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71.
The temperature rise in a castable refractory brick specimen of well-defined thermal properties was used to develop a correlation between the severities of the ASTM E119 and the ISO 834 fire tests. It was found that the ISO fire test is slightly less severe than the ASTM test, but the gain in fire endurance on account of conducting the test according to the ISO standard is usualy five minutes or less. 相似文献
72.
Sultan M Khan Tariq M Khan Richard D Wells David J Maslin Martin J Connock 《Journal of the science of food and agriculture》1992,58(3):443-445
An enzyme-based colorimetric assay for choline-containing phospholipids is described. When tested with egg yolk and serum, the method proved very sensitive, correlated well with other methods and avoided turbidity problems. The method is potentially applicable to a wide variety of samples. 相似文献
73.
Single straight-tube Coriolis mass flowmeter 总被引:6,自引:0,他引:6
G. Sultan 《Flow Measurement and Instrumentation》1992,3(4):241-246
The single straight-tube Coriolis mass flowmeter is modelled using the theory of vibrating beams, taking into account the effects of the added masses of the electromagnetic drive and detectors. Many experiments are conducted to assess the performance of an experimental flowmeter. Additionally, the influences of fluid temperature and external vibrations on the sensitivity of the flowmeter are identified. 相似文献
74.
The small-signal theory of the punch-through ‘barrier-injection and transit-time’ (BARITT) diode is given and the physical mechanisms of device operation are described. Both velocity modulation and charge density modulation components of current are included and the effects of carrier diffusion in the source regions of the device are taken into account by using an equivalent small-signal conductivity for the potential barrier which controls charge injection. It is shown how carrier bunching in the source regions creates space-charge waves which propagate through the source-drain space and generate power as the associated component of current moves into anti-phase with the local electric field.Theoretical curves are presented for a typical PNP silicon device and agree well with experimental measurements of series resistance and series capacitance. A device of area 1·25 × 10?8 m2 (5 thou. diameter) and source to drain spacing of 5 μm made in material was found to possess negative resistance over the wide frequency range from about 5 GHz to about 12 GHz with a maximum value of about — . 相似文献
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Drinking water is a complex mixture that contains thousands of naturally occurring and anthropogenic contaminants. Liquid chromatography-mass spectrometry (LC-MS) methods have gained a tremendous popularity in monitoring nonvolatile, highly polar, and thermally labile components in drinking water. It is well recognized, however, that there are difficulties or limitations of LC-MS methods associated with (1) significant resources (time and effort) involved in sample preparation (preconcentration, fractionation, separation), (2) low screening capacity for target contaminants, and (3) insufficient capabilities for structural identification (elucidation) of nontarget contaminants. Consequently, LC-MS methods are mainly used for the detection of target contaminants (compounds identified in drinking water before), seldom for the structural identification of abundant nontarget pollutants (unidentified pollutants in drinking water), and almost never for the structural identification of nontarget components at a trace level. The paper presents a new method of electrospray ionization high field asymmetric waveform ion mobility spectrometry mass spectrometry (ESI-FAIMS-MS), which can detect a large number of water pollutants in a quick and convenient fashion without preconcentration, fractionation, derivatization, or column separation. Most importantly, the method provides structural identification of nontarget contaminants including species present in drinking water at a sub-parts-per-billion concentration level. The identification of previously unknown contaminants was based on mass measurements of investigated ions and their fragments in mass and tandem mass spectrometry. Elemental compositions of these ions, determined by mass measurements, were used to link dissociation patterns of investigated species with their chemical structures. Characterization of nontarget contaminants of chlorine-treated drinking water by ESI-FAIMS-MS has revealed many previously unknown disinfection byproducts. The most intriguing compound, from a group of highly polar hydroxycarboxylic acids discovered in the study, was the most abundant component of drinking water, glycolic acid. Glycolic acid (toxic to kidneys and associated with a moderate maternal toxicity) has never been considered as a drinking water contaminant, despite the fact that it is present in drinking water at a higher concentration (high ppm) than concentrations of highly polar water pollutants that had attracted most attention in the past. The process of structural elucidation of discovered pollutants, including ultratrace contaminants representing a variety of carboxylic acids, will be presented in detail. The structural identification of highly polar contaminants in drinking water presented in the paper is rarely reported in the literature. The key experimental feature of the ESI-FAIMS-MS method is FAIMS separation, which significantly improves the identification capabilities of mass spectrometry. 相似文献
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Md. Nazibul Hasan Herman Wahid Nafarizal Nayan Mohamed Sultan Mohamed Ali 《国际能源研究杂志》2020,44(8):6170-6222
Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near-room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article. 相似文献