全文获取类型
收费全文 | 383篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 25篇 |
地球物理 | 78篇 |
地质学 | 157篇 |
海洋学 | 12篇 |
天文学 | 91篇 |
自然地理 | 17篇 |
出版年
2023年 | 2篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 18篇 |
2009年 | 29篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 18篇 |
2004年 | 11篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1984年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1975年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1967年 | 3篇 |
1958年 | 2篇 |
1956年 | 2篇 |
1953年 | 1篇 |
1952年 | 1篇 |
1951年 | 1篇 |
1950年 | 2篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1942年 | 1篇 |
1940年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有394条查询结果,搜索用时 78 毫秒
161.
Volker Hanisch 《Astronomische Nachrichten》1986,307(3):170-170
162.
The structure, symmetry and origin of the incommensurately modulated OS phase of tridymite (SiO2) and its lock-in to the OP three-fold superlattice structure are discussed in a computational study. The structure of the
OS phase (which has not been determined experimentally) is deduced as the only geometrically possible structure derived from
the parent OC phase by rotation and translation of the SiO4 tetrahedra without significant distortion of these units. It can be visualised conveniently in terms of the McConnell formalism
of two component difference structures C1 and C2 whose space group symmetries are derived. The results are in accordance with the known lock-in structure at wave vector Q=
a
*. In the latter, the ±C1 regions expand and the structure can square up in a very general way to take advantage of the lost symmetries (lost compared
with the OC phase).
Received: 4 August 1997 / Revised, accepted 24 November 1997 相似文献
163.
164.
Prof. Dr. Volker Jacobshagen 《International Journal of Earth Sciences》1992,81(1):185-197
Within the fracturai pattern of Morocco, 35–45° and 70–90° directions are predominant. Most of the faults originated already during the Upper Palaeozoic and were repeatedly reactivated, later on. Two of the large fracture systems are considered here.The South Atlas fault system (SAF) is composed of different faults with directions varying between 45–90°. They were not functionally connected to the southern hinge of the High Atlas until its Miocene uplift. Today, it seems to be inactive on the whole. Both the tectonic data and the facies distribution of Mesozoic strata contradict clearly the interpretation that the SAF is a huge wrench-fault or even the Mesozoic plate margin of Africa. The SW striking Transalboran fault system (TAF) is still active. It crosses Morocco from Melilla to Agadir, showing again singular faults which are unified to extended lineaments only in a few areas. The intervals between the faults are bridged by linear arrangements of earthquake hypocenters. Sinistral massflow within the deeper parts of the lithosphere seems to be compensated at the surface by movements along pre-existing faults. For the Moroccan segment of the TAF, a sinsitral displacement is testified at least since the Oligocene, while the northeastern segments from the Rif to Spain did not even originate until the Pliocene. This would mean that sinistral shear was transmitted from Africa into the accreted Alboran and Iberia blocks after the Miocene collision.
Zusammenfassung Unter den großen Störungen Marokkos dominieren die Richtungen 35–45° und 70–90°. Sie wurden zumeist im Jungpaläozoikum angelegt und später wiederholt reaktiviert. Zwei der großen Bruchsysteme wurden näher untersucht:Die Südatlas-Störungszone (SAF) besteht aus unzusammenhängenden Brüchen unterschiedlichen Alters, deren Streichrichtung von 45–90° variiert. Diese wurden erst bei der miozänen Heraushebung des Hohen Atlas zu dessen südlichem Scharnier umfunktioniert. Heute sind nur wenige Störungen des Systems aktiv. Diese Befunde und ebenso die stratigraphisch-fazielle Entwicklung im Mesozoikum Marokkos verbieten, die SAF als bedeutende Lateralverschiebungszone oder gar als nördliche Plattengrenze Afrikas zu interpretieren.Das noch heute aktive, SW-streichende Transalboran-Störungssystem (TAF) setzt sich durch Marokko von Melilla bis Agadir fort. Es besteht an der Oberfläche ebenfals aus singulären Brüchen, die sich nur bereichsweise zu längeren Linien zusammenschließen. Zwischen den Störungen vermitteln linear angeordnete Herde rezenter Erdbeben: Sinistraler Massentransport an einer Tiefenstörung wird an der Oberfläche durch Teilbewegungen an präexistenten Störungen kompensiert. Während in Marokko südlich des Rifs sinistraler Versatz mindestens seit dem Oligozän nachgewiesen ist, entstand die TAF vom Rif bis nach Spanien erst im Pliozän. Die sinistrale Scherung tritt also erst nach der miozänen Kollision von Afrika aus auf die nunmehr akkretierten Mikroplatten- Alboran-Block und Iberia - über.
Résumé Les grandes fractures du Maroc présentent les deux directions prédominantes de 35°-40° et 70°–90°. La plupart de ces fractures datent du Paléozoïque supérieur et ont été réactivées plusieurs fois au Mésozoïque et au Cénozoïque. Deux de ces grands systèmes de fractures sont considérés ici.L'accident sud-atlasien (SAF) est composé de fractures indépendantes d'âges divers dont la direction varie entre 45° et 90°. Ces fractures ne se sont connectées à la charnière du Haut Atlas qu'après le soulèvement miocène de celui-ci. Aujourd'hui, quelques failles seulement sont encore actives. Ces observations, ainsi que la distribution des faciès du Mésozoïque au Maroc sont en contradiction avec le modèle qui voit dans le SAF une grande zone de décrochement ou même la marge nord de la plaque africaine.L'accident transalboran (TAF), encore actif aujourd'hui, traverse le Maroc en direction sudouest de Mélilla à Agadir. Il est composé de failles discontinues, connectées entre elles seulement à quelques endroits. Les intervalles qui séparent ces failles sont jalonnés par des alignements rectilignes d'hypocentres de séismes récents. L'ensemble correspond à un décrochement sénestre profond compensé en surface par des mouvements le long de failles préexistantes. Ce décrochement sénestre, dans le segment du TAF situé au sud du Rif, s'est manifesté au moins depuis l'Oligocène, tandis que la partie qui s'étend du Rif à l'Espagne méridionale n'a été active qu'à partir du Pliocène. Ceci signifie que ce cisaillement sénestre ne s'est transmis de l'Afrique vers l'Europe qu'après l'accrétion, au Miocène, de la microplaque Alboran et du bloc ibérique.
35–40° 70–90°. , , , . . (SAF) , 45 90°. . . , - SAF , . Transalboran (TAF), , -, . , . , : . , , - , , F . .. - .相似文献
165.
Volker?St?hleEmail author Rainer?Altherr Mario?Koch Lutz?Nasdala 《Contributions to Mineralogy and Petrology》2004,148(2):150-159
A dense (~3.34 g cm–3) garnet–sillimanite-rich metamorphic rock from the suevite breccia of the Ries impact crater was studied by scanning-electron microscopy and Raman microprobe spectroscopy. In the strongly shocked rock clast kyanite was formed from sillimanite under momentary high pressures of natural shock waves. Kyanite aggregates were found as thin (~0.3–2.0 m) seams along grain boundaries between, and fractures within, sillimanite grains. Within these seams kyanite c-axes are oriented perpendicular to original grain boundaries and fractures. In addition, larger (up to 10 m) isolated kyanite grains were rarely found within host sillimanite. Filamentary kyanite aggregates and isolated crystals typically show shrinkage cracks due to volume decrease (~10%). Locally, broad interstices between sillimanite crystals are filled with aluminosilicate glass containing a high volume fraction of sub-micrometer-sized euhedral crystals. The silica-rich glass suggests incongruent melting of sillimanite at local post-shock temperatures significantly higher than 1,300°C. The edges of adjacent sillimanite grains are thermally and chemically altered. The local generation of temperature spikes is attributed to strong shock wave interactions due to very high shock impedance contrasts. 相似文献
166.
167.
Doz. Dr. Volker Fritsch 《Pure and Applied Geophysics》1950,17(3-4):199-203
168.
Doz. Dr. Volker Fritsch 《Pure and Applied Geophysics》1950,17(3-4):210-213
Summary Experiments to determine the thickness of glaciers by high frequency prospecting were carried out on the Austrian glacier Hintereisferner in 1938. After the war electrohydrographical measurements on glacier rivulets were carried out in the Kaprun Valley. The resistance of the glacier water fluctuates according to the time of season. It depends on the respective composition of these waters (Fig. 2). Therefore the geologic and mineralogic properties of the glacier-water may be deducted from the electric resistance. Especially the amount of surface water may be deducted (Fig. 3). An example is shown in Fig. 4. 相似文献
169.
Manfred Burianek Johannes Birkenstock Philipp Mair Volker Kahlenberg Olaf Medenbach Robert D. Shannon Reinhard X. Fischer 《Physics and Chemistry of Minerals》2016,43(7):527-534
Single crystals of B2O3 are needed for the precise determination of the refractive indices used to calculate the electronic polarizability α of 3-coordinated boron. The α(B) values in turn are used to predict mean refractive indices of borate minerals. Since the contribution of boron to the total polarizability of a mineral is very low, the synthetic compound B2O3 represents an ideal model system because of its high molar content of boron. Millimeter-sized crystals were synthesized at 1 GPa in a piston-cylinder apparatus. The samples were heated above the liquidus (800 °C), subsequently cooled at 15 °C/h to 500 °C and finally quenched. The refractive indices were determined by the immersion method using a microrefractometer spindle stage. The refractive indices n o = 1.653 (3) and n e = 1.632 (3) correspond to a total polarizability for B2O3 of α = 4.877 Å3. These values were used to determine the electronic polarizability of boron of α(B) = 0.16 Å3. Although the surface of the B2O3 crystals was coated with a hydrous film immediately after being exposed to air, its bulk crystallinity is retained for a period of at least 2 months. 相似文献
170.
Martin?IvanovEmail author Kirsten?Warrach-Sagi Volker?Wulfmeyer 《Theoretical and Applied Climatology》2018,132(1-2):239-261
A new approach for rigorous spatial analysis of the downscaling performance of regional climate model (RCM) simulations is introduced. It is based on a multiple comparison of the local tests at the grid cells and is also known as ‘field’ or ‘global’ significance. The block length for the local resampling tests is precisely determined to adequately account for the time series structure. New performance measures for estimating the added value of downscaled data relative to the large-scale forcing fields are developed. The methodology is exemplarily applied to a standard EURO-CORDEX hindcast simulation with the Weather Research and Forecasting (WRF) model coupled with the land surface model NOAH at 0.11 ° grid resolution. Daily precipitation climatology for the 1990–2009 period is analysed for Germany for winter and summer in comparison with high-resolution gridded observations from the German Weather Service. The field significance test controls the proportion of falsely rejected local tests in a meaningful way and is robust to spatial dependence. Hence, the spatial patterns of the statistically significant local tests are also meaningful. We interpret them from a process-oriented perspective. While the downscaled precipitation distributions are statistically indistinguishable from the observed ones in most regions in summer, the biases of some distribution characteristics are significant over large areas in winter. WRF-NOAH generates appropriate stationary fine-scale climate features in the daily precipitation field over regions of complex topography in both seasons and appropriate transient fine-scale features almost everywhere in summer. As the added value of global climate model (GCM)-driven simulations cannot be smaller than this perfect-boundary estimate, this work demonstrates in a rigorous manner the clear additional value of dynamical downscaling over global climate simulations. The evaluation methodology has a broad spectrum of applicability as it is distribution-free, robust to spatial dependence, and accounts for time series structure. 相似文献