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101.
ABSTRACT Spectroscopic applications of the recently described method of arc lamp stabilization by the addition of a small (<2v) alternating current (AC) to a direct current (DC) arc lamp are discussed. A possible explanation for the improved arc stability is presented. Evaluation of arc formation and spatial behavior is monitored by a series of still photographs of the arc image. Observation of the electrode surfaces in similar photographs provide insight into the distribution of heat in the inter-electrode region. A photodiode array imaging device is used to accurately detect lateral movement of the arc image over prolonged time periods. Advantages of AC stabilized lamps in spectroscopic applications are also presented. 相似文献
102.
Ruopeng Wang Sang-Ho Kim Sang-Hyeon Lee Seung-Bin You Jae-Whui Kim Un-Ku Moon Gabor C. Temes 《Analog Integrated Circuits and Signal Processing》2007,51(1):27-31
An oversampled digital-to-analog converter (DAC) with a 100-dB A-weighted dynamic range is presented. It uses a switched-capacitor
(SC) array to transfer the sampled charges directly into the headphone driver. The overall DAC gain is precisely controlled
by a novel reference stage. A new dynamic element matching algorithm, based on split-set data-weighted averaging (SDWA), is
used to improve the dynamic range and to reduce the nonlinearity caused by mismatches in the multibit DAC. 相似文献
103.
104.
Wellfield B, in the Great Artesian Basin (GAB), supplies 30 ML/day of fresh groundwater to BHP Billiton’s Olympic Dam mine and the town of Roxby Downs in South Australia. Groundwater use from Wellfield B is regulated according to the regional effects on pressures in the aquifer. Drawdown assessment criteria (allowing a maximum of 5?m as pressure drawdown measured in piezometers) were set at five sites, including two active pastoral production wells that existed prior to the commissioning of Wellfield B. Aquifer pressure in these production wells was measured after a predetermined recovery time. Pastoral flow was eliminated in 2009/10 in one of the wells, providing an opportunity to assess whether antecedent flow had affected the measured pressures and therefore the reported apparent drawdown. In the GAB, the combination of deep wells, high pressures, and hot water make flow and pressure measurements and the calculation of head more challenging than in cold aquifers. Pressures measured at the well head often decrease during recovery, and the influence of temperature has to be incorporated in head calculations. Based on one example, Jackboot Bore, it is clear that recovery times in the order of months are required, which is impractical. Hence, the use of an active production well for assessing compliance with drawdown criteria is not recommended in the GAB. 相似文献
105.
Sophie Salasca Bruno Cantone André Grosman Basilio Esposito Fabio Moro Daniele Morocco Rosaria Villari Maurizio Angelone Esther Rincon Carlos Hidalgo Daniel Nagy Gabor Kocsis Paulo Varela Gabor Porempovics Guillaume Perrollaz Kunal Patel Yuri Krivchenkov Michael Walsh 《Fusion Engineering and Design》2013,88(6-8):602-606
Diagnostics in ITER are mandatory to characterize the parameters of plasma and study its interactions with plasma-facing components. Diagnostics components in the vicinity of the plasma are supported by metallic structures called port plugs. At the tokamak mid-plane, these components are installed in port plugs through intermediate structures called drawers. Apart from hosting the diagnostics, the port plugs act as shielding against neutrons and gammas, in order to limit the nuclear loads in crucial components (such as diagnostics and superconducting coils) as well as the dose levels in the controlled zones of the tokamak. The radiation shielding function of the port plugs is ensured through an optimized mixture of heavy metallic materials and water, forming shielding blocks surrounding the diagnostics and called Diagnostic Shield Modules (DSMs). These DSMs constitute the rear part of the drawers (the front part being composed of the Diagnostic First Wall). This paper presents the main results of a study performed in Europe on the integration of a particular diagnostics port plug, the Equatorial Port Plug 1 (EPP1). The paper first provides the results of the EPP1 diagnostics integration analysis. In a second step it focuses on the design of the EPP1 DSMs and summarizes the major results of a thorough set of analyses aiming at studying the DSMs behaviour under different loads, suggesting recommendations to improve their current design. 相似文献
106.
107.
Zhenyong Zhang Jesper Steensgaard Gabor C. Temes Jian-yi Wu 《Analog Integrated Circuits and Signal Processing》2009,59(2):143-150
A dual-path 2-0 cascaded delta-sigma (MASH) ADC was implemented with fast digital correction of both DAC errors and MASH mismatch
errors. The digital correction techniques greatly reduced the requirements on the analog circuits. The dual-path structure
allows fast convergence and improved accuracy for the correction. Using a 20 MHz clock, the prototype chip achieved an 84 dB
dynamic range in a 1.25 MHz signal band, when fabricated in CMOS 0.18 μm process. 相似文献
108.
Previous research for detecting incipient wind turbine failures, using condition monitoring algorithms, concentrated on wind turbine Supervisory Control and Data Acquisition (SCADA) signals, such as power output, wind speed and bearing temperatures, using power‐curve and temperature relationships. However, very little research effort has been made on wind turbine SCADA alarms. When wind turbines are operating in significantly sized wind farms, these alarm triggers are overwhelming for operators or maintainers alike because of large number occurring in a 10 min SCADA period. This paper considers these alarms originating in two large populations of modern onshore wind turbines over a period of 1–2 years. First, an analysis is made on where the alarms originate. Second, a methodology for prioritizing the alarms is adopted from an oil and gas industry standard to show the seriousness of the alarm data volume. Third, two methods of alarm analysis, time‐sequence and probability‐based, are proposed and demonstrated on the data from one of the wind turbine populations, considering pitch and converter systems with known faults. The results of this work show that alarm data require relatively little storage yet provide rich condition monitoring information. Both the time‐sequence and probability‐based analysis methods have the potential to rationalize and reduce alarm data, providing valuable fault detection, diagnosis and prognosis from the conditions under which the alarms are generated. These methods should be developed and integrated into an intelligent alarm handling system for wind farms, aimed at improving wind turbine reliability to reduce downtime, increase availability and leading to a well‐organized maintenance schedule. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
109.
Iablokov V Beaumont SK Alayoglu S Pushkarev VV Specht C Gao J Alivisatos AP Kruse N Somorjai GA 《Nano letters》2012,12(6):3091-3096
Model cobalt catalysts for CO(2) hydrogenation were prepared using colloidal chemistry. The turnover frequency at 6 bar and at 200-300 °C increased with cobalt nanoparticle size from 3 to 10 nm. It was demonstrated that near monodisperse nanoparticles in the size range of 3-10 nm could be generated without using trioctylphosphine oxide, a capping ligand that we demonstrate results in phosphorus being present on the metal surface and poisoning catalyst activity in our application. 相似文献
110.
In this paper, we identify and describe the key ideas, concepts and software related to Medical Imaging that emerged from our research group, which is commonly known by the acronym MIPG, denoting Medical Image Processing Group. For the purpose of our presentation, we consider the entire discipline of Medical Imaging to consist of the areas of acquisition, postprocessing, evaluation, and application. We are indeed fortunate to be able to discuss seminal research from our group in each of these areas. In Section II, we identify relevant moments of inception and describe our past contributions. Our achievements, current activities, and future directions are summarized in Section III, Section IV, and Section V, respectively; the keys to our success are listed in Section V 相似文献