全文获取类型
收费全文 | 29442篇 |
免费 | 6028篇 |
国内免费 | 1747篇 |
专业分类
电工技术 | 2486篇 |
技术理论 | 1篇 |
综合类 | 2958篇 |
化学工业 | 2853篇 |
金属工艺 | 1187篇 |
机械仪表 | 3451篇 |
建筑科学 | 1395篇 |
矿业工程 | 399篇 |
能源动力 | 619篇 |
轻工业 | 1011篇 |
水利工程 | 428篇 |
石油天然气 | 369篇 |
武器工业 | 266篇 |
无线电 | 3318篇 |
一般工业技术 | 1310篇 |
冶金工业 | 590篇 |
原子能技术 | 217篇 |
自动化技术 | 14359篇 |
出版年
2024年 | 35篇 |
2023年 | 303篇 |
2022年 | 687篇 |
2021年 | 720篇 |
2020年 | 682篇 |
2019年 | 636篇 |
2018年 | 791篇 |
2017年 | 667篇 |
2016年 | 824篇 |
2015年 | 732篇 |
2014年 | 4184篇 |
2013年 | 3099篇 |
2012年 | 4096篇 |
2011年 | 4419篇 |
2010年 | 3792篇 |
2009年 | 3461篇 |
2008年 | 1756篇 |
2007年 | 1099篇 |
2006年 | 934篇 |
2005年 | 718篇 |
2004年 | 595篇 |
2003年 | 557篇 |
2002年 | 435篇 |
2001年 | 333篇 |
2000年 | 260篇 |
1999年 | 231篇 |
1998年 | 210篇 |
1997年 | 169篇 |
1996年 | 127篇 |
1995年 | 133篇 |
1994年 | 101篇 |
1993年 | 74篇 |
1992年 | 58篇 |
1991年 | 51篇 |
1990年 | 42篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 23篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
《Automatica》2014,50(12):3276-3280
This paper proposes a continuous-time framework for the least-squares parameter estimation method through evolution equations. Nonlinear systems in the standard state space representation that are linear in the unknown, constant parameters are investigated. Two estimators are studied. The first one consists of a linear evolution equation while the second one consists of an impulsive linear evolution equation. The paper discusses some theoretical aspects related to the proposed estimators: uniqueness of a solution and an attractive equilibrium point which solves for the unknown parameters. A deterministic framework for the estimation under noisy measurements is proposed using a Sobolev space with negative index to model the noise. The noise can be of large magnitude. Concrete signals issued from an electronic device are used to discuss numerical aspects. 相似文献
62.
63.
《Expert systems with applications》2014,41(3):886-892
This work presents a comparative analysis of specific, rather than general, mathematical programming implementation techniques of the quadratic optimization problem (QP) based on Support Vector Machines (SVM) learning process. Considering the Karush–Kuhn–Tucker (KKT) optimality conditions, we present a strategy of implementation of the SVM-QP following three classical approaches: (i) active set, also divided in primal and dual spaces, methods, (ii) interior point methods and (iii) linearization strategies. We also present the general extension to treat large-scale applications consisting in a general decomposition of the QP problem into smaller ones, conserving the exact solution approach. In the same manner, we propose a set of heuristics to take into account for a better than a random selection process for the initialization of the decomposition strategy. We compare the performances of the optimization strategies using some well-known benchmark databases. 相似文献
64.
《Expert systems with applications》2014,41(7):3343-3350
65.
《Computer methods and programs in biomedicine》2014,116(3):226-235
Breast cancer continues to be a significant public health problem in the world. Early detection is the key for improving breast cancer prognosis. Mammogram breast X-ray is considered the most reliable method in early detection of breast cancer. However, it is difficult for radiologists to provide both accurate and uniform evaluation for the enormous mammograms generated in widespread screening. Micro calcification clusters (MCCs) and masses are the two most important signs for the breast cancer, and their automated detection is very valuable for early breast cancer diagnosis. The main objective is to discuss the computer-aided detection system that has been proposed to assist the radiologists in detecting the specific abnormalities and improving the diagnostic accuracy in making the diagnostic decisions by applying techniques splits into three-steps procedure beginning with enhancement by using Histogram equalization (HE) and Morphological Enhancement, followed by segmentation based on Otsu's threshold the region of interest for the identification of micro calcifications and mass lesions, and at last classification stage, which classify between normal and micro calcifications ‘patterns and then classify between benign and malignant micro calcifications. In classification stage; three methods were used, the voting K-Nearest Neighbor classifier (K-NN) with prediction accuracy of 73%, Support Vector Machine classifier (SVM) with prediction accuracy of 83%, and Artificial Neural Network classifier (ANN) with prediction accuracy of 77%. 相似文献
66.
Joseph Akyeampong Silvanus Udoka Giandomenico Caruso Monica Bordegoni 《International Journal of Industrial Ergonomics》2014
This study evaluated newly proposed Human–Machine Interface (HMI) design concepts for improving the ergonomics of hydraulic excavators. The design concepts were based on an augmented interaction technique which involved the use of heads-up display (HUD) and coordinated control as HMI elements. Two alternative HMI designs were elaborated in order to separately evaluate the ergonomic impacts of the head-up display and the coordinated control by comparing them to the standard HMI design. The effectiveness of these three HMI designs in terms of the reduction of the operators' mental and physical workload were assessed by conducting experiments utilizing human subjects, ages 23–35 years. The National Aeronautics and Space Administration's Task Load Index (NASA TLX) method was used for collecting subjective workload scores based on a weighted average of ratings of six factors: Mental Demand, Physical Demand, Temporal Demand, Own Performance, Effort, and Frustration Level. The results showed that the type of HMI design affects different aspects of the operator's workload. Indeed, it showed how the proposed augmented interaction is an effective solution for reducing the ergonomic gaps in terms of mental workload, and to a lesser extent the physical workload, subjected by the standard HMI design. 相似文献
67.
The article investigates an integrated multi-layer supply chain model consisting of supplier, manufacturer and retailer while supply disruption, machine breakdown, safety stock, maintenance breakdown occur simultaneously. At beginning of the production, manufacturer keeps some raw materials in stock received from second supplier at high price, as safety stock due to supply disruption of first supplier. Corrective maintenance is done immediately to restore its normal stage when machine breakdown occurs. Stock out situations at manufacturer and retailer are considered due to disruption of production for machine breakdown. The integrated expected costs of the chain in centralized (collaborating) and decentralized (Stakelberg approach) system are compared. A numerical example and its sensitivity analysis are provided to test feasibility of the model. 相似文献
68.
《Expert systems with applications》2014,41(7):3333-3342
Early and accurate diagnosis of Parkinson’s disease (PD) is important for early management, proper prognostication and for initiating neuroprotective therapies once they become available. Recent neuroimaging techniques such as dopaminergic imaging using single photon emission computed tomography (SPECT) with 123I-Ioflupane (DaTSCAN) have shown to detect even early stages of the disease. In this paper, we use the striatal binding ratio (SBR) values that are calculated from the 123I-Ioflupane SPECT scans (as obtained from the Parkinson’s progression markers initiative (PPMI) database) for developing automatic classification and prediction/prognostic models for early PD. We used support vector machine (SVM) and logistic regression in the model building process. We observe that the SVM classifier with RBF kernel produced a high accuracy of more than 96% in classifying subjects into early PD and healthy normal; and the logistic model for estimating the risk of PD also produced high degree of fitting with statistical significance indicating its usefulness in PD risk estimation. Hence, we infer that such models have the potential to aid the clinicians in the PD diagnostic process. 相似文献
69.
70.