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排序方式: 共有216条查询结果,搜索用时 421 毫秒
111.
William Perrie Zhenxia Long Hayley Hung Amanda Cole Alexandra Steffen Ashu Dastoor Dorothy Durnford Jianmin Ma Jan W. Bottenheim Stoyka Netcheva Ralf Staebler James R. Drummond N. T. O’Neill 《Climatic change》2012,115(1):35-58
This paper summarizes the main elements of four IPY projects that examine the Arctic Atmosphere. All four projects focus on present conditions with a view to anticipating possible climate change. All four investigate the Arctic atmosphere, ocean, ice, and land interfacial surfaces. One project uses computer models to simulate the dynamics of the Arctic atmosphere, storms, and their interactions with the ocean and ice interface. Another project uses statistical methods to infer transports of pollutants as simulated in large-scale global atmospheric and oceanic models verifying results with available observations. A third project focuses on measurements of pollutants at the ice-ocean?Catmosphere interface, with reference to model estimates. The fourth project is concerned with multiple, high accuracy measurements at Eureka in the Canadian Archipelago. While these projects are distinctly different, led by different teams and interdisciplinary collaborators, with different technical approaches and methodologies, and differing objectives, they all strive to understand the processes of the Arctic atmosphere and climate, and to lay the basis for projections of future changes. Key findings include: ? Decreased sea ice leads to more intense storms, higher winds, reduced surface albedo, increased surface air temperature, and enhanced vertical mixing in the upper ocean. ? Arctic warming may affect toxic chemicals by remobilizing persistent organic pollutants and augmenting mercury deposition/retention in the environment. ? Changes in sea ice can dramatically change processes in and at the ice surface related to ozone, mercury and bromine oxide and related chemical/physical properties. ? Structure and properties of the Arctic atmospheric??troposphere to stratosphere??and tracking of transport of pollution and smoke plumes from mid-latitudes to the poles. 相似文献
112.
A GIS-based decision support system for analysis of route choice in congested urban road networks 总被引:2,自引:0,他引:2
Urban congestion patterns have become ubiquitous and complex. Traditional, “static” approaches are no longer adequate for
analyzing network flows and conducting minimum cost routing. This paper reports on a GIS-based decision support tool for modeling
dynamic network congestion and conducting minimum cost routing. The system predicts network flows at a detailed level of temporal
resolution, capturing dynamic congestion propagation effects. A Route Planner module solves for the combined departure time and minimum cost routing required for a trip to reach its destination by a
given deadline. The GIS provides effective decision support through its database management capabilities, graphical user interfaces
and cartographic visualization. This supports analyses of “what-if?” scenarios for strategic planning and tactical management
subject to unplanned network disturbances.
Received: 1 October 1999/Accepted: 21 September 2000 相似文献
113.
在联系到我国古代气象科学的成就时,在讨论到我国最早关于风的观测仪器的创制时,由于“候风地动仪”的问题,也都一致提到我国汉代这位有突出成就的大科学家张衡;并且认为张衡是世界上测风仪器最早的设计者。对于这种看法,为澄清日后的一些认识,有必要作一些核实的探讨。 相似文献
114.
Global P and PP traveltime tomography: rays versus waves 总被引:2,自引:1,他引:2
R. Montelli G. Nolet G. Masters F. A. Dahlen S.-H. Hung 《Geophysical Journal International》2004,158(2):637-654
115.
A laboratory study was conducted to determine the effect of bacterial augmentation with LLMO (liquid live microorganisms) on the activated sludge treatment of potato wastewaters. Completed mixed activated sludge bench scale reactors were used in this study. Parameters varied during the continuous reactor run included hydraulic detention time, LLMO addition, and powdered activated carbon addition. The hydraulic detention time lasted 1, 2, and 3 days, while the sludge age was maintained at 10 days for both reactors. The bio-augmented reactor had a better COD removal than the non-bio-augmented reactor at a lower MLVSS level in the reactor. It is concluded that bacterial augmentation with LLMO improved slightly the COD removal efficiency in treating potato wastewaters with the activated sludge process. The bio-augmentation increased the substrate removal rate, increased the oxygen utilization, and decreased the excess sludge production. 相似文献
116.
Speciation of dissolved selenium in the Kaoping and Erhjen rivers and estuaries,southwestern Taiwan 总被引:2,自引:0,他引:2
Analytical methods of dissolved Se species in river water and seawater were established and applied to study dissolved Se speciation in the Kaoping and Erhjen rivers and estuaries, southwestern Taiwan. The Kaoping and Erhjen rivers and estuaries were respectively in relatively oxygenated and oxygen-deficient conditions as revealed from the distributions of dissolved oxygen, DOC, nutrients, and dissolved Mn. Concentrations of dissolved total Se increased downstream in the riverine sections, ranging from 0.6 nM to 1.2 nM for the Kaoping River and from 0.8 nM to 1.05 nM for the Erhjen River. The dissolved total Se was only slightly higher in the Erhjen middle estuary than in the Kaoping middle estuary in spite of heavier pollution in the former. The dissolved total Se behaved rather conservatively in the Kaoping estuary but nonconservatively in the Erhjen estuary resulting from anthropogenic inputs, and in this respect showed similarities with the behavior of redox-sensitive Mn. The predominant species of selenium were Se(VI) and organic Se in the Kaoping River and Se(VI) in the Kaoping estuary. The elevated concentration of Se(VI) in the Kaoping estuary may stem from the degradation of organic Se and oxidation of Se(IV). On the other hand, Se(IV) and organic Se were equally dominant in the Erhjen River, and Se(IV) was predominant through most of the Erhjen estuary. The elevated distribution of Se(IV) in the Erhjen middle estuary may result mostly from partial decomposition of organic Se, but further oxidation of Se(IV) was inhibited in reducing waters. However, Se(VI) became dominant at Erhjen outer estuary where water was oxygenated by the replacement of intruded coastal seawater. Apparently, the speciation of dissolved Se was mainly controlled by the biological and redox processes in the Kaoping and Erhjen rivers and estuaries. 相似文献
117.
Fan-Chieh Yu Chien-Yuan Chen Tien-Chien Chen Feng-Yi Hung Sheng-Chi Lin 《Natural Hazards》2006,37(1-2):169-189
A GIS rules-based approach is proposed for delimiting areas potentially endangered by debris flow for downstream guarded areas.
Data were used to define rules for nine pilot areas in the Chen-You-Lan river watershed in Nantou County of Taiwan. A preliminary
regressed relationship between debris volume and runout distance in the pilot areas is first formulated. The GIS processes
for applying the rules are linked to delimit hazardous areas affected by debris within the first approximated debris fan.
Rules applied to delimit potentially endangered areas incorporate geomorphological factors (gradient or curvature, aspect),
direction of flow, fan angle of the debris and location of the overflow points. The delimited zone is then calibrated using
the regression formula for debris volume against the affected area. The verification of the delineation of the areas using
the adopted approach, with reference to micro-geomorphological results concerning pilot cases validates the proposed model.
The model can be used to delineate potentially hazardous zones approximately associated with debris flow in rivers in Taiwan. 相似文献
118.
Yoko Ota Yu-nong Nina Lin Yue-Gau Chen Hui-Cheng Chang Jih-Hao Hung 《Tectonophysics》2006,417(3-4):305-323
We found active faults in the fold and thrust belt between Tunglo town and the Tachia River in northwestern Taiwan. The surface rupture occurred in 1999 and 1935 nearby the study area, but no historical surface rupture is recorded in this area, suggesting that the seismic energy has been accumulated during the recent time. Deformed fluvial terraces aid in understanding late Quaternary tectonics in this tectonically active area. This area contains newly identified faults that we group as the Tunglo Fault System, which formed after the area's oldest fluvial terrace and appears at least 16 km long in roughly N–S orientation. Its progressive deformations are all recorded in associated terraces developed during the middle to late Quaternary. In the north, the system consists of two subparallel active faults, the Tunglo Fault and Tunglo East Fault, striking N–S and facing each other from opposite sides of the northward flowing Hsihu River, whose course may be controlled by interactions of above-mentioned two active faults. The northern part of the Tunglo Fault, to the west of the river, is a reverse fault with upthrown side on the west; conversely the Tunglo East Fault, to the east, is also a reverse fault, but with upthrown side on the east. Both faults are marked by a flexural scarp or eastward tilting of fluvial terraces. Considering a Quaternary syncline lies subparallel to the east of this fault system, the Tunglo Fault might be originated as a bending moment fault and the Tunglo East Fault as a flexural slip fault. However, they have developed as obvious reverse faults, which have progressive deformation under E–W compressive stress field of Taiwan. Farther south, a west-facing high scarp, the Tunglo South Fault, strikes NNE–SSW, oblique to the region's E–W direction of compression. Probably due to the strain partitioning, the Tunglo South Fault generates en echelon, elongated ridges and swales to accommodate right-lateral strike–slip displacement. Other structures in the area include eastward-striking portion of the Sanyi Fault, which has no evidence for late Quaternary surface rupture on this fault; perhaps slip on this part of Sanyi Fault ceased when the Tunglo Fault System became active. 相似文献
119.
Byung Sik Kim Hung Soo Kim Byung Ha Seoh Nam Won Kim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(4):457-373
The main purpose of this study is to investigate and evaluate the impact of climate change on the runoff and water resources
of Yongdam basin, Korea. First, we construct global climate change scenarios using the YONU GCM control run and transient
experiments, then transform the YONU GCM grid-box predictions with coarse resolution of climate change into the site-specific
values by statistical downscaling techniques. The downscaled values are used to modify the parameters of a stochastic weather
generator model for the simulation of the site-specific daily weather time series. The weather series is fed into a semi-distributed
hydrological model called SLURP to simulate the streamflows associated with other water resources for the condition of 2CO2. This approach is applied to the Yongdam dam basin in the southern part of Korea. The results show that under the condition
of 2CO2, about 7.6% of annual mean streamflow is reduced when it is compared with the current condition. Seasonal streamflows in
the winter and autumn are increased, while streamflow in the summer is decreased. However, the seasonality of the simulated
series is similar to the observed pattern
An erratum to this article can be found at 相似文献
120.
Acta Geotechnica - Soil freezing characteristic curve (SFCC) represents the relationship between soil temperature and unfrozen water content of soil during freezing and thawing processes. In this... 相似文献