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121.
Gustavo Avolio Dominique M. M.‐P. Schreurs Antonio Raffo Giovanni Crupi Alina Caddemi Giorgio Vannini B. Nauwelaers 《国际射频与微波计算机辅助工程杂志》2014,24(1):109-116
This work presents a straightforward approach aimed at modeling the dynamic I–V characteristics of microwave active solid‐state devices. The drain‐source current generator represents the most significant source of nonlinearity in a transistor and, therefore, its correct modeling is fundamental to predict accurately the current and voltage waveforms under large‐signal operation. The proposed approach relies on using a small set of low‐frequency time‐domain waveform measurements combined with numerical optimization‐based estimation of the nonlinear model parameters. The procedure is applied to a gallium nitride HEMT and silicon FinFET. The effectiveness of the modeling procedure in terms of prediction accuracy and generalization capability is demonstrated by validation of the extracted models under operating conditions different than the ones used for the parameters estimation. Good agreement between measurements and model simulations is achieved for both technologies and in both low‐ and high‐frequency range. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:109–116, 2014. 相似文献
122.
Material characterization has become increasingly important with the adoption of simulation‐based workflow for microwave electronics design. This article focuses on the characterization of printable electronics materials using transmission‐line measurements and demonstrates the capability of the multiline characterization method to separate dielectric and conductor losses when line geometry and material properties vary between the lines. The effects of multiline algorithm, number of line standards, and methods for selecting optimal line lengths are demonstrated. Consistent characterization results are obtained from inkjet‐printed transmission lines on two different substrate materials. In addition, local conductor thickness variations are demonstrated as an effective way to decrease losses. Finally, the simulation‐based procedure for determining the material properties is outlined and applied to printable electronics characterization. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:177–183, 2014. 相似文献
123.
微波辐射对甲苯磺酸催化合成乙酸环己酯 总被引:15,自引:0,他引:15
以冰醋酸和环己醇为原料 ,环已烷为带水剂 ,对甲苯磺酸作催化剂 ,采用微波辐射技术 ,在常压下直接合成乙酸环己酯。最适宜反应条件为 :n(环己醇 )∶n(乙酸 ) =1 5∶1 0 ,对甲苯磺酸用量 0 2 0 g ,带水剂用量 5mL ,微波功率 5 95W ,辐射时间 15min ,产率达 97%以上 相似文献
124.
以3-羟基丙胺和丙烯酸甲酯为起始原料,在微波辅助下进行Michael加成、Dieckmann环合和脱羧反应合成了1-(3-羟丙基)-4-哌啶酮.并对Michael加成、Dieckmann环合和脱羧反应的工艺参数进行了优化,通过核磁共振波谱对目标化合物和中间体的结构进行表征.得到的最优Michael加成工艺条件为:n(3-羟基丙胺):n(丙烯酸甲酯)=1.0:2.4,微波辐射功率为120 W,反应温度40℃,反应时间30 min.在该条件下制备3-[(2-甲氧羰乙基)(3-羟丙基)氨基]丙酸甲酯的收率为92.6%;在微波辐射功率为200 W下,Dieckmann环合反应和脱羧反应分别为20和25 min,以88.5%的收率得到1-(3-羟丙基)-4-哌啶酮;目标产物总收率为82.0%. 相似文献
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The emulsifier‐free emulsion polymerization of methyl methacrylate (MMA) was conducted with microwave irradiation. Superfine and monodisperse poly(methyl methacrylate) (PMMA) microspheres were obtained. Microwave irradiation notably promoted the polymerization reaction. This phenomenon was ascribed to the acceleration of the initiator [potassium persulfate (KPS)] decomposition by microwave irradiation. The experimental results revealed that the apparent activation energy of KPS decomposition decreased from 128.3 to 106.0 kJ/mol with microwave irradiation. The average particle size of the prepared PMMA latex was mainly controlled with the MMA concentration; it increased linearly from 103 to 215 nm when the MMA concentration increased from 0 to 0.3 mol/L and then remained almost constant at MMA concentrations of 0.3–1.0 mol/L. The KPS concentration had no effect on the average particle size, but the particle size dispersity was significantly reduced by a high KPS concentration. With a mixed polymerization phase (water/acetone = 1:3 v/v) or a redox initiation system, PMMA nanoparticles were obtained with an average particle size of 45 or 67 nm, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2815–2820, 2004 相似文献
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129.
以碳毡为预制体,N2为稀释气体,甲烷为碳源前驱体,其分压为10 kPa,滞留时间为0.15 s的工艺条件下,研究了不同沉积温度对微波热解化学气相渗透(chemical vapor infiltration,CVI)工艺制备碳/碳复合材料的致密化速率、样品的体积密度及其密度均匀性的影响,并对其组织结构进行了观察.分析了沉积温度对微波热解CVI工艺制备碳/碳复合材料的密度与组织结构的变化规律.结果表明:在微波热解CVI工艺中,随着沉积温度的降低,碳毡预制体的致密化速率及最终体积密度呈现先升后降,1100 ℃沉积制备复合材料的密度均匀性最好,并呈现从内到外逐步沉积的规律.热解碳的织构主要为中等织构. 相似文献
130.
Effectiveness of microwave heating in an activation treatment of zeolites was studied and utilization of zeolites for reusable desiccant was examined. X zeolite was chosen as a target material for its large adsorption capacity. Na-X zeolite easily caused a thermal runaway by microwave radiation of 500 W but Ca contained X zeolite merely reached ca. 573 K under the same conditions. Mixtures of Na-X and Ca-X with suitably mixed ratios did not cause the thermal runaway and their heating temperatures were controlled (>573 K) at will. Under the most suitable conditions, the mixture reached a dehydration degree of 92%. A degradation degree of adsorptive capacity of the mixture for water was examined after three treatments. The average degradation degree was 1.5% per treatment. The heating method is promising as a quick and easy technique to activate zeolite. By applying the method, the zeolites with suitable mixing ratios are usable as a reusable desiccant for home use. 相似文献