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61.
Flow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar,Turkey 下载免费PDF全文
Sophie Hage Aurélia Hubert‐Ferrari Laura Lamair Ulaş Avşar Meriam El Ouahabi Maarten Van Daele Frédéric Boulvain Mohamed Ali Bahri Alain Seret Alain Plenevaux 《Sedimentology》2017,64(7):1929-1956
Turbidity currents and their deposits can be investigated using several methods, i.e. direct monitoring, physical and numerical modelling, sediment cores and outcrops. The present study focused on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in eleven clusters of closely spaced thin beds. Depositional processes and sources for three of those eleven clusters are studied at three coring sites. Bathymetrical data and seismic reflection profiles are used to understand the specific geomorphology of each site. X‐ray, thin sections and CT scan imagery combined with grain‐size, geochemical and mineralogical measurements on the cores allow characterization of the turbidites. Turbidites included in each cluster were produced by remobilization of surficial slope sediment, a process identified in very few studies worldwide. Three types of turbidites are distinguished and compared with deposits obtained in flume studies published in the literature. Type 1 is made of an ungraded clayey silt layer issued from a cohesive flow. Type 2 is composed of a partially graded clayey sand layer overlain by a mud cap, attributed to a transitional flow. Type 3 corresponds to a graded clayey sand layer overlain by a mud cap issued from a turbulence‐dominated flow. While the published experimental studies show that turbulence is damped by cohesion for low clay content, type 3 deposits of this study show evidence for a turbulence‐dominated mechanism despite their high clay content. This divergence may in part relate to input variables, such as water chemistry and clay mineralogy, that are not routinely considered in experimental studies. Furthermore, the large sedimentological variety observed in the turbidites from one coring site to another is related to the evolution of a sediment flow within a field‐scale basin made of a complex physiography that cannot be tackled by flume experiments. 相似文献
62.
Lashkari Ali Shourijeh Piltan Tabatabaie Khorasani Seyed Saeid Sahebkar Irani Nazanin Rahman Md. Mizanur 《Acta Geotechnica》2022,17(11):4989-5007
Acta Geotechnica - This article presents an experimental program under the constant volume condition to investigate the influence of over-consolidation on flow instability of clean and silty sand... 相似文献
63.
S. Yousaf M. Anam N. Ali 《International Journal of Environmental Science and Technology》2017,14(7):1439-1450
The role of endogenous redox mediators has considerable importance in electron shuttling reactions and associated performance of microbial fuel cell. Single-chamber microbial fuel cell-II with dual air-cathode assembly (area = 18.84 cm2) supported highest bacterial (Pseudomonas aeruginosa) density (6.7 × 109) and active biomass [4.4 ± 0.3 mg cm?2 (carbon content = 0.48 ± 0.1 mg cm?2)] on anode thereby resulting in maximum production of redox metabolite, 5-methyl 1, hydroxy phenazine (301 ppm) and voltage (595 ± 5 mV) than similar cells with relatively less surface area of cathode. It was further revealed that 5-methyl 1, hydroxy phenazine production was positively correlated with chemical oxygen demand removal rate (77 ± 2.5%) and power generation (66.6 ± 2.2 mW cm?2) efficiency of single-chamber microbial fuel cell-II. Maximum power density of 258 ± 4.5 mW cm?2 was generated when reactor was supplemented with 2 ml crude extract of 5-methyl 1, hydroxy phenazine metabolite, whereas power output was about 229 ± 2.5 mW cm?2 when reactor was bio-stimulated with 1 ml pure extract of 5-methyl 1, hydroxy phenazine. With this concentration, the electrochemical response of mixed culture biofilm (sediment) was enhanced by 99.3%. However, further increase in concentration of endogenous mediator proved to be limiting on reactor performance. Pyrosequencing and phylogenetic analysis on the basis of partial 16S rRNA sequences demonstrated both culturable and unculturable bacterial species in anodic biofilm and relative abundance of family Pseudomonadaceae was found to be maximum, i.e., 61.7% followed by Rhodocyclaceae 19.2%, Xanthomonadaceae 6.3% and Opitutaceae 3.18%. 相似文献
64.
I. Safdar A. Raza A. Z. Khan E. Ali 《International Journal of Environmental Science and Technology》2017,14(8):1807-1818
The problem regarding environment has been considered as contemporary issue, and to cater this, various technologies have been revolutionized in vehicle transport field. Efforts have been made to make vehicle engine efficient and introducing hybridized vehicles with the aim of reducing emissions and less fuel dependency. In essence of this, trends of solar electric cars in different countries have been reviewed. Feasibility analysis is done by doing fuel cost analysis of two cases, i.e., simple hybrid vehicle and hybrid vehicle equipped with solar module and increased battery energy storage capacity for a specific round trip distance between two cities, i.e., Rawalpindi and Islamabad in comparison with feasibility of third case, i.e., proposed solar electric car model. The solar module selection along with desired number of batteries with charging and discharging time and motor power required to carry five persons weight (70 kg each) is calculated for third case. Moreover, total carbon dioxide emission analysis has been carried out from car material production to its assembly, manufacturing solar module and nickel metal hydride battery for each case. The annual carbon dioxide emitted from fuel in first two cases relative to electric outlet in third case for specific distance has been analyzed. On large scale, emission analyses for hundred cars of each case have been done at 100 km distance. From calculations, it is revealed that overall emissions in third case on large scale and from its material production, assembly, solar module and batteries manufacturing perspective are comparatively less than other cases. 相似文献
65.
A geomechanical model can reveal the mechanical behavior of rocks and be used to manage the reservoir programs in a better mode. Fluid pressure will be reduced during hydrocarbon production from a reservoir. This reduction of pressure will increase the effective stress due to overburden sediments and will cause porous media compaction and surface subsidence. In some oil fields, the compacting reservoir can support oil and gas production. However, the phenomena can also cause the loss of wells and reduced production and also cause irreparable damage to the surface structures and affect the surrounding environment. For a detailed study of the geomechanical behavior of a hydrocarbon field, a 3D numerical model to describe the reservoir geomechanical characteristics is essential. During this study, using available data and information, a coupled fluid flow-geomechanic model of Fahlian reservoir formation in X-field in SW of Iran was constructed to estimate the amount of land subsidence. According to the prepared model, in this field, the maximum amount of the vertical stress is 110 MPa and the maximum amount of the horizontal stress is 94 MPa. At last, this model is used for the prediction of reservoir compaction and subsidence of the surface. The maximum value of estimated ground subsidence in the study equals to 29 mm. It is considered that according to the obtained values of horizontal and vertical movement in the wall of different wells, those movements are not problematic for casing and well production and also the surrounding environment. 相似文献
66.
A. H. H. Ali M. N. Ibrahim 《International Journal of Environmental Science and Technology》2017,14(6):1253-1266
Depletion of conventional fuels, concerns about environmental pollution and the tightening of exhaust emission legislations are the main reasons for increasing research on alternative fuels produced from agricultural feedstock. In this study, biodiesel fuels produced from cotton and corn vegetable oils are investigated as renewable fuels for a gas turbine engine for aviation. The biodiesel fuels are defined as cotton methyl ester (CTME) and corn methyl ester. The performance characteristics and exhaust emissions of the gas turbine engine are investigated when the engine fueled with three blends of 10%(B10), 20%(B20) and 50%(B50) of biodiesel/JetA-1 by volume. The biodiesel fuels were produced using transesterification process and characterized according to ASTM biodiesel specifications. Chemical and physical properties show a real potential of using biodiesel blends as an alternative for JetA-1. The measured engine performance parameters and exhaust emissions are compared with that of pure JetA-1 over a range of throttle setting. The gas turbine engine used in this study is equipped with pressure, flow, temperature, thrust and speed sensors that connected to data acquisition system and control unit in addition to exhaust gas analyzer. The experimental results show that biodiesel fuels can be used up to blend of 50% with JetA-1 in gas turbine engines with slight enhancement in engine performance and significant improvements in exhaust emissions. The engine static thrust is increased with 2% for B50 at lower and medium engine speeds and decreased with 11% at high engine speed compared to conventional JetA-1 fuel. The thrust-specific fuel consumption for biodiesel blends is lower than that for regular JetA-1 fuel. The gas turbine engine efficiency is increased for biodiesel blends by 14% compared to JetA-1, and this is reported for CTME B50. For oxygen concentration in exhaust gases emissions, the higher the biodiesel blend, the higher the O2 concentration in the exhaust compared with JetA-1 fuel. The O2 level increased by 6% for biodiesel blend of B50 compared to JetA-1 fuel. The emissions of CO and HC emissions decreased by 5 and 37%, respectively, compared with conventional JetA-1. Additionally, the biodiesel blends achieve a higher CO2 and NOx emissions with 11 and 27%, respectively, compared to JetA-1. The sulfur dioxide SO2 decreased by 75% compared to the regular JetA-1 fuel. 相似文献
67.
Organic Material and Trace Elements of Bituminous Rocks in the Ozankiiy Field, Ankara, Turkey 下载免费PDF全文
Saday Azadoglu ALIYEV Ali SARI 《《地质学报》英文版》2007,81(4):658-667
Bituminous rocks in the Ozankoey (Ankara) field are different from those of the Paleocene- Eocene Mengen and Giineytepe (Bolu) regions in metal enrichment levels. Organic carbon (Corg) content of organic material-rich rocks in the Ozankoey (Ankara) field is 3.66-40.72% wt averaging 14.34%. The dominant organic materials are algae/amorphous accompanied by minor amount of herbaceous material (The dominant kerogen type is Type-I with a limited amount of Type-Ⅱ kerogen.). The bituminous rocks in the Ozankoey field are enriched in heavy metals such as Ni, Mn, As and Cr. In comparison with the average enrichment values of dements, Ni, Mn, As and Cr in bituminous shales of the Ozankoey field are as about 4.38, 14.93, 10.90 and 5.58 times as average values. The average concentrations of these heavy metals are also as high as 215× 10^-6, 828 × 10^-6, 58.54 × 10^-6, and 148 × 10^-6 respectively. In addition, sorption properties of day and organic materials are also important for metal enrichments in the bituminous shales. 相似文献
68.
69.
When a turbulent shear flow above a plane sand surface entrains sand grains,it generates a variety of sand patterns.Fluvial sand forms two major interfacial patterns:meso-scale dunes and antidunes,and large-scale bars.Measurements have evidenced that under erosive conditions,meso-scale patterns either change to or coexist with large-scale patterns.However,it remains elusive what exactly drives the switching of interfacial patterns and how the switching occurs.Here,we showdcombing a flow model with a grain transport model,allowing for both the surface and suspended sand fluxes dthat the switching of patterns emerges from the shear-driven complex feedback between grain transport and topographic perturbations.The switching predominantly depends on the magnitudes of the Rouse number and the grain size to undisturbed flow depth ratio.The model offers quantitative predictions of the maximum amplification of sand patterns and unveils a new attraction erepulsion phenomenon. 相似文献
70.
The added value of the joint pre-stack inversion of PP (incident P-wave and reflected P-wave) and PS (incident P-wave and reflected S-wave) seismic data for the time-lapse application is shown. We focus on the application of this technique to the time-lapse (four-dimensional) multicomponent Jubarte field permanent reservoir monitoring seismic data. The joint inversion results are less sensitive to noise in the input data and show a better match with the rock physics models calibrated for the field. Further, joint inversion improves S-impedance estimates and provides a more robust quantitative interpretation, allowing enhanced differentiation between pore pressure and fluid saturation changes, which will be extremely useful for reservoir management. Small changes in reservoir properties are expected in the short time between the time-lapse seismic acquisitions used in the Jubarte project (only 1 year apart). The attempt to recover subtle fourth-dimensional effects via elastic inversion is recurrent in reservoir characterization projects, either due to the small sensitivity of the reservoirs to fluid and pressure changes or the short interval between the acquisitions. Therefore, looking for methodologies that minimize the uncertainty of fourth-dimensional inversion outputs is of fundamental importance. Here, we also show the differences between PP only and joint PP–PS inversion workflows and parameterizations that can be applied in other projects. We show the impact of using multicomponent data as input for elastic seismic inversions in the analysis of the time-lapse differences of the elastic properties. The larger investment in the acquisition and processing of multicomponent seismic data is shown to be justified by the improved results from the fourth-dimensional joint inversion. 相似文献