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101.
102.
An evaluation of Arctic cloud and radiation processes during the SHEBA year: simulation results from eight Arctic regional climate models 总被引:1,自引:1,他引:0
K. Wyser C. G. Jones P. Du E. Girard U. Willén J. Cassano J. H. Christensen J. A. Curry K. Dethloff J.-E. Haugen D. Jacob M. Køltzow R. Laprise A. Lynch S. Pfeifer A. Rinke M. Serreze M. J. Shaw M. Tjernström M. Zagar 《Climate Dynamics》2008,30(2-3):203-223
Eight atmospheric regional climate models (RCMs) were run for the period September 1997 to October 1998 over the western Arctic
Ocean. This period was coincident with the observational campaign of the Surface Heat Budget of the Arctic Ocean (SHEBA) project.
The RCMs shared common domains, centred on the SHEBA observation camp, along with a common model horizontal resolution, but
differed in their vertical structure and physical parameterizations. All RCMs used the same lateral and surface boundary conditions.
Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path
and cloud cover from each model are evaluated against the SHEBA observation data. Downwelling surface radiation, vertically
integrated water vapour and liquid water path are reasonably well simulated at monthly and daily timescales in the model ensemble
mean, but with considerable differences among individual models. Simulated surface albedos are relatively accurate in the
winter season, but become increasingly inaccurate and variable in the melt season, thereby compromising the net surface radiation
budget. Simulated cloud cover is more or less uncorrelated with observed values at the daily timescale. Even for monthly averages,
many models do not reproduce the annual cycle correctly. The inter-model spread of simulated cloud-cover is very large, with
no model appearing systematically superior. Analysis of the co-variability of terms controlling the surface radiation budget
reveal some of the key processes requiring improved treatment in Arctic RCMs. Improvements in the parameterization of cloud
amounts and surface albedo are most urgently needed to improve the overall performance of RCMs in the Arctic. 相似文献
103.
An evaluation has been conducted to establish if using renewable energy is technically and economically feasible to pump water
in Sacala las Lomas, Guatemala. A deep groundwater well has been proposed and a multi-stage pump system is being considered
to distribute groundwater to users’ homes. A weather station was erected in Sacala to collect site-specific data. Wind velocity,
wind direction, solar insolation, temperature, precipitation, and barometric pressure data were collected over a 1-year study
period. The analysis of the data indicated that the potential power generated by a photovoltaic array or wind turbine would
be insufficient to economically pump water to the village under current conditions. Although there may be reasons other than
economics that make the potential renewable energy applications attractive, the space and maintenance required to install
and operate a sufficient off-grid system outweigh the benefits. A grid-intertie system would allow any number of solar panels
to be used in the system while still providing the electricity demand using grid-power. 相似文献
104.
Will Meredith Chen-Gong Sun Colin E. Snape Mark. A. Sephton Gordon D. Love 《Organic Geochemistry》2006,37(12):1705
This study describes the reduction of functionalised model compounds to their corresponding hydrocarbons by catalytic hydropyrolysis to provide information on the release of biomarkers from kerogens and asphaltenes covalently bound through the functional groups investigated. Five model compounds were investigated, the n-C18 carboxylic acids, stearic and oleic acids; the C24 steroidal acid, 5β-cholanic acid; and the saturated and unsaturated C27 sterols, 5α-cholestanol and cholesterol. The yield and distribution of the hydrocarbons generated were assessed for the model compounds adsorbed to silica and carbon substrates, and unsupported on a bed of catalyst. The n-C18 acids are shown to be reduced to the n-C18 alkane, with a selectivity of >95% for stearic acid, although due to its unsaturated structure, oleic acid is prone to cracking, with shorter chained n-alkanes also being formed. The conversion of these compounds, adsorbed to either silica or carbon is relatively low, even at hydropyrolysis temperatures significantly above their boiling point, suggesting that interactions between the acids and substrate leading to the formation of stable entities (Si–O–C linkages in the case of silica) significantly retard volatilisation. The yield can be increased by placing the compounds directly onto a bed of catalyst, but for low boiling compounds such as stearic acid this can result in volatilisation and cracking at temperatures below that of the activation point of the catalyst. This method produced improved yields of >95% pure product for higher boiling compounds such as 5β-cholanic acid. The presence of the functional group attached to the ring system of compounds such as 5α-cholestanol does not diminish the selectivity of the technique. The double bond in cholesterol resulted in more incomplete hydrogenation with sterenes being generated, and in addition to 5α and 5β-cholestane, diasteranes were also generated via migration of the double bond. 相似文献
105.
106.
107.
Shaun Cole Peder Norberg Carlton M. Baugh Carlos S. Frenk Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Nicholas Cross Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,326(1):255-273
108.
ZusammenfassungBergmännische Auffahrung eines U-Bahnhofes unter geringer Überdeckung Ein 600 m langes Baulos der Stadtbahn Bochum wurde in den Jahren 1975 und 1976 bergmännisch aufgefahren. Dabei waren ein unterirdischer Bahnhof sowie eingleisige und zweigleisige Streckenröhren herzustellen. Die Höhe der Überdeckung betrug 8 bis 3 m, wobei der gesamte Tunnelbereich entweder unter Straßen oder unter Gebäuden liegt. Der Untergrund besteht aus Mergeln stark unterschiedlicher Festigkeit und aus kohäsionsarmen, feinsandigen Schluffen und Kiesen. Teilweise wurden bei den Tunnelarbeiten auch alte Fundamentreste und Bombenschutt angetroffen. Die Tunnelarbeiten erfolgten entsprechend den Grundsätzen der Neuen Österreichischen Tunnelbauweise und wurden durch ein umfangreiches Meßprogramm kontrolliert. An keiner Stelle sind Beschädigungen an Gebäuden aufgetreten. Die Setzungen lagen im allgemeinen in Größenordnungen um 20 mm.Besondere Beachtung verdient die erstmals zur Anwendung gekommene Bauweise für die Erstellung unterirdischer Bahnhöfe. Dabei werden zwei zueinander parallel verlaufende Röhren nacheinander aufgefahren, die sich im Kämpferbereich schneiden, wobei die Kämpferlasten durch eine gemeinsame Mittelwand aufgenommen werden. Der hierfür notwendige Bauablauf und die erforderlichen Baumaßnahmen sowie die durchgeführten Messungen über und unter Tage werden beschrieben und diskutiert.
Vortrag gehalten auf dem XXV. Geomechanik-Kolloquium in Salzburg, 1976.
Mit 14 Abbildungen 相似文献
SummaryConstruction of a Subway Station With Low Cover A 600 m long lot of the Stadtbahn Bochum has been constructed by tunnelling in 1975 to 1976. A subway station as well as a one-rail- and a two-rail-tube had to be built. The height of the cover was between 8 and 3 m; the tunnel is laying either under roads or under buildings. The underground consists of marls with very different strength and of sandy silts and gravels with little cohesion. In some areas old building foundations and bomb ruins had to be passed. Tunnelling was executed according to the principles of the New Austrian Tunnelling Method and was controlled by an extensive measuring programme. Nowhere damages of the buildings occurred. The surface subsidences generally were measured in a magnitude of about 20 mm.Special attention should be drawn to the method applied for the first time to construct an underground station. The excavation of the whole cross-section is executed by tunnelling of two parallel tubes overlapping one the other in the middle. A central concrete wall is constructed in the first tube before driving the second tube. The sequence of operation and the necessary construction measures as well as the measurements on the surface and in the underground are described and discussed.
RésuméCreusement foré d'une station souterraine sous une couverture mince Un lot d'adjudication de 600 m de la métro de Bochum a été creusé par forage pendant 1975 et 1976. Une station souterraine et des tubes à voie unique et à double voie ont été à construire. La couverture a eu une épaisseur de 8 à 3 m, le rayon total du tunnel étant situé ou sous des rues ou sous des bâtiments. Le sous-sol consiste en marne de résistance très différente et en silt et gravier de cohésion minime et de sable fin. Partiellement aussi des restes de fondations de bâtiments anciens et de décombres de bombes ont été trouvés pendant les travaux, qui ont été exécutés d'après les principes de la méthode autrichienne de construction de tunnels. Un programme large de mesurages a contrôlé les travaux. En aucun lieu on a trouvé des dommages de bâtiments. En général les tassements étaient dans une étendue de 20 mm.Une considération particulière doit être attribuer à cette méthode pour la construction de stations souterraines, là employée pour la première fois. Deux tubes parallèles ont été creusés l'un après l'autre, se coupant dans la zone de culée, les charges des culées étant absorbées par un mur central commun. Le déroulement des travaux, les mesures de construction nécessaire pour cela et les mesurages exécutés à ciel ouvert et souterrain, sont décrits et discutés.
Vortrag gehalten auf dem XXV. Geomechanik-Kolloquium in Salzburg, 1976.
Mit 14 Abbildungen 相似文献
109.
Dr. Manfred Will 《International Journal of Earth Sciences》1976,65(1):733-747
Zusammenfassung Im Nordteil der Ostalpen, hauptsächlich im Gebiet zwischen Salzach und Inn, wurden bei Steinbruch-Sprengungen 11 Profile refraktions-seismisch vermessen. Weil die Geschwindigkeit seismischer Wellen im Bereich dieser Profile auch in lateraler Richtung relativ stark variiert, wurde zur Interpretation der Messungen ein vom Autor entwickeltes Computer-Programm für strahlenseismische Modellrechnungen in zweidimensional inhomogenen Medien verwendet. Für einige der Profile wurden damit Modelle abgeleitet, die als wichtigste Eigenschaft eine Unterlagerung der Kalkalpen bis mindestens 15 km von ihrem Nordrand nach Süden durch eine Schicht von maximal etwa 7 km Mächtigkeit zeigen. Diese Schicht kann nach ihrer Wellengeschwindigkeit aus Molasse und/oder Helvetikum und/oder Flysch bestehen.
In the northern part of the Eastern Alps, mainly in the region between Salzach and Inn, 11 seismic refraction profiles were measured using quarry blasts. There are relatively big changes of seismic velocity in this area even in lateral direction, and therefore the measurements were interpreted with a ray tracing method for twodimensional inhomogeneous mediums, the computer program for which was written by the author. Thus there were found models for some of the profiles in which the most important structure is a layer of about 7 km thickness lying under the Northern Calcareous Alps and stretching at least 15 km from their northern margin southwards. From its seismic velocity this layer can consist of Molasse and/or Helveticum and/or Flysch.
Résumé Dans la partie nord des Alpes Orientales 11 profils de seismique par réfraction ont été enrégistrés, en utilisant des explosions de carrières. La majorité des profils est située entre la Salzach et l'Inn. Les importantes variations latérales des vitesses de propagation nécessitèrent le développement d'un programme de calcul des rayons séismiques dans un milieu inhomogène à deux dimensions. L'interprétation de plusieurs des profils à l'aide de ce programme indique la présence d'une couche à faible vitesse sous les Alpes Calcaires s'étendant du bord nord des Alpes jusqu'à 15 km au moins vers le sud. L'épaisseur maximale de cette couche est environ de 7 km. Les vitesses indiquent qu'elle peut être composée de matériaux de la Molasse, des couches Helvétiques et du Flysch.
- II- , . ., . . . , . , , , 7 , , no- , 15 . , , .相似文献
110.
The compressibility of Fe0.941O has been measured by energy-dispersive X-ray diffraction methods in a diamond anvil squeezer up to 200 kbar. The data points can be described by the Murnaghan equation with K 0=1,540±50 kbar and K'=4. An analysis of previous investigations, X-ray diffraction and ultrasonic measurements yields for the general composition Fe1?xO a regression line K 0=5,438(1?x)?3,595 kbar for all known measurements. 相似文献