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991.
992.
《International Journal of Hydrogen Energy》2022,47(90):38432-38444
To promote the utilization of hydrogen (H2) in existing gas turbines, dimethyl ether (DME) was used to co-fire with H2 in a model combustor. The swirl combustion characteristics of DME/H2 mixtures were measured under the varying H2 content up to 0.7. The results show that the flow velocity elevates as the H2 content increases, which is associated with the increased flame temperature. The OH level firstly increases and subsequently keeps nearly unchanged as the H2 content increases. Meanwhile, the OH area nonlinearly increases with the increasing H2 content. Moreover, the increasing H2 content induces almost linearly decreased lean blowout limit (LBO), increased NO emission, and intensified combustion acoustics. Furthermore, the combustion characteristics of the 0.46DME/0.54H2 mixture and CH4 with the same volumetric heat value were compared. The 0.46DME/0.54H2 flame displays lower LBO and higher NO emission than the CH4 flame, which mainly results from the higher reactivity of 0.46DME/0.54H2 mixture. 相似文献
993.
Monopiles and gravity base foundations (GBF) are two of the most commonly used foundations for offshore wind turbines. As resonance can cause damage and even failure of wind turbines, understanding the difference between the dynamic responses of monopiles and GBFs under free vibration is important. However there is little experimental data regarding their natural frequency, especially from model tests carried out at correct stress levels. This paper presents the results of novel monopile and GBF tests using a centrifuge to directly determine the natural frequency (fn) of the foundation-soil system. The natural frequencies of wind turbine monopiles and GBFs in centrifuge models were measured during harmonic loading using a piezo-actuator, with the results confirming that soil-structure interaction must be considered to obtain the system’s natural frequency as this frequency reduces substantially from fixed-base values. These results will contribute in preventing resonance induced damage in wind-turbines. 相似文献
994.
Silvio Barbarelli Mario Amelio Teresa Castiglione Gaetano Florio Nino Michele Scornaienchi 《国际能源研究杂志》2021,45(1):661-690
The aim of this paper is to illustrate the design of a new wave energy converter, composed of a point absorber and a hydraulic system (power take off) and sized for recovering energy in calm seas from waves near the shore. The point absorber is consisting of a rectangular shaped buoy integrating a piston pump. The set buoy‐pump oscillates under the waves action and moves natural water in a closed circuit hydraulic system (power take off) composed of a piping connecting the piston pump itself, a pressurized reservoir, a hydraulic turbine and a discharge tank. The methodology adopted for designing the main constituents involves a 1D mathematical model, settled for understanding the motion of the buoy under the hypothesis of regular waves and fully developed sea, and a sizing procedure applied for the design of all the components of the hydraulic system. The project related to the Calabrian site of Cetraro (Mediterranean Sea—south Italy) led to designing a system with a 4 m large buoy, associated with a small 13 cm diameter micro Pelton turbine, so that more than 22 000 kWh could be recovered in a year. 相似文献
995.
李懿蛟 《海洋工程装备与技术》2020,7(1):35-41
常规的单立柱式(Spar)风力发电机平台,在水深较浅区域工作时,结构本身受吃水限制,工作效果较差。常规Spar重心较低,具有良好的稳定性,但是由于它往往具有超过100 m的吃水,因此使其不能应用于中近海域(水深小于100 m)。可设计研究一种适用于中国东海不超过100 m水深的中近海域新型浮式风机平台以解决此问题。针对NREL 5MW风机能应用于100 m水深的情况,对50 m吃水的新型Spar(SJTU-S4)及其系泊系统进行了概念设计研究。利用商业软件建立水动力模型,进行数值仿真,同时设计缩比模型试验,在上海交通大学海洋工程国家重点实验室(SKLOE)进行水动力性能测试。结果表明,本文研究的新阶梯式浅吃水单立柱浮式风机平台在100 m水深、多种海洋波浪环境下,通过试验和仿真验证,能够具有良好的运动响应,为风机提供较好的工作条件。 相似文献
996.
Weighted Self-Adaptive Threshold Wavelets for Interpolation Point Selection Used in Interconnect MOR
超高膨胀比涡轮噪声控制技术研究
赵辛午,黄洪雁
(哈尔滨工业大学 能源科学与工程学院,哈尔滨 150001)
中文说明:
气动噪声控制是提高鱼雷隐身性能的关键技术之一。本文讨论了局部进气的超高膨胀比涡轮气动噪声产生机理。相邻喷嘴与流道之间形成的三角形非出气区域引起的尾迹、圆周局部进气设计引起的不稳定性、喷嘴和转子之间区域形成的复杂激波系是这类涡轮气动噪声产生的三种主要来源。因此,本文提出了两种气动噪声控制方法,增加转静子之间的轴向间距,喷嘴下俯、双侧修型和尾缘吹气。数值模拟结果表明:在对原涡轮气动性能影响不大的情况下,优化后涡轮的气动噪声下降10 dB以上。
关键词:超高膨胀比涡轮、气动噪声、流动特性、优化
相似文献997.
叶片式液压摆动油缸正常运行的关键之一在于端面密封的密封可靠性。对叶片式液压摆动油缸端面密封在静密封条件下进行数学建模,通过对该模型求解得出端面密封与转子、定子之间的接触压力,同时运用有限元软件对端面密封与转子、定子的接触压力进行仿真求解。在预压缩量0~0.5 mm,油压0~20 MPa范围内,接触压力的解析解和有限元分析结果相近,同时样机实验结果也验证了在单侧预压缩量为0和0.1 mm,油压在0~20 MPa范围时模型的正确性,这表明所建立的端面密封模型可用于判断端面密封在静密封条件下的密封可靠性。 相似文献
998.
论述了应该用有效应力的新概念代替经典有效应力原理。总应力压缩模量与渗流水等效压缩模量的曲线相似;有效应力压缩模量起加劲作用,而不是起决定性作用。土的压缩变形计算中应用有效应力原理是错误的。对于起始水力坡降,引入饱和粘性土的自由水压力衰减概念。在饱和粘性土中,自由水通道率折减不大,相对自由水压力通过一定厚度后衰减为零。所以,新概念土力学的算法接近我国规范:"对粘性土宜按水土合算计算"。还解读了地下室浮力折减、流沙陷阱等等。 相似文献
999.
1000.
In this paper, we present a new contribution for the control of Wind-turbine energy systems, a nonlinear robust control of active and reactive power by the use of the Adaptative Backstepping approach based in double-fed asynchronous generator (DFIG-Generator).Initially, a control strategy of the MPPT for extraction of maximum power of the turbine generator is presented. Thereafter, a new control technique for wind systems is presented. This control system is based on an adaptive pole placement control approach integrated to a Backstepping control system. The stability of the system is shown using Lyapunov technique. Using the FPGA to implement the order gives us a better rapidity. A Benchmark was realized by a prototyping platform based on DFIG-generator, FPGA and wind-turbine; the experimental results obtained show the effectiveness and the benefit of our contribution. 相似文献