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971.
Sub-quality natural gas (SQNG) is defined as natural gas whose composition exceeds pipeline specifications of nitrogen, carbon dioxide (CO2) and/or hydrogen sulfide (H2S). Approximately one-third of the U.S. natural gas resource is sub-quality gas [1]. Due to the high cost of removing H2S from hydrocarbons using current processing technologies, SQNG wells are often capped and the gas remains in the ground. We propose and analyze a two-step hydrogen production scheme using SQNG as feedstock. The first step of the process involves hydrocarbon processing (via steam–methane reformation, autothermal steam–methane reformation, pyrolysis and autothermal pyrolysis) in the presence of H2S. Our analyses reveal that H2S existing in SQNG is stable and can be considered as an inert gas. No sulfur dioxide (SO2) and/or sulfur trioxide (SO3) is formed from the introduction of oxygen to SQNG. In the second step, after the separation of hydrogen from the main stream, un-reacted H2S is used to reform the remaining methane, generating more hydrogen and carbon disulfide (CS2). Thermodynamic analyses on SQNG feedstock containing up to 10% (v/v) H2S have shown that no H2S separation is required in this process. The Part I of this paper includes only thermodynamic analyses for SQNG pyrolysis and autothermal pyrolysis. 相似文献
972.
An ecological performance analysis for an irreversible dual-cycle cogeneration system has been performed. The objective function is called as the exergetic-performance coefficient (EPC) and defined as the ratio of total exergy output to the loss rate of availability. The general and optimal performances of the irreversible dual-cycle cogeneration system, having a finite-rate of heat transfer, heat leak and internal irreversibilities based on the EPC objective function have been investigated. Comparisons with respect to the optimal total-exergy output are also provided in order to establish the utility of the new exergetic-performance coefficient. The analyzed results of the dual-cycle cogeneration system considered, working at maximum EPC conditions, have a significant advantage in terms of entropy-generation rate and can be used for the selection of optimal design parameters. 相似文献
973.
A new process for generating hydrogen via near room temperature hydrolysis of AB complex using small amounts of platinum group metal catalyst has been studied. Using in situ 11B NMR spectroscopy, the overall rate of K2Cl6Pt catalyzed hydrolysis of AB complex was calculated to be third-order. The pre-exponential factor (A) and the activation energy (Ea) of Arrhenius equation, ln k = ln A − Ea/RT, were determined to be: A = 1.6 × 1011 L mol−1 s−1 and Ea = 86.6 kJ mol−1 for temperature range of (25–35 °C). X-ray photoelectron spectroscopy of the residue suggested that the platinum salt was reduced from Pt4+ to Pt0 within the course of the reaction and X-ray diffraction analysis pattern for the residue showed crystallized single-phase boric acid. 相似文献
974.
Payam Khosravinia Mohammad Reza Nikpour Amir Malekpour Ali Hosseinzadeh Dalir 《河流研究与利用》2019,35(2):159-168
In an open‐channel confluence, deep scour holes and depositional point bars are usually formed due to high bed‐shear stresses and secondary circulations. In the present study, presuming the effectiveness of channel geometry on the flow dynamics at the confluence, some variables including different side slope angles of the main channel (θ = 45°, 60°, 75°, 90°), lateral to downstream discharge ratio (Qr), and downstream densimetric Froude number (Frg3) were experimentally studied under clear‐water condition for the confluence angle α = 90°. According to the results, the increase of θ led to a greater penetration of scour hole across the main and tributary channels, whereas a little scour development was observed along those channels. Meanwhile, an increase in Qr and Frg3 caused further scouring, but their effects on the dimensions of scour hole diminished with increase of θ. Thus, with increase of Qr from 0.194 to 0.552, the mean penetration rate of scour hole to all directions for θ = 45°, 60°, 75°, and 90° was obtained 42.8%, 32.4%, 25%, and 20.5%, respectively. In addition, considering the effect of θ, Qr, and Frg3, some empirical relationships were obtained for estimating the penetration length of scour hole. The derived relationships show that Frg3 plays more important role on the dimensions of scour hole than θ. 相似文献
975.
Water Resources Management - This work presents an analytical solution for the linearized Boussinesq equation describing the nature of well hydraulics in equilateral triangular-shaped unconfined... 相似文献
976.
Over recent years, there has been a clear increase in the frequency of reported flooding events around the world. Gabion structures offer one means of flood mitigation in dam spillways. These types of structures provide an additional challenge to the computational modeller in that flow through the porous gabions must be simulated. We have used a computational model to investigate the flow over gabion stepped spillways. The model was first validated against published experimental results. Then, gabion stepped spillways with four different step geometries were tested under the same conditions in order to facilitate inter-comparisons and to choose the best option in terms of energy dissipation. The results show that normal gabion steps can dissipate more energy than overlap, inclined, and pooled steps. An intensive set of tests with varying slope, stone size, and porosity were undertaken. The location of the inception point and the water depth at this point obtained from this study were compared with those from existing formulae. Two new empirical equations have been derived, on the basis of a regression analysis, to provide improved results for gabion stepped spillways. 相似文献
977.
Mohammad Hossein Keshavarz Alireza Ramadan Ali Mousaviazar Karim Esmaeilpour Fariborz Atabaki 《Journal of Energetic Materials》2013,31(1):46-60
In this work, the effect of low volatile hydroxyethylhydrazine (HEH) as a solute on unsymmetrical dimethylhydrazine (UDMH) has been studied in order to reduce harmful effects of UDMH vapors. Desirable physical properties of binary mixtures UDMH/HEH have been measured and compared to pure UDMH. These properties include boiling point, viscosity, density, and vapor pressure that are important for using binary mixtures of UDMH/HEH as less dangerous liquid propellants. Due to the formation of strong hydrogen bonding between UDMH and HEH, the volatility of UDMH has been reduced appreciably upon the addition of HEH. It is indicated that the measured physical properties may deviate significantly compared to corresponding predicted values. Binary mixtures of UDMH/HEH can also react spontaneously in contact with nitrogen tetroxide (NTO) and red fuming nitric acid (RFNA), so they can be called hypergolic propellants. 相似文献
978.
Latif H. Ali Saadallah T. Sulaiman Mohammed Y. Al-Tamer 《Petroleum Science and Technology》2013,31(8):1209-1219
ABSTRACT A model study on the hydrodesulphurization of dimethyl sulphide, di n-prophyl sulphide, di n-butyl sulphide and dimethyl disulphide on Co-Mo-A12O3 surface was conducted using stopped-flow chromatographic technique. The plots for the rates of hydrocarbon formation agreed well with the first order reaction at the surface of the catalyst. Activation energies for the hydrodesulphurization of (C2H5)2S, (C3H7)2S, n-(C4H9)2S and (CH3)2S2 are 57.55, 70.67, 72.74 and 37.80 Kj mole?1 respectively. 相似文献
979.
Abstract The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525° to 750°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure. The yields of char, condensibles and gaseous products were determined at 25°C intervals. Gaseous products were analysed for H2, CO, CO2, CH4 and C2+. Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700°C. Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time. The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced. 相似文献
980.
This study focuses on the rheological and physiochemical characterization of three samples of light crude oil and fuel oil from the United Arab Emirates. The dependence of density on temperature ranging from 20 to 200°C was determined. Also, the impact of temperature was investigated on viscosity, shear stress τ, shear rate, yield stress, and thixotropic behavior, and characterized by the Haake RheoStress. The exponential decrease of viscosity over temperature range was modeled using Arrhenius equation. The shear stress–viscosity data revealed that crude oil A solely exhibited Newtonian behavior while crude oils B and C and fuel oil followed the Herschel-Bulkley model. 相似文献