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71.
72.
We focus on Swiss earthquakes in antiquity and the early medieval period before A.D. 1000. We have information on less than
half a dozen earthquakes within this era, since written records for the first half of the first millennium A.D. are minimal,
and there is little hope of finding more written evidence for earthquakes. Furthermore, interpreting the documents at hand
is somewhat complex. For the 6th century Gregory of Tours in Historia Francorum gives hints of a rockslide near the castle Tauredunum (Le Grammont) in the Swiss canton Valais, an event that has been considered in the literature as caused by an earthquake. The Carolingian period (ca. 750–950) included the rise of some very important cultural centers in various parts of today’s Switzerland. For
instance, the ecclesiastical culture in St. Gallen generated a remarkable number of written records, which survived for our
use in a unique manner. From the 9th and 10th centuries, we have evidence for earthquakes in the years 849, 867, 902, and
944. However, information on them remains so scarce that their location and intensity are generally difficult to assess. Nevertheless,
the finding of a new document - a memoir written by the abbot of Reichenau - offers some insight into the A.D. 849 event and
its reportedly aftershocks.
相似文献
Monika GislerEmail: |
73.
Santosh Sapkota Saurav Sarup Khadka Gautam Sabin Karki Monika Adhikari Binod Mishra Roshan Kumar Klausner Virginia Dhungana Beni Madhav 《Geomagnetism and Aeronomy》2022,62(1-2):125-137
Geomagnetism and Aeronomy - Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere creates geomagnetic disturbances recorded on the ground. This work... 相似文献
74.
75.
This study explores the surface variability of alluvial fans from digital elevations model (DEM) derivatives generated from 1-m planimetric resolution airborne laser swath mapping data. Channel and interfluve dimensions of debris flow (DF) fans and fans generated from predominantly fluvial flows and some older debris flows (mixed flow [MF]) are extracted with the aid of a planimetric curvature classification. Significant differences are identified between the fan surface topography of DF and MF fans. MF fans tend to have smaller channel and interfluve widths, have smaller elevation differences between the crest of the interfluve and channel, and are more dissected than DF fans. The morphometric differences between the two fan classes can be explained by differences in the primary processes that develop the surficial features, but also the preponderance for secondary erosional processes acting on the MF fans. 相似文献
76.
A modification of the spectrophotometric method for the determination of fluoride ions in iron‐rich materials is proposed. In this method the iron matrix was successfully removed using Diphonix® resin. The studied sample was a ferruginous mineral which contained about 38% of iron. The Euronorm certified reference material (ECRM) 676‐1 (Iron Ore Sinter), as a commercially available material having a similar matrix (39.76% w/w Fe) and fluoride level (0.1% w/w), was used to validate the method. After partial digestion in concentrated hydrochloric acid the samples were diluted and passed through Diphonix® resin. The concentration of fluoride ions was determined by a spectrophotometric method using a Zr:ER complex (λ = 540 nm). The result obtained for the ECRM was in good agreement with the certificate specification and thus proved the method to be applicable for the determination of fluoride ions in iron‐rich materials. Due to the easy digestion step and simple requirements for equipment, this method can be used in most laboratories. 相似文献
77.
We investigated a natural Brazilian Fe–Ti-containing andalusite and its thermal behavior by polarized infrared and optical spectroscopy. Polarized infrared spectra of the Brazilian andalusite and their evolution at thermal annealing in air clearly evidence that there are several types of OH-groups in the structure. Optical spectra and their evolution with temperature indicate that the incorporated iron (about 0.43 wt% calculated as FeO) is in the ferrous and ferric state. Incorporation of ferrous iron in the Al-sites of andalusite is discussed as a possible incorporation mechanism for hydrogen. The weakening and disappearance of the Fe2+/Ti4+ IVCT band in the andalusite spectra under annealing in air is caused by oxidization of Fe2+ to Fe3+ in Fe2+/Ti4+ IVCT pairs. The process of oxidation is accompanied by a rearrangement of the hydroxyl groups and dehydration of the sample, especially vivid at the final stage of the thermal annealing at 1,200 °C. During thermal annealing, structural hydroxyls of different types apparently transform into each other: the most distinct are the hydroxyls causing the doublet at 3,516 and 3,527 cm?1 (i.e., H bonded to O1) which seem to transform into the hydroxyls causing the line at 3,461 cm?1 (i.e., H bonded to O2). The infrared spectra scanned across differently colored zones of the crystal clearly show that some amount of hydroxyls is related to Fe2+/Ti4+ IVCT pairs which are the cause of the red-to-black coloration of the sample in E||c-polarized illumination: it is evident that in a part of the hydroxyl groups, OH-vector changes orientation aligning directly along crystallographic a-axis due to some kind of interaction with Fe2+/Ti4+ IVCT pairs. 相似文献
78.
79.
Joanna Mirosław-Grabowska Monika Niska Elwira Sienkiewicz 《Journal of Paleolimnology》2009,42(4):467-481
We present isotope, cladoceran and diatom results from investigations of Eemian sediments of the palaeolake at Ruszkówek,
central Poland. Our analyses of the 15-m-thick sediments indicate that sandy silts occur on the bottom, followed by calcareous
gyttja, interbedded with lake marl. The upper part of the sequence contains peat and peaty sands. Values of δ18O change from −9.4‰ to −3.3‰ and δ13C values oscillate between −3.2‰ and +7.0‰. Nine isotope zones (Is) were defined and characterized using stable isotope analysis
of carbonates. Fifteen species of subfossil Cladocera were found and six faunal zones were distinguished (Cladocera zones).
One hundred and twenty-three diatom taxa, representing 31 genera were identified, enabling us to discern six Diatom Assemblage
Zones. The isotope, cladoceran, and diatom data correlate well with pollen data that define seven phases of evolution of the
palaeolake at Ruszkówek. The palaeolake began during the final phase of the Wartanian (Late Saalian Glaciation). During the
early Eemian, the palaeolake reached its maximum depth. During the Early Vistulian glaciation, the palaeolake declined. Changes
in the cladoceran and diatom communities indicate initial oligotrophic conditions in the lake, then an increase to mesotrophy,
and finally eutrophic conditions. 相似文献
80.
Michail N. Taran Monika Koch-Müller Richard Wirth Irmgard Abs-Wurmbach Dieter Rhede Ansgar Greshake 《Physics and Chemistry of Minerals》2009,36(4):217-232
Synthetic ringwoodite γ-(Mg1?x Fe x )2SiO4 of 0.4 ≤ x ≤ 1.0 compositions and variously colored micro-grains of natural ringwoodite in shock metamorphism veins of thin sections of two S6-type chondrites were studied by means of microprobe analysis, TEM and optical absorption spectroscopy. Three synthetic samples were studied in addition with Mössbauer spectroscopy. The Mössbauer spectra consist of two doublets caused by VIFe2+ and VIFe3+, with IS and QS parameters close to those established elsewhere (e.g., O’Neill et al. in Am Mineral 78:456–460, 1993). The Fe3+/Fetotal ratio evaluated by curve resolution of the spectra, ranges from 0.04 to 0.1. Optical absorption spectra of all synthetic samples studied are qualitatively very similar as they are directly related to the iron content. They differ mostly in the intensity of the observed absorption features. The spectra consist of a very strong high-energy absorption edge and a series of absorption bands of different width and intensity. The three strongest and broadest absorptions of them are attributed to splitting of electronic spin-allowed 5 T 2g → 5 E g transitions of VIFe2+ and intervalence charge-transfer (IVCT) transition between ferrous and ferric ions in adjacent octahedral sites of the ringwoodite structure. The spin-allowed bands at ca. 8,000 and 11,500 cm?1 weakly depend on temperature, whilst the Fe2+/Fe3+ IVCT band at ~16,400 cm?1 displays very strong temperature dependence: i.e., with increasing temperature it decreases and practically disappears at about 497 K, a behavior typical for bands of this type. With increasing pressure the absorption edge shifts to lower energies while the spin-allowed bands shift to higher energy and strongly decreases in intensity. The IVCT band also strongly weakens and vanishes at about 9 GPa. We assigned this effect to pressure-induced reduction of Fe3+ in ringwoodite. By analogy with synthetic samples three broad bands in spectra of natural (meteoritic) blue ringwoodite are assigned to electronic spin-allowed transitions of VIFe2+ (the bands at ~8,600 and ~12,700 cm?1) and Fe2+/Fe3+ IVCT transition (~18,100 cm?1), respectively. Spectra of colorless ringwoodite of the same composition consist of a single broad band at ca. 12,000 cm?1. It is assumed that such ringwoodite grains are inverse (Fe, Mg)2SiO4-spinels and that the single band is caused by the split spin-allowed 5 E → 5 T 2 transition of IVFe2+. Ringwoodite of intermediate color variations between dark-blue and colorless are assumed to be partly inversed ringwoodite. No glassy material between the grain boundaries in the natural colored ringwoodite aggregates was found in our samples and disprove the cause of the coloration to be due to light scattering effect (Lingemann and Stöffler in Lunar Planet Sci 29(1308), 1998). 相似文献