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71.
72.
Artur Roll 《International Journal of Earth Sciences》1952,40(2):243-248
Ohne Zusammenfassung 相似文献
73.
Tassia R.G. Passos Adriana G. Artur Gabriel N. Nóbrega Xosé L. Otero Tiago O. Ferreira 《Geo-Marine Letters》2016,36(3):223-233
The performance of the Walkley–Black wet oxidation chemical method for soil organic carbon (SOC) determination in coastal wetland soils (mangroves, coastal lagoons, and hypersaline tidal flats) was evaluated in the state of Ceará along the semiarid coast of Brazil, assessing pyrite oxidation and its effects on soil C stock (SCS) quantification. SOC determined by the chemical oxidation method (CWB) was compared to that assessed by means of a standard elemental analyzer (CEA) for surficial samples (<30 cm depth) from the three wetland settings. The pyrite fraction was quantified in various steps of the chemical oxidation method, evaluating the effects of pyrite oxidation. Regardless of the method used, and consistent with site-specific physicochemical conditions, higher pyrite and SOC contents were recorded in the mangroves, whereas lower values were found in the other settings. CWB values were higher than CEA values. Significant differences in SCS calculations based on CWB and CEA were recorded for the coastal lagoons and hypersaline tidal flats. Nevertheless, the CWB and CEA values were strongly correlated, indicating that the wet oxidation chemical method can be used in such settings. In contrast, the absence of correlation for the mangroves provides evidence of the inadequacy of this method for these soils. Air drying and oxidation decrease the pyrite content, with larger effects rooted in oxidation. Thus, the wet oxidation chemical method is not recommended for mangrove soils, but seems appropriate for SOC/SCS quantification in hypersaline tidal flat and coastal lagoon soils characterized by lower pyrite contents. 相似文献
74.
Nicole Kowalski Olaf Dellwig Melanie Beck Maik Grunwald Sibylle Fischer Maike Piepho Thomas Riedel Holger Freund Hans-Jürgen Brumsack Michael E. Böttcher 《Ocean Dynamics》2009,59(2):333-350
Tidal and seasonal behaviour of the redox-sensitive trace metals Mn, Fe, Mo, U, and V have been investigated in the open-water
column and shallow pore waters of the backbarrier tidal flats of the island of Spiekeroog (Southern North Sea) in 2002 and
2007. The purpose was to study the response of trace metal cycles on algae blooms, which are assumed to cause significant
changes in the redox state of the entire ecosystem. Trace metal data were complemented by measurements of nutrients and enumeration
of algae cells in 2007. Generally, Mn and V show a tidal cyclicity in the water column with maximum values during low tide
which is most pronounced in summer due to elevated microbial activity in the sediments. Mo and U behave almost conservatively
throughout the year with slightly increasing levels towards high tide. Exceptions are observed for both metals after summer
algae blooms. Thus, the seasonal behaviour of the trace metals appear to be significantly influenced by productivity in the
water column as the occurrence of algae blooms is associated with an intense release of organic matter (e.g. transparent exopolymer
particles, TEP) thereby forming larger organic-rich aggregates. Along with elevated temperatures in summer, the deposition
of such aggregates favours microbial activity within the surface sediments and release of DOC, nutrients and trace metals
(Mn, Mo and V) during the degradation of the aggregates. Additionally, pronounced reducing conditions lead to the reduction
of Mn(IV)-oxides and Fe(III)-(oxihydr)oxides, thereby releasing formerly scavenged compounds as V and phosphate. Therefore,
pore-water profiles show significant enrichments in trace metals especially from July to September. Finally, the trace metals
are released to the open water column via draining pore waters (esp. Mo, Mn, and V) and/or fixed in the sediment as sulphides
(Fe, Mo) and bound to organic matter (U). Non-conservative behaviour of Mo in oxygenated seawater, first observed in the investigation
area by Dellwig et al. (Geochim Cosmochim Acta 71:2745–2761, 2007a), was shown to be a recurrent phenomenon which is closely coupled to bacterial activity after the breakdown of algae blooms.
In addition to the postulated fixation of Mo in oxygen-depleted micro-zones of the aggregates or by freshly formed organic
matter, a direct removal of Mo from the water column by reduced sediment surfaces may also play an important role. 相似文献
75.
Six members of the annite–siderophyllite join were synthesized in a three step process – crystallization of biotite from
gels, decomposition of the fine-grained biotite under oxidizing conditions and resynthesis of Fe-Al biotite with planned compositions
from these products – producing biotite crystals with thicknesses of up to 10 μm. The biotite was characterized by microprobe,
electron microscopy and X-ray diffraction. Heat capacities of these biotites were measured with a DSC (differential scanning
calorimeter) over the temperature range 143 to 623 K. Using a least-squares technique, the data were fitted to a cp-polynomial, c
p
=k
0+k
1
T
−0.5+ k
2
T
−2+k
3
T
−3. In the temperature range 143 to 250 K, heat capacities of the different annite–siderophyllite members decrease linearly
with increasing Al content. At higher temperatures, however, the cp-polynomial of biotites with intermediate composition (except Ann79Sid21) exhibit a steeper slope than those of other biotites. This produces positive excess heat capacities in the annite–siderophyllite
join at higher temperatures. The activity-composition data of the same binary derived from phase equilibrium experiments (Benisek
et al. 1996) and the data of this study suggest two compositional regions along this join, with different extent of deviation
from ideality. One at X
Sid < 0.3, characterized by a small deviation, one at X
Sid > 0.3 showing a higher nonideality, resulting in a discontinuity visible at this composition. Powder IR-spectra of these
solid solutions were measured with a FTIR-spectrometer and used to calculate heat capacities according to the vibrational
model of Kieffer (1979). The comparison of the vibrational function with the cp-polynomials shows that the vibrational function reproduces well the DSC-data of the siderophyllite-poor and -rich members,
but deviates for intermediate compositions, where the excess heats of mixing occur. With increasing Tschermak vector, the
tetrahedral rotation angle α increases from 0 to 13° for annite to siderophyllite, respectively. At the composition of the
discontinuity, this rotation angle α reaches a value of ∼8∘. The processing of ∼300 chemical data of natural biotites indicates that over 90% of them have a tetrahedral rotation angle
that lies between 7 and 9°. It would appear that biotites with these structural characteristics are most stable.
Received: 27 August 1998 / Accepted: 10 November 1998 相似文献
76.
Artur Radecki-Pawlik Karol Plesiński Bartosz Radecki-Pawlik Piotr Kuboń Russell Manson 《山地科学学报》2018,15(11):2335-2346
Boulder block ramps are river engineering structures used to stabilise river beds. Block ramps provide a semi-natural and aesthetically pleasing solution to certain river engineering problems in mountain streams. When constructing block ramps,one can use the dissipative behaviour of large macroroughness elements randomly placed on the river bed to enhance fish migration in an upstream direction thus, in this sense, meeting the requirements of the EU Water Framework Directive. Block ramps are often designed and constructed to replace damaged drop hydraulic structures in the channels of mountain streams. This paper investigates the resilience of a particular block ramp placed in the Krzczonówka stream(Polish Carpathians) in terms of the engineering design function and its durability against damaging. A hydrodynamic analysis of a block ramp is presented before and after a flood event that changed the configuration of the blocks. The seminatural unstructured hydraulic structure was built on the Krzczonowka stream to protect gas pipes which are located beneath it. As a result of several floods, the boulder block chute described in this paper was damaged, and some boulders were dislodged and transported downstream. Our post-flood investigations of bathymetry and velocity revealed that even damaged boulder blocks, removed from the chute and displaced downstream of the structure, still provide significant energy dissipation of the flowing water. The novel of our paper is for the first time showing very detailed analysis of unstructured block ramp hydrodynamics parameters done in the field.Also the novel finding of our investigations shows that before and after the flood event the unstructured block ramp structure, is still fish friendly in terms of hydrodynamics. 相似文献
77.
Marcin Frankowski Anetta Zioła-Frankowska Artur Kowalski Jerzy Siepak 《Environmental Earth Sciences》2010,60(6):1165-1178
The study presents the results of Cu, Pb, Zn, Mn and Fe determination in the samples of bottom sediments collected from the
Oder and Warta rivers. The sequential extraction of metals in the samples of bottom sediments was performed after introducing
the modification of the extraction scheme suggested by Tessier et al. (Anal Chem 51(7):844–851, 1979). The extraction times
of particular stages were optimised. The fifth stage was altered by introducing the new methods of performing extraction.
The samples of bottom sediments submitted the following granulometric analyses: dry, wet and wet with (HMP) dispersing reagent.
Seven granulometric fractions with the following grain sizes were isolated: >2.0, 2.0–1.0, 1.0–0.5, 0.5–0.25, 0.25–0.1, 0.1–0.063
and <0.063 mm. The sequential extraction of particular granulometric fractions was performed. The concentration of metals
variability was analysed depending on the method of sample preparation for the chemical analysis, granulometric fraction of
sediments subjected to the analysis, extraction conditions and the site of samples collection. The lack of linearity between
the metal concentration and the size of granulometric fraction was observed. The highest concentrations of metals were observed
in fractions >2.0, 2.0–1.0 and 0.1–0.063 and <0.063 mm while the lowest concentrations occurred in fractions 1.0–0.5, 0.5–0.25,
and 0.25–0.1 mm. The atomic absorption spectrometry with flame atomisation (F-AAS) was used for the determination of the investigated
elements. 相似文献
78.
Artur Sobczyk Ryszard K. Borówka Janusz Badura Renata Stachowicz-Rybka Julita Tomkowiak Anna Hrynowiecka Joanna Sławińska Michał Tomczak Mateusz Pitura Mariusz Lamentowicz Piotr Kołaczek Monika Karpińska-Kołaczek Dariusz Tarnawski Marcin Kadej Piotr Moska Marek Krąpiec Krzysztof Stachowicz Bartosz Bieniek Krzysztof Siedlik Małgorzata Bąk Jan van der Made Adam Kotowski Krzysztof Stefaniak 《第四纪科学杂志》2020,35(4):539-558
The sedimentary succession exposed in the Gorzów Wielkopolski area includes Eemian Interglacial (MIS 5e) or Early Weichselian (MIS 5d–e) deposits. The sedimentary sequence has been the object of intense interdisciplinary study, which has resulted in the identification of at least two palaeolake horizons. Both yielded fossil remains of large mammals, alongside pollen and plant macrofossils. All these proxies have been used to reconstruct the environmental conditions prevailing at the time of deposition, as well as to define the geological context and the biochronological position of the fauna. Optically stimulated luminescence dating of the glaciofluvial layers of the GS3 succession to 123.6 ± 10.1 (below the lower palaeolake) and 72.0 ± 5.2 ka (above the upper palaeolake) indicate that the site formed during the Middle–Late Pleistocene (MIS 6 – MIS 5). Radiocarbon-dating of the lacustrine organic matter revealed a tight cluster of Middle Pleniglacial Period (MIS 3) ages in the range of ~41–32 ka cal bp (Hengelo – Denekamp Interstadials). Holocene organic layers have also been found, with 14C ages within a range of 4330–4280 cal bp (Neolithic). Pollen and plant macrofossil records, together with sedimentological and geochemical data, confirm the dating to the Eemian Interglacial. 相似文献
79.
The analysis of low-field anisotropy of magnetic susceptibility (AMS) was used to reconstruct the subglacial deposition conditions during the Main Stadial of the Odranian Glaciation (MIS 6) in till deposits from a site in Dębe (central Poland). Based on the AMS parameters, six till beds were identified (intervals 1–6). The declination of the maximum magnetic susceptibility axis (k1) indicates that the ice sheet was moving in from the northwest. The obtained results confirm the thesis about the preferred direction of ice-sheet transgression during the Odranian Glaciation (MIS 6) in this part of Poland. This interpretation is also confirmed by data obtained from measurements of the long axis of clasts, which agree with the orientation of k1. Based on the AMS results, a significant part of the profile was deformed through simple shear and direct interaction of the ice sheet with the underlying sediment (beds 2–5). The lowest part of the till (bed 6) may have been deposited on a southeast-trending slope or post-depositional deformed by uneven loading of the ice cover. The upper part of the profile (especially in interval 1) could be deposited with an impact of pore water. 相似文献
80.
Several samples of peat from 6 bogs located in southern Poland were investigated for occurrence and distribution types of biomarkers present in their extractable organic matter fraction. It was found that there are inputs from two different sources of organic compounds differing in their characteristics and origin: (1) recent immature peat organic matter deposited in situ which is the source of all polar functionalized compounds, most of n-alkanes, and acyclic isoprenoids, and (2) mature fossil fuels, most probably bituminous coals from the Upper Silesia Coal Basin of vitrinite reflectance equivalent values of 0.9–1.1%. The latter compounds were most probably transported with fly ash to bogs from nearby settlements utilizing such fuel in domestic ovens. This group includes pentacyclic triterpenoids (hopanes and moretanes), minor amounts of n-alkanes, and numerous alkyl naphthalenes and alkyl phenanthrenes. All these compounds show distributions and values of geochemical ratios characteristic for mature organic matter confirming there ex situ origin. 相似文献