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161.
In this work the analysis of sloshing of water in rectangular open tanks has been extensively carried out. Two mathematical models are employed, respectively the Reynolds Averaged Navier Stokes Equations (RANSE) and the Shallow Water Equations (SWE). The RANSE are solved using a modified form of the well established MAC method (SIMAC) able to treat both the free surface motion and the viscous stresses over the rigid walls accurately. The Shallow Water Equations are solved by means of a simple and powerful algorithm (CE-SE) able to deal with large impacting waves over the tank walls.Successively, in order to validate the mentioned algorithms and for a better understanding of the sloshing phenomenon, experimental tests have been carried out using a 0.5 m breadth rectangular tank in periodic roll motion.It has been shown that RANSE provide more accurate solutions than SWE for small or moderate amplitudes of excitation. In particular in this paper it is proved that the shallow water approximation can be efficiently adopted within liquid depth to tank breadth RATIO = 0.15, when examining the sloshing problem. By increasing the water level inside the tank, results by SWE show large qualitative and quantitative disagreement with experiments. Nevertheless, in the case of large amplitude excitation, when sprays and large breaking waves are expected, SWE provide a fairly good estimate of the sloshing induced waves.Finally a simple baffle configuration inside the tank has been considered. By the analysis of numerical results, it has been observed that the presence of a vertical baffle at the middle of the tank dramatically changes the sloshing response compared to the unbaffled configuration. It produces a jump-like effect, resulting in a weak magnification of the dynamic loads on the vertical walls out of resonance, and a strong reduction of the dynamic loads in the resonance condition. 相似文献
162.
Auckpath Sawangsuriya Meissa Fall Dante Fratta 《Geotechnical and Geological Engineering》2008,26(5):567-578
A rapid, low-cost evaluation methodology using the wave-based techniques is proposed in this study in order to determine the
design parameters e.g., elastic modulus and Poisson’s ratio of the laboratory compacted lateritic soils. Knowing the elastic
wave velocities as measured with the wave propagation technique (i.e., a small-strain non-destructive test) and total mass
density of the specimens, the elastic moduli and Poisson’s ratio of the soil specimens can be determined. In addition, the
unconfined compression test (i.e., a large-strain destructive test) is also performed on the same specimens under the same
unconfined testing condition in order to compare the moduli corresponding to different strain levels. The experimental results
showed the potentials and limitations of using impulse signal for the determination of the elastic moduli and Poisson’s ratio
for laboratory compacted soil specimens from elastic wave propagation techniques. 相似文献
163.
Leone Melluso Ciro Cucciniello Chiara M. Petrone Michele Lustrino Vincenzo Morra Massimo Tiepolo Lopo Vasconcelos 《Journal of African Earth Sciences》2008,52(4-5):139-151
The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique contains different silicic units in the form of pyroclastic rocks, and two different basalt types. The silicic units in the lower part of the Lebombo sequence are formed by a lower unit of dacites and rhyolites (67–80 wt.% SiO2) with high Ba (990–2500 ppm), Zr (800–1100 ppm) and Y (130–240 ppm), which are part of the Jozini–Mbuluzi Formation, followed by a second unit, interlayered with the Movene basalts, of high-SiO2 rhyolites (76–78 wt.%; the Sica Beds Formation), with low Sr (19–54 ppm), Zr (340–480 ppm) and Ba (330–850 ppm) plus rare quartz-trachytes (64–66 wt.% SiO2), with high Nb and Rb contents (240–250 and 370–381 ppm, respectively), and relatively low Zr (450–460 ppm). The mafic rocks found at the top of the sequence are basalts and ferrobasalts belonging to the Movene Formation. The basalts have roughly flat mantle-normalized incompatible element patterns, with abundances of the most incompatible elements not higher than 25 times primitive mantle. The ferrobasalt has TiO2 4.7 wt.%, Fe2O3t = 16 wt.%, and high Y (100 ppm), Zr (420 ppm) and Ba (1000 ppm). The Movene basalts have initial (at 180 Ma) 87Sr/86Sr = 0.7052–0.7054 and 143Nd/144Nd = 0.51232, and the Movene ferrobasalt has even lower 87Sr/86Sr (0.70377) and higher 143Nd/144Nd (0.51259). The silicic rocks show a modest range of initial Sr-(87Sr/86Sr = 0.70470–0.70648) and Nd-(143Nd/144Nd = 0.51223–0.51243) isotope ratios. The less evolved dacites could have been formed after crystal fractionation of oxide-rich gabbroic cumulates from mafic parental magmas, whereas the most silica-rich rhyolites could have been formed after fractional crystallization of feldspars, pyroxenes, oxides, zircon and apatite from a parental dacite magma. The composition of the Movene basalts imply different feeding systems from those of the underlying Sabie River basalts. 相似文献
164.
165.
166.
Michele Baggio 《Estuaries and Coasts》2016,39(6):1816-1826
This article proposes a quantitative investigation of the claim that improving water quality does not yield rents in commercial fisheries that are inefficiently managed. Specifically, a combined model of the resource dynamics and fishing effort is used to investigate the effects of policy scenarios on water quality improvements on the American lobster fishery in Long Island Sound. Results indicate that short-run positive rents can be extracted from the lobster fishery even when inefficiently managed, but they dissipate in the long-run as suggested by the economic literature. 相似文献
167.
Evolution of an early Eocene pull‐apart basin in the Central Pontides (Northern Turkey): New insights into the origin of the North Anatolian Shear Zone 下载免费PDF全文
Giuseppe Ottria Luca Pandolfi Rita Catanzariti Simone Da Prato Alessandro Ellero Chiara Frassi Mehmet Cemal Göncüoğlu Michele Marroni Leonardo Ruffini Kaan Sayit 《地学学报》2017,29(6):392-400
Although the North Anatolian Shear Zone is one of the main lithospheric‐scale strike‐slip deformation zone in the world, playing a prominent role in the complex geodynamic interaction among the Eurasian, Anatolian and Arabian plates, the onset time of its activity remains highly controversial. Here, we tackle this issue by utilizing nannofossil biostratigraphy on deposits from the Ta?cilar basin, a pull‐apart basin that we have identified inside the North Anatolian Shear Zone overprinting the Intra‐Pontide suture zone. The syn‐tectonic sedimentary succession of the Ta?cilar basin developed completely during the early Eocene (Ypresian; CNE4–CNE5 Zones). The strike‐slip faulting related to the initial onset of the North Anatolian Shear Zone can likely be constrained within the Ypresian, suggesting that the westward escape of the Anatolian plate along the North Anatolian Shear Zone started in the early Eocene. 相似文献
168.
Michele Zema Mark D. Welch Roberta Oberti 《Contributions to Mineralogy and Petrology》2012,163(5):923-937
The thermoelastic behaviour of a natural gedrite having the crystal-chemical formula ANa0.47
B(Na0.03 Mg1.05 Fe0.862+ Mn0.02 Ca0.04) C(Mg3.44 Fe0.362+ Al1.15 Ti0.054+) T(Si6.31 Al1.69)O22
W(OH)2 has been studied by single-crystal X-ray diffraction to 973 K (Stage 1). After data collection at 973 K, the crystal was heated to 1,173 K to induce dehydrogenation, which was registered by significant
changes in unit-cell parameters, M1–O3 and M3–O3 bond lengths and refined site-scattering values of M1 and M4 sites. These changes and the crystal-chemical formula calculated from structure refinement show that all Fe2+ originally at M4 migrates into the ribbon of octahedrally coordinated sites, where most of it oxidises to Fe3+, and there is a corresponding exchange of Mg from the ribbon into M4. The resulting composition is that of an oxo-gedrite with an inferred crystal-chemical formula ANa0.47
B(Na0.03 Mg1.93 Ca0.04) C(Mg2.56 Mn0.022+ Fe0.102+ Fe1.223+ Al1.15 Ti0.054+) T(Si6.31 Al1.69) O22
W[O1.122− (OH)0.88]. This marked redistribution of Mg and Fe is interpreted as being driven by rapid dehydrogenation at the H3A and H3B sites, such that all available Fe in the structure orders at M1 and M3 sites and is oxidised to Fe3+. Thermoelastic data are reported for gedrite and oxo-gedrite; the latter was measured during cooling from 1,173 to 298 K
(Stage 2) and checked after further heating to 1,273 K (Stage 3). The thermoelastic properties of gedrite and oxo-gedrite are compared with each other and those of anthophyllite. 相似文献
169.
Michel Magny Sébastien Joannin Didier Galop Boris Vannière Jean Nicolas Haas Michele Bassetti Paolo Bellintani Romana Scandolari Marc Desmet 《Quaternary Research》2012,77(3):382-396
A lake-level record of Lake Ledro (northern Italy) spans the entire Holocene with a chronology derived from 51 radiocarbon dates. It is based on a specific sedimentological approach that combines data from five sediment profiles sampled in distinct locations in the littoral zone. On a millennial scale, the lake-level record shows two successive periods from 11,700 to 4500 cal yr BP and from 4500 cal yr BP to the present, characterized by lower and higher average lake levels, respectively. In addition to key seasonal and inter-hemispherical changes in insolation, the major hydrological change around 4500 cal yr BP may be related to a non-linear response of the climate system to orbitally-driven gradual decrease in insolation. The Ledro record questions the notion of an accentuated summer rain regime in the northern Mediterranean borderlands during the boreal insolation maximum. Moreover, the Ledro record highlights that the Holocene was punctuated by successive centennial-scale highstands. Correlations with the Preboreal oscillation and the 8.2 ka event, and comparison with the atmospheric 14C residual record, suggest that short-lived lake-level fluctuations developed at Ledro in response to (1) final steps of the deglaciation in the North Atlantic area and (2) variations in solar activity. 相似文献
170.
Local structural relaxation around Co2+ along the hardystonite–Co-?kermanite melilite solid solution
Six pure compounds belonging to the hardystonite (Ca2ZnSi2O7)–Co-?kermanite (Ca2CoSi2O7) solid solution were investigated by the combined application of X-ray powder diffraction and electronic absorption spectroscopy. Structural refinements of the XRPD data revealed a negative excess volume of mixing due to the single isovalent substitution of Co for Zn in the tetrahedral site. In agreement with the diffraction data, deconvolution of the optical spectra showed a progressive decreasing of the crystal field strength parameter 10Dq moving toward the Co-?kermanite end-member, meaning that the local cobalt–oxygen bond distance, $ \langle {\text{Co}}{-}{\text{O}}\rangle^{\text{local}} $ , increased along the join with the amount of cobalt. The calculated structural relaxation coefficient around the fourfold coordinated Co2+ in the Ca2(Zn1?x Co x )Si2O7 join was ε?=?0.69, very far from the one predicted by the Vegard’s law (ε?=?0) and at variance with ε?=?0.47 previously found for tetrahedrally coordinated Co2+ in gahnite–Co-aluminate spinel solid solution. This difference is consistent with the largest constraints existing on the spinel structure, based on cubic closest packing, compared to the more flexible layered melilite structure. 相似文献