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41.
Dušan Trávníček 《GeoJournal》1994,32(3):189-190
Main features of the history and activities of the Czech Geographical Society are described. 相似文献
42.
B. Trček 《Environmental Geology》2008,55(2):269-276
The role of the unsaturated zone in the karst aquifer hydraulic behaviour was brought into focus in these studies of the catchment
of the Hubelj spring (SW Slovenia). The variations of natural tracers in precipitation and in groundwater during a summer
storm event made it possible to trace local flow and solute transport in the observed aquifer. The results produced data on
the aquifer recharge, storage and discharge processes, as well as on mechanisms that affected them, which reflects a karst
groundwater dynamics also at a regional scale. They point out the significance of effects of the fast preferential flow—epiflow
that is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. Numerous arguments indicate
that the karst aquifer flow and solute transport mechanisms depend on the hydraulic behaviour of the epikarst zone. 相似文献
43.
Al-Mazraa is a heavily populated suburb of Damascus (Syria) with agricultural activity. It is adjacent to the Cretaceous Qassioun Mountain Range, from which it is structurally separated by the Damascus fault. Al-Mazraa waterworks abstracts from a shallow Quaternary aquifer, whose recharge processes are unidentified. The functions of Qassioun Mountain, the Damascus fault, the agricultural activities, the ascending deeper groundwater, and the through-flowing Tora River are not well understood and they are, hence, subject to study. The application of hydrochemical parameters and ratios in combination with signatures of δD and δ18O revealed that recharge predominantly occurs in the outcropping Cretaceous rocks through subsurface passages rather than through influent conditions of the Tora River or through direct rainfall. Interestingly, high Na/Cl ratios indicate contact with volcanic rocks which exist within the Cretaceous anticline and also in the subsurface of the studied Quaternary aquifer. Evidence for deeper circulating groundwater is given, since replenishing waters are up to 4 °C warmer and have much lower nitrate concentrations than the groundwater in the study area. From these points, it is indicated that the Damascus fault is conductive in respect to groundwater, rather than being impermeable, as it is elsewhere. 相似文献
44.
R. G. Trønnes 《Mineralogy and Petrology》2002,74(2-4):129-148
Summary The phase relations of K-richterite, KNaCaMg5Si8O22(OH)2, and phlogopite, K3Mg6 Al2Si6O20(OH)2, have been investigated at pressures of 5–15 GPa and temperatures of 1000–1500 °C. K-richterite is stable to about 1450 °C
at 9–10 GPa, where the dp/dT-slope of the decomposition curve changes from positive to negative. At 1000 °C the alkali-rich,
low-Al amphibole is stable to more than 14 GPa. Phlogopite has a more limited stability range with a maximum thermal stability
limit of 1350 °C at 4–5 GPa and a pressure stability limit of 9–10 GPa at 1000 °C. The high-pressure decomposition reactions
for both of the phases produce relatively small amounts of highly alkaline water-dominated fluids, in combination with mineral
assemblages that are relatively close to the decomposing hydrous phase in bulk composition. In contrast, the incongruent melting
of K-richterite and phlogopite in the 1–3 GPa range involves a larger proportion of hydrous silicate melts.
The K-richterite breakdown produces high-Ca pyroxene and orthoenstatite or clinoenstatite at all pressures above 4 GPa. At
higher pressures additional phases are: wadeite-structured K2SiVISiIV
3O9 at 10 GPa and 1500 °C, wadeite-structured K2SiVISiIV
3O9 and phase X at 15 GPa and 1500 °C, and stishovite at 15 GPa and 1100 °C. The solid breakdown phases of phlogopite are dominated
by pyrope and forsterite. At 9–10 GPa and 1100–1400 °C phase X is an additional phase, partly accompanied by clinoenstatite
close to the decomposition curve. Phase X has variable composition. In the KCMSH-system (K2CaMg5Si8O22(OH)2) investigated by Inoue et al. (1998) and in the KMASH-system investigated in this report the compositions are approximately K4Mg8Si8O25(OH)2 and K3.7Mg7.4Al0.6Si8.0O25(OH)2, respectively.
Observations from natural compositions and from the phlogopite-diopside system indicate that phlogopite-clinopyroxene assemblages
are stable along common geothermal gradients (including subduction zones) to 8–9 GPa and are replaced by K-richterite at higher
pressures. The stability relations of the pure end member phases of K-richterite and phlogopite are consistent with these
observations, suggesting that K-richterite may be stable into the mantle transition zone, at least along colder slab geotherms.
The breakdown of moderate proportions of K-richterite in peridotite in the upper part of the transition zone may be accompanied
by the formation of the potassic and hydrous phase X. Additional hydrogen released by this breakdown may dissolve in wadsleyite.
Therefore, very small amounts of hydrous fluids may be released during such a decomposition.
Received April 10, 2000; revised version accepted November 6, 2000 相似文献
45.
Lisse C. M. Dennerl K. Englhauser J. Trümper J. Marshall F. E. Petre R. Valinia A. Kellett B. J. Bingham R. 《Earth, Moon, and Planets》1997,77(3):283-291
The discovery of X-ray emission from comets has created a number of questions about the physical mechanism producing the radiation.
There are now a variety of explanations for the emission, from thermal bremsstrahlung of electrons off neutrals or dust, to
charge exchange induced emission from solar wind ions, to scattering of solar X-rays from attogram dust, to reconnection of
solar magnetic field lines. In an effort to understand this new phenomenon, we observed but failed to detect in the X-ray
the very dusty and active comet C/Hale-Bopp 1995 O1 over a two year period, September 1996 to December 1997, using the ROSAT
HRI imaging photometer at 0.1–2.0 keV and the ASCA SIS imaging spectrometer at 0.5–10.0 keV. The results of our Hale-Bopp
non-detections, when combined with spectroscopic imaging 0.08–1.0 keV observations of the comet by EUVE and BeppoSAX, show
that the emission has the same spectral shape and strong variability seen in other comets. Comparison of the ROSAT photometry
of the comet to our ROSAT database of 8 comets strongly suggests that the overall X-ray faintness of the comet was due to
an emission mechanism coupled to gas, and not dust, in the comet’s coma.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
46.
47.
G. Krämer H. J. Einighammer G. Elwert H. Bräuninger H. H. Fink J. Trümper 《Solar physics》1978,57(2):345-367
Soft X-ray photographs of the Sun taken at O vii 21.6 Å and in a spectral band ranging from 13.2 to 22.1 Å have been analysed in order to establish spatially resolved maps of temperature and emission measure for several active regions in the corona. The photographs were taken on 11 March, 1971, and on 2 March, 1972, with Fresnel zone plate cameras which were flown on ESRO and NRL sounding rockets.In Part I of this paper we first deal with those aspects of the instrumentation which are important for setting up a suitable image analysis procedure. We discuss the characteristics of the wavelength dependent image formation by zone plates combined with absorption filters. Results of the calibration of the X-ray film are given. Then we describe a specific iterative data reduction procedure and finally present the resulting maps of temperature and emission measure for a selected active region. In Part II corresponding results for further active regions will be given and discussed. 相似文献
48.
49.
Rudolf Trümpy 《International Journal of Earth Sciences》1982,71(3):711-723
Zusammenfassung Kurze Übersicht über paläogeographische, paläotektonische und paläoklimatologische Probleme der Trias, unter Ausklammerung des Germanischen Beckens; allgemeiner Rahmen zu den Referaten der Trias-Tagung 1982 in Würzburg.
Short review of paleogeographic, paleotectonic and paleoclimatological problems of the Triassic system, outside of the Germanic Basin. General framework to the papers presented at the 1982 symposium on the Triassic.
Résumé Brève vue d'ensemble des problèmes paléogéographiques, paléotectoniques et paléoclimatiques du Trias, en dehors du bassin germanique. Cadre général des communications présentées lors du symposium sur le Trias de 1982.
, , .相似文献
50.
von Engelhardt W. Goguel Jean Hubbert M. King Prentice J. E. Price R. A. Trümpy R. 《Environmental Geology》1976,1(4):193-206
The earth with all its inhabitants, including man, has had a long history as a slowly evolving complex system which normally
exists in a state of stable dynamic equilibrium. Explosive growth in the human population, in the per capita use of nonrenewable
resources, and in the degree of human disruption of established ecosystems — the hallmark of man's recent and rapid emergence
as the dominant species on the face of the earth — represents a major departure from this state of equilibrium and an ecological
crisis of global dimensions. This growth, and the rapid changes that arise from it, have had such a pervasive influence on
the collective experience of man that they have come to be regarded as the normal course of events on a stable earth. This
has fostered the notion that growth will always be essential for further improvements in the quality of human life.
The emergence of a global technological civilization results from man's ingenuity in devising ways of using an ever increasing
proportion of energy available at the earth's surface. Rapid growth began only two hundred years ago when the developing technology
of the industrial revolution made possible the large-scale exploitation of the earth's fossil-fuel resources and the creation
of positive feedback between growth in technology and growth in fossil-fuel production.
Annual growth rates in world production of fossil fuels and ores of representative industrial metals, when compared with the
nature and finite magnitude of the earth's resources, lead to the inescapable conclusion that the present episode of exponential
growth can only be a transitory epoch of a few centuries duration within the totality of human history. Solar radiation offers
the prospect of large supplies of energy with minimal environmental impact. However, constraints on growth due to the finite
nature of food and mineral resources and the effects of environmental degradation can only be loosened in this way, not removed.
Mankind faces an inevitable transition from a brief interlude of exponential growth to a stable condition characterized by
rates of growth so slow as to be regarded essentially as a state of no growth. Failure to respond rationally and promptly
to this situation could be disastrous. 相似文献