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241.
ZHANGLei DanielTODD XIEHui CHENWenyan WUYingmei JIANGWei 《地理学报(英文版)》2005,15(1):61-70
Greenhouse-gas (GHG) emissions in China have aroused much interest, and not least in recent evidence of their reduction. Our intent is to place that reduction in a larger context, that of the process of industrialization. A lengthy time perspective is combined with a cross-sectional approachChina plus five other countries-and addressed through two general models. The findings are salutary. First, they suggest that a diversified economic structure is consistent with diminished intensity in energy use. Secondly, and the obverse of the first, they imply that a diversified energy structure promotes reductions in CO2 emissions. Finally, one is led inevitably to the conclusion that, together, the findings point to a path for countries to transform their economies while at the same time undertaking to drastically moderate their energy use, switching from a pattern of heavy carbon emissions to one in which lighter carbon emissions prevail. The implications of such findings for environmental management are enormous. 相似文献
242.
243.
The southern shore of Lake Michigan is the type area for many of ancestral Lake Michigan’s late Pleistocene lake phases, but
coastal deposits and features of the Algonquin phase of northern Lake Michigan, Lake Huron, and Lake Superior are not recognized
in the area. Isostatic rebound models suggest that Algonquin phase deposits should be 100 m or more below modern lake level.
A relict shoreline, however, exists along the lakeward margin of the Calumet Beach that was erosional west of Deep River and
depositional east of the river. For this post-Calumet shoreline, the elevation of basal foreshore deposits east of Deep River
and the base of the scarp west of Deep River indicate a slightly westward dipping water plane that is centered at ∼184 m above
mean sea level. Basal foreshore elevations also indicate that lake level fell ∼2 m during the development of the shoreline.
The pooled mean of radiocarbon dates from the surface of the peat below post-Calumet shoreline foreshore deposits indicate
that the lake transgressed over the peat at 10,560 ± 70 years B.P. Pollen assemblages from the peat are consistent with this
age. The elevation and age of the post-Calumet shoreline are similar to the Main Algonquin phase of Lake Huron. Recent isostatic
rebound models do not adequately address a high-elevation Algonquin-age shoreline along the southern shore of Lake Michigan,
but the Goldthwait (1908) hinge-line model does. 相似文献
244.
Influence of surface heterogeneity on scalar dissimilarity in the roughness sublayer 总被引:1,自引:8,他引:1
Christopher A. Williams Todd M. Scanlon John D. Albertson 《Boundary-Layer Meteorology》2007,122(1):149-165
While it is generally known that surface heterogeneity weakens the application of Monin–Obukhov similarity (MOS), few studies
have investigated how seasonal changes in the degree of surface heterogeneity at a particular site may influence the validity
of the similarity application. Exploiting seasonal changes in forest function associated with senescence, we conduct a unique
evaluation of the effects of surface heterogeneity on the validity of similarity theory at two sites through time. Using high
frequency (10 Hz) velocity and scalar time series collected within the roughness sublayer over mixed hardwood deciduous and
coniferous forests during both periods of peak leaf area and senescence of deciduous foliage, we examined conformity with
proposed universal flux-variance predictions and agreement amongst normalized standard deviations of different scalars (temperature,
water vapour and carbon dioxide concentrations). Normalized scalar standard deviations were elevated above MOS flux-variance
predictions, with more pronounced deviations observed during and following senescence, particularly in the case of CO2. Power-law scaling of normalized standard deviations as a function of stability was upheld and robust to seasonal changes
in surface heterogeneity. However, dissimilarity of normalized standard deviations for the scalars increased during senescence,
as heterogeneity in the source/sink field increased. Scalewise decomposition of scalar time series using wavelet analysis
indicated that correlations between scalars were conservative through much of the inertial cascade but decayed for eddies
< 10 m. Senescence lowered correlations between scalars over a wide range of eddy sizes. These results demonstrate how seasonal
changes in surface physiology can cause a temporal production of heterogeneity in the source/sink field, thus weakening similarity
applications in the roughness sublayer. 相似文献
245.
An atlas of photospheric magnetic field observations and computed coronal magnetic fields: 1976–1985
Daily magnetogram observations of the large-scale photospheric magnetic field have been made at the John M. Wilcox Solar Observatory at Stanford since May of 1976. These measurements provide a homogeneous record of the changing solar field through most of solar cycle 21.Using the photospheric data, the configuration of the coronal and heliospheric fields can be calculated using a Potential Field - Source Surface model. This provides a three - dimensional picture of the heliospheric field evolution during the solar cycle.In this note we announce the publication of UAG Report No. 94, an Atlas containing the complete set of synoptic charts of the measured photospheric magnetic field, the computed field at the source surface, and the coefficients of the multipole expansion of the coronal field. The general underlying structures of the solar and heliospheric fields, which determine the environment for solar-terrestrial relations and provide the context within which solar activity related events occur, can be approximated from these data. 相似文献
246.
International borders, ground water flow, and hydroschizophrenia 总被引:1,自引:0,他引:1
A substantial body of research has been conducted on transboundary water, transboundary water law, and the mitigation of transboundary water conflict. However, most of this work has focused primarily on surface water supplies. While it is well understood that aquifers cross international boundaries and that the base flow of international river systems is often derived in part from ground water, transboundary ground water and surface water systems are usually managed under different regimes, resulting in what has been described as "hydroschizophrenia." Adding to the problem, the hydrologic relationships between surface and ground water supplies are only known at a reconnaissance level in even the most studied international basins, and thus even basic questions regarding the territorial sovereignty of ground water resources often remain unaddressed or even unasked. Despite the tensions inherent in the international setting, riparian nations have shown tremendous creativity in approaching regional development, often through preventive diplomacy, and the creation of "baskets of benefits," which allow for positive-sum, integrative allocations of joint gains. In contrast to the notion of imminent water wars, the history of hydropolitical relations worldwide has been overwhelmingly cooperative. Limited ground water management in the international arena, coupled with the fact that few states or countries regulate the use of ground water, begs the question: will international borders serve as boundaries for increased "flows" of hydrologic information and communication to maintain strategic aquifers, or will increased competition for shared ground water resources lead to the potential loss of strategic aquifers and "no flows" for both ground water users? 相似文献
247.
Estimates of area-averaged tidal bottom stress are made for four channel segments of the Great Bay Estuary, N.H. Current and sealevel measurements are used to estimate acceleration and pressure gradient terms in the equation of motion, while the equation of motion itself is used to infer the remaining stress term. Dynamic terms, bottom stress values, friction coefficients and energy dissipation rates are estimated for each site. The analysis shows that while throughout the estuary the principal force balance is between the frictional stress and the pressure gradient forcing, RMS values of total bottom stress range from 2·67 to 10·38 Nm?2 and friction coefficients vary from 0·015 to 0·054. Both stress and energy dissipation are largest in the seaward portion of the estuary with an order of magnitude decrease in dissipation at the most inland site.These distributions of stress and energy dissipation are consistent with cotidal charts of the principal semi-diurnal tidal constituent (M2) which indicate that the estuary is composed of a highly dissipative more progressive tidal wave regime seaward and a less dissipative standing wave regime landward. 相似文献
248.
249.
Todd K Hinkley 《Bulletin of Volcanology》1991,53(5):395-400
In order to gain information on the distribution of metals between particles and gaseous forms in the plume of Kilauea volcano, a filter designed to collect metals associated with particles was followed in series by two other collectors intended to trap metals present in gaseous (atomic, molecular, or complexed) form: first an acid-bubbler bath and then a cold trap. Of the six metals measured, all of the In, Tl and Bi, and almost all of the Cd, Pb and Cu were found on the filter. None of any of the metals was detected in the acid-bubbler bath. Masses equivalent to 0.3% of the amount of Cd on the filter, 0.4% of the amount of Pb, and 9.3% of the Cu, were measured in the cold trap. The results indicate that all or nearly all of the six metals were partitioned to the particulate portion of the physical mixture of gases and particles that constitutes a volcanic plume, but that there may be systematic differences between chalcophile metals in the ways they are partitioned between particulate and gaseous phases in a cooled plume, and possibly differences in the acidity or other chemical properties of the molecular phases. 相似文献
250.
Grant Heiken Napoleon Ramos Wendell Duffield John Musgrave Kenneth Wohletz Sue Priest James Aldrich Wilmer Flores Alexander Ritchie Fraser Goff Dean Eppler Carlos Escobar 《Journal of Volcanology and Geothermal Research》1991,45(1-2)
The Platanares geothermal area, Departamento de Copán, Honduras, is located within a graben that is complexly faulted. The graben is bounded on the north by a highland composed of Paleozoic (?) metamorphic rocks in contact with Cretaceous - Tertiary redbeds of unknown thickness. These are unconformably overlain by Tertiary andesitic lavas, rhyolitic ignimbrites, and associated sedimentary rocks. The volcanic rocks are mostly older than 14 Ma, and thus are too old to represent the surface expression of an active crustal magma body. Thermal fluids that discharge in the area are heated during deep circulation of meteoric water along faults in a region of somewhat elevated heat flow. Geothermometry based upon the chemical composition of thermal fluids from hot springs and from geothermal gradient coreholes suggests that the reservoir equilibrated at temperatures as high as 225 to 240°C, within the Cretaceous redbed sequence. Three continuously cored geothermal gradient holes have been drilled; fluids of about 165°C have been produced from two drilled along a NW-trending fault zone, from depths of 250 to 680 m. A conductive thermal gradient of 139°C/km, at a depth of 400 m, was determined from the third well, drilled 0.6 km west of that fault zone. These data indicate that the Platanares geothermal area holds considerable promise for electrical generation by moderate- to hightemperature geothermal fluids. 相似文献