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71.
Juan C. Bidegain Marcos A. E. Chaparro Débora C. Marié Sandra Jurado 《Environmental Earth Sciences》2011,62(4):847-855
Environmental pollution and its harmful consequences for the population’s health derived from coal production in the locality
of Ensenada (Argentina) is studied by magnetic and non-magnetic means. Coke is used for the production of industrial coal.
This is a final product obtained in petroleum refineries. Coke is a non-magnetic material showing values of magnetic susceptibility
close to zero. Conversely, the magnetic susceptibility of the coal released from factory chimneys is considerably enhanced
due to the building of magnetic fibers and spherules inside the furnace, used for coal production. Due to this property, the
magnetic content of coal can be used as environmental proxy for studying the environmental impact caused by coal industries
in urban areas. The values of magnetic susceptibility decrease as the distance from the contamination source increases. This
indicates that magnetic concentration is lower. The grain size of magnetic particles also decreases according to the distance,
which is seen when analyzing the grain size parameters. According to the different non-magnetic approaches applied, the particles
released by the industry, which affect the region, fall within the rank of breathable particles (<2.5 μm). Besides, inhalable
particles are also found (2.5–10 μm). Such determinations are consistent with inter-parametric ratios applied in the study
of grain sizes. The undesirable dust of the local coal industry also carries heavy metals which are dangerous for the population’s
health, like Zn, Cu, Pb and V. 相似文献
72.
Israel Medina-Gómez Björn Kjerfve Ismael Mariño Jorge Herrera-Silveira 《Estuaries and Coasts》2014,37(6):1329-1342
Bahia de la Ascension (BA) is a shallow, mangrove-fringed coastal bay connected to the Caribbean through two inlets, outlined by the Mesoamerican Barrier Reef System. This work represents an initial investigation of the relative contribution of hydrometeorological and hydrodynamic forcing on salinity variation in this lagoon. Our objective is to assess the sensitivity of the salinity in BA to fluctuations in freshwater inflow and coastal oceanography. Two field trips were undertaken during rainy and dry seasons in 2007. Surface salinity was mapped across the system and CTD deployments carried out within BA and in the sea end-member to characterize temperature, conductivity, and water level. Also, cross-sectional CTD profiles were implemented to examine vertical stratification. The water balance indicated that 16 % of rainfall over the drainage basin (DB) becomes groundwater discharge plus surface runoff into BA during dry season, while 68 % of the precipitation input to the DB is supplied through groundwater–surface runoff to the bay during rainfalls. This combined inflow showed larger fluctuations than direct rainfall and, thus, has a greater potential to alter the seasonal salinity variations within BA. The tidal signal is selectively attenuated within BA, as diurnal frequencies are more readily filtered out than semidiurnal frequencies. Mesohaline conditions in the southwest bay are associated with freshwater sources, while saline water masses in the inlet are influenced by prevalent SE winds in the region and tidal phase, establishing a strong horizontal SW-NE estuarine salinity gradient. 相似文献
73.
Marian Marschalko Işık Yilmaz David Lamich Marián Drusa Darja Kubečková Tomáš Peňaz Tereza Burkotová Vladimír Slivka Martin Bednárik David Krčmář Miloš Duraj Alena Sochorková 《Environmental Earth Sciences》2014,72(1):11-20
This article aims to explain and demonstrate the origin and development of a subsidence basin caused by coal mining as well as to point out important aspects of this phenomenon in engineering geology. Engineering geology needs to deal with a number of issues related to the origin and development of subsidence basins in areas affected by deep coal mining. An interesting case study from the Upper-Silesian Basin in the northeast of the Czech Republic near the Polish border is presented in this paper. There is a clear time chronological succession in the ground surface changes manifested by a ground subsidence gradation, both in their absolute values as well as in their spatial distribution. The phenomenon is documented by aerial photo time series, which optimally depict the origin and development of the subsidence. In the study area, there are changes in the landscape elements and it is essential to be considered in future land use plans. The marginal conditions of the Quaternary geological structure and hydrogeological conditions are responsible for an unconfined aquifer which manifests there as a water body in an undrained depression in the course of the ground subsidence. 相似文献
74.
75.
The Petrology and Geochemistry of Oto-Zan Composite Lava Flow on Shodo-Shima Island, SW Japan: Remelting of a Solidified High-Mg Andesite Magma 总被引:1,自引:0,他引:1
TATSUMI Y.; SUZUKI T.; KAWABATA H.; SATO K.; MIYAZAKI T.; CHANG Q.; TAKAHASHI T.; TANI K.; SHIBATA T.; YOSHIKAWA M. 《Journal of Petrology》2006,47(3):595-629
The Oto-Zan lava in the Setouchi volcanic belt is composed ofphenocryst-poor, sparsely plagioclase-phyric andesites (sanukitoids)and forms a composite lava flow. The phenocryst assemblagesand element abundances change but SrNdPb isotopiccompositions are constant throughout the lava flow. The sanukitoidat the base is a high-Mg andesite (HMA) and contains Mg- andNi-rich olivine and Cr-rich chromite, suggesting the emplacementof a mantle-derived hydrous (7 wt % H2O) HMA magma. However,Oto-Zan sanukitoids contain little H2O and are phenocryst-poor.The liquid lines of descent obtained for an Oto-Zan HMA at 0·3GPa in the presence of 0·72·1 wt % H2Osuggest that mixing of an HMA magma with a differentiated felsicmelt can reasonably explain the petrographical and chemicalcharacteristics of Oto-Zan sanukitoids. We propose a model wherebya hydrous HMA magma crystallizes extensively within the crust,resulting in the formation of an HMA pluton and causing liberationof H2O from the magma system. The HMA pluton, in which interstitialrhyolitic melts still remain, is then heated from the base byintrusion of a high-T basalt magma, forming an H2O-deficientHMA magma at the base of the pluton. During ascent, this secondaryHMA magma entrains the overlying interstitial rhyolitic melt,resulting in variable self-mixing and formation of a zoned magmareservoir, comprising more felsic magmas upwards. More effectiveupwelling of more mafic, and hence less viscous, magmas througha propagated vent finally results in the emplacement of thecomposite lava flow. KEY WORDS: high-Mg andesite; sanukitoid; composite lava; solidification; remelting 相似文献
76.
Giuseppe Leto Marián Jakubík Tomáš Paulech Luboš Neslušan Piotr A. Dybczyński 《Earth, Moon, and Planets》2009,105(2-4):263-266
We simulate the formation of the Oort cloud (OC) till the age of 2 Gyr starting from an initial disc of planetesimals made by 10 038 test particles. The results on the outer part of the distant comet reservoir are reported by Neslu?an et al. (this issue). Here we deal with the evolution of the population and structure at 2 Gyr of the complementary inner part of the Oort cloud. The dynamical evolution of the massless test particles was followed via the numerical integration of their orbits. We considered the perturbations produced by four giant planets assuming they have their current orbits and masses, as well as the perturbations caused by the Galactic tide and passing stars. The efficiency of the formation of inner OC is found to be very low: only about 1.1% of all considered particles ended in this part of the OC. At 2 Gyr, the dynamics of the inner cloud is mainly governed by the dominant z-term of the Galactic tide. The number density of the bodies is proportional to the heliocentric distance, r, as r ?3.53. The directional distribution of orbits is still strongly inhomogeneous. There are large empty regions in the space angles around the Galactic Equator points with the galactic longitude 90 and 270° (non-rotating frame), or there are only few bodies having the ecliptical latitude higher than +60° or lower than 60°. A strong concentration of objects at the Ecliptic is apparent up to ≈1,000 AU, with a possible—but still not proved—extension to ≈1,500 AU. Beyond r ≈ 6,000 AU, bodies directly above and below the Sun, with respect to the Ecliptic, are absent. 相似文献
77.
We present a statistical analysis of the relationship between the kinematics of the leading edge and the eruptive prominence
in coronal mass ejections (CMEs). We study the acceleration phase of 18 CMEs in which kinematics was measured from the pre-eruption
stage up to the post-acceleration phase. In all CMEs, the three part structure (the leading edge, the cavity, and the prominence)
was clearly recognizable from early stages of the eruption. The data show a distinct correlation between the duration of the
leading edge (LE) acceleration and eruptive prominence (EP) acceleration. In the majority of events (78%) the acceleration
phase onset of the LE is very closely synchronized (within ± 20 min) with the acceleration of EP. However, in two events the
LE acceleration started significantly earlier than the EP acceleration (> 50 min), and in two events the EP acceleration started
earlier than the LE acceleration (> 40 min). The average peak acceleration of LEs (281 m s−2) is about two times larger than the average peak acceleration of EPs (136 m s−2). For the first time, our results quantitatively demonstrate the level of synchronization of the acceleration phase of LE
and EP in a rather large sample of events, i.e., we quantify how often the eruption develops in a “self-similar” manner. 相似文献
78.
Vršnak Bojan Warmuth Alexander Maričić Darije Otruba Wolfgang Ruždjak Vladimir 《Solar physics》2003,217(1):187-198
A huge filament eruption of 12 September 2000 associated with a two-ribbon spotless flare is described. During the acceleration phase the shape of the filament changed, and signatures of topological restructuring of large-scale coronal magnetic fields were inferred by tracking changes of nearby coronal holes. At the same time electron beams associated with the flare impulsive phase escaped into interplanetary space. Based on the time–spatial relationships a hypothesis is put forward, according to which the reconnection between the arcade magnetic field and the ambient field provides a temporary link between the open field lines and the flare energy release site, enabling the escape of electron beams into interplanetary space. 相似文献
79.
This paper presents a chance-constrained programming model for optimal control of a multipurpose reservoir and its modification to a model for single reservoir design. An algorithm is developed for solving complex stochastic problems of multipurpose reservoir planning and design. The complexity of the problem is resolved by a two-step algorithm: (1) transformation of chance constraints on the state and control variables is performed at the first step; and (2) the choice of optimum control or optimal reservoir storage is carried out in the second step. The method of iterative convolution is chosen for the first step, while linear programming is selected for the second step. The algorithm allows the use of random inflows and random demands together with other deterministic demands. The reservoir design problem is presented as a modified optimal control problem. The procedure is illustrated with an example of a hypothetical reservoir design problem with three different types of downstream releases (hydropower production, municipal water supply, and irrigation). 相似文献
80.
Liberto de Pablo-Galán Mari´a Lourdes Chávez-Garci´a Alfonso Huanosta Tera 《Physics and Chemistry of Minerals》1997,24(2):90-101
The electrical properties of opal-CT are validated at temperatures from 600 to 840 °C and frequencies from 5 Hz to 10 MHz.
The opals are hydrothermal, containing less than 11270 ppm total of Al, Fe, Ca, Na, and K, and from 1.17 to 17.63 wt% H2O interstitial and structural. Opal-CT shows fine crystallites, measuring from 19.4 to 22.7 μm, of an ordered tridymite-M
stratification with high-cristobalite, embedded in a non-crystalline matrix. When heated to 600 °C, the non-crystalline phase
devitrifies to the same stacked high-cristobalite-tridymite-M crystals. Opals containing less than 2070 ppm of cationic impurities
are characterized by one single high-frequency complex impedance arc corresponding to the bulk polarization of the crystalline
phase, of capacitances between 25 and 30×10−12 F and resistances from 132 to 890 ohm. Opals having over 6300 ppm of cationic impurities show two superimposed high- and
low-frequency complex impedance arcs. The high-frequency arc corresponds to the bulk polarization of the crystalline phase,
of capacitance between 8 and 15.7×10−12 F and resistance from 14 to 236 ohm, less than the capacitance of 0.25 to 0.53×10−9 F and resistance from 26 to 360 ohm of the non-crystalline minor intergranular material represented by the low-frequency
impedance arc. The electric module shows one single vertex, ascribed to the bulk polarization of the crystalline phase. The
conductivities are from 10−7 to 10−4 ohm−1cm−1, in the range of poor ionic conductors, essentially constant below 1.8 kHz, rapidly increasing at higher frequencies, due
to ionic and electronic charge carriers. The activation energy changes between 0.905 and 1.003 eV for the conduction mechanism
in the crystalline phase and from 0.924 to 1.087 eV in the non-crystaline phase. X-ray diffraction and impedance spectroscopy
confirm that opal-CT is a crystalline stacked sequence of tridymite-M and cristobalite-high, in a non-crystalline matrix.
Received October 20, 1995/Revised, accepted June 15, 1996 相似文献