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1.
Experimental data for the densities, dynamic viscosities, sound speeds, and relative permittivities and for three binary systems of methyl methacrylate (MMA)+di-ethers (ethyl, isopropyl, and butyl) at 298.15 and 308.15 K and at atmospheric pressure are reported. The mixture viscosities are correlated by Grunberg–Nissan, McAllister, and Auslander equations over the complete composition range. The sound speeds for the mixtures are also calculated by using free length and collision factor theories, and Nomoto and Junjie equations. From the measured primary properties, deviation functions such as deviations in viscosities, sound speeds, relative permittivities, molar polarizations, excess isentropic compressibilities, and molar electrical susceptibilities were calculated, and the compositional dependence of each of the functions was expressed with a Redlich–Kister type equation. The variation of the Kirkwood correlation factor was determined over the complete composition range. 相似文献
2.
本文介绍利用Visual Basic工具开发金属切削机床主传动非常规变速系统的设计总体结构,功能和方法,以重复转速的传动系统为例,重点介绍转速图的拟定过程,本系统具有界面美观,操作方便,易于理解的特点。 相似文献
3.
The fluid dynamics of stirred aerated slurry reactors with A-310® propeller, 4-blade 45° pitch turbine and 6-blade Rushton disc turbine were studied over a wide range of gas flow rates. With respect to power consumption, gas hold-up, and fluid dynamically limiting cases, viz., suspension and flooding, the Rushton disc turbine was found to be the best in stirred aerated slurry reactors. The influence of particle density, shape and mass fraction and of liquid properties on gassed critical stirrer speed, Njsg, and of gassed power input per unit volume, Pjsg, on particle suspension and gas dispersion, were investigated. Empircal correlations in combination with that of Zwietering were established for scale-up design in three-phase slurry reactors. 相似文献
4.
We propose a general method for predicting multiple steps ahead of our target system and estimating simultaneously the prediction errors in a real time. The requirement of the proposed method is that we have a time series of the target system. We demonstrate the method by artificial data, real wind speed data, and real solar irradiation data. 相似文献
5.
Benjamin N. Passow Mario A. Gongora Adrian A. Hopgood Sophy Smith 《Applied Soft Computing》2012,12(11):3313-3324
Acoustic sensing to gather information about a machine can be highly beneficial, but processing the data can be difficult. In this work, a variety of methodologies have been studied to extract rotor speed information from the sound signature of an autonomous helicopter, with no a-priori knowledge of its underlying acoustic properties. 相似文献
6.
Automated extraction and classification of thunderstorm and non-thunderstorm wind data for extreme-value analysis 总被引:2,自引:0,他引:2
Franklin T. Lombardo Joseph A. Main Emil Simiu 《Journal of Wind Engineering & Industrial Aerodynamics》2009,97(3-4):120-131
Design wind loads are partly based on extreme value analyses of historical wind data, and limitations on the quantity and spatial resolution of wind data pose a significant challenge in such analyses. A promising source of recent wind speed and direction data is the automated surface observing system (ASOS), a network of about 1000 standardized US weather stations. To facilitate the use of ASOS data for structural engineering purposes, procedures and software are presented for (a) extraction of peak gust wind data and thunderstorm observations from archived ASOS reports, (b) classification of wind data as thunderstorm or non-thunderstorm to enable separate analyses, and (c) construction of data sets separated by specified minimum time intervals to ensure statistical independence. The procedures are illustrated using approximately 20-year datasets from three ASOS stations near New York City. It is shown that for these stations thunderstorm wind speeds dominate the extreme wind climate at long return periods. Also presented are estimates based on commingled data sets (i.e., sets containing, indiscriminately, both non-thunderstorm and thunderstorm wind speeds), which until now have been used almost exclusively for extreme wind speed estimates in the US. Analyses at additional stations will be needed to check whether these results are typical for locations with both thunderstorm and non-thunderstorm winds. 相似文献
7.
This paper focuses on the problem of extreme wind gust and direction change recognition (EG&DR) and control (EEC). An extreme wind gust with direction change can lead to large loads on the turbine (causing fatigue) and unnecessary turbine shutdowns by the supervisory system caused by rotor overspeed. The proposed EG&DR algorithm is based on a non‐linear observer (extended Kalman filter) that estimates the oblique wind inflow angle and the blade effective wind speed signals, which are then used by a detection algorithm (cumulative sum test) to recognize extreme events. The non‐linear observer requires that blade root bending moments measurements (in‐plane and out‐of‐plane) are available. Once an extreme event is detected, an EEC algorithm is activated that: (i) tries to prevent the rotor speed from exceeding the overspeed limit by fast collective blade pitching; and (ii) reduces 1p blade loads by means of individual pitch control algorithm, designed in an ?∞ optimal control setting. The method is demonstrated on a complex non‐linear test turbine model. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
9.
Fast reactions with nano- and micrometer aluminum: A study on oxidation versus fluorination 总被引:2,自引:0,他引:2
The use of fluorine as an oxidizing agent in aluminum (Al)-based thermite reactions yields higher peak pressures and an increase in gas production compared with oxygen-containing oxidizers, such as molybdenum trioxide (MoO3). Thus fluorination reactions have the potential to excel in situations that require high pressures and flame speeds. This study compares the combustion behaviors of Al/Teflon, Al/MoO3/Teflon, and Al/MoO3 in an effort to determine the effects that the replacement of oxygen with fluorine has on the reaction dynamics in both open and confined burning configurations. Data were collected from pressure sensors and high-speed imaging. The mass percent of Al was varied from 10 to 90% to study the effects of composition. The composites were then further tested at the optimum stoichiometry using either 50 nm or 1-3 μm Al to examine the effect of Al particle size. The addition of Teflon in an open configuration hinders the reaction due to a loss of liberated gas. Confining the reaction enables the trapped gases to enhance convection, yielding increased flame speeds. For confined conditions, the reactions containing Teflon exhibit higher peak pressures but lower flame speeds than the reactions with MoO3. These results imply that a direct relationship between generated gas pressures and flame speeds does not generally exist when comparing different oxidizers. The theoretically predicted relationship for the relative flame speed versus relative particle size based on the melt-dispersion mechanism agrees with experimental data for all Al particle sizes and for the fluorination reaction. Particle synthesis parameters are suggested that could be controlled to enable micrometer-scale Al particles to achieve the performance of nanoscale Al particles. This is of significant practical importance, because nanoparticles are 30 to 50 times more expensive than the micrometer particles. 相似文献
10.