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121.
Professional conduct of scientists during volcanic crises 总被引:1,自引:0,他引:1
IAVCEI Subcommittee for Crisis Protocols: Chris Newhall · Shigeo Aramaki · Franco Barberi · Russell Blong · Marta Calvache · Jean-Louis Cheminee · Raymundo Punongbayan · Claus Siebe · Tom Simkin · Stephen Sparks · Wimpy Tjetjep Chris Newhall 《Bulletin of Volcanology》1999,60(5):323-334
Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work on a prime research topic while a colleague with longer-standing investment is still busy with public safety work. Some problems arise within existing scientific teams; others are brought on by visiting scientists. Friction can also arise between volcanologists and public officials. Two general measures may avert or reduce friction: (a) National volcanologic surveys and other scientific groups that advise civil authorities in times of volcanic crisis should prepare, in advance of crises, a written plan that details crisis team policies, procedures, leadership and other roles of team members, and other matters pertinent to crisis conduct. A copy of this plan should be given to all current and prospective team members. (b) Each participant in a crisis team should examine his or her own actions and contribution to the crisis effort. A personal checklist is provided to aid this examination. Questions fall generally in two categories: Are my presence and actions for the public good? Are my words and actions collegial, i.e., courteous, respectful, and fair? Numerous specific solutions to common crisis problems are also offered. Among these suggestions are: (a) choose scientific team leaders primarily for their leadership skills; (b) speak publicly with a single scientific voice, especially when forecasts, warnings, or scientific disagreements are involved; (c) if you are a would-be visitor, inquire from the primary scientific team whether your help would be welcomed, and, in general, proceed only if the reply is genuinely positive; (d) in publications, personnel evaluations, and funding, reward rather than discourage teamwork. Models are available from the fields of particle physics and human genetics, among others. 相似文献
122.
A global analysis of cities’ geosocial temporal signatures for points of interest hours of operation
Kevin Sparks Gautam Thakur Amol Pasarkar Marie Urban 《International journal of geographical information science》2020,34(4):759-776
ABSTRACTThe temporal nature of humans interaction with Points of Interest (POIs) in cities can differ depending on place type and regional location. Times when many people are likely to visit restaurants (place type) in Italy, may differ from times when many people are likely to visit restaurants in Lebanon (i.e. regional differences). Geosocial data are a powerful resource to model these temporal differences in cities, as traditional methods used to study cross-cultural differences do not scale to a global level. As cities continue to grow in population and economic development, research identifying the social and geophysical (e.g., climate) factors that influence city function remains important and incomplete. In this work, we take a quantitative approach, applying dynamic time warping and hierarchical clustering on temporal signatures to model geosocial temporal patterns for Retail and Restaurant Facebook POIs hours of operation for more than 100 cities in 90 countries around the world. Results show cities’ temporal patterns cluster to reflect the cultural region they represent. Furthermore, temporal patterns are influenced by a mix of social and geophysical factors. Trends in the data suggest social factors influence unique drops in temporal signatures, and geophysical factors influence when daily temporal patterns start and finish. 相似文献
123.
The volatile content of hypabyssal kimberlite magmas: some constraints from experiments on natural rock compositions 总被引:1,自引:0,他引:1
Richard A. Brooker R. Stephen J. Sparks Janine L. Kavanagh Matthew Field 《Bulletin of Volcanology》2011,73(8):959-981
Kimberlites are volatile rich magmas that ascend from deep in the mantle at high velocities, then as they reach a ‘root zone’
at 1–3 km in depth they either discharge explosively through to the surface or stall to form dykes and sills. Understanding
this eruptive behaviour is difficult due to a lack of data on volatile solubility, particularly at conditions where the magmas
enter the ‘root zone’ (∼30–80 MPa). In this study, we perform experiments on some putative primary kimberlite magma compositions
to assess the amount of CO2 and H2O retained if these compositions represent magma as it enters the root zone. At the conditions investigated (100–200 MPa and
1,275–1,100°C) the results suggest that none of these particular kimberlite compositions reproduce a magma that can retain
the observed high volatile content when intruded at these pressures (∼4–8 km). In our experiments, the low volatile retention
is due to a combination of factors including a high proportion of solid phases, none of which are volatile-bearing, and inadequate
volatile solubilities in the subordinate amounts of melt present. Modelled solubilities also suggest that the dissolved volatile
contents remain too low even at super-liquidus temperatures (i.e. 100% melt). For water, the higher values observed in natural
rocks can be explained by the addition of H2O associated with ubiquitous post-emplacement serpentinization. The high CO2 contents in hypabyssal rocks are unlikely to be related to alteration. We suggest that most kimberlites originally had lower
SiO2 contents and as such may have been ‘transitional’ between silicate and carbonate melts. This results in both higher CO2 solubilities and lower liquidus temperatures. For such compositions, it is possible that both CO2 and water solubility may first decrease and then increase as magmas decompress and crystallize. Such unusual behaviour can
help explain why kimberlite magmas can be very explosive or form shallow hypabyssal intrusions. 相似文献
124.
Giovanni Fontana Conall Mac Niocaill Richard J. Brown R. Stephen J. Sparks Matthew Field 《Bulletin of Volcanology》2011,73(8):1063-1083
Palaeomagnetic techniques for estimating the emplacement temperatures of volcanic deposits have been applied to pyroclastic
and volcaniclastic deposits in kimberlite pipes in southern Africa. Lithic clasts were sampled from a variety of lithofacies
from three pipes for which the internal geology is well constrained (the Cretaceous A/K1 pipe, Orapa Mine, Botswana, and the
Cambrian K1 and K2 pipes, Venetia Mine, South Africa). The sampled deposits included massive and layered vent-filling breccias
with varying abundances of lithic inclusions, layered crater-filling pyroclastic deposits, talus breccias and volcaniclastic
breccias. Basalt lithic clasts in the layered and massive vent-filling pyroclastic deposits in the A/K1 pipe at Orapa were
emplaced at >570°C, in the pyroclastic crater-filling deposits at 200–440°C and in crater-filling talus breccias and volcaniclastic
breccias at <180°C. The results from the K1 and K2 pipes at Venetia suggest emplacement temperatures for the vent-filling
breccias of 260°C to >560°C, although the interpretation of these results is hampered by the presence of Mesozoic magnetic
overprints. These temperatures are comparable to the estimated emplacement temperatures of other kimberlite deposits and fall
within the proposed stability field for common interstitial matrix mineral assemblages within vent-filling volcaniclastic
kimberlites. The temperatures are also comparable to those obtained for pyroclastic deposits in other, silicic, volcanic systems.
Because the lithic content of the studied deposits is 10–30%, the initial bulk temperature of the pyroclastic mixture of cold
lithic clasts and juvenile kimberlite magma could have been 300–400°C hotter than the palaeomagnetic estimates. Together with
the discovery of welded and agglutinated juvenile pyroclasts in some pyroclastic kimberlites, the palaeomagnetic results indicate
that there are examples of kimberlites where phreatomagmatism did not play a major role in the generation of the pyroclastic
deposits. This study indicates that palaeomagnetic methods can successfully distinguish differences in the emplacement temperatures
of different kimberlite facies. 相似文献
125.
Models are presented for the cooling of tephra during fallout from explosive eruption columns. All tephra particles are assumed to be spherical and heat loss is considered to occur by radiation and forced convection. Grainsize is the most important control on the cooling. Clasts larger than 25 cm diameter suffer little heat loss, whereas clasts smaller than 1.6 cm diameter are completely cold on deposition. Large clasts form a well-developed chilled margin during fallout and a breadcrust texture can result if vesiculation of the hot interior occurs. The results of these calculations are combined with a model for fallout from the margins of an eruption column to predict the proximal temperature variation with distance from the vent in the deposits. Temperatures high enough for dense welding in proximal fallout deposits can extend from a few hundred metres to nearly 2 km. Extent of the welded facies increases with column height, mean grainsize and magmatic temperature. Welded fallout deposits are only predicted to occur for high temperature silicic and intermediate magmas with temperatures >850°C. These predictions are in good agreement with observations, in that welded fallout deposits have only been documented in high temperature dacites, rhyolites and panellerites. A postulated fallout origin for welded rocks that can be traced significantly further than 2 km from vent must be suspect. 相似文献
126.
127.
The infant mortality rate is a fundamental measure of population health used internationally. In the United States, the infant mortality rate is higher than what would be expected for a country of its affluence. We present an analysis of US county infant mortality rates using modern Bayesian spatial statistical methodologies. Our key predictors in our statistical analysis are residential racial and poverty segregation, measured by the dissimilarity, interaction and spatial proximity indexes. We use both Exploratory Spatial Data Analysis methods and Hierarchical Bayesian spatial regression models to examine the influences of these segregation measures on the infant mortality rate for each county, net of income inequality, degree of rurality and relative socioeconomic deprivation. The spatial measures of racial segregation suggest that when blacks live in close proximity to each other, this tends to increase the infant mortality rate. The results for poverty segregation suggest the same pattern, when poor populations live in close proximity to one another this is generally detrimental to the county infant mortality rate. However, interaction between blacks and whites and poor and non-poor residents of an area is protective for infant mortality. 相似文献
128.
Pele has been the most intense high-temperature hotspot on Io to be continuously active during the Galileo monitoring from 1996-2001. A suite of characteristics suggests that Pele is an active lava lake inside a volcanic depression. In 2000-2001, Pele was observed by two spacecraft, Cassini and Galileo. The Cassini observations revealed that Pele is variable in activity over timescales of minutes, typical of active lava lakes in Hawaii and Ethiopia. These observations also revealed that the short-wavelength thermal emission from Pele decreases with rotation of Io by a factor significantly greater than the cosine of the emission angle, and that the color temperature becomes more variable and hotter at high emission angles. This behavior suggests that a significant portion of the visible thermal emission from Pele comes from lava fountains within a topographically confined lava body. High spatial resolution, nightside images from a Galileo flyby in October 2001 revealed a large, relatively cool (<800 K) region, ringed by bright hotspots, and a central region of high thermal emission, which is hypothesized to be due to fountaining and convection in the lava lake. Images taken through different filters revealed color temperatures of 1500±80 K from Cassini ISS data and 1605±220 and 1420±100 K from small portions of Galileo SSI data. Such temperatures are near the upper limit for basaltic compositions. Given the limitations of deriving lava eruption temperature in the absence of in situ measurement, it is possible that Pele has lavas with ultramafic compositions. The long-lived, vigorous activity of what is most likely an actively overturning lava lake in Pele Patera indicates that there is a strong connection to a large, stable magma source region. 相似文献
129.
130.