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排序方式: 共有114条查询结果,搜索用时 15 毫秒
61.
硼特效树脂离子交换法分离B的研究 总被引:4,自引:0,他引:4
本文对Amberlite IRA 743 硼特效树脂交换分离B的特征及其影响因素进行了研究。它适用于各种地质样品中B的分离提取,特别是在B同位素地球化学研究时必须进行B纯化的场合。 相似文献
62.
混合震源采集技术相对于传统地震数据采集具有改善成像质量、提高采集效率的优势.减小混合炮中单炮之间的随机延时范围能够有效的提高采集效率,但这也给之后的混采数据分离带来了影响.混采数据经伪分离后非共炮域数据中的混叠噪声明显更加集中,不利于对混叠噪声进行压制.本文提出基于脉冲检测方法对混采数据进行分离,并且与迭代的多级中值滤波方法作对比,时间延时范围较大时,两种方法都能得到很好的分离结果;时间延时范围较小时,本文方法能更有效的去除混叠噪声,同时也能更好的保留细节信息.实际数据计算结果表明,本文方法一定程度上还能够有效压制其他随机噪声.
相似文献63.
Separation of small nonferrous particles using a two successive steps eddy-current separator with permanent magnets 总被引:1,自引:0,他引:1
The paper presents a method for separating the small metallic nonferrous particles from two component metallic nonferrous mixtures using a new type of dynamic eddy-current separator with permanent magnets. The so-called two successive steps eddy-current separator (TSECS) consists of a horizontal rotary drum covered with permanent magnets, alternately N–S and S–N oriented. The separation process takes place in two stages, first the strongly conducting particles are separated on the upper part of the drum, and then the remaining undecided and poorly conducting particles are separated at the lower part of the magnetic drum. The experimental results and comments regarding the values obtained for separation efficiency, grade and recovery for wastes consisting in Cu–Pb and Cu–Al mixtures are given. The obtained results are in good agreement with the theoretical analysis. 相似文献
64.
Water-Tank Studies of Separating Flow Over Rough Hills 总被引:1,自引:1,他引:0
J. B. R. Loureiro A. S. Monteiro F. T. Pinho A. P. Silva Freire 《Boundary-Layer Meteorology》2008,129(2):289-308
The present work investigates the lower boundary condition for flows over a steep, rough hill. Simple asymptotic arguments
together with the mixing-length hypothesis are used to derive a local analytical solution that is tested against three different
flow conditions. In all, 36 velocity profiles are compared with the proposed expression. The experiments were carried out
in a water channel and velocity measurements were made through laser Doppler anemometry. The extent of separated flow was
made to vary as a function of the roughness and the Reynolds number. The analysis includes regions of attached as well as
separated flow. In particular, the solution of Stratford is studied at the points of separation and re-attachment and found
to apply equally well in rough walls. 相似文献
65.
The recovery and emission of landfill gas (LFG) is an important topic in landfill management. To produce an effective engineering design for an LFG collection system, designers must understand the migration of gas from the waste body to horizontal extraction wells. This paper develops a two-dimensional analytical solution to enable the study of the gas pressure distribution, well pressure and recovery efficiency in layered landfills with horizontal wells. A horizontal layered structure is used to accommodate the non-homogeneity of various municipal solid waste (MSW) aspects with respect to depth, including gas generation, permeability and temperature. The governing equations, subject to boundary and continuity conditions, are solved by using separation of variables and double finite integral transforms. The solution was verified against another analytical solution and a numerical simulation. Subsequently, a sensitivity analysis of single-well model parameters is performed to optimize a double-well system. The results show that a landfill with horizontal collection systems cannot be assumed to be one dimensional with increasing well spacing. Additionally, both the operational vacuum and maximum gas pressure can be reduced through the design of a double- or multiple-well system. Therefore, the proposed solution can be used for the verification of more complex models and the preliminary design of a horizontal well system. 相似文献
66.
Systematics of zircon crystallisation in the Cretaceous Separation Point Suite, New Zealand, using U/Pb isotopes, REE and Ti geothermometry 总被引:2,自引:3,他引:2
Robert Bolhar Steve D. Weaver J. Michael Palin Jim W. Cole Lorraine A. Paterson 《Contributions to Mineralogy and Petrology》2008,156(2):133-160
Plutonic zircons from the Cretaceous Separation Point Suite (SPS) were analysed by LA-ICPMS for U–Pb isotope ratios and trace
element concentrations. Pooled 206Pb/238U ages range from 112 to 124 Ma. Cathodoluminescence imaging reveals minor inheritence and textural evidence of repeated dissolution
and re-precipitation of zircon. Core and rim spot analyses, however, document zircon growth during extended periods of time
(>2 myr). Protracted crystallisation histories for simple plutonic systems are inconsistent with generalised thermal constraints,
which predict cooling below the solidus within <1 myr. Consequently, we conclude that the SPS granitoids sampled in this study
were not emplaced rapidly but incrementally over extended time periods. Zircon Th/U and Zr/Hf ratios are positively correlated
with crystallisation temperatures, consistent with crystallisation from evolving melts. However, highly variable trace element
concentrations, along with temperature reversals are indicative of complex crystallisation histories involving continuous
fractional crystallisation repeatedly punctuated by hotter, more mafic magma recharge. Normalised abundances of the redox-sensitive
elements Eu and Ce in zircon vary systematically with degrees of whole rock differentiation, pointing to evolutionary trends
in magmatic oxidation states coupled with feldspar crystallisation. 相似文献
67.
面波压制是地震数据处理中的一个重要问题. 常规的处理方法虽然能在一定程度上压制面波,但是在处理过程中只是单一的利用面波的一种特性,例如频率域滤波中利用面波与有效信号频率之间的差别,因此难以有效地压制面波. 利用Ridgelet变换可将原始地震记录拓展到(a,τ,p)三维空间,从而可以同时利用地震记录的视速度、时间和尺度域特性差别,实现有效信号与面波的分离. 文中通过理论合成记录及实际地震记录的算例,证实了基于Ridgelet变换的面波压制方法是有效且可行的. 相似文献
68.
69.
Influence of the Temperature on the Formation of Magnetite as an Additive for Magnetic Separation To investigate the influence of the temperature on the formation of magnetite in aqueous solution, experiments were performed in which ferrous hydroxide was precipitated from oxygen-free ferrous sulfate solution (c0(Fe) = 5 mmol·dm?3) and subsequently oxidized with synthetic air. The precipitates so obtained are a mixture of solids whose compositions depend on the temperature and on the rate of aeration. Above all, magnetite, goethite, and δ-FeOOH had been formed. Magnetite occurs at temperatures above about 15 °C, goethite above 35 °C, and δ-FeOOH below about 10 °C. Referring to the thermogravimetric plots and to the relationship between the temperature of formation and the pH measured upon completion of the reaction, it is justified to assume that also sulfate is contained in the precipitates. The values of the magnetic moment of the precipitates, which are crucial in magnetic separation, made evident the dependence on the temperature of formation expected on the basis of solid analyses and confirmed the presence of δ-FeOOH at rather low temperatures. At the rates of aeration applied, it was possible to obtain from about 15 °C on solids having magnetic moments which are sufficient for magnetic separation. 相似文献
70.
由于目前计算机内存和速度的限制,在对大面积重力资料进行三维密度反演时,已有的反演方法很难奏效.文中提出了一种基于位场分离与延拓的视密度快速反演方法:首先应用场分离的切割法对平面上的重力场进行不同深度层源的切割分离;然后运用大深度向下延拓方法将各层的场延拓至相应的深度;最后反演出各深度层的密度.反演得到的密度是各深度层密度的近似分布,称为视密度反演.本反演方法克服了传统已有方法计算时间特别长、解稳定性差的缺点,在主频1.99 GHz的微机上,反演128×128×10个密度值的计算时间小于20 s,理论模型和实际资料的应用表明反演具有较好的效果. 相似文献