全文获取类型
收费全文 | 165篇 |
免费 | 1篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 17篇 |
地球物理 | 35篇 |
地质学 | 34篇 |
海洋学 | 43篇 |
天文学 | 18篇 |
自然地理 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1972年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有170条查询结果,搜索用时 15 毫秒
91.
Atsuhiko Isobe Masafumi Kamachi Yukio Masumoto Hiroshi Uchida Tsurane Kuragano 《Journal of Oceanography》2004,60(2):321-328
The seasonal variation of the Kuroshio transport south of Japan has been investigated using the results of an assimilation
model. Annual and semiannual variations of the transport and dynamic depth anomaly are reconstructed by CEOF (complex orthogonal
empirical function) analysis. In the basin west of the Izu-Ogasawara Ridge, the annual component of the variation propagates
westward with the phase speed of the long Rossby wave associated with the first baroclinic mode. The variation also shows
a similar tendency to that reproduced in a wind-driven, two-layer model with a ridge. This suggests that the annual variation
revealed in the assimilation model is associated with the baroclinic first mode of motion excited above the Izu-Ogasawara
Ridge. Furthermore, it is found that both the semiannual component and the annual component are important members determining
the seasonal variation of the Kuroshio transport south of Japan. The semiannual component is revealed as a double gyre pattern
in the basin west of the Izu-Ogasawara Ridge.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
92.
Sensitivity of the Interannual Kuroshio Transport Variation South of Japan to Wind Dataset in OGCM Calculation 总被引:1,自引:2,他引:1
Hiroshi Yoshinari Motoyoshi Ikeda Kiyoshi Tanaka Yukio Masumoto 《Journal of Oceanography》2004,60(2):341-350
Numerical experiments were carried out using OGCM (Ocean General Circulation Model), MOM2.2 (Modular Ocean Model Ver. 2.2),
over realistic topography data, ETOPO5 (Earth Topography - 5 Minute), to investigate the interannual variability of the Kuroshio
transport in 1960–2000 south of Japan; 1) the PN line located off the East China Sea, and 2) the ASUKA (Affiliated Surveys
of the Kuroshio off Cape Ashizuri) line located off Cape Ashizuri. We adopted two wind datasets as driving forces of the OGCM:
1) the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis monthly
mean wind stress data, and 2) the ECMWF (European Centre for Medium-range Weather Forecasts) daily wind data. In the ECMWF
experiments we replaced the NCEP/NCAR data only in 1979–1993 because of the availability of the data. The OGCMs and observation
basically agree on the temporal variation patterns of the transports until 1986 on the PN line with correlation coefficients
of about 0.6. During the 1990s, when data were collected on the ASUKA line, the NCEP/NCAR experiments give lower correlation
coefficients (less than 0.3), on both PN and ASUKA lines, while the ECMWF experiments have a higher value on the ASUKA line
(0.5). One of the reasons for the disagreement between the observations and OGCMs during the 1990s might arise from the NCEP/NCAR
data. An additional analysis of a wind-driven circulation was performed to examine the sensitivity of integrated Sverdrup
transport along the western boundary to the propagation speed of a baroclinic Rossby wave, which is varied by stratification.
A variation of the stratification, which might be induced by variability of air-sea heat and freshwater fluxes, cannot be
a main cause of the disagreement.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
93.
Akiko Sugimoto Yukio Nobe Takafumi Yamazaki Yasuhide Yamaguchi Kiyoshi Yamagishi Yusaburo Segawa Humihiko Takei 《Physics and Chemistry of Minerals》1997,24(5):333-339
Cr-droped and Cr,Li-doped forsterite crystals were grown and their optical properties were investigated. It was shown that when only Cr is doped, Cr3+ is substituted at the site of low crystal field, and the energy level 2E lie above the 4T2 level, while 4T2 is just above 2E when Cr and Li are codoped. The difference was rationalized by a deformation of the Cr substituted site with the introduction of Li. 相似文献
94.
Yukio Sadahiro 《Journal of Geographical Systems》2011,13(4):373-391
A spatial tessellation is a set of regions that are collectively exhaustive and mutually exclusive except for the boundaries.
In geographical analysis, it may represent such administrative units as census tracts, postal zones, and electoral or school
districts. Spatial tessellations of a certain area are often closely related to each other. Areas of local communities are
related to school districts, market areas of retail stores, and administrative units. Postal zones and census tracts are determined
by collecting or dividing administrative units. Analysis of such relations among tessellations often reveals their underlying
spatial phenomena. To this end, this paper proposes a new exploratory method for analyzing the relations among spatial tessellations.
It aims to detect spatial patterns, especially those with a hierarchical structure, and to provide a tessellation classification
scheme. Topological relations and similarity measures are introduced to evaluate the relations between tessellation pair.
For more tessellations, tree representations are proposed. These not only visualize relations, but also provide a means of
classifying tessellations. The method is applied to the analysis of two sets of spatial tessellations: one with five hypothetical
tessellations, and another with 34 candidate plans for the new Doshusei administrative system in Japan. The application reveals
the properties of the method and quantitative measures used in analysis. 相似文献
95.
Nearly 15 years after the proposal of the superanoxia concept (Isozaki, Y., 1994. Superanoxia across the Permo–Triassic boundary: record in accreted deep-sea pelagic chert in Japan. In: Embry, A.F., Beauchamp, B., Glass, D.J. (Eds.), Pangea: Global Environments and Resources. Memoir, Canadian Society of Petroleum Geologists, 17, pp. 805–812.), it is an appropriate timing to re-evaluate its geological context with the updated dataset. Kakuwa (Kakuwa, Y., 2008. Evaluation of palaeo-oxygenation of the ocean bottom across the Permian–Triassic boundary. Global and Planetary Change 63, 40–56.) lately discussed that the deep-sea anoxia across the Permian–Triassic boundary (P–TB) may have been much shorter than previously proposed, on the basis of ichnofabrics and geochemical data; however, his interpretations of the data do not appear straightforward nor persuading, and thus his claim is likely misled. Here we raise comments to his explanation on the following four issues: 1) invalid application of ichnofabric indices for shallow sea sediments to deep-sea cherts, 2) misinterpretation of Ce anomaly as a redox indicator, 3) improper application of various redox sensitive trace elements, and 4) questionable interpretations of δ34S data of pyrites. 相似文献
96.
Noriyuki Narukage Masahito Kubo Ryohko Ishikawa Shin-nosuke Ishikawa Yukio Katsukawa Toshihiko Kobiki Gabriel Giono Ryouhei Kano Takamasa Bando Saku Tsuneta Frédéric Auchère Ken Kobayashi Amy Winebarger Jim McCandless Jianrong Chen Joanne Choi 《Solar physics》2017,292(3):40
Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-\(\upalpha \) (Ly\(\upalpha \); 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Ly\(\upalpha \) optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Ly\(\upalpha \), whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (\(\sim 5~\%\) on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Ly\(\upalpha \) line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015. 相似文献
97.
Immediately before the extinction of the end‐Guadalupian (Middle Permian; ca 260 Ma), a significant change to the global carbon cycle occurred in the superocean Panthalassa, as indicated by a prominent positive δ13C excursion called the Kamura event. However, the causes of this event and its connection to the major extinction of marine invertebrates remain unclear. To understand the mutual relationships between these changes, we analyzed the sulfur isotope ratio of the carbonate‐associated sulfate (CAS) and HCl‐insoluble residue, as well as the carbon isotope ratio of bulk organic matter, for the Middle‐Upper Permian carbonates of an accreted mid‐oceanic paleo‐atoll complex from Japan, where the Kamura event was first documented. We detected the following unique aspects of the stable carbon and sulfur isotope records. First, the extremely high δ13C values of carbonate (δ13Ccarb) over +5 ‰ during the Capitanian (late Guadalupian) were associated with large isotopic differences between carbonate and organic matter (Δ13C = δ13Ccarb ? δ13Corg). We infer that the Capitanian Kamura event reflected an unusually large amount of dissolved organic matter in the expanded oxygen minimum zone at mid‐depth. Second, the δ34S values of CAS (δ34SCAS) were inversely correlated with the δ13Ccarb values during the Capitanian to early Wuchiapingian (early Late Permian) interval. The Capitanian trend may have appeared under increased oceanic sulfate conditions, which were accelerated by intense volcanic outgassing. Bacterial sulfate reduction with increased sulfate concentrations in seawater may have stimulated the production of pyrite that may have incorporated iron in pre‐existing iron hydroxide/oxide. This stimulated phosphorus release, which enhanced organic matter production and resulted in high δ13Ccarb. Low δ34SCAS values under high sulfate concentrations were maintained and the continuous supply of sulfate cannot by explained only by the volcanic eruption of the Emeishan Trap, which has been proposed as a cause of the extinction. The Wuchiapingian δ34SCAS–δ13Ccarb correlation, likely related to low sulfate concentration, may have been caused by the removal of oceanic sulfate through the massive evaporite deposition. 相似文献
98.
Though high rates of nitrate (NO3−) leaching from forests are undesirable, the factors significantly regulating stream NO3− concentration is not clarified yet. In Japan, not only near metropolitan areas but also the Japan Sea-side area with heavy snowfall is well known for receiving more than 10 kg-N ha−1 year−1 of nitrogen (N) deposition. However, NO3− concentration in stream water is relatively low in the Japan Sea-side area compared with its concentration in other areas. We examined important environmental factors regulating stream NO3− concentrations at baseflow condition in a large region of Japan, the Kinki region (KIN) including a part of Japan Sea-side (JSK) using Random Forest regression. The amounts of N deposition and precipitation were common regulating factors for stream NO3− concentration at baseflow condition. Random forest showed the significant correlation between the factors related to ecosystem N retention and stream NO3− concentration at baseflow condition, and it suggests that large N deposited during the growing season was incorporated into the ecosystem in the entire KIN. Heavy rain and snow flush N and wash out N accumulated in the surface soil, causing small N accumulation in forests. Also, large precipitation dilute NO3− concentration in baseflows. These things lowered stream NO3− concentration at baseflow condition. Especially in JSK, most of N deposed with the heavy snow flushed out during the snowmelt period. We provided the first statistical confirmation using Random Forest regression that N accumulation and cycling in forest ecosystems were related to NO3− leaching from forests into streams. 相似文献
99.
A detailed examination of a high-temperature catalytic oxidation method for liquid samples in the analysis of total nitrogen dissolved in seawater is reported. The nitrogenous compounds in liquid samples are oxidized on a platinum catalyzer at 680°C under oxygen atmosphere and the generated NO2 is absorbed into a chromogenic reagent, followed by a spectrophotometric determination. The results of this method are much higher than those of wet oxidation methods. Molecular size dependency of the results clearly indicates that the above discrepancy is caused by the low oxidation capacity of the wet oxidation method against high-polymer organic matter dissolved in seawater. The results revealed that the concentration of total nitrogen in seawater is nearly constant from surface to bottom, ranging from 30 to 40 μM 1?1, which organic nitrogen concentration higher in the surface layer, and a rapid decrease with depth. An examination of molecular size distribution indicates that the concentration of high-polymer organic nitrogen decreases rapidly from surface to deeper layers, with molecular sizes ranging from 5 × 103 to 3 × 104. Because of the well-defined principle of the oxidation process, its reliability, ease of sample handling and of analytical procedure on board or in the land laboratory, the present method is much more suitable for the marine analytical chemistry of total and organic nitrogen than the other previous methods. 相似文献
100.
Journal of Geographical Systems - This paper develops a new method for evaluating the degree of spatial and temporal avoidance in spatial point patterns. We consider point patterns that change over... 相似文献