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961.
962.
Sylwia Tomecka-Suchoń 《Acta Geophysica》2012,60(2):386-398
Georadar methodology has a considerable potential as a tool for verification of archeological hypotheses. I applied it in
the present study to resolve a discussion on the importance of a Proto-Romanesque structure located on Lasota Hill. It is
one of the oldest structures on the right bank of Vistula River in Kraków in Poland and some archeologists believe that it
was the first seat of the rulers of Lesser Poland in the 9th century. After few decades, the prince’s castle was built on
Wawel Hill, where subsequently the royal castle was constructed. On the place of the abandoned Proto-Romanesque edifice, a
small St. Benedict’s Church was raised, but the importance of its predecessor was discussed. Archeological excavations suggested
that it served as the prince’s residence, but this view would be much strengthened if traces of a prince’s building — palatium — could be found. With this in mind, I undertook a search for traces of palatium, employing georadar methodology. I carried out the measurements using Georadar PROEX produced by MALA Geoscience with a set
of shielded antennas of frequencies 500 and 800 MHz. They permitted to construct echogram profiles, whose interpretation suggested
the existence of palatium. Thus, the georadar data supported the archeological hypothesis about the important role of the Proto-Romanesque structures
on Lasota Hill in the early medieval era in Poland, and at the same time demonstrated the usefulness of introducing geophysical
methods to archaeology. 相似文献
963.
Methods of computing the deflections of flexible vegetation elements under the dynamic pressure of water were presented in the paper. Two methods, based on Euler-Bernoulli beam theory, were discussed, one designed for small deflections and the other, generalized one, also for larger deflections. The choice of the method for computations of deflections was discussed from the perspective of the computation of flow velocities above flexible vegetation. Computational results were compared with laboratory experiments and it was found that the simplified, computationally less expensive method may be used in many practical situations without deterioration of the results. 相似文献
964.
Harmelin-Vivien M Bodiguel X Charmasson S Loizeau V Mellon-Duval C Tronczyński J Cossa D 《Marine pollution bulletin》2012,64(5):974-983
Consumption of marine organisms represents one of the main exposure sources of contaminants for human populations. To obtain a global view of the contamination in commercial fish in the NW Mediterranean Sea, we analysed four types of priority contaminants (PCBs, PBDEs, Hg and (137)Cs) in the European hake, Merluccius merluccius, from the Gulf of Lions in relation with organism's trophic level (δ(15)N). All contaminants presented a significant increase in concentration in hake muscle with trophic level. However, obvious differences between contaminants were evidenced. Biomagnification factors (BMF and FWMF) along the hake food web were higher for Hg and CB-153 than for BDE-47 and (137)Cs, and increase in contaminant concentration with trophic level occurred at different rates depending on contaminants. Such differences of biomagnification patterns can be related to physico-chemical properties of the different contaminants. 相似文献
965.
Beata Górka-Kostrubiec El?bieta Król Maria Jeleńska 《Studia Geophysica et Geodaetica》2012,56(3):861-877
This study reports systematic analysis of air pollution concentration by particulate matter (PM) in relation to annual changes of metrological conditions. The concentration of PM collected on filters was evaluated by magnetic properties. Long series of filters collected during 1977, 1980, 1981 and 1985 in Warsaw have been used for measurement. Such long time series allowed a better determination of correlation between seasonal susceptibility changes and meteorological conditions and to verify the repeatability of annual behavior. The magnetic susceptibility normalized by mass (??) has been used as a proxy of pollution. Monthly variations of ?? (??m) demonstrated slow and small seasonal changes disturbed by quick, high peaks. The filters with high susceptibilities contain a mixture of magnetic single and multidomain grains which is characteristic for anthropogenic pollution, with the frequency-dependent susceptibility ??fd being less than 4%. The low susceptibility samples are characterized by admixture of small amount of pseudo-single domain (PSD) and possible small amount of superparamagnetic (SP) grains. Detailed analysis of reduced mean monthly susceptibility ??R revealed that temperature and absolute humidity correlate positively in cold period of year and negatively in warm months. The linear correlation coefficients range from 0.7 to 0.9 and from 0.3 to 0.4 for negative and positive linear correlation, respectively. The dispersion of pollutants in a city depends on the way of ventilation. The big cities like Warsaw are urban heat islands which act the most effective way for the warm period and for the cold time. The correlation of ??R with absolute humidity is similar to that for temperature but for different reasons. The presence of big amount of water vapor particles in the atmosphere can favor the adhesion of smaller ferromagnetic grains to their surface which can accelerate the process of falling down of such agglomerates. Such a process can take place during wintertime. We do not observe clear correlation between ??R and precipitation. 相似文献
966.
Mount Morning is a Cenozoic, alkaline eruptive center in the south-west Ross Sea, Antarctica. New ages on 17 Mount Morning
volcanic rocks (combined with 34 existing ages) allows division of Mount Morning volcanism into two phases, erupted between
at least 18.7 Ma and 11.4 Ma, and 6.13 and 0.02 Ma. The position of Mount Morning on the active West Antarctic Rift System
within the stationary Antarctic plate is a key factor in the eruptive center’s longevity. The earliest, mildly alkaline, Phase
I volcanism comprises predominantly trachytic rocks produced by combined assimilation and fractional crystallization processes
over 7.3 m.y. Strongly alkaline Phase II volcanism is dominated by a basanite – phonolite lineage, with the youngest (post
last glacial maximum) activity dominated by small volume primitive basanite eruptions. The evolution from mildly to strongly
alkaline chemistry between phases reflects magma residence time in the crust, the degree of mantle melting, or the degree
of magma—country-rock interaction. Phase I magmatism occurred over a comparable area to the present-day, Phase II shield.
The 5.2 m.y. volcanic hiatus separating Phase I and II coincides with a cycle of eruption and glacial erosion at the nearby
Minna Bluff eruptive center. Mount Morning is the likely source of volcanic detritus in Cape Roberts drill-core (about 24.1
to 18.4 Ma) and in ANDRILL drill-hole 1B (about 13.6 Ma), located 170 km north and 105 km north-east respectively, of Mount
Morning. Based upon the timing of eruptions and high heat-flow, Mount Morning should be considered a dormant volcano. 相似文献
967.
Quantifying hyporheic solute dynamics has been limited by our ability to assess the magnitude and extent of stream interactions with multiple domains: mobile subsurface storage (MSS, e.g., freely flowing pore water) and immobile subsurface storage (ISS, e.g., poorly connected pore water). Stream-tracer experiments coupled with solute transport modeling are frequently used to characterize lumped MSS and ISS dynamics, but are limited by the ability to sample only “mobile” water and by window of detection issues. Here, we couple simulations of near-surface electrical resistivity (ER) methods with conservative solute transport to directly compare solute transport with ER interpretations, and to determine the ability of ER to predict spatial and temporal trends of solute distribution and transport in stream–hyporheic systems. Results show that temporal moments from both ER and solute transport data are well correlated for locations where advection is not the dominant solute transport process. Mean arrival time and variance are especially well-predicted by ER interpretation, providing the potential to estimate rate-limited mass transport (i.e. diffusive) parameters from these data in a distributed domain, substantially increasing our knowledge of the fate and transport of subsurface solutes. 相似文献
968.
Joshua Kurek Jennifer B. Korosi Adam Jeziorski John P. Smol 《Journal of Paleolimnology》2010,44(2):603-612
The effects of low counts on assemblage inferences in paleolimnological investigations have been examined for many biological
proxies, but not yet for Cladocera. Established guidelines leading to the determination of an adequate, minimum count are
absent with respect to sampling cladoceran remains from lake sediments. Using simulated subsamples derived from observed assemblages
of considerably higher counts, we investigated the effect of counting effort on three principal characteristics of an assemblage:
richness, number of new taxa encountered, and the absolute differences in relative abundances of dominant taxa. Results from
six lakes located within diverse ecological regions (i.e. Subarctic, Canadian Shield, Acadian Forest) suggest that a minimum
of between 70 and 100 individuals is satisfactory to characterize most assemblages. Doubling counting effort from 100 to 200
individuals leads to only modest gains in subsample relatedness to the observed assemblage. Greater counting effort may be
necessary when the primary interest is in presence-absence or distributional data, or when abundances of ecologically relevant
taxa are exceptionally low. 相似文献
969.
The paper summarizes the findings about a seismic event on January 22, 2010, near Bełchatów, Poland, in terms of data, event
location, magnitude and source parameters. 相似文献
970.
Bogusław M. Domański 《Acta Geophysica》2010,58(2):174-194
The singular integral equations method makes it possible to determine a general analytical solution to the problem of a crack
subjected to any stresses, including singular ones. The singularity of stresses means that they tend to infinity in the concentration
point. In exponential functions describing this relationship, the exponent characterizes the stress curvature growth. Also
the energy released by crack opening can be described by a simple analytical formula. The problem is solvable for an exponent
greater than −1. The class of all the cracks subject to stresses that exponentially grow to one of the crack ends is divided
into three sub-classes. One of these embraces most of crack types, also Griffith’s. The remaining two are a source of microcracks
in an elastic medium. The onset of such a stress concentration gives rise to a microcrack which cancels the stress singularity
up to that with the exponent of −1/2, ensuring a strong stability of the medium. An analysis of the nucleation of such cracks
brought about a concept of elastic field rupture without destruction of interatomic bonds, which has implications relating
to the conductivity of metals. A general formula for the crack energy singles out a special crack of unit length, whose energy
is constant and independent of stress concentration. 相似文献