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351.
Konrad Richter 《International Journal of Earth Sciences》1937,28(1-2):69-77
Zusammenfassung Bändertone, Osbuckel und Toteiskragen der Diluviallandschaft Norddeutschlands werden auf ihre Brauchbarkeit als Geochronometer untersucht. Es zeigt sich stets, daß nur überraschend kleine Zahlenwerte festzustellen sind. Ein Versuch, die Gesamtdauer der Weichseleiszeit zu errechnen, scheint aussichtsreich, obwohl er nicht exakt durchführbar ist. Es wird dadurch zumindestens bewiesen, daß in der Strahlungskurve vonMilankowitsch lediglich die Klimazacke vor 22 300 Jahren mit der gesamten Weichseleiszeit identifiziert werden könnte. 相似文献
352.
Max Richter 《International Journal of Earth Sciences》1936,27(1):91-96
Ohne Zusammenfassung 相似文献
353.
Gerhard Richter 《International Journal of Earth Sciences》1934,25(2):95-97
Ohne ZusammenfassungVorläufiger Bericht! Eine ausführlichere Veröffentlichung der Untersuchungen erfolgt an anderer Stelle. 相似文献
354.
M. Richter 《International Journal of Earth Sciences》1933,24(3-4):271-271
Ohne Zusammenfassung 相似文献
355.
356.
Rud Richter 《International Journal of Earth Sciences》1928,19(2):155-160
Ohne Zusammenfassung 相似文献
357.
B. A. Ridley T. Zeng Y. Wang E. L. Atlas E. V. Browell P. G. Hess J. J. Orlando K. Chance A. Richter 《Journal of Atmospheric Chemistry》2007,57(3):255-280
During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) program, aircraft flights during April 7–11, 2000
revealed a large area air mass capped below ∼500 m altitude over Hudson Bay, Canada in which ozone was reduced from normal
levels of 30–40 ppbv to as low as 0.5 ppbv. From some of the in-situ aircraft measurements, back-trajectory calculations,
the tropospheric column of BrO derived from GOME satellite measurements, and results from a regional model, we conclude that
the event did not originate from triggering of reactive halogen release in the sub-Arctic region of Hudson Bay but resulted
from such an event occurring at higher latitudes over the islands of the northern Canada Archipelago and nearby Arctic Ocean
with subsequent transport over a distance of 1,000–1,500 km to Hudson Bay. BrO
x
remained active during this transport despite considerable changes in the conditions of the underlying surface suggesting
that chemical recycling during transport dominated any local halogen input from the surface. If all of the tropospheric column
density of BrO is distributed uniformly within the surface layer, then the mixing ratio of BrO derived from the satellite
measurements is at least a factor of 2–3 larger than derived indirectly from in situ aircraft measurements of the NO/NO2 ratio. 相似文献
358.
Stefan Niggemann Augusto Mangini Detlev K Richter 《Earth and Planetary Science Letters》2003,216(4):539-547
Calcitic stalagmites from caves in the Sauerland, Germany, prove the existence of sub-Milankovitch cycles in precipitation during the last 6000 yr. The δ18O record dated with Th/U is interpreted as an indicator of paleohumidity. Spectral analysis of δ18O from 6000 a BP up to the recent top of a stalagmite from the Atta cave yields statistically significant peaks at 1450, 117, 64 and 57 a. Additionally we find a good correlation of the stalagmite’s δ18O and Δ14C from European tree rings. The 1450 a cycle in the stalagmite probably is analogous to the pervasive millennial scale climate cycle described by Bond et al. [Science 278 (1997) 1257-1266; 294 (2001) 2130-2136] derived from the amount of ice rafted debris in deep sediments from the North Atlantic. Our results suggest that the centennial to millennial shifts observed in the North Atlantic are accompanied by synchronous shifts of the climate in Northern and Central Europe, which most probably can be attributed to solar irradiation variations. 相似文献
359.
Because South Africa is situated in a semi-dry region, the limited water resources are placed under increasing pressure by
consumers from different sectors. Irrigation consumes more than half of the available water resources in South Africa. In
the Northwest Province large volumes of water are found in dolomitic aquifers. Since 1970 irrigation from these aquifers has
resulted in an exponential growth in the withdrawal of groundwater. The purpose of this study is to evaluate the effectiveness
of groundwater utilization with centre-pivot irrigation in the Northwest Province, as well as to identify the most important
variables that influence this effectiveness. Factor Analysis and Multiple Regression Analysis were used to establish a model
with which the probable effectiveness of groundwater utilization on a specific farm can be predicted. The results show that
four variables have a significant effect on the net profit margin from centre-pivot irrigation in the study area, namely:
• Knowledge regarding the water capacity of the soil • Adjusting irrigation according to precipitation • The use of a yield
target for fertiliser application, and • Soil characteristics The above parameters were used to develop a model with which
farmers in the study area can be ranked according to the effectiveness of their water usage for centre-pivot irrigation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
360.
Experimental diffusion couples were used to study chemical diffusion between molten rhyolite and basalt with special emphasis on the associated fractionation of calcium and lithium isotopes. Diffusion couples were made by juxtaposing firmly packed powders of a natural basalt (SUNY MORB) and a natural rhyolite (Lake County Obsidian) and then annealing them in a piston cylinder apparatus for times ranging from 0.1 to 15.7 h, temperatures of 1350-1450°C, and pressures of 1.2-1.3 GPa. Profiles of the major elements and many trace elements were measured on the recovered quenched glasses. The diffusivities of all elements except lithium were found to be remarkably similar, while the diffusivity of lithium was two to three orders of magnitude larger than that of any of the other elements measured. Chemical diffusion of calcium from molten basalt into rhyolite was driven by a concentration ratio of ∼18 and produced a fractionation of 44Ca from 40Ca of about 6 ‰. Because of the relatively low concentration of lithium in the natural starting materials a small amount of spodumene (LiAlSi2O6) was added to the basalt in order to increase the concentration difference between basalt and rhyolite, which was expected to increase the magnitude of diffusive isotopic fractionation of lithium. The concentration ratio between Li-doped basalt and natural rhyolite was ∼15 and the resulting diffusion of lithium into the rhyolite fractionated 7Li from 6Li by about 40‰. We anticipate that several other major rock-forming elements such as magnesium, iron and potassium will also exhibit similarly larger isotopic fractionation whenever they diffuse between natural melts with sufficiently large differences in the abundance of these elements. 相似文献