首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   157篇
  免费   12篇
电工技术   1篇
化学工业   57篇
金属工艺   4篇
建筑科学   5篇
矿业工程   2篇
能源动力   7篇
轻工业   19篇
水利工程   1篇
无线电   10篇
一般工业技术   23篇
冶金工业   1篇
原子能技术   1篇
自动化技术   38篇
  2023年   5篇
  2022年   15篇
  2021年   13篇
  2020年   11篇
  2019年   6篇
  2018年   15篇
  2017年   8篇
  2016年   5篇
  2015年   5篇
  2014年   14篇
  2013年   15篇
  2012年   9篇
  2011年   12篇
  2010年   4篇
  2009年   7篇
  2008年   4篇
  2007年   4篇
  2006年   4篇
  2005年   4篇
  2004年   1篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  1996年   1篇
  1993年   1篇
  1989年   1篇
排序方式: 共有169条查询结果,搜索用时 15 毫秒
91.
92.
A new recurrent neural model for crack growth process of aluminium alloy is developed in this work. It is shown that a recurrent neural network with the feedback loops at the output layer is constructed to model the dynamic relationship between the crack growth and cyclic stress excitations of aluminium alloy. The output feedback loops in the neural model play the role of capturing the fine changes of crack growth dynamics. The Extreme Learning Machine is then used to uniformly randomly assign the input weights in a proper range and globally optimize both the output weights and feedback parameters, to ensure that the dynamics of crack growth under variable-amplitude loading can be accurately modeled. The simulation results with the averaged experimental data of the 2024-T351 aluminium alloy show that the excellent modeling and prediction performance of the recurrent neural model can be achieved for fatigue crack growth of aluminium alloys.  相似文献   
93.
The iron hexagonal mesoporous silica (Fe‐HMS)‐n photocatalyst, where n is the molar ratio Si/Fe in the precursor gel (=50), has been successfully synthesized at an ambient temperature using hexadecylamine as template agent. The material was characterized by X‐ray diffraction, N2 adsorption measurement Brunauer, Emmet, Taller (BET) and Barrett–Joyner–Halenda theory, UV–Vis spectroscopy, high‐resolution transmission electron microscopy and electron spin resonance. The electrical conductivity follows an Arrhenius‐type law with activation energy of 0.04 eV. Fe2O3 is uniformly dispersed on the HMS surface; it works synergistically to make Fe‐HMS photoelectrochemically active. The flat band potential (?0.75 VSCE) is higher than the potential of hydrogen generation (?0.50 VSCE at pH~7), and the material shows high efficiency for hydrogen evolution upon visible light. The photoactivity in Na2SO4 and Na2SO3 (0.1 M) solution was found to be 136 and 175 µmol g‐1 min‐1, respectively under full light (29 mW cm‐2). The tendency to saturation, observed only in SO32‐ electrolyte, is ascribed to the competitive reduction of the end product, namely S2O62‐ with the water reduction. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
94.
In this work we report the synthesis of a new family of surfactants based on aryl alkyl disulfonates; the latter compounds were derived from a mixture of linear alkylbenzene with the resulting disulfonate groups residing on the linear alkyl side-chain rather than the usual aromatic ring structure. The Reed sulfochlorination reaction was successfully utilized to selectively promote the formation of disulfonates on the alkyl group. A number of analytical methods in the form of liquid chromatography–mass spectrometry (LC–MS), gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were used to characterize the resulting compounds and intermediates. The critical micelle concentration, the surface tension at the critical micelle concentration, the surface excess concentration at surface tension, and the area per molecule were measured at different concentrations and temperatures. Thermodynamic parameters and Krafft temperature were also determined. The obtained results were compared to those of commercial n-dodecylbenzene sulfonates and linear alkylbenzene sulfonates surfactants, showing that these new synthesized surfactants present good surface properties.  相似文献   
95.
Journal of Superconductivity and Novel Magnetism - In this paper, the structural, mechanical and optoelectronic properties of X $$_3$$ P $$_2$$ (X= Mg, Ca) have been investigated by using the...  相似文献   
96.
Most children and elderly people worldwide die from pneumonia, which is a contagious illness that causes lung ulcers. For diagnosing pneumonia from chest X-ray images, many deep learning models have been put forth. The goal of this research is to develop an effective and strong approach for detecting and categorizing pneumonia cases. By varying the deep learning approach, three pre-trained models, GoogLeNet, ResNet18, and DenseNet121, are employed in this research to extract the main features of pneumonia and normal cases. In addition, the binary dipper throated optimization (DTO) algorithm is utilized to select the most significant features, which are then fed to the K-nearest neighbor (KNN) classifier for getting the final classification decision. To guarantee the best performance of KNN, its main parameter (K) is optimized using the continuous DTO algorithm. To test the proposed approach, six evaluation metrics were employed namely, positive and negative predictive values, accuracy, specificity, sensitivity, and F1-score. Moreover, the proposed approach is compared with other traditional approaches, and the findings confirmed the superiority of the proposed approach in terms of all the evaluation metrics. The minimum accuracy achieved by the proposed approach is (98.5%), and the maximum accuracy is (99.8%) when different test cases are included in the evaluation experiments.  相似文献   
97.
Machine learning (ML) becomes a familiar topic among decision makers in several domains, particularly healthcare. Effective design of ML models assists to detect and classify the occurrence of diseases using healthcare data. Besides, the parameter tuning of the ML models is also essential to accomplish effective classification results. This article develops a novel red colobuses monkey optimization with kernel extreme learning machine (RCMO-KELM) technique for epileptic seizure detection and classification. The proposed RCMO-KELM technique initially extracts the chaotic, time, and frequency domain features in the actual EEG signals. In addition, the min-max normalization approach is employed for the pre-processing of the EEG signals. Moreover, KELM model is used for the detection and classification of epileptic seizures utilizing EEG signal. Furthermore, the RCMO technique was utilized for the optimal parameter tuning of the KELM technique in such a way that the overall detection outcomes can be considerably enhanced. The experimental result analysis of the RCMO-KELM technique has been examined using benchmark dataset and the results are inspected under several aspects. The comparative result analysis reported the better outcomes of the RCMO-KELM technique over the recent approaches with the of 0.956.  相似文献   
98.
99.
Mobile ad hoc networks (MANETs) are characterized by multiple entities, a frequently changing network topology and the need for efficient dynamic routing protocols. In MANETs, nodes are usually powered by batteries. Power control is tightly coupled with both the physical and medium access layers (MACs). However, if we increase the transmission power, at the same time we increase the interference to other nodes which diminish the transport capacity of wireless systems. Thus, the routing protocols based on hop count metric suffer from performance degradation when they operate over MANET. Routing in ad hoc wireless networks is not only a problem of finding a route with shortest length, but it is also a problem of finding a stable and good quality communication route in order to avoid any unnecessary packet loss. Cross-layer design of ad hoc wireless networks has been receiving increasing attention recently. Part of these researches suggests that routing should take into account physical layer characteristics. The goal of this paper is to improve the routing reliability in MANET and to reduce power consumption through cross-layer approach among physical, MAC and network layers. The proposed cross-layer approach is based on signal to interference plus noise ratio (SINR) and received signal strength indication (RSSI) coming from the physical layer. This solution performs in one hand the ad hoc on-demand distance vector routing protocol by choosing reliable routes with less interferences using SINR metric and in another hand; it permits to reduce the power transmission when sending the data packets by using RSSI metric.  相似文献   
100.
One of the most common kinds of cancer is breast cancer. The early detection of it may help lower its overall rates of mortality. In this paper, we robustly propose a novel approach for detecting and classifying breast cancer regions in thermal images. The proposed approach starts with data preprocessing the input images and segmenting the significant regions of interest. In addition, to properly train the machine learning models, data augmentation is applied to increase the number of segmented regions using various scaling ratios. On the other hand, to extract the relevant features from the breast cancer cases, a set of deep neural networks (VGGNet, ResNet-50, AlexNet, and GoogLeNet) are employed. The resulting set of features is processed using the binary dipper throated algorithm to select the most effective features that can realize high classification accuracy. The selected features are used to train a neural network to finally classify the thermal images of breast cancer. To achieve accurate classification, the parameters of the employed neural network are optimized using the continuous dipper throated optimization algorithm. Experimental results show the effectiveness of the proposed approach in classifying the breast cancer cases when compared to other recent approaches in the literature. Moreover, several experiments were conducted to compare the performance of the proposed approach with the other approaches. The results of these experiments emphasized the superiority of the proposed approach.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号