全文获取类型
收费全文 | 154篇 |
免费 | 13篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 10篇 |
地球物理 | 38篇 |
地质学 | 29篇 |
海洋学 | 40篇 |
天文学 | 41篇 |
综合类 | 3篇 |
自然地理 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2021年 | 13篇 |
2020年 | 4篇 |
2019年 | 10篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 376 毫秒
41.
Eko Siswanto Junwu Tang Hisashi Yamaguchi Yu-Hwan Ahn Joji Ishizaka Sinjae Yoo Sang-Woo Kim Yoko Kiyomoto Keiko Yamada Connie Chiang Hiroshi Kawamura 《Journal of Oceanography》2011,67(5):627-650
A bio-optical dataset collected during the 1998?C2007 period in the Yellow and East China Seas (YECS) was used to provide alternative empirical ocean-color algorithms in the retrieval of chlorophyll-a (Chl-a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) absorption coefficients at 440 nm (ag440). Assuming that remote-sensing reflectance (Rrs) could be retrieved accurately, empirical algorithms for TChl (regionally tuned Tassan??s Chl-a algorithm) in case-1 waters (TChl2i in case-2 waters), TTSM (regionally tuned Tassan??s TSM algorithm), and Tag440 or Cag440 (regionally tuned Tassan??s or Carder??s ag440 algorithm) were able to retrieve Chl-a, TSM, and ag440 with uncertainties as high as 35, 46, and 35%, respectively. Applying the standard SeaWiFS Rrs, TChl was not viable in the eastern part of the YECS, which was associated with an inaccurate SeaWiFS Rrs retrieval because of improper atmospheric correction. TChl behaved better than other algorithms in the turbid case-2 waters, although overestimation was still observed. To retrieve more reliable Chl-a estimates with standard SeaWiFS Rrs in turbid water (a proxy for case-2 waters), we modified TChl for data with SeaWiFS normalized water-leaving radiance at 555 nm (nLw555) > 2 mW cm?2 ??m?1 sr?1 (TChl2s). Finally, with standard SeaWiFS Rrs, we recommend switching algorithms from TChl2s (for case-2 waters) to MOCChl (SeaWiFS-modified NASA OC4v4 standard algorithm for case-1 waters) for retrieving Chl-a, which resulted in uncertainties as high as 49%. To retrieve TSM and ag440 using SeaWiFS Rrs, we recommend empirical algorithms for TTSM (pre-SeaWiFS-modified form) and MTag440 or MCag440 (SeaWiFS Rrs-modified forms of Tag440 or Cag440). These could retrieve with uncertainties as high as 82 and 52%, respectively. 相似文献
42.
43.
David Savage Josep M. SolerKohei Yamaguchi Colin WalkerAkira Honda Manabu InagakiClaire Watson James WilsonSteven Benbow Irina GausJoerg Rueedi 《Applied Geochemistry》2011,26(7):1138-1152
The use of cement and concrete as fracture grouting or as tunnel seals in a geological disposal facility for radioactive wastes creates potential issues concerning chemical reactivity. From a long-term safety perspective, it is desirable to be able model these interactions and changes quantitatively. The ‘Long-term Cement Studies’ (LCS) project was formulated with an emphasis on in situ field experiments with more realistic boundary conditions and longer time scales compared with former experiments. As part of the project programme, a modelling inter-comparison has been conducted, involving the modelling of two experiments describing cement hydration on one hand and cement-rock reaction on the other, with teams representing the NDA (UK), Posiva (Finland), and JAEA (Japan).This modelling exercise showed that the dominant reaction pathways in the two experiments are fairly well understood and are consistent between the different modelling teams, although significant differences existed amongst the precise parameterisation (e.g. reactive surface areas, dependences of rate upon pH, types of secondary minerals), and in some instances, processes (e.g. partition of alkali elements between solids and liquid during cement hydration; kinetic models of cement hydration). It was not conclusive if certain processes such as surface complexation (preferred by some modellers, but not by others) played a role in the cement-rock experiment or not. These processes appear to be more relevant at early times in the experiment and the evolution at longer timescales was not affected. The observed permeability profile with time could not be matched. The fact that no secondary minerals could be observed and that the precipitated mass calculated during the simulations is minor might suggest that the permeability reduction does not have a chemical origin, although a small amount of precipitates at pore throats could have a large impact on permeability.The modelling exercises showed that there is an interest in keeping the numerical models as simple as possible and trying to obtain a reasonable fit with a minimum of processes, minerals and parameters. However, up-scaling processes and model parameterisation to the timescales appropriate to repository safety assessment are of considerable concern. Future modelling exercises of this type should focus on a suitable natural or industrial analogue that might aid assessing mineral-fluid reactions at these longer timescales. 相似文献
44.
Predicting Soil-Water and Soil-Air Transport Properties and Their Effects on Soil-Vapor Extraction Efficiency 总被引:1,自引:0,他引:1
Tjalfe G. Poulsen Per Moldrup Toshiko Yamaguchi Per Schjønning Jens Aage Hansen 《Ground Water Monitoring & Remediation》1999,19(3):61-70
Accurate prediction of water and air Iran sport parameters in variably saturated soil is necessary for modeling of soil-vapor extraction (SVE) at soil sites contaminated with volatile organic chemicals (VOCs). An expression for predicting saturated water permeability (kl,s ) in undisturbed soils from the soil total porosity and the field capacity soil-water content was developed by fitting a tortuous-tube fluid flow model to measured water permeability and gas diffusivity data. The new kl,s expression gave accurate predictions when tested against independent kl,s data. The kl,s expression was implemented in the Campbell relative water permeability model to yield a predictive model for water permeability in variably saturated, undisturbed soil. The water permeability model, together with recently developed predictive equations for gas permeability and gas diffusivity, was used in a two-dimensional numerical SVE model that also included non-equilibrium mass transfer of VOC from a separate phase (nonaqueous phase liquid [NAPL]) to the air phase. SVE: calculations showed that gas permeability is likely the most important factor controlling VOC migration and vapor extraction efficiency. Water permeability and gas diffusivity effects became significant at water contents near and above field capacity. The NAPL-air mass transfer coefficient also had large impacts on simulated vapor extraction efficiency. The calculations suggest that realistic SVE models need to include predictive expressions for both conveciive, diffusive. and phase-partitioning processes in natural, undisturbed soils. 相似文献
45.
Anomalously narrow and missing rings in trees 12 m from Mount St. Helens' floating island lava flow, and synchronous growth increases in trees farther from the flow margin, are evidence that this andesitic flow was extruded between late summer 1799 and spring 1800 a.d., within a few months after the eruption of Mount St. Helens' dacitic layer T tephra. For ease of reference, we assign here an 1800 a.d. date to this flow. The new date shows that the start of Mount St. Helens' Goat Rocks eruptive period (1800–1857 a.d.) resembled the recent (1980–1986) activity in both petrochemical trends and timing. In both cases, an initial explosive eruption of dacite was quickly succeeded by the eruption of more mafic lavas; dacite lavas then reappeared during an extended concluding phase of activity. This behavior is consistent with a recently proposed fluid-dynamic model of magma withdrawal from a compositionally zoned magma chamber. 相似文献
46.
Sooji Shimura Yukuya Yamaguchi Yusho Aruga Yoshihiko Fujita Shun-ei Ichimura 《Journal of Oceanography》1978,34(5):181-188
Extracellular release of photosynthetic products by a pelagic blue-green alga,Trichodesmium thiebautii, was scrutinized in relation to pre-treatments in14C-method for measuring the primary productivity.The extracellular release increased markedly by the pre-treatments with such strong fixative solutions as formaldehyde and mercuric chloride. In such a case, the amount of extracellular fraction reached even almost 78 % of the total photosynthates. The extracellular release of photosynthates was dependent both on light intensity and on physiological state of algal cells. When photosynthesis was terminated by a fixative, the extracellular release was noticed even just after the fixation, and it increased with time. Thus, it appears to be difficult to deduce the real photosynthetic production capacity from the amount of cellular fraction only.The amount of extracellular fraction for unfixed samples filtered immediately after the incubation was less than 8 % of the total photosynthetic products inT. thiebautii. This value is nearly comparable to the amount of excretion reported in many cultured algae. 相似文献
47.
Keisuke?Yamaguchi Ju?Lin Arata?KanekoEmail author Tokuo?Yayamoto Noriaki?Gohda Hong-Quang?Nguyen Hong?Zheng 《Journal of Oceanography》2005,61(2):283-294
Tidal current structures at the Hayatomono-Seto of the Kanmon Strait are mapped continuously during March 17 to 20, 2003, including a spring tide, by the eight coastal acoustic tomography (CAT) systems distributed on both the sides of the strait. Detailed structures of strong tidal currents and their associated vortices are well reconstructed by the inverse analysis of travel-time difference data obtained from the reciprocal sound transmission between the paired CAT systems located at both sides of the strait mainly. The results are well compared to the shipboard acoustic Doppler current profiler (ADCP) data at the correlation rate of 0.84/0.82 and the RMS difference of 0.47/0.48 ms−1 for the east-west/north-south current after the selection of good data. During the observation period, the maximum hourly mean volume transport for the upper 7 m layer across the strait reached 13,314 m3 s−1 for the eastward and 5,547 m3 s−1 for the westward. The daily mean transport is directed to the eastward and estimated 1,470 m3 s−1 and 2,140 m3 s−1 for March 18 and 19, respectively, when a spring tide occurs. 相似文献
48.
Michael K. Weisberg Caroline Smith Gretchen Benedix Christopher D. K. Herd Kevin Righter Henning Haack Akira Yamaguchi Hasnaa Chennaoui Aoudjehane Jeffrey N. Grossman 《Meteoritics & planetary science》2009,44(9):1355-1397
Abstract— The Meteoritical Bulletin No. 96 contains a total of 1590 newly approved meteorite names with their relevant data. These include 12 from specific locations within Africa, 76 from northwest Africa, 9 from the Americas, 13 from Asia, 1 from Australia, 2 from Europe, 950 from Antarctica recovered by the Chinese Antarctic Research Expedition (CHINARE), and 527 from the American Antarctic program (ANSMET). Among these meteorites are 4 falls, Almahata Sitta (Sudan), Sulagiri (India), Ash Creek (United States), and Maribo (Denmark). Almahata Sitta is an anomalous ureilite and is debris from asteroid 2008 TC3 and Maribo is a CM2 chondrite. Other highlights include a lunar meteorite, a CM1 chondrite, and an anomalous IVA iron. 相似文献
49.
Koterayama W. Yamaguchi S. Yokobiki T. Jong-Hwan Yoon Hase H. 《Oceanic Engineering, IEEE Journal of》2000,25(1):130-138
A research project to develop observation systems for heat, momentum, and material circulation in the ocean and atmosphere was carried out from 1992 to 1997. A pitch, roll, and depth controllable towed vehicle called “Flying Fish” was developed which houses an acoustic Doppler current profiler, CO2 analyzer, and sensors for measuring temperature, salinity, dissolved oxygen, pH, turbidity, and chlorophyll. The length of the vehicle is 3.84 m, the breadth is 2.26 m, the height is 1.4 m, the weight in air is 1400 kg, and the weight in water is roughly 0 kg. Flying Fish enables us to obtain space-continuous data of physical and chemical properties efficiently in the upper mixed layer of the ocean, From 1994 to 1997, the vehicle was used for observations in the northern, southern, and central parts of the Japan Sea in a collaborative study by Japan, Korea, and Russia. Examples of data obtained are shown in this paper and the results of current velocities are compared with those taken by other observation systems 相似文献
50.
Electrokinetic phenomena associated with a water injection experiment at the Nojima fault on Awaji Island, Japan 总被引:2,自引:0,他引:2
Hideki Murakami Takeshi Hashimoto Naoto Oshiman Satoru Yamaguchi Yoshimori Honkura Norihiko Sumitomo 《Island Arc》2001,10(3-4):244-251
Abstract Self-potential variations were measured to estimate the magnitude of electrokinetic and hydrological parameters (zeta potential and permeability) of the Nojima Fault zone in Awaji, Japan. The study observed self-potential variations that seemed to be associated with water flow from the injection well to the fracture zone, which were induced by turning the injection on and off. Amplitudes of the variations were a few to 0.03 V across 320–450 m dipoles. These variations can be explained well with an electrokinetic model. The quantity k/ζ (permeability/zeta potential) is in the range 1.6 × 10−13 − 5.4 × 10−13 m2 /V. Permeability of the Nojima fault zone can be estimated as approximately 10−16 –10−15 m2 on the assumption that the zeta potential is in the range –0.01 to –0.001 V. 相似文献