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81.
Walther Klüpfel 《International Journal of Earth Sciences》1925,16(3):190-211
Ohne Zusammenfassung 相似文献
82.
83.
Über das Alter junger Gebirgserhebung,die Datierung von Hochflächen und die Deutung von Höhenreliefs
Walther Klüpfel 《International Journal of Earth Sciences》1931,22(5):308-313
Ohne ZusammenfassungErweiterung einer Diskussionsbemerkung auf der Hauptversammlung der Geologischen Vereinigung in Frankfurt a. M. Januar 1931. 相似文献
84.
85.
This paper presents a model of mobile space in the Sahel based on the two logics of circulation and production. An overview of the epistemological origins of the model shows how spatial structuring in (and of) the Sahel has been progressively transformed by the territorial action of economic actors, colonial powers, states and development programmes. The particular focus is on nomadic and cross‐border spaces – configurations that offer an ideal perspective on the mobility of space. The model confirms the hypothesis that economic actors, states and development agencies all aim to improve the way uncertainty is managed, but remain profoundly divided over what strategies to adopt. Whereas free flows allow economic actors to obtain products wherever these may be available, states and development agencies conceive of territory as a resource that must drive the specialization of production. The proposed model also suggests that mobile space is not peculiar to the Sahel and that the spatial logics of circulation and production in the Sahel are also present in the process of globalization. It provides conceptual resources that could lead to other models potentially applicable to understanding uncertainty in a highly mobile, globalized world. 相似文献
86.
David T. A. Symons Kazuo Kawasaki Sabine Walther Gregor Borg 《Mineralium Deposita》2011,46(2):137-152
Syngenetic, diagenetic and epigenetic models have been proposed for the Cu?CZn?CPb Kupferschiefer mineralization at Sangerhausen, Germany. Paleomagnetic and rock magnetic measurements have been made on 205 specimens from mine workings on the margin of the Sangerhausen Syncline. The mineralization is richest in the ??0.5-m-thick Upper Permian (258?±?2?Ma) Kupferschiefer black marly shale (nine sites) and dies out over ??0.2?m in the underlying Weisliegend sandstones (three sites) and overlying Zechstein carbonates (two sites). Except for one site of fault zone gypsum, characteristic remanent magnetization directions were isolated for all 14 sites using alternating field and thermal step demagnetization. These directions provide a negative fold test, indicating that the remanence postdates Jurassic fault block tilting. Rock magnetic measurements show that the Kupferschiefer shale marks a redox front between the oxidized Weissliegend sandstones and non-oxidized Zechstein carbonates. The 14 site directions give a Late Jurassic paleopole at 149?±?3?Ma. It is significantly different from the paleopole reported by E.C. Jowett and others for primary or early diagenetic Rote F?ule alteration that gives an age of 254?±?6?Ma on the current apparent polar wander path and is associated with Kupferschiefer mineralization. We suggest that the Late Jurassic extensional tectonic event that formed the nearby North German Basin also reactivated Variscan basement faults and extended them up through the overlying strata, thereby allowing hydrothermal basement fluids to ascend and epigenetically mineralize the Kupferschiefer shale. The possibility of a 53?±?3?Ma mineralization age is also considered. 相似文献
87.
Walther N. Spjeldvik 《Planetary and Space Science》1981,29(11):1215-1226
Ions in the trapping region of the earth's magnetosphere are subject to physical and chemical interactions which control their absolute and relative abundances. Charge exchange reactions act to establish a distribution of ionic states that is largely determined by the chemical properties of the individual species. Convection (“drift”) mechanisms and cross-L diffusion cause ions to be distributed over the entire trapping region with flux intensities determined by the nature and strength of the ion source, transport and loss mechanisms which in general are dependent on energy, mass and charge. Current theories describe ion transport through path tracing for individual particles or by radial diffusion for a population as a whole based on stochastic analysis; a comprehensive treatment of the combined convection and diffusion for trapped and non-trapped ions is yet to be developed. Even in studies where diffusion is the sole transport mechanism considered, only equatorially mirroring particles () have been theoretically treated. There are clearly both upper and lower bounds on the ion energy beyond which diffusion theory ceases to be valid: at high energies where the ion gyroradius becomes too large for the adiabatic approximations to be valid and at low energies where convective drift is a dominant process. In spite of the known shortcomings of the diffusion theory and associated modeling, intriguing theoretical predictions of the relative ionic composition of the radiation belts have been made and some of them are now confirmed by direct observation. Among them is the predicted importance of ions heavier than protons at ring current energies of tens of keV which follows from the charge exchange chemistry. 相似文献
88.
H.-J. Walther 《洁净——土壤、空气、水》1991,19(6):710-710
89.
90.
Prof. Dr. Walther E. Petrascheck 《International Journal of Earth Sciences》1973,62(3):617-626
The typical features of metallogenic provinces in the orogenic belts are described and explained in the sense of the modern plate tectonics. Some phenomena, however, are not in agreement with the scheme of “consuming margins” — particulary the timing of the magmatic-tectonic cycles and the assembly of ore metals in mountain chains. Therefore the older assumption of a synorogenic anatexis of the continental crust has to be maintained. The metals of the continental crust got combined with the volatiles and with the metals of the basaltic magma to form ore deposits. The Alpine-Mediterranean metallogenesis seems to be the result of repeated and interfering subduction (producing deposits of Cu, Fe, Cr) and palingenesis (producing deposits of Pb-Zn, Au, Ag etc.) in Cretaceous and in Tertiary time. In the cratonic areas, three types of metallogenic provinces can be distinguished: Huge lakkolithes of liquid basic mantle magma with Cr, Ni, Cu, Pt — areas of granitization with a haphazard distribution of different ores — and the simple stratiform deposits in the stable platform cover; the latter as well as the small deposits along rifts and separating margins can best be explained as mobilisates created by heat flow and some mantle volatiles. 相似文献