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31.
简要介绍地震与爆炸的震源物理性质及地震波激发机制特征。利用地震观测波形直达纵横波震相能量释放的差异,在时间域引进标志事件震源性质的参量a。132个台站记录的22个不同震源类型事件的计算结果表明,a值具有震源性质依附效应,展现出在事件识别领域的应用前景。 相似文献
32.
Locating regional seismic events with global optimization based on interval arithmetic 总被引:4,自引:0,他引:4
Matti Tarvainen Timo Tiira & Eystein S. Husebye 《Geophysical Journal International》1999,138(3):879-885
More than 1000 seismic events in northern Europe at distances of up to 400 km from the detecting network are located using an optimization method in which the global minimum of the traveltime function residuals is searched for using an Interval Arithmetic (IA) method. Epicentres are determined using P waves detected by the Finnish national seismic network: up to 15 stations were used in the analysis. The IA results coincide with locations provided by the University of Helsinki bulletins with a median location bias of 7.6 km.
A second data set of 59 explosions in the Siilinjärvi mine in central Finland was examined in detail, because the locations of the explosions were known exactly. In this case, the median difference of IA locations was 3.8 km from the average location of mine explosions, while all 59 events were located within 9 km of the 'true' epicentres. The corresponding median error of the University of Helsinki locations was smaller (3.2 km), but some Helsinki locations were well over 10 km from the mine. The convergence towards the global optimum using interval arithmetic was fast when compared with the conventional least-squares approaches for epicentre determinations. 相似文献
A second data set of 59 explosions in the Siilinjärvi mine in central Finland was examined in detail, because the locations of the explosions were known exactly. In this case, the median difference of IA locations was 3.8 km from the average location of mine explosions, while all 59 events were located within 9 km of the 'true' epicentres. The corresponding median error of the University of Helsinki locations was smaller (3.2 km), but some Helsinki locations were well over 10 km from the mine. The convergence towards the global optimum using interval arithmetic was fast when compared with the conventional least-squares approaches for epicentre determinations. 相似文献
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35.
In the monitoring of earthquakes and nuclear explosions using a sparse worldwide network of seismic stations, it is frequently
necessary to make reliable location estimates using a single seismic array. It is also desirable to screen out routine industrial
explosions automatically in order that analyst resources are not wasted upon detections which can, with a high level of confidence,
be associated with such a source. The Kovdor mine on the Kola Peninsula of NW Russia is the site of frequent industrial blasts
which are well recorded by the ARCES regional seismic array at a distance of approximately 300 km. We describe here an automatic
procedure for identifying signals which are likely to result from blasts at the Kovdor mine and, wherever possible, for obtaining
single array locations for such events. Carefully calibrated processing parameters were chosen using measurements from confirmed
events at the mine over a one-year period for which the operators supplied Ground Truth information. Phase arrival times are
estimated using an autoregressive method and slowness and azimuth are estimated using broadband f{-}k analysis in fixed frequency bands and time-windows fixed relative to the initial P-onset time. We demonstrate the improvement
to slowness estimates resulting from the use of fixed frequency bands. Events can be located using a single array if, in addition
to the P-phase, at least one secondary phase is found with both an acceptable slowness estimate and valid onset-time estimate.
We evaluate the on-line system over a twelve month period; every event known to have occured at the mine is detected by the
process and 32 out of 53 confirmed events were located automatically. The remaining events were classified as “very likely”
Kovdor events and were subsequently located by an analyst. The false alarm rate is low; only 84 very likely Kovdor events
were identified during the whole of 2003 and none of these were subsequently located at a large distance from the mine. The
location accuracy achieved automatically by the single-array process is remarkably good, and is comparable to that obtained
interactively by an experienced analyst using two-array observations. The greatest problem encountered in the single array
location procedure is the difficulty in determining arrival times for secondary phases, given the weak Sn phase and the complexity
of the P-coda. The method described here could be applied to a wide range of locations and sources for which the monitoring
of seismic activity is desirable. The effectiveness will depend upon the distance between source and receiver, the nature
of the seismic sources and the level of regional seismicity. 相似文献
36.
Little is known about the spatial and temporal distribution of blast fishing which hampers enforcement against this activity. We have demonstrated that a triangular array of hydrophones 1 m apart is capable of detecting blast events whilst effectively rejecting other sources of underwater noise such as snapping shrimp and nearby boat propellers. A total of 13 blasts were recorded in Sepangor bay, North of Kota Kinabalu, Sabah, Malaysia from 7th to 15th July 2002 at distances estimated to be up to 20 km, with a directional uncertainty of 0.2 degrees . With such precision, a network of similar hydrophone arrays has potential to locate individual blast events by triangulation to within 30 m at a range of 10 km. 相似文献
37.
We consider the time, angular, and energy distributions of SN 1987A events and discuss the quality of their agreement with
the expectations. A global interpretation is made by considering a simple model based on the standard scenario for the explosion.
Despite the contrasting and confusing indications, a straightforward fit to the data provides a result that does not contradict
but rather supports the expectations. The calculated electron antineutrino flux is applied to predict the relic neutrino signal.
The article was translated by the authors. 相似文献
38.
G. R. Dargahi-Noubary 《Mathematical Geology》1981,13(2):119-133
Stochastic models are derived for two source formulations for explosions. Using this kind of model, a comparison is made between source time functions due to Blake, Haskell, Mueller and Murphy, and Von Seggern and Blandford, for explosions, and between -square (Aki, Brune)and -cube (Aki, Haskell)models for earthquakes. When seeking a stochastic model for records of Rayleigh waves from atmospheric explosions, the k-model corresponding to Haskell's time function was found to be an appropriate choice. 相似文献
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40.
An analytical method based on Penny-Taylor model has been modified and applied for the estimation of the final cavity radius
for contained peaceful nuclear explosions. The calculated cavity radii for some nuclear explosions in granite, alluvium and
sandstone rocks are in good agreement with measured values. 相似文献