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211.
Norbert B?ttcher Joshua Taron Olaf Kolditz Chan-Hee Park Rudolf Liedl 《Environmental Earth Sciences》2012,67(2):481-495
Three commonly used thermal equations of state for carbon dioxide, as well as the ideal gas law, have been compared against a large number of measurement data taken from the literature. Complex equations of state reach a higher accuracy than simple ones. The inaccuracy of the density function can cause large errors in fluid property correlations, such as heat capacity or viscosity. The influence of this inaccuracy on the results of numerical simulations have been evaluated by two examples: The first one assumes isothermal gas expansion from a volume, while the second one considers heat transport along a fracture. For both examples, different equations of state have been utilized. The simulations have been performed on the scientific software platform OpenGeoSys. The difference among the particular simulation results is significant. Apparently small errors in the density function can cause considerably different results of otherwise identical simulation setups. 相似文献
212.
New excavations in the famous Monte San Giorgio area, close to the historical sites where the Cassina beds crop out (Lower
Meride Limestone, Early Ladinian), revealed an interesting vertebrate fauna, including several specimens of the actinopterygian
fish Saurichthys. Among the prepared specimens, three specimens of Saurichthys contain embryos, and in one example the embryos are preserved with traces of the soft parts, most probably phosphatized musculature.
This discovery is of particular relevance because fossil embryos with preserved soft parts are extremely rare. In addition,
although viviparity had previously been described for Saurichthys, the new specimens are rather better evidence and add further support to this reproductive mode. 相似文献
213.
214.
Резюме Крутизна кривых захода и восхода Солнца, отображающаяся в годовом ходе изменений в виде вечернего возрастания или утреннего
убывания коэффициента конверсии проявляется весьма неравномерио. Здесь уместно провести параллель с явлениями имеющими место
в периоде летних месяцев (март— октябрь), когда переход от дня к ночи и наоборот осуществляется быстро. Годовой ход коэффициента
конверсип в периоде от зимы к лету характеризуется возрастанием значений ϱ согласно закону положения Солнца относителяно слояE; такое возрастание весной и осенью прерывается вследствие явлений, связанных с перемещением дрейфующей системы на поверхости
отражения. В летних месяцах кривая значений ϱ имеет более низкие явления. Влияние повышенной солнечной возмущающей активности
в равноденствиях проявляется в особенности на северном участке (245кец) в виде соответствующего расположения минимумов на кривой изменений. Помимо этого в максимуме солнечных пятен был обнаружен
27 дневный период повторяемости коэффициента конверсии, который отчетливо проявляется в скользящих средних значений ϱ полученных
в результате вычислений, осуществленных непрерывно в десятидневных интервалах в течение 1958 г.
Anschrift: Geophysikalisches Observatorium, Collm über Oschatz, DDR. 相似文献
Anschrift: Geophysikalisches Observatorium, Collm über Oschatz, DDR. 相似文献
215.
Manfred Schidlowski Peter W.U Appel Rudolf Eichmann Christian E Junge 《Geochimica et cosmochimica acta》1979,43(2):189-199
One hundred and twenty-four carbonate samples from the meta-sedimentary sequence of the 3.7 × 109 yr old Isua supracrustal belt (W-Greenland) have yielded a δ13Ccarb average of ?2.5 ± 1.7%. vs PDB and a δ18Ocarb average of +13.0 ± 2.5%. vs SMOW. The oxygen mean comes fairly close to the averages of other early Precambrian carbonates. The carbon average, however, is some 2%. more negative than those of younger marine carbonates. In terms of a simple terrestrial 13C mass balance, if δ13Ccarb values are original sedimentary values, this more negative δ13C average would imply a considerably smaller ratio in the sedimentary shell during Isua times, and would thus support the concept of a gradual buildup of a sedimentary reservoir of organic carbon during the early history of the Earth. Since, however, the Isua supracrustal rocks have experienced amphibolite-grade metamorphism, which in other areas has been shown to lower δ13Ccarb values, it is most likely that the original values of these rocks were approx 0%.. This indicates that Corx and Ccarb were present in the ancient carbon reservoir in about ‘modern’ proportions. Unless this early stabilization of the terrestrial carbon cycle in terms of a constant partitioning of carbon between the reduced and oxidized species is shown to have been caused by some inorganic geochemical process, a considerably earlier start of chemical evolution and spontaneous generation of life must be considered than is presently accepted. 相似文献
216.
Ohne Zusammenfassung 相似文献
217.
Clayton J. Williams Rudolf Jaffé William T. Anderson Frank J. Jochem 《Estuarine, Coastal and Shelf Science》2009
A stable carbon isotope approach was taken to identify potential organic matter sources incorporated into biomass by the heterotrophic bacterial community of Florida Bay, a subtropical estuary with a recent history of seagrass loss and phytoplankton blooms. To gain a more complete understanding of bacterial carbon cycling in seagrass estuaries, this study focused on the importance of seagrass-derived organic matter to pelagic, seagrass epiphytic, and sediment surface bacteria. Particulate organic matter (POM), seagrass epiphytic, seagrass (Thalassia testudinum) leaf, and sediment surface samples were collected from four Florida Bay locations with historically different organic matter inputs, macrophyte densities, and primary productivities. Bulk (observed and those reported previously) and compound-specific bacterial fatty acid δ13C values were used to determine important carbon sources to the estuary and benthic and pelagic heterotrophic bacteria. The δ13C values of T. testudinum green leaves with epiphytes removed ranged from −9.9 to −6.9‰. Thalassia testudinum δ13C values were significant more enriched in 13C than POM, epiphytic, and sediment samples, which ranged from −16.4 to −13.5, −16.2 to −9.6, and −16.7 to −11.0‰, respectively. Bacterial fatty acid δ13C values (measured for br14:0, 15:0, i15:0, a15:0, br17:0, and 17:0) ranged from −25.5 to −8.2‰. Assuming a −3‰ carbon source fractionation from fatty acid to whole bacteria, pelagic, epiphytic, and sediment bacterial δ13C values were generally more depleted in 13C than T. testudinum δ13C values, more enriched in 13C than reported δ13C values for mangroves, and similar to reported δ13C values for algae. IsoSource mixing model results indicated that organic matter derived from T. testudinum was incorporated by both benthic and pelagic bacterial communities, where 13–67% of bacterial δ13C values could arise from consumption of seagrass-derived organic matter. The IsoSource model, however, failed to discriminate clearly the fraction of algal (0–86%) and mangrove (0–42%) organic matter incorporated by bacterial communities. These results indicate that pelagic, epiphytic, and sediment surface bacteria consumed organic matter from a variety of sources. Bacterial communities incorporated consistently seagrass-derived organic matter, the dominant macrophyte in Florida Bay, but seagrass δ13C values alone could not account fully for bacterial δ13C values. 相似文献
218.
Rudolf Leutelt Leuchs Wilckens W. Salomon Chudoba L. Rüger Otto Wilckens 《International Journal of Earth Sciences》1929,20(4-5):371-383
Ohne Zusammenfassung 相似文献
219.
Rudolf Leutelt 《International Journal of Earth Sciences》1931,22(3-4):156-160
Zusammenfassung Junge Krustenbewegungen sind tektonische Vorgänge, die nach Vollendung des strukturellen Baues das Formenstockwerkgebäude verändern. Solche Bewegungen können nur aus den Formen selbst mit zwingender Sicherheit nachgewiesen werden. Der geologische Befund allein erweist die Bewegung nicht als unbedingt jung. Das Hauptargument für eine allgemeine Verbreitung junger Verbiegungen, die angenommenen Einwalmungen der Gipfelflur, basiert auf nicht zutreffenden Voraussetzungen. Auch die beiden klassischen Beispiele junger Krustenbewegungen, die Brennerquerfurche und die Inntallängsfurche sind nicht als solche erweisbar. Mit jungen Krustenbewegungen als Arbeitshypothese ist ganz besondere Vorsicht am Platze. 相似文献
220.
Malte Drobe Mnica G. Lpez de Luchi Andr Steenken Robert Frei Rudolf Naumann Siegfried Siegesmund Klaus Wemmer 《Journal of South American Earth Sciences》2009,28(3):239-262
Provenance studies have been performed utilising major and trace elements, Nd systematics, whole rock Pb–Pb isotopes and zircon U/Pb SHRIMP data on metasedimentary rocks of the Sierra de San Luis (Nogolí Metamorphic Complex, Pringles Metamorphic Complex, Conlara Metamorphic Complex and San Luis Formation) and the Puncoviscana Formation of the Cordillera Oriental. The goal was the characterisation of the different domains in the study area and to give insights to the location of the source rocks. An active continental margin setting with typical composition of the upper continental crust is depicted for all the complexes using major and trace elements. The Pringles Metamorphic Complex shows indications for crustal recycling, pointing to a bimodal provenance. Major volcanic input has to be rejected due to Th/Sc, Y/Ni and Cr/V ratios for all units. The εNd(540 Ma) data is lower for the San Luis Formation and higher for the Conlara Metamorphic Complex, as compared to the other units, in which a good consistency is given. This is similar to the TDM ages, where the metapsammitic samples of the San Luis Formation are slightly older. The spread of data is largest for the Pringles Metamorphic Complex, again implying two different sources. The whole rock 207Pb/206Pb isotopic data lies in between the South American and African sources, excluding Laurentian provenances. The whole rock Pb–Pb data is almost indistinguishable in the different investigated domains. Only the PMC shows slightly elevated 208Pb/204Pb values. Possible source rocks for the different domains could be the Quebrada Choja in the Central Arequipa–Antofalla domain, the Southern domain of the Arequipa–Antofalla basement, the Brazilian shield or southern Africa. Zircon SHRIMP data point to a connection between the Puncoviscana Formation and the Conlara Metamorphic Complex. Two maxima around 600 Ma and around 1000 Ma have been determined. The Nogolí Metamorphic Complex and the Pringles Metamorphic Complex show one peak of detrital zircons around 550 Ma, and only a few grains are older than 700 Ma. The detrital zircon ages for the San Luis Formation show age ranges between 590 and 550 Ma. A common basin can be assumed for the Conlara Metamorphic Complex and the Puncoviscana Formation, but the available data support different sources for the rest of the Complexes of the Sierra de San Luis. These share the diminished importance or the lack of the Grenvillian detrital peak, a common feature for the late Cambrian–early Ordovician basins of the Eastern Sierras Pampeanas, in contrast to the Sierras de Córdoba, the PVF and the Conlara Metamorphic Complex. 相似文献