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排序方式: 共有134条查询结果,搜索用时 19 毫秒
1.
Amy E. Clifton Carolina Pagli Jna Finndís Jnsdttir Kristjana Eythorsdttir Kristin Vogfjr 《Tectonophysics》2003,369(3-4):145-154
Three large earthquakes (Mw>4.5) were triggered within 5 min, 85 km west of a Mw 6.5 earthquake in the South Iceland Seismic Zone (SISZ). We report on surface effects of these triggered earthquakes, which include fresh rupture, widespread rockfall, disrupted rockslides and block slides. Field data confirm that the earthquakes occurred along N-striking right-lateral strike-slip faults. Field data also support the conclusion from modeling of InSAR data that deformation from the second triggered event was more significant than for the other two. A major hydrological effect was the draining of water through an open fissure on a lake bed, lowering the lake level by greater than 4 m. Field relationships suggest that a component of aseismic slip could have been facilitated by water draining into the fault zone. 相似文献
2.
The purpose of this study was to examine physiological correlates to the phenomenon of epidermal browning and saguaro decline in Saguaro National Monument. Gas exchange characteristics, surface temperatures, and the extent of epidermal browning in tissues of both healthy and declining saguaro cacti (Carnegiea gigantea) at different solar orientations were examined in eight long-term monitoring plots in the Rincon Mountain District of the Saguaro National Monument near Tucson, Arizona during both wet and dry seasons and years.Daily maximum surface temperatures were greatest on west-oriented tissues, as predicted by a simple model. However, south- and south-west-oriented tissues showed the highest browning indices, suggesting that browning may be more related to cumulative thermal loading than to extreme late afternoon temperature events. During the wet season, maximum nocturnal CO2uptake rates and total nocturnal CO2uptake were negatively correlated with browning index. Uptake rates during dry seasons and dry years was minimal, and not related to browning indices. However, healthy tissues of saguaros that also had tissues with high browning indices had wet-season maximum CO2uptake rates as high as saguaros without damaged tissues, suggesting that the browning is not systemic but rather is tissue- and angle-specific. Instantaneous measures of water-use efficiency did not vary significantly or predictably by angle, but rather were greatest during night-time and in tissues when CO2uptake was greatest. We suggest that browning symptoms on cacti are most likely due to natural abiotic stress, and are unrelated to systemic pollution stress or increased UV-B radiation. 相似文献
3.
Increased use of wood can substitute more energy demanding products and thus contribute to a long-term solution to the global warming problem. The aim of this article is to provide an empirical study on this substitution impact, its cost-effectiveness, and which methodological assumptions that are of highest importance for the results obtained. We have made a case study where we compare use of various flooring materials. The results show that floor covering in solid oak causes lower greenhouse gas (GHG) emissions than the other materials. The difference can be ranked in the following order, after their potential for reduction in GHG emissions: Carpet in wool, carpet in polyamide, vinyl, and linoleum. At 2% pro anno discount rate, the avoided GHG emission in tons per m3 of oak flooring used is 0.1–1.9 for linoleum, and 11.8–15.5 for wool carpets. Unless the solution in solid oak is on total less expensive over the lifetime of the building, only the price of avoided emissions from a substitution between solid oak and carpet in wool is reasonable, compared to present carbon fees. The assumptions that influence the result most are choice of discount rate, carbon fixation on forest area, and waste handling. Empirical case studies like this indicate GHG emission reduction potentials caused by substitution, but should be complemented by dynamic input/output analyses and econometric studies. To analyse the flow of CO2 over time, they should also be linked to forest management models. 相似文献
4.
Arsenic mobility in alteration products of sulfide-rich, arsenopyrite-bearing mine wastes, Snow Lake, Manitoba, Canada 总被引:2,自引:0,他引:2
Kristin A. Salzsauler Nikolay V. Sidenko Barbara L. Sherriff 《Applied Geochemistry》2005,20(12):2303-2314
The Arsenopyrite Residue Stockpile (ARS) in Snow Lake, Manitoba contains approximately 250,000 tons of cyanide treated, refractory arsenopyrite ore concentrate. The residue was deposited between 1950 and 1959 in an open waste rock impoundment, and remained exposed until 2000, when the pile was capped with layers of waste rock and clay. During the time when the ARS was exposed to the atmosphere, arsenopyrite, pyrrhotite, pyrite and chalcopyrite were oxidized producing scorodite, jarosite and two generations of amorphous Fe sulfo-arsenates (AISA). These secondary phases attenuated some of the As released to pore water during oxidation in the upper layers of the ARS. The imposition of the cap prevented further oxidation. The secondary As minerals are not stable in the reduced environment that currently dominates the pile. Therefore, As currently is being released into the groundwater. Water in an adjacent monitoring well has concentrations of >20 mg/L total As with relative predominance of As(III). 相似文献
5.
A numerical simulation of residual circulation in Tampa Bay. Part I: Low-frequency temporal variations 总被引:1,自引:0,他引:1
Steven D. Meyers Mark E. Luther Monica Wilson Heather Havens Amanda Linville Kristin Sopkin 《Estuaries and Coasts》2007,30(4):679-697
The residual (time-average) salinity and circulation in a numerical ocean model of the Tampa Bay estuary are shown to experience
significant temporal variation under realistic forcing conditions. A version of the Estuarine Coastal Ocean Model developed
for Tampa Bay with 70 by 100 horizontal grid points and 11 sigma levels is examined for the years 2001–2003. Model output
variables are averaged over the entire time of the simulation to generate long-term residual fields. The residual axial current
is found to be dominated by the buoyancy-driven baroclinic circulation with an outflow (southwestward) at the surface and
to the sides of the shipping channel, and an inflow (northeastward) usually occurring subsurface within or above the shipping
channel. Averages over 30 d are used to examine variations in the residual fields. During the simulation the average surface
salinity near the head of Tampa Bay varies with the freshwater inflow, from 12‰ to 33%. At the bay mouth salinity varies from
30%. to 36%.. A localized measure of the baroclinic circulation in the shipping channel indicates the residual circulation
can vary strongly, attaining a magnitude triple the long-term mean value. The baroclinic circulation can be disrupted, going
to near zero or even reversing, when the buoyancy-driven flow is weak and the surface winds are to the northeast. Three time
periods, representing different environmental conditions, are chosen to examine these results in detail. A scaling argument
indicates the relative strength of buoyancy versus wind as ΔρgH2(LC
Dω2)−1, where δρ is head-to-mouth density difference across the bay,g is gravitational acceleration,H is depth,L is bay length,C
D is the surface wind drag coefficient, andw is wind speed. Tampa Bay is usually in the buoyancy dominated regime. The importance of winds in the weak-buoyancy case is
demonstrated in an additional simulation without wind stress. 相似文献
6.
7.
8.
D. Heath Jones Will Saunders Matthew Colless Mike A. Read Quentin A. Parker Fred G. Watson Lachlan A. Campbell Daniel Burkey Thomas Mauch Lesa Moore Malcolm Hartley Paul Cass Dionne James Ken Russell Kristin Fiegert John Dawe John Huchra Tom Jarrett Ofer Lahav John Lucey Gary A. Mamon Dominique Proust Elaine M. Sadler Ken-ichi Wakamatsu 《Monthly notices of the Royal Astronomical Society》2004,355(3):747-763
9.
Multilayer coatings for reflecting hard X-rays up to 80 keV, like W/Si and Pt/C, have been studied for several years. To go to higher energies, in the range of 100 keV to 250 keV, one needs coatings with smaller d-spacings than can currently be made with these material combinations, and a lower interfacial roughness. With the new material combinations of WC/SiC the interface roughness can be reduced down to between 0.23 nm and 0.25 nm enabling bi-layer thicknesses down to 1.0 nm to reflect efficiently. The production of thinner period coatings thus enables the possibility for focusing optic designs with reasonable focal lengths and throughput up to 250 keV. 相似文献
10.