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排序方式: 共有106条查询结果,搜索用时 78 毫秒
81.
In machine learning the so-called curse of dimensionality, pertinent to many classification algorithms, denotes the drastic increase in computational complexity and classification error with data having a great number of dimensions. In this context, feature selection techniques try to reduce dimensionality finding a new more compact representation of instances selecting the most informative features and removing redundant, irrelevant, and/or noisy features. In this paper, we propose a filter-based feature selection method for working in the multiple-instance learning scenario called ReliefF-MI; it is based on the principles of the well-known ReliefF algorithm. Different extensions are designed and implemented and their performance checked in multiple instance learning. ReliefF-MI is applied as a pre-processing step that is completely independent from the multi-instance classifier learning process and therefore is more efficient and generic than wrapper approaches proposed in this area. Experimental results on five benchmark real-world data sets and 17 classification algorithms confirm the utility and efficiency of this method, both statistically and from the point of view of execution time. 相似文献
82.
Mykola Zajcew 《Journal of the American Oil Chemists' Society》1958,35(9):475-477
Summary A good quality of castor wax was prepared in the laboratory at 100°C. and 45 p.s.i.g., using a modified palladium catalyst.
The product obtained had an iodine value of 4, a hydroxy value of 145, and acid value of 1.8, and a capillary melting point
of 86°. 相似文献
83.
Three inorganic adsorbents were applied as templates to produce porous carbons from polystyrene-based organic polymers. As matrices, amorphous silica gel, mesoporous alumina and microporous zeolite 13X were used. Organic precursors were polystyrene sulfonic acid (co-maleic acid) sodium salt and polystyrene co-maleic acid isobutyl/methyl mixed ester. The impregnated templates were carbonized at 800 °C. After removal of inorganic matrices porous carbons were obtained. Materials were characterized by adsorption of nitrogen, thermal analysis, potentiometric titration and SEM. Owing to the template carbonization, highly mesoporous carbons were obtained (SBET up to 1500 m2/g, Vt up to 3 cm3/g) with majority of pores with sizes between 20–200 Å. Although the carbons were not replicas of their matrices, the carbonization within the confined space with utilization of self-released pore formers resulted in unique carbonaceous materials with very acidic surface. That acidity is linked to either exothermic effect of sodium reactivity with moist air or susceptibility for air oxidation of small graphene layers formed in the confined pore space. 相似文献
84.
Mykola Zajcew 《Journal of the American Oil Chemists' Society》1962,39(6):301-304
Satisfactory margarine stocks have been made with a palladium on carbon catalyst in laboratory, pilot plant, and plant processing.
The catalyst was shown to make a satisfactory product even when, on continued re-use, the ratio of oil to metal used reached
400,000 to 1. 相似文献
85.
Alexander M. Puziy Olga I. Poddubnaya Catherine A. Reinish Mykola M. Tsyba Luba I. Mikhalovska Sergey V. Mikhalovsky 《Carbon》2011,(2):599-604
Functionalized nanostructured carbons were obtained by template method using sucrose as carbon precursor and silica gel SG60 as structure directing agent. To introduce acid groups into carbon a different amount of phosphoric acid was added to sucrose (impregnation ratio 0–1) before filling the pores of silica gel. After carbonization at 800 °C silica template was removed by dissolution in HF. Carbons were characterized by SEM/EDX, nitrogen adsorption at 77 K and acid–base titration. Pore size distributions (PSD) indicated that carbons obtained at impregnation (IR) of 0–0.75 have pores with size less than 4 nm due to crack during carbonization and activating action of phosphoric acid. Templated pores with 5.1 nm are observed in all carbons. PSD significantly changed at IR = 1 showing additional large mesopores of 8.2 nm. Acid–base titration revealed very high concentration of acid surface groups (4.1–4.7 mmol/g), significant amount of which (46 ± 3%) belongs to phosphate groups (pK = 2.3 ± 0.1). Another surface groups are weak carboxylic (pK = 5.9 ± 0.3), lactone and/or enol (pK = 7.2 ± 0.2, pK = 8.8 ± 0.3) and phenol groups (pK = 10.5 ± 0.3). SEM showed smooth carbon surface up to impregnation ratio 0.5 and increasing roughness at higher amount of phosphoric acid. 相似文献
86.
针对时空正则目标跟踪算法无法有效利用特征,为了缓解边界效应扩大搜索区域导致的滤波器倾向于从背景中学习的问题,提出基于通道可靠性和异常抑制的目标跟踪算法.构造通道正则项,在训练阶段求解不同特征通道对应的权重,实现对不同特征通道的加权,降低通道冗余并提高定位精度.在目标函数中加入异常抑制正则项,约束当前帧的响应图,实现滤波器模型的平滑约束.利用交替方向乘子法将求解目标问题转化为求滤波器、辅助因子以及通道权重的最优解.将所提算法在OTB2015、TempleColor128以及UAV20L公开数据集测试并与其他跟踪算法进行对比.实验结果表明,所提算法在快速运动、光照变化场景中的跟踪效果稳定,基本满足实时性要求. 相似文献
87.
Liu Shiwei Ni’mah Iftitahu Menkovski Vlado Mocanu Decebal Constantin Pechenizkiy Mykola 《Neural computing & applications》2021,33(15):9625-9636
Neural Computing and Applications - Recurrent neural networks (RNNs) have achieved state-of-the-art performances on various applications. However, RNNs are prone to be memory-bandwidth limited in... 相似文献
88.
Artem Musiienko Davide Raffaele Ceratti Jindřich Pipek Mykola Brynza Hassan Elhadidy Eduard Belas Marián Betušiak Geraud Delport Petr Praus 《Advanced functional materials》2021,31(48):2104467
The interaction of free carriers with defects and some critical defect properties are still unclear in methylammonium lead halide perovskites (MHPs). Here, a multi-method approach is used to quantify and characterize defects in single crystal MAPbI3, giving a cross-checked overview of their properties. Time of flight current waveform spectroscopy reveals the interaction of carriers with five shallow and deep defects. Photo-Hall and thermoelectric effect spectroscopy assess the defect density, cross-section, and relative (to the valence band) energy. The detailed reconstruction of free carrier relaxation through Monte Carlo simulation allows for quantifying the lifetime, mobility, and diffusion length of holes and electrons separately. Here, it is demonstrated that the dominant part of defects releases free carriers after trapping; this happens without non-radiative recombination with consequent positive effects on the photoconversion and charge transport properties. On the other hand, shallow traps decrease drift mobility sensibly. The results are the key for the optimization of the charge transport properties and defects in MHP and contribute to the research aiming to improve perovskite stability. This study paves the way for doping and defect control, enhancing the scalability of perovskite devices with large diffusion lengths and lifetimes. 相似文献
89.
90.