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排序方式: 共有148条查询结果,搜索用时 46 毫秒
71.
In this paper, a novel composite material the silica grafted by poly(N‐vinyl imidazole) (PVI), i.e., PVI/SiO2, was prepared using 3‐methacryloxypropyl trimethoxysilane (MPS) as intermedia through the “grafting from” method. The adsorption behavior of metal ions by PVI/SiO2 was researched by both static and dynamic methods. Experimental results showed that PVI/SiO2 possessed very strong adsorption ability for metal ions. For different metal ions, PVI/SiO2 exhibited different adsorption abilities with the following order of adsorption capacity: Cu2+ > Cd2+ > Zn2+. The adsorption material PVI/SiO2 was especially good at adsorbing Cu(II) ion and the saturated adsorption capacity could reach up to 49.2 mg/g. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. Higher temperatures facilitated the adsorption process and thus increased the adsorption capacity. The pH and grafting amount of PVI had great influence on the adsorption amount. In addition, PVI/SiO2 particles had excellent eluting and regenerating property using diluted hydrochloric acid solution as eluent. The adsorption ability trended to steady during 10 cycles. 相似文献
72.
Malcolm Richard Gent Mario Menéndez Alvarez Jesús José María García Iglesias Javier TaraÑo Álvarez 《Marine Georesources & Geotechnology》2013,31(1-2):39-59
ABSTRACT Results of offshore water-jet sediment sampling demonstrate the potential for interstadial placer deposits of industrial minerals in the shore-face to inner-shelf of Cape Ortegal, NW Spain. Placer deposition is interpreted to have occurred during glacial interstadials since the Last Glacial Maximum, and deposits sampled at 24 to 42 m. BSL were formed during the Younger Dryas, and subsequently preserved as a result of very rapid rising sea-levels. The sediments are almost entirely terrestrially derived with a particularly high heavy mineral content (Sp. Gr. >2.9), of more than 75% in all samples. Reworked garnet from earlier-sedimentary deposits constitutes an important fraction of the placer deposits identified but is generally absent in other sediments. Indications of the presence of +5 m-thick paleo-placer deposits with sections include:
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Placer garnet + spinel grades increase with depth in those sediments at 24 to 42 m BSL to the ocean-floor.
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The d50 of sediments with background grades decrease with depth while those of placer deposits do not display any significant trend.
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Garnets in non-mineralized sediments are almost entirely angular, whereas in placer enriched sediments they vary in form from well-rounded to angular. Some grains in the latter display surface morphologies typical of reworked sediment while none of the former do.
73.
74.
A.?M.?KorzhenkovEmail author E.?V.?Deev D.?V.?Luzhanskii S.?V.?Abdieva A.?R.?Agatova J.?V.?Mazeika M.?Yu.?Men’shikov E.?A.?Rogozhin S.?N.?Rodina M.?V.?Rodkin A.?A.?Sorokin A.?B.?Fortuna T.?A.?Charimov J.?Shen A.?S.?Yudakhin 《Izvestiya Atmospheric and Oceanic Physics》2017,53(7):734-747
A number of archeological monuments in the northern Issyk-Kul Lake region (Tien Shan) in the basins of the Chet-Koysuu and Chon-Koysuu rivers are studied. All monuments have undergone significant seismogenic deformations and destructions. A cromlech (7th century BC to 8th centuries AD) was displaced along the sinistral strike-slip fault. A kurgan (7th–13th centuries AD) was deformed in a front of the reverse fault scarp. A fortress (14th–15th centuries AD) was submerged beneath the lake water during the catastrophic subsidence of the coastal zone. We identify a zone of the seismogenic rupture. It is located along the Kultor border fault, which separates the Issyk-Kul depression and its surrounding mountains (Kungey Ala-Too Range). During the earthquake, the seismogenic reverse fault scarp was formed. A total of 1.6 m was offset along the rupture, which corresponds to an earthquake with М S ≥ 7 and seismic intensity of I 0 ≥ IX. Judging by numerous radiocarbon datings of submerged wood, which was used in building the fortress (end of 14th to the beginning of 15th centuries AD), the earthquake occurred in the 16th century AD and could have caused the decline of the Mogul civilization in the northern Issyk-Kul Lake region. 相似文献
75.
The ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity Using Optical Devices] Optimized for Gravitation Wave Detection), the mission of the laser astrodynamical gravitational wave detection, is the scheme of optimality of the gravitational wave detection on which the ASTROD is concentrated. Its spacecraft orbits form a triangular array close to an equilateral triangle in the vicinity of the solar-terrestrial Lagrangian points L3, L4 and L5. The length of the interference arm is about 2.6 × 108 km and the detectable wavelength of the gravitational wave is 52 times larger than that detected by the LISA (Laser Interferometer Space Antenna). In this article, the design and optimization method of the ASTROD-GW orbit are summarized. After the orbit is optimized, the variation in the arm length difference (which can be called the interference difference in laser interferometry) within 10 years is in the order of magnitude of 10−4 AU. The Doppler velocities in the three arm length directions are smaller than 4 m/s, and all of them are less than that required by the LISA. Therefore the laser ranging techniques developed by the LISA can be applied to the ASTROD-GW. 相似文献
76.
W. Guo Y. Ai B. Men S. Wang 《International Journal of Environmental Science and Technology》2017,14(9):1889-1896
A biochar derived from the pyrolysis of excess sludge of sewage treatment plant at 700 °C was used to remove phenanthrene and pyrene from aqueous solution. The adsorption equilibrium for phenanthrene and pyrene was achieved within 7.5 and 15 h, respectively. The adsorption kinetics of phenanthrene and pyrene were well fitted to pseudo-second-order model, and the isotherms were well fitted to Freundlich adsorption isotherm model (R 2 > 0.96). The effect of variation of pH on the adsorption of the biochar was observed to be insignificant. The hydrophobic action and pore filling might be the main mechanisms of the adsorption of phenanthrene and pyrene on the biochar. The density functional theory calculations confirmed that the adsorption depended mainly on the biochar structure and the molecular volumes of phenanthrene and pyrene. Phenanthrene molecule is smaller than the pyrene molecule and therefore showed better adsorption characteristics with the biochar than the pyrene molecule. 相似文献
77.
Fulu Men 《地震工程与工程振动(英文版)》2002,1(2):281-291
In this paper, mantle circulation flow, continental drift, earthquake origin and other mechanical principles are examined
as they apply to earthquake engineering, seismology and dynamics of fluid saturated porous medium. The relationship of mantle
flow to earthquakes is examined and clarified, and a new model, different from Haskell’s, is proposed for the earthquake mechanism.
The proposed new model is based on the discovery that two pairs of jump stress and jump velocity will start to act from the
fault plane. Records obtained directly from recent earthquakes nearby and right on the fault break show a very large velocity
impulse, which verify, indirectly, the new mechanism proposed by the author. Further, at least two physical parameters that
characterize the seismic intensity must be specified, because according to the discontinuous (jump) wave theory, at the earthquake
source, the stress jump and the velocity jump of particle motion should act simultaneously when a sudden break occurs. The
third key parameter is shown to be the break (fracture) propagation speed together with the break plane area. This parameter
influences the form of the unloading time function at the source. The maximum seismic stress in and displacement of a building
are estimated for two unfavorable combinations of the building and its base ground in terms of their relative rigidity. Finally,
it is shown that Biot’s theory of wave propagation in fluid saturated porous media is valid only when fluid flow cannot occur. 相似文献
78.
门可佩 《地震地磁观测与研究》1993,(2)
江苏-南黄海地区自16世纪以来已发生17次6级以上强震,经研究发现它们存在着时间间隔为74年、57年、26年、7年的有序性结构,利用这种强震活动的有序性和可公度性理论相结合,试对该区6级以上强震进行预测探索,结论是1995-1996年、2001-2002年前后该区有发生6级以上强震的可能。 相似文献
79.
新疆及其邻近地区M≥7强震活动在时间分布上具有明显的有序性。自1716年以来的21次M≥7强震存在着时间间隔为11、25、30、41和60年的有序值。利用强震活动时间的有序性结构,可对该区7级强震进行预测探索。本文同时还应用熵和经验分布函数,讨论了下次强震发生的地点和概率。 相似文献
80.