首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   70篇
  免费   1篇
  国内免费   1篇
测绘学   1篇
大气科学   9篇
地球物理   23篇
地质学   27篇
海洋学   5篇
天文学   4篇
自然地理   3篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2018年   2篇
  2017年   1篇
  2016年   1篇
  2014年   8篇
  2013年   3篇
  2012年   3篇
  2011年   3篇
  2010年   1篇
  2009年   3篇
  2008年   4篇
  2007年   5篇
  2006年   3篇
  2005年   2篇
  2003年   1篇
  2002年   3篇
  2001年   3篇
  2000年   4篇
  1999年   1篇
  1998年   3篇
  1996年   1篇
  1994年   2篇
  1990年   2篇
  1989年   2篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有72条查询结果,搜索用时 171 毫秒
31.
32.
This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.  相似文献   
33.
The evaporation regime of Lake Ladoga is specified using the renewed meteorological data. The traditional approach is supplemented with a new method of estimating the impact of shallow-water zones on the evaporation intensification worked out by G.N. Panin. The obtained results corroborate that the level of precipitation minus evaporation varies in different zones of the lake that can influence the water mass redistribution in the lake in certain seasons.  相似文献   
34.
Temperature is critical to maintaining seed viability under long-term storage conditions. It has been common practice to use refrigeration systems to maintain required storage temperatures. A seed repository constructed in permafrost in Yakutsk, Russia is the first seed storage facility that relies solely on natural cold. This paper describes the design and performance of the cooling system of the repository. An innovative aspect of the cooling system is that it utilizes the patterns of temperature wave propagation in permafrost. Predicted and measured ground temperatures for the first year of operation are presented and analyzed. Results indicate that convection air cooling systems can be used to control the temperature regime in underground facilities in permafrost.  相似文献   
35.
Three stages were identified in the development of meandering rivers and the formation of floodplains with natural levees in Northern Eurasia: the development of rivers with size larger than that of the modern ones; the development of rivers smaller than the modern ones; and the development of rivers of the present-day morphodynamic type. Small oxbows of the second stage are widespread in the floodplains of lowland rivers in Northern Eurasia. The largest amount of floodplain segments with such oxbows can be seen in the forest zone, mostly in the coniferous forests of northeastern European Russia. The available radiocarbon datings show that river channel were significantly decreasing in size and the steepness of meanders was increasing during the Atlantic period of the Holocene. Data on changes in the size of river channels were used to evaluate the ratios between paleo- and modern discharges and to construct a map of difference between runoff depths in the Holocene optimum and in the present and assess changes in water runoff volume. The discharges in the basins of the Vyatka and middle Irtysh accounted for as little as 40–50% of their current values. North, east, and west from those basins, the ratio of ancient and present-day discharges increases. During the Holocene optimum, water runoff from the northern megaslope of the East European Plain was ∼180 km3/year, which is 30% less than the present runoff from the same drainage area. The annual runoff in Volga basin was ∼134 km3, which is almost half as large as the present value. The runoff in Don and Dnieper basins during the Holocene optimum was 40% less, and that in the Ob and Irtysh basin was 30% less than the present one. If we accept the hypothesis that the Holocene optimum was a climate analogue of global anthropogenic warming of the mid-XXI century, the obtained estimates of the state of water resources in Northern Eurasia acquire great prognostic importance.  相似文献   
36.
Large volumes of rock mass, mined-out and moved within these deposits, resulted in irreversible changes in the geodynamic regime in the upper earth's crust of the adjacent territory. These changes manifest themselves in a more frequent occurrence of such intensive dynamic phenomena as tectonic rock bursts due to fault movement adjacent to the area which is mined-out and man-made earthquakes which sharply decrease mining safety and result in great material losses.To develop the prediction techniques of such phenomena, a monitoring system is created, based on the program of the Kola Complex of geodynamic measuring stations. Most of this system is realized in the region of the Khibiny apatite mines. The system provides regional seismological monitoring, local prediction of seismicity in separate areas of a rock mass and, determination of stress and strain in rock masses, local geophysical monitoring over the state of rocks in a rock mass as well as physical and mathematical modelling of geodynamic processes in the upper earth's crust.The investigations have resulted in the distinguishing of some regularities in manifestations of induced seismicity and tectonic rock bursts and in the determination of strain precursors of intensive seismic events in the Khibiny mines.The mechanism is provided by the induced seismicity which resulted from the anthropogenic impact on the geological medium. A geodynamic monitoring complex is described, which is used to reveal the precursors of powerful seismic eventsin situ, and monitoring results are shown, obtained in the Kola Complex of geodynamic stations. Methods of preventing tectonic rock bursts and induced earthquakes are presented.  相似文献   
37.
Simultaneous measurements of wind velocity, air humidity and sea surface wave-elevation fluctuations obtained on a platform in the open Caspian Sea are analyzed.It is shown that wave noises exist in the spectra and cospectra of the lower part of the atmospheric boundary layer, not only for the frequency of the main energy transporting component of the sea waves, but also in other parts of the spectra, at both lower and higher frequencies. The high frequencies are noncoherent with the sea waves and could be considered as measurement errors due to the existence of the waves. A method of elimination of the coherent wave noises from the spectra and cospectra is suggested and the effectiveness of its application is demonstrated.The essential difference between cases of developing and decaying wind waves is demonstrated.  相似文献   
38.
Panin  G. N.  Dzuyba  A. V. 《Water Resources》2003,30(2):177-185
Regularities in the rearrangement of the surface atmospheric circulation in the Caspian Sea region are studied. It is found that during the current rise in the Caspian Sea level, a statistically significant decrease in the wind speed modulus occurred (mainly in autumn and winter winds of zonal directions). This caused a decrease in the rate of evaporation in the region. The results of this study testify to a need for developing a deterministic model of current variations in the Caspian Sea water regime at varying global and regional climate.  相似文献   
39.
The central area of the Russian Plain received substantial amounts Cs-137 fallout as a result of the Chernobyl accident in 1986, with inventories exceeding 40 kBq m−2 in many of the areas close to Chernobyl. Concern over the longer-term fate of this contamination has focused attention on the need to predict the post-fallout redistribution of the radiocaesium and, thus, future changes in the spatial distribution of contamination in the landscape. Since radiocaesium reaching the land surface as fallout is rapidly and strongly adsorbed by soil and sediment particles, any attempt to predict its post-fallout redistribution must focus on erosion and sediment delivery processes and must rely heavily on a knowledge of the geomorphological processes involved. This paper reports a detailed investigation of post-fallout Cs-137 redistribution in the 2.18-km2 Lapki catchment in the Middle-Russian Upland, which has required consideration of soil erosion processes, sediment delivery pathways, sediment delivery ratios and sediment sinks. The time elapsed since the Chernobyl accident is currently insufficient to result in significant reduction of Cs-137 inventories in eroding areas, but areas of deposition on both the lower slopes and on the balka sides and bottoms are already marked by significant increases in Cs-137 inventories. The results obtained emphasise that any attempt to develop meaningful predictions of the longer-term redistribution of Chernobyl-derived Cs-137 fallout within the Russian Plain must be based on a sound and detailed understanding of the linkage between the slopes and the balka systems and the fate of sediment entering the balka systems.  相似文献   
40.
A brief review is given of some of the results of studies of air-sea interactions carried out at the Institute of Water Problems (Moscow) over the last 2 decades.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号