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131.
132.
Regional hydrological thresholds for landslides and floods in the Tiber River Basin (central Italy) 总被引:11,自引:0,他引:11
The definition of landslide warning thresholds, based on the analysis of hydrological data, is proposed. In the Tiber River
Basin of central Italy historical information on landslides and floods, for the period 1918–1990, was available from a nationwide
bibliographical and archive inventory on geohydrological catastrophes. Hydrological data were obtained from mean daily discharge
records at various gauging stations within the basin. Several hundred hydrological events, broadly defined as a series of
consecutive days having mean daily discharge exceeding a predefined value, were identified. Hydrological parameters obtained
from the discharge records were used to rank the events according to their probability to trigger mass movements or inundations
and to define regional thresholds for the occurrence of landslides and floods. The proposed approach, not lacking limitations,
has conceptual and operational advantages, among which is the possibility of using historical information on geohydrological
catastrophes.
Received: 20 November 1996 · Accepted: 25 June 1997 相似文献
133.
A method is proposed to assess the risk for sinkhole formation in dolomitic areas where changes in land use are envisaged.
Data from geotechnical site investigations are used for the zoning and characterization of sites in terms of the hazard (maximum
size of sinkhole that can form), while the inherent risk for this hazard to occur is assessed by assuming that the site may
be developed or treated incorrectly (abused). By considering both the hazard and the inherent risk, it is possible to select
appropriate types of development and precautionary measures to reduce the final (development) risk to an acceptable level.
Received: 15 September 1996 · Accepted: 12 May 1998 相似文献
134.
云南省崩塌滑坡泥石流灾害及防治 总被引:7,自引:0,他引:7
王宇 《地质灾害与环境保护》1998,9(4):38-41,47
对云南省崩塌,滑坡,泥石流灾害概况,时空分布特征,以及防治工作作了系统总结,并对今后的工作提出建议,对云南省的地质灾害研究及防治工作有参考意义。 相似文献
135.
The Washington State/Local Tsunami Work Group adopted the NOAA Weather Radio All-Hazards Warning System to warn citizens quickly and effectively of not only tsunami hazards but also other natural or man-made hazards. In concert with an array of deep ocean tsunami detectors, land-based seismic sensors, and warning messages issued by the tsunami warning centers, NWR provides a means to expeditiously get critical decision-making information to emergency managers, elected officials, and first responders. To implement the NWR strategy effectively, a partnership was developed to add a repeater to the NWR system to provide complete coverage to the coast of Washington and to shipping lanes off the coast. The Work Group also recognized the need to disseminate time critical hazard information on tsunamis to the public on beaches and in high traffic areas, so it developed a new notification system, with the first prototype installed on 2 July 2003 in Ocean Shores, Washington. A public education program also was developed to improve the impacted communities understanding of the tsunami hazard, the warning system, and actions they should take if a tsunami occurs. 相似文献
136.
Landslides and debris flows occurr in China frequently and cause disastrous losses of life and property. The risk assessment of landslides and debris flows and their spatial variations were comparatively analyzed in this paper, which has great significance for disaster prevention. This article selected 1 km×1 km grid as the assessment unit and with support of GIS technique, analyzed landslide and debris-flow risk distribution and their spatial variations from 2000 to 2010. The research results indicated that the spatial distribution of risk classes in 2000 and 2010 was obviously discrepant. Overall, taking the Heihe-Tengchong population density line as the boundary, the west of the line is mainly low risk area; the east of the line is mainly high risk area. Compared with the risk of 2000, the risk values of 2010 increased, with the high risk area and low risk area enlarged, moderate risk area reduced. The moderate risk area is the most unstable and sensitive risk area, and its risk class variation is significant. However, China is not a region with the high risk of landslide and debris-flow hazard at present. In the following next 10 years, the risk of landslides and debris flows in China will continue to increase. 相似文献
137.
Paleoliquefaction features can be used to estimate lower bounds on the magnitude and ground motion associated with the earthquake that caused the liquefaction feature. The engineering back-analysis of paleoliquefaction features is usually conducted using state of the practice liquefaction-triggering analysis methodologies. Recent studies have shown that these methodologies are associated with variable probabilities of liquefaction depending on the soil parameters. This would imply that estimates of magnitude and ground motion intensity obtained from these methodologies would not be consistent for all soil sites. Moreover, these estimates could be unconservative. In this paper, the use of a probabilistic methodology for the back-analysis of paleoliquefaction features is proposed. The proposed methodology permits the incorporation of model and parameter uncertainty into the analysis and results in more robust estimates of past magnitude and a measure of the uncertainty associated with these predictions. Previously published paleoliquefaction data are used to demonstrate the applicability of the proposed method. Magnitude estimates obtained with the proposed method do not differ significantly from those obtained using deterministic methodologies, but the proposed methodology permits a quantification of the uncertainty associated with magnitude estimates. 相似文献
138.
Sinkhole distribution in a rapidly developing urban environment: Hillsborough County, Tampa Bay area, Florida 总被引:4,自引:1,他引:3
Sinkhole formation in Florida is a common event. The Florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state. We present in this paper a morphometric analysis of karst depressions in the Tampa Bay area, and the relation with the known distribution of sinkholes. We selected the Tampa Bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built-up environment. Karst depressions were mapped from the 1:24,000 USGS topographic maps and a morphometric analysis was performed by using parameters such as shape, circularity index, perimeter, area, length, width, and orientation. Maps showing the distribution of depression density, and the sectors with greatest areas of karst depression were produced using a GIS. These results were compared with data compiled from the database of sinkhole occurrences in Florida maintained by the Florida Geological Survey. Our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes, indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past. 相似文献
139.
During the Mitch Hurricane event (October 1998), severe floods occurred in the village of La Trinidad (Departamento de Estelí,
NW Nicaragua), which spreads at the margin of La Trinidad river. As a consequence, the need for hazard assessment and land
use planning to reduce the effects of these natural processes arose. Nicaragua is a developing country, which means that there
is a scarcity of good quality data on which to base these hazard assessments (i.e., lack of detailed topographic maps, lack
of meteorological and discharge data series). Therefore, the main objective of the present work was to generate a flood hazard
map of La Trinidad by means of a simple method, with a resulting map easy to understand and to use by the municipality for
land use planning. There is no topographic map of the area at a more detailed scale than 1:50,000. So the main document that
supports all the data and on which the final hazard map was based is the orthophotograph at 1:5,000 scale (generated from
vertical aerial photographs taken in 2000). The method used was based on classical interpretation of vertical aerial photographs
(pre Mitch and a post Mitch event), detailed field work, inquiries among the population and analysis of the main pattern of
storms occurring in the area. All these data allowed the reconstruction of different extensions and water levels corresponding
to events of different frequency and magnitude, and the qualitative association of them to three hazard levels by means of
energy and frequency. The use of orthophotographs of 1:5,000 proved to be very useful both for the development of the work
and for the presentation of the final map, because they are very easily understandable for people not trained in the interpretation
of topographic maps. 相似文献
140.
This paper addresses the temporal variation of rainfall-triggered landslide hazard within the broader context of natural risk
evolution. Analysis of a sequence of aerial photos covering a period of 60 years allowed the establishment of a record of
landsliding for a site in the Wellington region, New Zealand. The data show one very dominant peak in the magnitude of landslide
occurrence in the late 1970s, followed by a continuous decrease. Landslide hazard can be expressed by the frequency and magnitude
of the landslide events, with the total surface area affected used as a surrogate for magnitude. However, the distinct decline
of landslide magnitude through time from the 1980s onwards indicates that landslide hazard may change with time. This possibility
is further explored by correlating potential landslide triggering storms with the magnitude of the landslide event, using
the ‘Antecedent Soil Water Status’ model in combination with daily rainfall. The relation between magnitudes of rainfall and
magnitudes of landslide events is found to be weak, suggesting that a given ‘Critical Water Content’ (antecedent soil water
status and rainfall on the day) does not produce similar magnitudes of landsliding. Furthermore, the study shows that reactivation
of previous landslides before the peak landslide occurrence of the late 1970s is low, while the situation is reversed after
this peak and reactivation in the subsequent years plays a larger role. It is concluded that the pattern of landsliding cannot
be explained by the pattern of rainfall and other factors are controlling the variation of landslide hazard in time. A possible
explanation is a change of the geomorphological system with time, instigated by a massive period of landsliding (the late
1970s peak). Subsequent sediment exhaustion of source areas resulting from this period appears to alter the system’s subsequent
reaction to an external trigger such as rainfall. The study demonstrates that landslide hazard analysis in general should
not rely on the integral of the frequency–magnitude relationship only, but should include potential non-linear changes of
system settings to increase the understanding of future system behaviour, and therefore hazard and risk.
相似文献
Gabi HufschmidtEmail: |