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51.
Elmar BUCHNER Martin SCHMIEDER Gero KURAT Franz BRANDSTÄTTER Utz KRAMAR Theo NTAFLOS Jörg KRÖCHERT 《Meteoritics & planetary science》2012,47(9):1491-1501
Abstract– The fall of meteorites has been interpreted as divine messages by multitudinous cultures since prehistoric times, and meteorites are still adored as heavenly bodies. Stony meteorites were used to carve birds and other works of art; jewelry and knifes were produced of meteoritic iron for instance by the Inuit society. We here present an approximately 10.6 kg Buddhist sculpture (the “iron man”) made of an iron meteorite, which represents a particularity in religious art and meteorite science. The specific contents of the crucial main (Fe, Ni, Co) and trace (Cr, Ga, Ge) elements indicate an ataxitic iron meteorite with high Ni contents (approximately 16 wt%) and Co (approximately 0.6 wt%) that was used to produce the artifact. In addition, the platinum group elements (PGEs), as well as the internal PGE ratios, exhibit a meteoritic signature. The geochemical data of the meteorite generally match the element values known from fragments of the Chinga ataxite (ungrouped iron) meteorite strewn field discovered in 1913. The provenance of the meteorite as well as of the piece of art strongly points to the border region of eastern Siberia and Mongolia, accordingly. The sculpture possibly portrays the Buddhist god Vai?ravana and might originate in the Bon culture of the eleventh century. However, the ethnological and art historical details of the “iron man” sculpture, as well as the timing of the sculpturing, currently remain speculative. 相似文献
52.
Adam S. Parris Paul R. Bierman Anders J. Noren Maarten A. Prins Andrea Lini 《Journal of Paleolimnology》2010,43(1):29-49
The frequency and timing of Holocene paleofloods in the hilly terrain of New Hampshire and Maine are identified using 14C and high-resolution (cm-by-cm) particle size analysis of sediment cores taken from six post-glacial lakes (~0.1–1.4 km2). A total of nine sediment cores (4.5–6 m long) were taken near the base of stream delta foreslopes. End-member modeling
of the particle-size frequency distributions from each core produces 3–5 representative end member distributions, or end members
(EMs). Concurrent increases in mean and median particle size, and in the relative abundance of the coarsest EM(s), indicate
increased transport capacity of inflowing tributaries, resulting from rainstorms. In all 9 cores, particle size data show
clear signs of episodic, high-energy sediment transport events where proxy measurements such as loss-on-ignition and magnetic
susceptibility do not, demonstrating the sensitivity of particle size analysis in paleostorm investigations made using lake
sediment cores. Floods caused by storms in this region peaked around 1.4, 2.1, 3.0, 3.9, 6.8, 8.2, and 11.5 ka cal BP, and
presently appear to be increasing in frequency. Periods of storminess in New Hampshire and Maine correlate well with other
records of precipitation and climate in the northeastern United States during the Holocene, further supporting modern records
which show tropical air masses as a primary driver of extreme precipitation events in New England (Ludlum 1996; Konrad 2001; Sisson and Gyakum 2004). 相似文献
53.
Regular aquifer storage recovery, ASR, is often not feasible for small‐scale storage in brackish or saline aquifers because fresh water floats to the top of the aquifer where it is unrecoverable. Flow barriers that partially penetrate a brackish or saline aquifer prevent a stored volume of fresh water from expanding sideways, thus increasing the recovery efficiency. In this paper, the groundwater flow and mixing is studied during injection, storage, and recovery of fresh water in a brackish or saline aquifer in a flow‐tank experiment and by numerical modeling to investigate the effect of density difference, hydraulic conductivity, pumping rate, cyclic operation, and flow barrier settings. Two injection and recovery methods are investigated: constant flux and constant head. Fresh water recovery rates on the order of 65% in the first cycle climbing to as much as 90% in the following cycles were achievable for the studied configurations with constant flux whereas the recovery efficiency was somewhat lower for constant head. The spatial variation in flow velocity over the width of the storage zone influences the recovery efficiency, because it induces leakage of fresh water underneath the barriers during injection and upconing of salt water during recovery. 相似文献
54.
Claudia Pittiglio Andrew K. SkidmoreHein A.M.J. van Gils Herbert H.T. Prins 《International Journal of Applied Earth Observation and Geoinformation》2012,14(1):61-72
The role of corridors in mitigating the effects of landscape fragmentation on biodiversity is controversial. Recent studies have highlighted the need for new approaches in corridor design using long-term datasets. We present a method to identify transit corridors for elephant at a population scale over a large area and an extended period of time using long-term aerial surveys. We investigated environmental and anthropogenic factors directly and indirectly related to the wet versus dry season distribution of elephant and its transit corridors. Four environmental variables predicted the presence of elephant at the landscape scale in both seasons: distance from permanent water, protected areas and settlements and vegetation structure. Path analysis revealed that altitude and monthly average NDVI, and distance from temporary water had a significant indirect effect on elephant distribution at local scale in dry and wet seasons respectively. Five transit corridors connecting Tarangire National Park and the northern as well as south-eastern wet season dispersal areas were identified and matched the wildlife migration routes described in the 1960s. The corridors are stable over the decades, providing landscape connectivity for elephant. Our approach yielded insights how advanced spatial analysis can be integrated with biological data available from long-term datasets to identify actual transit corridors and predictors of species distribution. 相似文献
55.
As containerization enters its peak growth years, its potential future developments over maritime and inland freight transport
systems are being questioned. A series of issues can either further accelerate the adoption of containerization worldwide
or, alternatively, could impose an upper limit to the extraordinary contribution that containers have implied for logistics
systems and global commodity chains. These mainly include macro-economic, technical/operational and governance factors. Future
containerization will be largely determined by interactions within and between four domains ranging from a functional to a
spatial perspective. The logistical domain involves the functional organization of transport chains and their integration
in supply chains. The transport domain involves the operation of transport services and intermodal operations. The infrastructural
domain involves the provision and management of basic infrastructure for both links and nodes in the transport system. The
locational domain relates to the geographical location of nodes and sites in the economic space and forms a basic element
for their intrinsic accessibility in terms of centrality or intermediacy. It is underlined that the future of containerization
will dominantly be shaped by inland transport systems. 相似文献
56.
The use of decision tree models for predicting activity-travel choice is receiving increasing attention, but raises two related problems that are considered in this study. First, commonly used deterministic action-assignment rules should be replaced by probabilistic action-assignment rules. We develop such probabilistic rules for both discrete and continuous choice problems. Second, common goodness-of-fit measures such as the hit-ratio need to be replaced by likelihood measures. In this paper, we develop and empirically illustrate the interrelated methods and measures. The findings suggest that the new measures add information to existing statistics for discrete as well as the continuous choice. 相似文献
57.
Utilizing data from NCEP/ NCAR reanalysis, the summertime atmospheric diabatic heating due to different physical processes
is investigated over the Sahara desert, the Tibetan Plateau, and the Bay of Bengal. Atmospheric circulation systems in summer
over these three areas are also studied. Thermal adaptation theory is employed to explain the relationship between the circulation
and the atmospheric diabatic heating.
Over the Sahara desert, heating resulting from the surface sensible heat flux dominates the near-surface layer, while radiative
cooling is dominant upward from the boundary layer. There is positive vorticity in the shallow boundary layer and negative
vorticity in the middle and upper troposphere. Downward motion prevails over the Sahara desert, except in the shallow near—surface
layer where weak ascent exists in summer. Over the Tibetan Plateau, strong vertical diffusion resulting from intense surface
sensible heat flux to the overlying atmosphere contributes most to the boundary layer heating, condensation associated with
large—scale ascent is another contributor to the lower layer heating. Latent heat release accompanying deep convection is
critical in offsetting longwave radiative cooling in the middle and upper troposphere. The overall diabatic heating is positive
in the whole troposphere in summer, with the most intense heating located in the boundary layer. Convergence and positive
vorticity occur in the shallow near—surface layer and divergence and negative vorticity exist deeply in the middle and upper
troposphere. Accordingly, upward motion prevails over the Plateau in summer, with the most intense rising occurring near the
ground surface. Over the Bay of Bengal, summertime latent heat release associated with deep convection exceeds longwave radiative
cooling, resulting in intense heating in almost the whole troposphere. The strongest heating over the Bay of Bengal is located
around 400 hPa, resulting in the most intense rising occurring between 300 hPa and 400 hPa, and producing positive vorticity
in the lower troposphere and negative vorticity in the upper troposphere. It is also shown that the divergent circulation
is from a heat source region to a sink region in the upper troposphere and vice versa in lower layers.
This work was jointly supported by “ National Key Program for Developing Basic Sciences” G1998040904 by NSFC projects 49805003,
49635170, 49823002, and 49825504. 相似文献
58.
Theo L. Hills Dr. 《GeoJournal》1982,6(2):151-156
In many parts of South America, the socio-economic condition of the population is such that in many respects the people, because of their vulnerable state, are a disaster waiting to occur. The triggering action of the disaster will be an extreme physical or biophysical event. If any advance is to be made in natural hazard management, then the focus must be upon people first. Halt the process of underdevelopment in South American societies and you have taken a major step forward in natural hazard management. The major concern of this paper is not so much with the competition for first place in hazard proneness in South America, but rather the elaboration of the total ecology of what we commonly designate as disasters, which ordinarily occur at the interface of extreme natural phenomena and vulnerable settlement patterns, and which should be seen, as the extreme situation which is implicit in the everyday condition of the population. Vulnerability is the key concept in this relationship. South American nations vary greatly in their hazard proneness, in the vulnerability of sectors in their societies, in the losses and general repercussions of hazardous events, and in their ability to cope effectively with the post-disaster situation, either alone or with international aid. 相似文献
59.