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281.
针对全固态直线变压器驱动源(LTD)中大规模开关同步触发的需求,设计了一款基于ZYNQ-7000 SoC平台的全数字多路脉冲延时系统。介绍了该系统各功能模块,并重点从时间数字转换器(TDC)、多路脉冲输出及ARM核控制三个模块进行分析设计。详细阐述了TDC模块抽头延时法原理及高精度进位链的构造;采用粗延时和细延时结合设计多路脉冲输出模块,有效提高信号的延时精度和范围,且模块化设计提高了通道数目的可扩展性;阐述ARM核控制流程,实现了响应快、稳定性高的控制。最后对系统进行了仿真验证,固化后在器件上进行了实测。实验结果表明,系统能够对外部触发信号实现多路延时输出,信号脉冲宽度1200 ns,幅值1.8 V,延时步进1 ns,延时调节范围0~4.29 s,输出误差低于1 ns。 相似文献
282.
283.
Xiaowei Xu Jingyi Feng Liu Zhan Zhixiong Li Feng Qian Yunbing Yan 《Entropy (Basel, Switzerland)》2021,23(3)
As a complex field-circuit coupling system comprised of electric, magnetic and thermal machines, the permanent magnet synchronous motor of the electric vehicle has various operating conditions and complicated condition environment. There are various forms of failure, and the signs of failure are crossed or overlapped. Randomness, secondary, concurrency and communication characteristics make it difficult to diagnose faults. Meanwhile, the common intelligent diagnosis methods have low accuracy, poor generalization ability and difficulty in processing high-dimensional data. This paper proposes a method of fault feature extraction for motor based on the principle of stacked denoising autoencoder (SDAE) combined with the support vector machine (SVM) classifier. First, the motor signals collected from the experiment were processed, and the input data were randomly damaged by adding noise. Furthermore, according to the experimental results, the network structure of stacked denoising autoencoder was constructed, the optimal learning rate, noise reduction coefficient and the other network parameters were set. Finally, the trained network was used to verify the test samples. Compared with the traditional fault extraction method and single autoencoder method, this method has the advantages of better accuracy, strong generalization ability and easy-to-deal-with high-dimensional data features. 相似文献
284.
《Journal of separation science》2018,41(12):2640-2650
Analytical instruments able to provide extremely high sensitivities, separation efficiencies, and peak capacities are important for both applied sciences and basic research. It is even more interesting if this can be achieved within organic, aqueous, and physiological solutions without restricting the operation parameters, such as buffer pH, temperature, ionic strength, and background electrolyte composition. Toroidal capillary electrophoresis offers this potential, as was recently proposed and demonstrated. In this platform, the analytes perform continuous round trips inside a fused‐silica capillary having a torus‐like shape. In the present work, the equations of the number of plates and peak capacity are deduced when on‐column cyclic thermal band compression is applied. They are expressed as a function of the number of turns performed by the analyte, axial length of the toroid, number of microholes (reservoirs), compression factor, number of compression events performed per turn, and applied voltage. It was found that the variances of the bands reach a steady state, regardless of the number of dispersion mechanisms present. Consequently, the number of theoretical plates grows indefinitely as the square of time. The expression of peak capacity shows a well‐defined limiting value that remains constant over time. 相似文献
285.
286.
Synchronous fluorescence spectroscopy for quantitative determination of virgin olive oil adulteration with sunflower oil 总被引:2,自引:0,他引:2
Adulteration of extra virgin olive oil with sunflower oil is a major issue for the olive oil industry. In this paper, the
potential of total synchronous fluorescence (TSyF) spectra to differentiate virgin olive oil from sunflower oil and synchronous
fluorescence (SyF) spectra combined with multivariate analysis to assess the adulteration of virgin olive oil are demonstrated.
TSyF spectra were acquired by varying the excitation wavelength in the region 270–720 nm and the wavelength interval (Δλ) in the region from 20 to 120 nm. TSyF contour plots for sunflower, in contrast to virgin olive oil, show a fluorescence
region in the excitation wavelength range 325–385 nm. Fifteen different virgin olive oil samples were adulterated with sunflower
oil at varying levels (0.5–95%) resulting in one hundred and thirty six mixtures. The partial least-squares regression model
was used for quantification of the adulteration using wavelength intervals of 20 and 80 nm. This technique is useful for detection
of sunflower oil in virgin olive oil at levels down to 3.4% (w/v) in just two and a half minutes using an 80-nm wavelength
interval. 相似文献
287.
288.
289.
Theoretical relationships suitable for both constant-wavelength and variable-angle synchronous fluorescence in the wavelength domain were obtained for the calculation of peak location, intensity, and half-width of synchronous fluorescence spectra. The calculated values were compared with experimental data and the data derived from the literature equations, indicating that the proposed methods are feasible, less formidable, and more straightforward in the wavelength domain than previous ones. The proposed approaches provide a theoretical guide for the experimental design of synchronous fluorescence spectrometric methods in the wavelength domain. On the basis of the theoretical derivation, special characteristics of the peak half-bandwidths of the spectra were revealed. In certain cases, the bandwidth of a variable-angle synchronous spectrum is of less practical meaning. 相似文献
290.
针对整车控制参数引发的车辆异响问题,介绍了一种基于整车控制参数与NVH数据同步采集的分析方法,通过采用数据协议和格式的双转换,实现了整车/发动机控制参数和整车NVH测试数据的同步采集,并通过控制参数和NVH信号的时域相关性分析,快速准确地定位异响原因。通过底盘冲击异响、涡轮气流异响、整车换挡抖动异响三个案例,介绍了整车控制参数同步采集在工程中的实际应用,快速准确的识别异响原因,并完成优化验证,为异响排查和控制提供了新的方法和思路。
关键词:整车异响;车辆控制参数;数据同步采集;相关性分析 相似文献