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131.
Rahman Zahid Rehman Khaista Ali Wajid Ali Amir Burton Paul Barkat Adnan Ali Asghar Qadri S. M. Talha 《Journal of Seismology》2021,25(6):1461-1481
Journal of Seismology - The Pamir-Hindu Kush region is seismically the most dynamic and active zone that went through many devastating earthquakes. While much research is ongoing to produce seismic... 相似文献
132.
Decolorization of C.I. Basic Blue 3 (BB3) by oxalate catalyzed photoelectro‐Fenton process based on carbon nanotube‐polytetrafluoroethylene (CNT‐PTFE) electrode as cathode under visible light was studied. A comparison of electro‐Fenton, photoelectro‐Fenton, and photoelectro‐Fenton/oxalate processes for decolorization of the solution containing BB3 has been performed. The results showed that color removal follows the decreasing order: photoelectro‐Fenton/oxalate > photoelectro‐Fenton > electro‐Fenton. Response surface methodology (RSM) was employed to assess individual and interactive effects of the four main independent parameters on the decolorization efficiency. A central composite design (CCD) was employed for optimization of photoelectro‐Fenton/oxalate treatment of BB3. The analysis of variance (ANOVA) showed a high coefficient of determination value (R2 = 0.958) and satisfactory prediction second‐order regression. This study clearly showed that RSM was one of the suitable methods to optimize the operating conditions. 相似文献
133.
The authors would like to thank the discusser for his considerations and comments. The discusser believes that some of the derived formulations need to be referred to his previously published works and also some related studies have not been cited. 相似文献
134.
Amir Hasanzadeh 《Astrophysics and Space Science》2012,339(2):211-221
About 70 years ago “André Danjon” a French astrophysicist showed that as elongation of the moon decreases the arc length of
crescent gets less too. By studying the recent observational data, he concluded that at 7 degree elongation, the length of
arc (cusp to cusp) will reach zero degree. Today, this value is named as Danjon limit, which points to the limit at which
the moon crescent is formed. Danjon believed that the effective factor for occurring this limit was the shadows of moon’s
mountains. Later researchers have obtained different values for this limit. In this research based on the new data, the decreasing
dependence of length of arc versus elongation was obtained. The results show that the Danjon limit is about 5 degrees. The
effective factors to form the Danjon limit are then given and discussed. By considering the effects of astronomical seeing
and shadows of lunar features, the values of the arc length were calculated and compared with the observational data curve.
The results of this study show good agreement with the observational data. The present research shows that the above-mentioned
effects can reduce the length of arc. The effect of libration and roughness of the lunar terrain of the moon in forming the
moon crescent were also considered, and the possibility of observing thinner crescents by photometric model and breaking the
Danjon limit were given. 相似文献
135.
136.
Effect of Temporal Changes in Air Injection Rate on Air Sparging Performance Groundwater Remediation
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Air sparging (AS) is a commonly applied method for treating groundwater contaminated with volatile organic compounds (VOCs). When using a constant injection of air (continuous mode), a decline in remediation efficiency is often observed, resulting from insufficient mixing of contaminants at the pore scale. It is well known that turning the injection on and off (pulsed mode) may lead to a better remediation performance. In this article, we investigate groundwater mixing and contaminant removal efficiency in different injection modes (i.e., continuous and pulsed), and compare them to those achieved in a third mode, which we denote as “rate changing.” In this mode, injection is always on, and its rate is varying with time by abrupt changes. For the purpose of this investigation, we conducted two separate sets of experiments in a laboratory tank. In the first set of experiments, we used dye plume tracing to characterize the mixing induced by AS. In the second set of experiments, we contaminated the tank with a VOC and compared the remediation efficiency between the different injection modes. As expected, we observed that time‐variable injection modes led to enhanced mixing and contaminant removal. The decrease in contaminant concentrations during the experiment was found to be double for the “rate changing” and “pulsed” modes compared to the continuous mode, with a slightly preferable performance for the “rate changing” mode. These results highlight the critical role that mixing plays in AS, and support the need for further investigation of the proposed “rate changing” injection mode. 相似文献
137.
Stability of the time‐domain analysis method including a frequency‐dependent soil–foundation system
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A number of methods have been proposed that utilize the time‐domain transformations of frequency‐dependent dynamic impedance functions to perform a time‐history analysis. Though these methods have been available in literature for a number of years, the methods exhibit stability issues depending on how the model parameters are calibrated. In this study, a novel method is proposed with which the stability of a numerical integration scheme combined with time‐domain representation of a frequency‐dependent dynamic impedance function can be evaluated. The method is verified with three independent recursive parameter models. The proposed method is expected to be a useful tool in evaluating the potential stability issue of a time‐domain analysis before running a full‐fledged nonlinear time‐domain analysis of a soil–structure system in which the dynamic impedance of a soil–foundation system is represented with a recursive parameter model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
138.
Vertical earthquake response of megawatt‐sized wind turbine with soil‐structure interaction effects
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The dynamic response of a wind turbine on monopile is studied under horizontal and vertical earthquake excitations. The analyses are carried out using the finite element program SAP2000. The finite element model of the structure is verified against the results of shake table tests, and the earthquake response of the soil model is verified against analytical solutions of the steady‐state response of homogeneous strata. The focus of the analyses in this paper is the vertical earthquake response of wind turbines including the soil‐structure interaction effects. The analyses are carried out for both a non‐homogeneous stratum and a deep soil using the three‐step method. In addition, a procedure is implemented which allows one to perform coupled soil‐structure interaction analyses by properly tuning the damping in the tower structure. The analyses show amplification of the ground surface acceleration to the top of the tower by a factor of two. These accelerations are capable of causing damage in the turbine and the tower structure, or malfunctioning of the turbine after the earthquake; therefore, vertical earthquake excitation is considered a potential critical loading in design of wind turbines even in low‐to‐moderate seismic areas. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
139.
The simultaneous effects of soil–structure interaction, foundation uplift and inelastic behavior of the superstructure on total displacement response of soil–structure systems are investigated. The superstructure is modeled as an equivalent single‐degree‐of‐freedom system with bilinear behavior mounted on a rigid foundation resting on distributed tensionless Winkler springs and dampers. It is well known that the behavior of soil–structure systems can be well described using a limited number of nondimensional parameters. Here, by introducing two new parameters, the concept is extended to inelastic soil–structure systems in which the foundation is allowed to uplift. An extensive parametric study is conducted for a wide range of the key parameters through nonlinear time history analyses. It is shown that while uplifting soil–structure systems experience excessive displacements, in comparison with systems that are not allowed to uplift, ductility demand in the superstructure generally decreases owing to foundation uplift. A new inelastic displacement ratio (IDR) is proposed in conjunction with a nonlinear static analysis of uplifting soil–structure systems. Simplified expressions are also provided to estimate the proposed IDR. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
140.
Kamal Jeet Singh Srikanta Murthy Anju Saxena Husain Shabbar 《Journal of Earth System Science》2017,126(2):25
The coal-bearing sequences of Barakar and Raniganj formations exposed in Bina and Jhingurdah open-cast collieries, respectively, are analysed for their macro- and miofloral content. The sediment successions primarily comprise of sandstones, shales, claystones and coal seams. In addition to the diverse glossopterid assemblage, four palynoassemblage zones, namely Zones I and II in Bina Colliery and Zones III and IV in Jhingurdah Colliery, have also been recorded in the present study. The megafossil assemblage from the Barakar strata of Bina Colliery comprises of three genera, namely Gangamopteris, Glossopteris and cf. Noeggerathiopsis. Palynoassemblage-I is characterised by the dominance of non-striate bisaccate pollen genus Scheuringipollenites and subdominance of striate bisaccate Faunipollenites and infers these strata to be of Early Permian (Artinskian) age (Lower Barakar Formation). The palynoassemblage has also yielded a large number of naked fossil spore tetrads, which is the first record of spore tetrads from any Artinskian strata in the world and has a significant bearing on the climatic conditions. The palynoassemblage-II is characterised with the dominance of Faunipollenites over Scheuringipollenites and is indicative of Kungurian age (Upper Barakar Formation). The megafossil assemblage from the Raniganj Formation of Jhingurdah Colliery comprises of five genera with 26 species representing four orders, viz., Equisetales, Cordaitales, Cycadales and Glossopteridales. The order Glossopteridales is highly diversified with 23 taxa and the genus Glossopteris, with 22 species, dominates the flora. The mioflora of this colliery is represented by two distinct palynoassemblages. The palynoassemblage-III is correlatable with the palynoflora of Early Permian (Artinskian) Lower Barakar Formation. The assemblage suggests the continuity of older biozones into the younger ones. The palynoassemblage-IV equates the beds with composition V: Striatopodocarpites–Faunipollenites–Gondisporites assemblage zone of Tiwari and Tripathi (1992) of Late Permian (Lopingian) Raniganj Formation in Damodar Basin. The FAD’s of Alisporites, Klausipollenites, Falcisporites, Arcuatipollenites pellucidus and Playfordiaspora cancellosa palynotaxa in this assemblage enhance the end Permian level of the Jhingurdah Top seam, as these elements are the key species to mark the transition of Permian into the Lower Triassic. 相似文献