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   4688篇
  免费   1239篇
  国内免费   970篇
电工技术   467篇
综合类   487篇
化学工业   151篇
金属工艺   60篇
机械仪表   318篇
建筑科学   38篇
矿业工程   116篇
能源动力   60篇
轻工业   60篇
水利工程   32篇
石油天然气   29篇
武器工业   40篇
无线电   722篇
一般工业技术   256篇
冶金工业   33篇
原子能技术   8篇
自动化技术   4020篇
  2024年   9篇
  2023年   72篇
  2022年   138篇
  2021年   181篇
  2020年   224篇
  2019年   207篇
  2018年   193篇
  2017年   265篇
  2016年   278篇
  2015年   376篇
  2014年   440篇
  2013年   387篇
  2012年   562篇
  2011年   613篇
  2010年   427篇
  2009年   459篇
  2008年   478篇
  2007年   463篇
  2006年   363篇
  2005年   261篇
  2004年   171篇
  2003年   89篇
  2002年   70篇
  2001年   29篇
  2000年   26篇
  1999年   29篇
  1998年   20篇
  1997年   12篇
  1996年   9篇
  1995年   10篇
  1994年   2篇
  1993年   3篇
  1991年   1篇
  1990年   3篇
  1989年   6篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1984年   4篇
  1983年   5篇
  1981年   1篇
  1980年   3篇
  1977年   1篇
排序方式: 共有6897条查询结果,搜索用时 62 毫秒
41.
文章介绍了高效超细粉煤灰专用分级机的研究,在此基础上,重点介绍了DS-M型超细分级机的工作原理及性能特点,分析了DS-M型超细分级机组成的圈流粉磨分选系统的应用效果。实践证明,针对超细粉煤灰分选的选粉机的设计是成功的,在45μm的超细粒径下的分级效率达到80%~90%  相似文献   
42.
Disc bulge and disc desiccation are the most common abnormalities occurring in the spine, which leads to severe low back pain. Despite computer-aided automatic abnormality diagnostic imaging systems are available still there is a need for betterment in diagnostic accuracy and in processing time. Image processing with combined imaging features like shape and texture has given better diagnostic ability when compared with processing with individual features. In the present study, the desiccated and bulged Intervertebral Discs (IVDs) are diagnosed automatically by combining shape features extracted using Histogram of Oriented Gradients (HOG) and texture feature extracted using novel Local Sub-Rhombus Binary Relation Pattern (LS-RBRP) techniques with Random Forest (RF) classifier. The performance analysis projects that the RF with HOG+LS-RBRP has an overall better accuracy of 94.7% when compared with HOG (87%) and LS-RBRP (90.2%) with RF classifier separately in categorizing the normal IVD, disc bulge and disc desiccation in the lumbar spine MRI.  相似文献   
43.
In sport sceneries, automatically recognizing human actions is a useful technique that can be popularly applied in may domains, such as human body tracking and athlete behavior analysis Most state-of-the-art deep architectures have achieved competitive performance in recognizing human action. However, it is still a challenging task due to the unavoidable occlusion, camera angle changes, and varied human posture. In this paper, we propose a novel deep multimodal feature fusion algorithm for human action recognition. The key technique is a multi-model feature fusion scheme. More specifically, we fuse visual feature, skeleton posture, probability maps and audio signal into a hybrid feature, which is utilized to represent human action. Then these feature channels are optimally combined using a deep model, wherein the weights of multiple feature channels can be predicted intelligently. Finally, the optimally fused feature are fed into a multi-class SVM for conducting human action recognition. Extensive comparative results and parameter analysis have shown the effectiveness of our proposed method.  相似文献   
44.
工程机械液压系统发生冲击故障时,振动信号会出现相应的时频特性的变化,准确捕捉液压缸冲击振动信号,提取信号的典型特征是故障诊断的关键。该文首先运用SVM延拓解决EEMD方法的端点效应,然后通过改进的三次样条插值方法拟合包络线,再利用互相关分析与频谱分析对特征模态分量进行筛选,选取出能够代表信号特征的IMF分量。最后使用改进的EEMD方法对液压系统突然换向引起的冲击振动信号进行分析,选取出能够代表信号特征的IMF分量,为以后的智能诊断故障特征提取提供依据。  相似文献   
45.
针对不同状态的浮选泡沫图像之间纹理结构相似、颜色差异不明显的问题,提出一种基于色调、饱和度和亮度(HSV)颜色空间的完全局部二进制模式(CLBP)纹理提取的浮选泡沫状态识别方法。首先使用双域去噪在保留纹理细节的同时滤除图像噪声,然后转换为HSV图像,在H、S和V颜色分量上分别提取三个尺度的CLBP纹理特征。将提取的纹理特征归一化后线性排列,建立高维度的纹理分类模型。最后通过一对一模式的支持向量机分类器对四类泡沫状态的样本集进行纹理提取后的分类训练与测试。结果表明,该方法对不同浮选泡沫状态的分类正确率较高,优于其他纹理描述方法,适用于浮选泡沫状态的识别。  相似文献   
46.
The classification of imbalanced data is a major challenge for machine learning. In this paper, we presented a fuzzy total margin based support vector machine (FTM-SVM) method to handle the class imbalance learning (CIL) problem in the presence of outliers and noise. The proposed method incorporates total margin algorithm, different cost functions and the proper approach of fuzzification of the penalty into FTM-SVM and formulates them in nonlinear case. We considered an excellent type of fuzzy membership functions to assign fuzzy membership values and got six FTM-SVM settings. We evaluated the proposed FTM-SVM method on two artificial data sets and 16 real-world imbalanced data sets. Experimental results show that the proposed FTM-SVM method has higher G_Mean and F_Measure values than some existing CIL methods. Based on the overall results, we can conclude that the proposed FTM-SVM method is effective for CIL problem, especially in the presence of outliers and noise in data sets.  相似文献   
47.
Lifelog is a digital record of an individual’s daily life. It collects, records, and archives a large amount of unstructured data; therefore, techniques are required to organize and summarize those data for easy retrieval. Lifelogging has been utilized for diverse applications including healthcare, self-tracking, and entertainment, among others. With regard to the image-based lifelogging, even though most users prefer to present photos with facial expressions that allow us to infer their emotions, there have been few studies on lifelogging techniques that focus upon users’ emotions. In this paper, we develop a system that extracts users’ own photos from their smartphones and configures their lifelogs with a focus on their emotions. We design an emotion classifier based on convolutional neural networks (CNN) to predict the users’ emotions. To train the model, we create a new dataset by collecting facial images from the CelebFaces Attributes (CelebA) dataset and labeling their facial emotion expressions, and by integrating parts of the Radboud Faces Database (RaFD). Our dataset consists of 4,715 high-resolution images. We propose Representative Emotional Data Extraction Scheme (REDES) to select representative photos based on inferring users’ emotions from their facial expressions. In addition, we develop a system that allows users to easily configure diaries for a special day and summaize their lifelogs. Our experimental results show that our method is able to effectively incorporate emotions into lifelog, allowing an enriched experience.  相似文献   
48.
针对近红外光下现有的人眼定位算法普遍存在准确性不高、泛化能力不佳等问题,提出了一种基于方向梯度直方图(HOG)和支持向量机(SVM)相结合的双眼虹膜图像的人眼定位算法。利用HOG提取虹膜图像的人眼特征,并结合SVM分类器对HOG特征进行训练从而实现人眼的精确定位。为了减少漏检和误检,进一步提高定位准确率,又提出了多级级联SVM分类器算法;另外针对近红外光线下虹膜图像独特的灰度分布特点,设计了一种图像预处理方法,能够显著提高人眼定位速度。在MIR2016和CASIA-IRIS-Distance数据集上的实验结果表明,基于HOG和SVM的双眼虹膜图像的人眼定位算法具有高准确率、强泛化能力和高实时性。  相似文献   
49.
张宗堂  陈喆  戴卫国 《计算机应用》2019,39(5):1364-1367
针对传统集成算法不适用于不平衡数据分类的问题,提出基于间隔理论的AdaBoost算法(MOSBoost)。首先通过预训练得到原始样本的间隔;然后依据间隔排序对少类样本进行启发式复制,从而形成新的平衡样本集;最后将平衡样本集输入AdaBoost算法进行训练以得到最终集成分类器。在UCI数据集上进行测试实验,利用F-measure和G-mean两个准则对MOSBoost、AdaBoost、随机过采样AdaBoost(ROSBoost)和随机降采样AdaBoost(RDSBoost)四种算法进行评价。实验结果表明,MOSBoost算法分类性能优于其他三种算法,其中,相对于AdaBoost算法,MOSBoost算法在F-measureG-mean准则下分别提升了8.4%和6.2%。  相似文献   
50.
Lung cancer causes a high mortality rate in the world than any other cancers. That can be minimised if the symptoms and cancer cells have been detected early. One of the techniques used to detect lung cancer is by computed tomography (CT) scan. CT scan images have been used in this study to identify one of the lesion characteristics named ground glass opacity (GGO). It has been used to determine the level of malignancy of the lesion. There were three phases in identifying GGO: image cropping, feature extraction using grey level co-occurrence matrices (GLCM) and classification using Naïve Bayes Classifier. In order to improve the classification results, the most significant feature was sought by feature selection using gain ratio evaluation. Based on the results obtained, the most significant features could be identified by using feature selection method used in this research. The accuracy rate increased from 83.33% to 91.67%, the sensitivity from 82.35% to 94.11% and the specificity from 84.21% to 89.47%.  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