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101.
分别以分析纯Al2 O3和AlCl3为铝源,以分析纯MgO为镁源,在NaCl和KCl混合熔盐介质中,分别在1000、1100、1200和1250℃保温3 h合成了镁铝尖晶石粉体,研究了试样的物相组成、微观形貌和化学组成.结果表明:1)温度的升高有利于MgAl2 O4的形成和结晶.2)以Al2 O3为铝源合成的镁铝尖晶石在Al2 O3原料表面成核生长,晶体结构随着温度的升高趋于完善;以AlCl3为铝源合成的镁铝尖晶石颗粒粒径约为3μm且呈正八面体结构. 相似文献
102.
采用熔融共混法制备了癸酸/膨胀石墨定型相变材料(DA/EG-PCMs)、月桂酸/膨胀石墨定型相变材料(LA/EG-PCMs)和石蜡/膨胀石墨定型相变材料(PA/EG-PCMs),利用接触角测量仪、FT-IR、DSC、TG-DSC和热渗出实验分别对三种膨胀石墨基定型相变材料的亲疏水性、特征基团、热性能、热稳定性和耐久性进行表征。结果表明:膨胀石墨能很好的将癸酸、月桂酸和石蜡吸附住,三种相变材料与膨胀石墨之间仅存在物理结合作用。DA/EG-PCMs和LA/EG-PCMs都表现出亲水的特性,PA/EG-PCMs疏水。在膨胀石墨的高导热网络结构包覆下,三种膨胀石墨基定型相变材料相变温度提前,耐久性提高,DA/EG-PCMs与LA/EG-PCMs的热稳定降低,PA/EG-PCMs热稳定提高。 相似文献
103.
简要介绍了MCM-41介孔分子筛的特点,应用和改性原因.综述了MCM-41介孔分子筛的合成方法,主要包括水热合成法,室温合成法,微波合成法等,列出了每种合成方法的优缺点和合成过程中的影响因素,pH值、晶化时间、晶化温度、模板剂的种类及用量等都会对MCM-41介孔分子筛的结构和孔径产生很大影响.阐述了MCM-41介孔分子筛的改性方法,包括金属杂原子取代法,如主族金属、过渡金属、稀土金属等,有机修饰或功能化法,负载型改性法,如负载金属氧化物、无机酸、杂多酸、有机碱、金属的配合物等.最后就MCM-41介孔分子筛的应用前景做了展望. 相似文献
104.
Both two‐fluid models embedding the kinetic theory of granular flow for particulate phase stress (TFM) and discrete particle models (DPM) are widely used for the numerical simulation of gas fluidization. In this study, a detailed comparison between results obtained from both TFM and DPM is reported, including axial and radial solid concentration profiles, solids circulation patterns, pressure drop and its standard deviation and granular temperature. It was shown that good agreement can be obtained even in cases of low restitution coefficient, which suggests the possible applicability of kinetic theory of granular flow beyond its nominal range of validity and clearly indicates that the continuum treatment of the solids phase in TFM provides a good approximation of its discrete nature. 相似文献
105.
106.
针对当前人体动作识别算法检测精度不佳和实验场景多样性的问题,提出了一种混合卷积神经网络?隐马尔可夫模型(CNN-HMM)的人体动作识别方法。建立了抬腿、深蹲和仰卧臀桥3组分别包含1个标准动作姿态和5个非标准动作姿态的人体康复训练动作模型库,结合可穿戴式惯性动作捕捉系统PN2.0获取实验数据。最后从准确率、灵敏度和特异性3个方面进行性能评估。实验结果表明,该方法能够以较高识别率将6种不同动作姿态区分开,其平均识别准确率为97.00%,相较于单一CNN方法提高了5.78%。 相似文献
107.
108.
Toward a mesoscale‐structure‐based kinetic theory for heterogeneous gas‐solid flow: Particle velocity distribution function 下载免费PDF全文
Mesoscience has recently been proposed as a possible general concept for describing complex systems far from equilibrium, however, concrete formulations are needed, and particularly, a statistical mechanics foundation of mesoscience remains to be explored. To this end, the mathematical theory of stochastic geometry is combined with the energy minimization multi‐scale (EMMS) principle under the concept of mesoscience to propose a statistical mechanics framework. An EMMS‐based particle velocity distribution function is then derived as an example to show how the proposed framework works, and more importantly, as a first key step toward a generalized kinetic theory for heterogeneous gas‐solid flow. It was shown that the resultant EMMS‐based distribution is bimodal, instead of the widely‐used Maxwellian distribution, but it reduces to the Maxwellian distribution when the gas‐solid system is homogeneous. The EMMS‐based distribution is finally validated by comparing its prediction of the variance of solid concentration fluctuation and granular temperature with experimental data available in literature. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2649–2657, 2016 相似文献
109.
The swelling behaviors of polyacrylate superabsorbent in the mixtures of water and hydrophilic solvents, including methanol, ethanol, ethylene glycol, glycerol, acetone, dimethyl formamide, and dimethyl sulfoxide, were investigated. In 20 wt % solvent–water mixture, the superabsorbent with granularity between 40‐ and 80‐mesh could reach swelling equilibrium at 25°C in several hours. It was also found that mixture temperature between 15 and 35°C had little influence on absorbency. Furthermore, the influence of water temperature between 0.5 and 99°C on absorbency was also rather limited when the superabsorbent was swelled by distilled water. The mixture concentration influenced absorbency significantly by changing the solubility parameter of the solvent–water mixture, particularly when the solubility parameter of the solvent–water mixture was < 20. The equilibrium absorbency was very high when the solubility parameter of the mixture was > 20, whereas the absorbing capacity of the superabsorbent was very low when the solubility parameter was < 17.5. The polarity fraction of solvents did not have any obvious influence on equilibrium absorbency, but not enough polarity fraction might affect the absorbing rate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1331–1338, 2000 相似文献
110.