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161.
Variability in the Relative Penetration of Ultraviolet Radiation to Photosynthetically Available Radiation in Temperate Coastal Waters, Japan 总被引:1,自引:0,他引:1
Victor S. Kuwahara Tatsuki Toda Koji Hamasaki Tomohiko Kikuchi Satoru Taguchi 《Journal of Oceanography》2000,56(4):399-408
UVR and PAR wavelengths are attenuated to different extents within the water column, causing variations in spectral composition with depth. The present investigation (a) describes the variability of UVR and PAR penetration at a station in the temperate coastal waters of Sagami Bay and determines (b) the characteristics of relative UVR penetration to the euphotic zone. Examination of the seasonal irradiance profile measurements indicated eight measurements displaying two distinct attenuation coefficients (K
d) for specific UVR wavelengths and PAR. The two attenuation coefficients observed from specific wavelengths in the water column may be caused not only by chlorophyll pigments, but also by dissolved organic material in the upper layer. The 1% depth of surface UVR at 305, 320, 340, and 380 nm averaged 10.8 ± 5.7, 14.9 ± 9.5, 19.8 ± 12.1, and 30.4 ± 17.6 m, respectively. The depth of euphotic layer displayed less variability averaging 62 ± 15 m throughout the entire study. Relative UVR penetration within the euphotic zone averaged 17.8 ± 8.1, 22.9 ± 10, 30.5 ± 13.8, and 46 ± 46.9% for 305, 320, 340, and 380 nm, respectively. A large variation of the relative transmission of UVR within the euphotic zone was found although the spectral composition was relatively stable in the air throughout the study. 相似文献
162.
Satoru Itoh 《GeoJournal》2000,52(3):223-235
The purpose of this paper is to clarify the diurnal variations in structure of an urban area from the viewpoint of time distance.
To accomplish this, for one entire day, and for the morning, noon, and evening periods, time maps are delineated by using
MDS; also, the indices of accessibility and circuity are computed from the time distances. As a result, the difference in
shape between the time and actual maps becomes clear especially in the morning and also in the evening. Both the accessibility
and circuity measured from the time distance show a concentrically shaped pattern where the regional disparity is especially
distinct within the morning and evening periods. The diurnal variations as described above are thought to occur against the
backdrop of the topological traffic conditions within the study area.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
163.
Kiyoshi Ichimoto Takako T. Ishii Kenichi Otsuji Goichi Kimura Yoshikazu Nakatani Naoki Kaneda Shin’Ichi Nagata Satoru UeNo Kumi Hirose Denis Cabezas Satoshi Morita 《Solar physics》2017,292(4):63
A new solar imaging system was installed at Hida Observatory to observe the dynamics of flares and filament eruptions. The system (Solar Dynamics Doppler Imager; SDDI) takes full-disk solar images with a field of view of \(2520~\mbox{arcsec} \times 2520~\mbox{arcsec}\) at multiple wavelengths around the \(\mathrm{H}\alpha\) line at 6562 Å. Regular operation was started in May 2016, in which images at 73 wavelength positions spanning from \(\mathrm{H}\alpha -9~\mathring{\mathrm{A}}\) to \(\mathrm{H}\alpha +9~\mathring{\mathrm{A}}\) are obtained every 15 seconds. The large dynamic range of the line-of-sight velocity measurements (\({\pm}\,400~\mbox{km}\,\mbox{s}^{-1}\)) allows us to determine the real motions of erupting filaments in 3D space. It is expected that SDDI provides unprecedented datasets to study the relation between the kinematics of filament eruptions and coronal mass ejections (CME), and to contribute to the real-time prediction of the occurrence of CMEs that cause a significant impact on the space environment of the Earth. 相似文献
164.
Water content in natural eclogite and implication for water transport into the deep upper mantle 总被引:14,自引:0,他引:14
Infrared spectroscopy and ion micro-probe measurements showed that the major constituent minerals of eclogites from the Kokchetav massif, which have been subducted to 180 km depths, contain significant amounts of water up to 870 ppm H2O (by weight) in omphacite, 130 ppm H2O in garnet and 740 ppm H2O in rutile. Omphacite shows three hydroxyl absorption bands at 3440–3460, 3500–3530 and 3600–3625 cm− 1, garnet has a single band at 3580–3630 cm− 1 and rutile has a single sharp band at 3280 cm− 1. The hydroxyl absorbance at these wavenumbers changes with the crystal orientation in polarized infrared radiation, indicating that the water is structurally incorporated in these minerals. The water contents in omphacite and garnet increase systematically with the metamorphic pressure of the host eclogites. The partitioning coefficient of the water content between coexisting garnet and omphacite is similar in different eclogites, DGrt/Omp0.1–0.2, but decreases slightly at high pressure. Based on the mineral proportions of the eclogites, we estimate bulk-rock water content in the eclogites ranging from 3070 to 300 ppm H2O (by weight). Although hydrous minerals are absent in the diamond-grade eclogite (60 kbar and 1000 °C), trace amounts of water are incorporated in the nominally anhydrous minerals such as omphacite and garnet. The presence of significant water in these minerals implies that the subducting oceanic crust can transport considerable amounts of water into the deep upper mantle beyond the stability of hydrous minerals. Such water may be stored in the deep upper mantle and have an important influence on dynamics in the Earth's interior. 相似文献
165.
Yuko Ogata Kaoruko Mizukawa Satoru Iwasa Yukie Mato Keiji Okuda Michio Murakami Ruchaya Booyatumanondo Le Quang Dung Carlos Miguez Charles Moore Steven Weerts Erick Burres Michael Van Velkenburg Richard C. Lang Brenda Danner Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446
Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale. 相似文献
166.
Michinori Honda Shintaro Ohno Atsushi Iizuka Katsuyuki Kawai Hideki Ohta 《Geotechnical and Geological Engineering》2011,29(2):171-180
An evaluation method for the mechanical behavior of unsaturated soils is studied in this paper. Although the mechanical behavior
of unsaturated soils is complicated, a simple modeling is preferable in practice. This is because the soil properties are
not homogeneous and ground data is limited when structures are being designed. In addition, in order to evaluate the reliability
of the design, the physical meanings of the parameters applied in the prediction model should be clear. Firstly, the authors
study the relationship between compaction curves and compression indexes in the unsaturated state that is used in the proposed
constitutive model. Based on the constitutive model, the stress paths for constant volume shear tests are formulated under
a constant void ratio condition and the stress paths for undrained shear tests are calculated under a constant water content
condition. In the case of unsaturated specimens, the volume of these specimens changes with the shear deformation and the
stress paths depend on the initial degree of saturation. The results of the calculation qualitatively describe the test results
by considering the changes in effective confining pressure in the undrained condition and the water retention curves. 相似文献
167.
168.
Hajime Kawakami Makio C. Honda Kazuhiko Matsumoto Tetsuichi Fujiki Shuichi Watanabe 《Journal of Oceanography》2010,66(1):71-83
Observations of primary productivity, 234Th, and particulate organic carbon (POC) were made from west to east across the northern North Pacific Ocean (from station
K2 to Ocean Station Papa) during September–October 2005. Primary productivities in this region varied longitudinally from
approximately 236 to 444 mgC m−2d−1 and clearly indicate the West High East Low (WHEL) trend. We estimated east-west variations in the POC flux from the surface
layer (0–100 m) by using 234Th as a tracer. POC fluxes in the western region (44–53 mgC m−2d−1) were higher than those in the eastern region (21–34 mgC m−2d−1). However, the export ratios (e-ratios) ranged from approximately 8% to 16% and did not show the WHEL trend. Contrary to our expectation, no relation between
POC flux (or e-ratio) and diatom biomass (or dominance) was apparent in autumn in the northern North Pacific. 相似文献
169.
The effect of swell on the drag coefficient, C
D, observed at the Hiratsuka Tower Station, presented by Suzuki et al. (1998, 2002), has been investigated. C
D increases sharply with the windsea Reynolds number, R
B, when there is a counter swell against the windsea direction, and only gradually when the swell comes from a mixture of directions.
In cases where 2-D wave spectra were unavailable (1998, and others), swells showed a scattering effect compared with the pure
windsea case on the C
D-R
B Diagram. R
B is a useful parameter for investigating the effect of swells and further systematic accumulation of appropriate data is needed. 相似文献
170.
Marryanna Lion Yoshiko Kosugi Satoru Takanashi Shoji Noguchi Masayuki Itoh Masanori Katsuyama Naoko Matsuo Siti‐Aisah Shamsuddin 《水文研究》2017,31(24):4338-4353
To evaluate water use and the supporting water source of a tropical rainforest, a 4‐year assessment of evapotranspiration (ET) was conducted in Pasoh Forest Reserve, a lowland dipterocarp forest in Peninsular Malaysia. The eddy covariance method and isotope signals of rain, plant, soil, and stream waters were used to determine forest water sources under different moisture conditions. Four sampling events were conducted to collect soil and plant twig samples in wet, moderate, dry, and very dry conditions for the identification of isotopic signals. Annual ET from 2012 to 2015 was quite stable with an average of 1,182 ± 26 mm, and a substantial daily ET was observed even during drought periods, although some decline was observed, corresponding with volumetric soil water content. During the wet period, water for ET was supplied from the surface soil layer between 0 and 0.5 m, whereas in the dry period, approximately 50% to 90% was supplied from the deeper soil layer below 0.5‐m depth, originating from water precipitated several months previously at this forest. Isotope signatures demonstrated that the water sources of the plants, soil, and stream were all different. Water in plants was often different from soil water, probably because plant water came from a different source than water that was strongly bound to the soil particles. Plants showed no preference for soil depth with their size, whereas the existence of storage water in the xylem was suggested. The evapotranspiration at this forest is balanced and maintained using most of the available water sources except for a proportion of rapid response run‐off. 相似文献