations.
Received: 27 April 1999 / Accepted: 1 March 2000 相似文献
300.
Akihiko Morimoto Shoichiro Kojima Sen Jan Daisuke Takahashi 《Estuarine, Coastal and Shelf Science》2009
We investigated the movement of the Kuroshio axis on the northeast shelf of Taiwan associated with the passage of typhoons, using sea surface current data observed by the ocean radar system on Yonaguni and Ishigaki islands. First, we examined daily Kuroshio axis variation on the northeast shelf of Taiwan during typhoon events. The ocean radar data showed that the Kuroshio axis moved onto the shelf after passages of typhoons. The Kuroshio moved onto the shelf and stayed there after the passage of Typhoon Hai-Tang; while the Kuroshio maintained this pattern, southerly wind blew continuously for 4 days. The mean current speed northeast of Taiwan after the typhoon's passage increased by 18 cm s−1. In addition, the sea level difference between two satellite altimetry tracks east of Taiwan increased by 14.4 cm. These results suggest that coastal upwelling east of Taiwan caused by the southerly wind generated an east–west sea level difference that, in turn, generated a northward geostrophic current. This current could have enhanced the Kuroshio east of Taiwan, and pushed it onto the shelf. 相似文献