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1.
Dr. Ulrike Barth-Wirsching Dr. H. Höller Dr. D. Klammer Dr. B. Konrad 《Mineralogy and Petrology》1993,48(2-4):275-294
Summary The starting material used was expanded perlite with a grain size < 40 m (74.5 wt.% SiO2; 12.5 wt.% Al2O3). This material is a waste product obtained during the production of expanded perlite. The experiments were carried out with KOH solutions, mixtures of KOH and NaOH solutions (1:1) as well as NaOH solutions in the concentration range 0.5 N to 6.0 N at temperatures of between 100° and 140°C and with reaction periods of 2 hours to 13 days in closed system. In the experiments with KOH containing solutions zeolite ZK-19 (phillipsite), W (merlinoite), G (chabazite) and F (edingtonite) formed. Without addition of aluminium high percentages of zeolite ZK-19 (80–100 wt.%) and zeolite W (90–100 wt.%) were obtained. The addition of aluminium rendered possibly the formation of 90 to 100 wt.% of zeolite G and 85 to 100 wt.% of zeolite F, respectively. In the experiments with NaOH solutions analcime, zeolite Na-Pc (gismondine), zeolite HS (sodalite hydrate) and zeolite A formed. High percentages of zeolite Na-Pc (90–100 wt.%), zeolite HS (up to 100 wt.%) and analcime (up to 100 wt.%) were synthesized without addition of aluminium. The formation of high percentages of zeolite A (95–100 wt.%), however, needs the addition of aluminium, NaCI and seed crystals. The temperature stability of the zeolites decreases in the following sequence: K-F > K-W K-ZK-19 (Na), K-W Na, K-F Gsi-rich (Na), K-ZK-19 >> Na-Pc Gsi-poor. Zeolite A has a very good temperature stability up to temperatures of } 550 °C similar to that of zeolite K-W. At higher temperatures, however, its stability is very poor. The NH4
+-exchange capacities (meq/g) of the different zeolites amount to the following values: ZK-19:2.8 - 3.2; W:3.0 - 3.2; G:2.3 - 3.6; A:3.1 - 3.2; Na-Pc:3.5 - 3.6; F : 3.9 - 4.8.
With 2 Figures 相似文献
Zeolithsynthese aus Blähperlit—Art, Bildungsbedingungen und Eigenschaften
Zusammenfassung Ausgangsmaterial der experimentellen Untersuchungen war Blähperlit mit einer Korngröße < 40 ,m (74,5 Gew.-% SiO2; 12,5 Gew.-% Al2O3). Dieses Material ist ein Abfallprodukt, das bei der Produktion von Blähperlit anfällt. Die Experimente wurden mit KOH-Lösungen, Lösungsgemischen aus KOH und NaOH (1:1) sowie mit NaOH-Losungen im Konzentrationsbereich 0,5 n-6,0 n bei Temperaturen von 100° – 140°C und über Reaktionszeiten von 2 Stunden bis zu 13 Tagen im geschlossenen System durchgeführt. In den Experimenten mit KOH-hältigen Lösungen bildeten sich die Zeolithe ZK-19 (Phillipsit), W (Merlinoit), G (Chabasit) und F (Edingtonit). Hohe Prozentgehalte an Zeolith ZK-19 (80 – 100 Gew.-%) und Zeolith W (90–100 Gew.-%) entstehen nur ohne Zugabe von Aluminium. Die Bildung von 90–100 Gew.-% Zeolith G bzw. 85–100 Gew. % Zeolith F ist dagegen durch die Zugabe von Aluminium möglich. In den Experimenten mit NaOH-Lösungen bildeten sich die Zeolithe Analcim, Na-Pc (Gismondin), HS (Sodalithhydrat) und Zeolith A. Hohe Prozentanteile an Zeolith Na-Pc (90–100 Gew.-%), HS (bis zu 100 Gew. %) und Analcim (bis zu 100 Gew.-%) wurden ohne Aluminium-Zugabe synthetisiert. Die Bildung von hohen Gehalten an Zeolith A (95–100 Gew. %) ist jedoch nur unter Zugabe von Aluminium, NaCl und Kristallkeimen möglich.Die Temperaturbeständigkeit der Zeolithe nimmt in der folgenden Reihenfolge ab: K-F > K-W - K-ZK-19 (Na), K-W Na, K-F Gsi-reich (Na), K-ZK-19 >> Na-Pc Gsi-am. Zeolith A weist bis zu Temperaturen von etwa 550°C eine gute Temperaturbeständigkeit auf, die in etwa der von Zeolith K-W entspricht. Bei höheren Temperaturen ist die Beständigkeit jedoch sehr gering.Die NH4+-Austauschkapazitäten (mÄqu/g) der verschiedenen Zeolithe erreichen folgende Werte: ZK-19:2,8 - 3,2; W:3,0 - 3,2; G:2,3 - 3,6; A:3,1 - 3,2; Na-Pc:3,5 -3,6; F:3,9 - 4,8.
With 2 Figures 相似文献
2.
3.
Rolf Zimmermann Konrad Hammerschmidt Gerhard Franz 《Contributions to Mineralogy and Petrology》1994,117(2):175-186
The40Ar-39Ar degassing spectra of white micas and amphiboles from three tectonic units of the central Tauern Window (Pennine basement and cover in the Eastern Alps) have been measured. White micas are classified as (1) pre-Alpine low-Si relic micas with an age value of 292 Ma, variously disturbed by the Alpine metamorphism; (2) Alpine phengitic micas of variable composition with an age between 32 and 36 Ma; (3) Alpine low-Si micas with a maximum age of 27 Ma. We attribute the higher Alpine ages to a blueschist facies event, whereas the lower age reflects the late cooling of the nappe pile. Blueschist facies phengites from the basement (Lower Schieferhülle) and the tectonic cover (Upper Schieferhülle) crystallized at a temperature below the closure temperature (T
c) for argon diffusion in white mica and record ages of 32 to 36 Ma. At the same time a thin, eclogite facies unit (Eclogite Zone) was thrust between the Lower and the Upper Schieferhülle and cooled from eclogite facies conditions at about 600°C at 20 kbar to blueschist facies conditions at 450°C or even 300°C at >10 kbar. Eclogite facies phengites closed for argon diffusion and record cooling ages, coinciding with the crystallization ages in the hanging and the footwall unit. Amphibole age spectra (actinolite, glaucophane, barroisite) are not interpretable in terms of geologically meaningful ages because of excess argon. 相似文献
4.
Konrad Dennerl 《Planetary and Space Science》2008,56(10):1414-1423
X-ray observations of Venus are so challenging that the first detection of Venusian X-rays succeeded only in January 2001, with the Chandra satellite. The X-rays from Venus were found to result from fluorescent scattering of solar X-rays in the Venusian thermosphere. An additional component, caused by charge exchange of highly charged heavy ions in the solar wind with atoms in the Venusian exosphere, was suspected, but could not be unambiguously detected. This was hampered by the fact that the observation occurred during solar maximum, when the solar X-ray flux is highest. In order to investigate the presence of an additional charge exchange component, Venus was observed again in March 2006 and October 2007 with Chandra, taking advantage of the fact that the solar X-ray flux had decreased considerably on its way to solar minimum. In fact, these subsequent observations were able to show that also the Venusian exosphere is emitting X-rays, due to its interaction with the solar wind. Here an overview of all the existing X-ray observations of Venus is presented, including first results from the most recent one, which took place after the arrival of Venus Express, providing the first ever opportunity to combine a remote X-ray observation of a planetary exosphere with simultaneous in situ measurements of the solar wind. 相似文献
5.
Recent observations of the surface of Mars have shown several fresh mid-latitude craters. Some of these craters show exposed ice (Byrne, S. et al. [2009]. Science 325, 1674-1676.). In some craters, albedo of ice slowly decreases, while in others, it remains nearly constant. We attempt to determine influence of the regolith structure on the rate of sublimation of ice. For this purpose we performed numerical simulations describing evolution of the exposed ice in model craters located at middle latitudes.We consider a new model for the structure and evolution of the material at- and beneath the crater floors. In contrast to the previous study by Dundas and Byrne (Dundas, C.M., Byrne, S. [2010]. Icarus 206, 716-728.) we do not investigate sublimation of dirty ice, and the related formation of a sublimation lag. Instead, we consider sublimation of a pure ice layer on top of layered regolith. In our model the observed reflectivity decreases due to the sublimation-driven changes of the optical properties of thinning clean ice. This offers an alternative to the deposition of the dust embedded in ice (sublimation lag).We have shown that in our model among many parameters affecting ice sublimation rate, volumetric fraction of water ice in the subsurface beneath the crater has the strongest influence. Hence observed darkening of the ice patch on the crater floor might be sufficient to determine the content of water ice in the subsurface. Our calculations show that an albedo decrease of fresh ice patches in mid-latitude craters can be explained by either strong dust sedimentation or, if this is excluded, by sublimation of a thin layer of water ice from the regolith with large thermal inertia. This is consistent with a large volumetric fraction of water ice beneath the crater floor and contributes to evidence for an extended subsurface water reservoir on Mars.The overall conclusion of our work is that a thin post-impact surface ice coating over ice-rich ground beneath the crater floors is consistent with the observations. 相似文献
6.
Hannes Konrad Malte Thoma Ingo Sasgen Volker Klemann Klaus Grosfeld Dirk Barbi Zdeněk Martinec 《Surveys in Geophysics》2014,35(6):1441-1458
We apply a coupled thermomechanical ice sheet—self-gravitating viscoelastic solid Earth model (SGVEM), allowing for the dynamic exchange of ice thickness and bedrock deformation, in order to investigate the effect of viscoelastic deformation on ice dynamics and vice versa. In a synthetic glaciation scenario, we investigate the interaction between the ice sheet and the solid Earth deformation, the glacial-isostatic adjustment (GIA), accounting for an atmospheric forcing depending on the ice sheet surface altitude. We compare the results from the coupled model to runs with the common elastic lithosphere/relaxing asthenosphere (ELRA) model, where the lithosphere is represented by a thin plate and the mantle relaxes with one characteristic relaxation time, as well as to a rigid Earth without any deformation. We find that the deformational behaviour of the SGVEM on ice dynamics (i.e. stored ice volume, ice thickness and velocity field) is comparable to the ELRA for an optimal choice of the parameters in steady state, but exhibits differences in the transient behaviour. Beyond the ice sheet, in the region of peripheral forebulge, the differences in the transient surface deformation between ELRA and SGVEM are substantial, demonstrating the inadequacy of the ELRA model for interpreting constraints on GIA in the periphery of the ice sheet, such as sea-level indicators and GPS uplift rates. 相似文献
7.
8.
Konrad Cehak 《Climatic change》1982,4(3):297-311
A Markov-chain model is fitted to the series of winter-strength parameters of five stations in the upper Danube Region. The
validity of the model is tested by an appropriate Gaussian test-statistic. Having calculated the matrices of transition probabilities,
boundaries for them are derived from the theory of Markov-chains as well as means of the first transition times with their
standard deviations; further, forecasts are derived for the next but one winter. As in all cases the standard deviations for
prognostic values are rather large one should be very careful in making annual forecasts, which is also demonstrated by a
testforecast. 相似文献
9.
10.
Konrad Cehak 《Meteorology and Atmospheric Physics》1964,14(2):210-212
Zusammenfassung Es wird ein Diagramm für dent-Test gegeben, aus dem man bei Kenntnis vonf, d undS allein entscheiden kann, ob die Stichprobe einent-Wert ergibt, der größer alst
ist, oder nicht.
Mit 1 Textabbildung 相似文献
Summary A graph is given for thet-test, by means of which one can decide whether the sample would give a value oft larger thant or not, only from the knowledge. off, d andS.
Résumé L'auteur présente, pour le testt, un diagramme qui permet de dire si la valeur det dépasse celle det ou non, à la seule connaissance def, d etS.
Mit 1 Textabbildung 相似文献