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排序方式: 共有48条查询结果,搜索用时 15 毫秒
1.
A simple constant-head injection test for streambed hydraulic conductivity estimation 总被引:4,自引:1,他引:3
A fast, efficient constant-head injection test (CHIT) for in situ estimation of hydraulic conductivity (K) of sandy streambeds is presented. This test uses constant-head hydraulic injection through a manually driven piezometer. Results from CHIT compare favorably to estimates from slug testing and grain-size analysis. The CHIT combines simplicity of field performance, data interpretation, and accuracy of K estimation in flowing streams. 相似文献
2.
3.
Vitaly Salnikov Galina Turulin Svetlana Polyakov Marat Moldahmetov Lyazzat Mahmudova 《寒旱区科学》2013,5(1):0109-0113
Methods of calculating the basic hydrological characteristics of a water resource assessment, as well as the planning and management
of their long-term use are based upon the concept of stationarity of long-term flow fluctuations. However, data of researches
by hydrologists and climatologists clearly indicate that there are long-period changes in the characteristics of precipitation and river
flow. This article discusses the variations of annual precipitation and river flow in the Ishim River Basin in Kazakhstan, based
on the W, C and E classification developed by G.Y. Vangengeim who analyzed the long-term variability of anomalies by the number
of days with some form of atmospheric circulation. From this study, the largest anomaly of the macro-circulation processes
was revealed, and a comparative analysis of the number of days with various forms of atmospheric circulation and precipitation
anomalies was made. It was demonstrated that the nature of atmospheric circulation depends on the distribution of precipitation;
however, precipitation is also highly dependent on local physiographic conditions. The analysis of anomalous precipitation during
the maximum number of days of positive anomalies with various forms of atmospheric circulation was also carried out. This study
presents some results from the preliminary analysis of annual river flow linked with forms of atmospheric circulation. 相似文献
4.
Vitaly A. Zlotnik 《Ground water》2015,53(4):509-510
5.
We present the closed form of a general steady-state shape factor for a partially penetrating well in a uniform anisotropic aquifer. Our simple analytical expression for the shape factor has a uniform representation for full range of parameters and meets or exceeds the accuracy of previous results obtained through semiempirical methods (e.g., Bouwer and Rice [1976] equations). This general shape factor pertains to the flow of fluids (water or air) in subsurface formations when the upper formation boundary has constant potential and the lower boundary is impermeable. The results of our investigation are directly applicable to analyses of (1) slug tests with falling or rising head and (2) injection/extraction tests with constant head, essential techniques for the characterization of hydraulic conductivity of aquifers, streambeds, or lakebeds as well as the design of aquifer and soil remediation systems. 相似文献
6.
Steen Christensen Vitaly A. Zlotnik Daniel M. Tartakovsky 《Journal of Hydrology》2009,375(3-4):554-565
We analyze the optimal design of a pumping test for estimating hydrogeologic parameters that are subsequently used to predict stream depletion caused by groundwater pumping in a leaky aquifer. A global optimization method is used to identify the test’s optimal duration and the number and locations of observation wells. The objective is to minimize predictive uncertainty (variance) of the estimated stream depletion, which depends on the sensitivities of depletion and drawdown to relevant hydrogeologic parameters. The sensitivities are computed analytically from the solutions of Zlotnik and Tartakovsky [Zlotnik, V.A., Tartakovsky, D.M., 2008. Stream depletion by groundwater pumping in leaky aquifers. ASCE Journal of Hydrologic Engineering 13, 43–50] and the results are presented in a dimensionless form, facilitating their use for planning of pumping test at a variety of sites with similar hydrogeological settings. We show that stream depletion is generally very sensitive to aquitard’s leakage coefficient and stream-bed’s conductance. The optimal number of observation wells is two, their optimal locations are one close to the stream and the other close to the pumping well. We also provide guidelines on the test’s optimal duration and demonstrate that under certain conditions estimation of aquitard’s leakage coefficient and stream-bed’s conductance requires unrealistic test duration and/or signal-to-noise ratio. 相似文献
7.
Potentiomanometers (PMs) are commonly used to determine flux directions across interfaces between surface waters and aquifers. We describe a complementary function: estimating small‐scale hydraulic conductivity (K) in a lakebed, using the constant‐head injection test (CHIT) by Cardenas and Zlotnik (2003) with the PM designed by Winter et al. (1988). A piezometer with a small screen is inserted into the lakebed. Local head potential is obtained by measuring the head difference between the test point and the aquifer interface. The piezometer is then used for water injection. This technique is illustrated by measurements taken from Alkali Lake in the Sand Hills, Nebraska, United States. Lakebed K and seepage fluxes ranged from 0.037 to 0.090 m/d and Darcy velocities ranged from 0.004 to 0.027 m/d. Results were consistent with the supplementary data gathered using a modified CHIT and a cone penetrometer. The compact size of the device and the small volumes used for injection enable this method to estimate lakebed K values as low as 0.01 to 0.1 m/d, a range seldom explored in lake‐aquifer interface systems. 相似文献
8.
Jozsef Szilagyi Vitaly A. Zlotnik John B. Gates Janos Jozsa 《Hydrogeology Journal》2011,19(8):1503-1513
Mean annual recharge in the Sand Hills of Nebraska (USA) over the 2000?C2009 period was estimated at a 1-km spatial resolution as the difference of mean annual precipitation (P) and evapotranspiration (ET). Monthly P values came from the PRISM dataset, while monthly ET values were derived from linear transformations of the MODIS daytime land-surface temperature values into pixel ET rates with the help of ancillary atmospheric data (air temperature, humidity, and global radiation). The study area receives about 73?mm of recharge (with an error bound of ±73?mm) annually, which is about 14?±?14% of the regional mean annual P value of 533?mm. The largest recharge rates (about 200?±?85?mm or 30?±?12% of P) occur in the south-eastern part of the Sand Hills due to smoother terrain and more abundant precipitation (around 700?mm), while recharge is the smallest (about 40?±?59?mm or 10?±?14% of P) in the western part, where annual precipitation is only about 420?mm. Typically, lakes, wetlands, wet inter-dunal valleys, rivers, irrigated crops (except in the south-eastern region) and certain parts of afforested areas in the south-central portion of the study area act as discharge areas for groundwater. 相似文献
9.
Vitaly A.Stepanov 《世界地质(英文版)》2004,7(2)
The Bamsk gold-ore deposit is located in the Amur region, the Far East of Russia. It is confined to the Early Cretaceous volcanic-plutonic uplift of central type, located in the Stanov folded-clumpy Pre-Cambrian system. The deposit is presented by a series of gold-bearing quartz and carbonate-quartz vein-stringer zones. They are confined to the super-intrusive zone of the Nevachansk subvolcanic intrusion of sienite-porphyric composition. The mineralization is being controlled by zone of fractures developed in the autochthone ofthe Bamsk fault. Quartz, carbonates and sericite prevail in the composition of ores. The quantity of ore minerals doesn't exceed 1%~5%. Pyrite, chalcopyrite, galena and native gold are widely spread. Sheelite, gold and silver tellurides, sulphobismuthites, acanthite, sphalerite and cinnabar are less developed. Four stages of mineralization have been distinguished. Gold-sulphide-sulphosalt ore with tellurides of gold and silver is productive for gold. The following set of elements is typomorphic for the ores of the deposit: Au, Ag, Cu, Bi,Mo, Pb and Sb (W1, Pb1, Mo) -Cu- (Ag, Bi, Sb, Mn, W1, Pb2) form the vertical series of zoning. Rocks, enclosing the mineralization are exposed to the processes of listvenitization-beresitization. The processes of gumbeization and argillization are less manifested. The age of the gold mineralization, determined by Rb-Sr method on ore-accompanying minerals, is 130.6 Ma. 相似文献
10.
We propose a new method for groundwater recharge rate estimation in regions with stream-aquifer interactions, at a linear scale on the order of 10 km and more. The method is based on visual identification and quantification of classically recognized water table contour patterns. Simple quantitative analysis of these patterns can be done manually from measurements on a map, or from more complex GIS data extraction and curve fitting. Recharge rate is then estimated from the groundwater table contour parameters, streambed gradients, and aquifer transmissivity using an analytical model for groundwater flow between parallel perennial streams. Recharge estimates were obtained in three regions (areas of 1500, 2200, and 3300 km2) using available water table maps produced by different methods at different times in the area of High Plains Aquifer in Nebraska. One region is located in the largely undeveloped Nebraska Sand Hills area, while the other two regions are located at a transition zone from Sand Hills to loess-covered area and include areas where groundwater is used for irrigation. Obtained recharge rates are consistent with other independent estimates. The approach is useful and robust diagnostic tool for preliminary estimates of recharge rates, evaluation of the quality of groundwater table maps, identification of priority areas for further aquifer characterization and expansion of groundwater monitoring networks prior to using more detailed methods. 相似文献