全文获取类型
收费全文 | 2107篇 |
免费 | 155篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 28篇 |
综合类 | 1篇 |
化学工业 | 465篇 |
金属工艺 | 42篇 |
机械仪表 | 75篇 |
建筑科学 | 104篇 |
能源动力 | 164篇 |
轻工业 | 375篇 |
水利工程 | 14篇 |
石油天然气 | 9篇 |
无线电 | 125篇 |
一般工业技术 | 430篇 |
冶金工业 | 71篇 |
原子能技术 | 13篇 |
自动化技术 | 350篇 |
出版年
2024年 | 8篇 |
2023年 | 23篇 |
2022年 | 53篇 |
2021年 | 93篇 |
2020年 | 87篇 |
2019年 | 92篇 |
2018年 | 103篇 |
2017年 | 90篇 |
2016年 | 121篇 |
2015年 | 70篇 |
2014年 | 100篇 |
2013年 | 196篇 |
2012年 | 126篇 |
2011年 | 172篇 |
2010年 | 117篇 |
2009年 | 149篇 |
2008年 | 132篇 |
2007年 | 109篇 |
2006年 | 76篇 |
2005年 | 61篇 |
2004年 | 55篇 |
2003年 | 40篇 |
2002年 | 40篇 |
2001年 | 13篇 |
2000年 | 14篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 11篇 |
1996年 | 17篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有2266条查询结果,搜索用时 15 毫秒
41.
Recovery of sensor embedded washing machines using a multi-kanban controlled disassembly line 总被引:1,自引:0,他引:1
Product recovery involves the recovery of materials and components from returned or end-of-life products. Disassembly, an element of product recovery, is the systematic separation of an assembly into its components, subassemblies or other groupings. Stricter environmental regulations together with dramatic decrease in natural resources and landfills have increased the importance of disassembly as all product recovery options require some level of disassembly. Due to changes made during the lifetime of a product by customers or service personnel, the number and the version of components prior to disassembly is unknown. Customers may also discriminate between and demand different versions of components. The existence of non-functional components further adds to the uncertainty associated with disassembly yield. Sensors implanted into products during their production can address this uncertainty by providing information on the number, condition and version of components prior to disassembly. In this study, we evaluate the impact of sensor embedded products (SEPs) on the various performance measures of a washing machine (WM) disassembly line controlled by a multi-kanban system, which takes into consideration the highly stochastic behavior of the line while managing material and kanban flows. First, separate design of experiments studies based on orthogonal arrays are performed for conventional products and SEPs. In order to observe the response of each experiment, detailed discrete event simulation (DES) models for both types of products are developed considering the precedence relationships among the components of a WM. Then, pair-wise t-tests are conducted to compare the two cases based on different performance measures. According to the results, SEPs provide significant reductions in all costs (viz., backorder, holding, disassembly, disposal, testing and transportation) while increasing revenue and profit. 相似文献
42.
Abdulnasir Yildiz Mehmet Akın Mustafa Poyraz 《Expert systems with applications》2011,38(10):12880-12890
Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder. The traditional diagnosis methods of the disorder are cumbersome and expensive. The ability to automatically identify OSA from electrocardiogram (ECG) recordings is important for clinical diagnosis and treatment. In this study, we proposed an expert system based on discrete wavelet transform (DWT), fast-Fourier transform (FFT) and least squares support vector machine (LS-SVM) for the automatic recognition of patients with OSA from nocturnal ECG recordings. Thirty ECG recordings collected from normal subjects and subjects with sleep apnea, each of approximately 8 h in duration, were used throughout the study. The proposed OSA recognition system comprises three stages. In the first stage, an algorithm based on DWT was used to analyze ECG recordings for the detection of heart rate variability (HRV) and ECG-derived respiration (EDR) changes. In the second stage, an FFT based power spectral density (PSD) method was used for feature extraction from HRV and EDR changes. Then, a hill-climbing feature selection algorithm was used to identify the best features that improve classification performance. In the third stage, the obtained features were used as input patterns of the LS-SVM classifier. Using the cross-validation method, the accuracy of the developed system was found to be 100% for using a subset of selected combination of HRV and EDR features. The results confirmed that the proposed expert system has potential for recognition of patients with suspected OSA by using ECG recordings. 相似文献
43.
Differentiating types of muscle movements using a wavelet based fuzzy clustering neural network 总被引:1,自引:1,他引:0
Abstract: The electromyographic signals observed at the surface of the skin are the sum of many small action potentials generated in the muscle fibres. After the signals are processed, they can be used as a control source of multifunction prostheses. The myoelectric signals are represented by wavelet transform model parameters. For this purpose, four different arm movements (elbow extension, elbow flexion, wrist supination and wrist pronation) are considered in studying muscle contraction. Wavelet parameters of myoelectric signals received from the muscles for these different movements were used as features to classify the electromyographic signals in a fuzzy clustering neural network classifier model. After 1000 iterations, the average recognition percentage of the test was found to be 97.67% with clustering into 10 features. The fuzzy clustering neural network programming language was developed using Pascal under Delphi. 相似文献
44.
This paper introduces a software tool based on illustrative applications for the development, analysis and application of multiobjective evolutionary algorithms. The multiobjective evolutionary algorithms tool (MOEAT) written in C# using a variety of multiobjective evolutionary algorithms (MOEAs) offers a powerful environment for various kinds of optimization tasks. It has many useful features such as visualizing of the progress and the results of optimization in a dynamic or static mode, and decision variable settings. The performance measurements of well-known multiobjective evolutionary algorithms in MOEAT are done using benchmark problems. In addition, two case studies from engineering domain are presented. 相似文献
45.
We show that biogeography-based optimization (BBO) is a generalization of a genetic algorithm with global uniform recombination (GA/GUR). Based on the common features of BBO and GA/GUR, we use a previously-derived BBO Markov model to obtain a GA/GUR Markov model. One BBO characteristic which makes it distinctive from GA/GUR is its migration mechanism, which affects selection pressure (i.e., the probability of retaining certain features in the population from one generation to the next). We compare the BBO and GA/GUR algorithms using results from analytical Markov models and continuous optimization benchmark problems. We show that the unique selection pressure provided by BBO generally results in better optimization results for a set of standard benchmark problems. We also present comparisons between BBO and GA/GUR for combinatorial optimization problems, include the traveling salesman, the graph coloring, and the bin packing problems. 相似文献
46.
IT outsourcing is a complex and opaque decision problem. Managers facing a decision about IT outsourcing have difficulty in
framing what needs to be thought about further in their discourses. Framing is one of the most crucial steps of human decision
making and needs to be assisted to better understand a decision situation. In this research, we examine a number of decision
primitives in the context of an IT outsourcing decision situation. We demonstrate how the decision primitives can be employed
so that managers can probe deep to better understand a decision situation and to establish a decision basis. In the organizational
setting, we exemplify the use of the decision primitives in relation to the perceived outsourcing implications for the managers
looking for assistance in accommodating a knowledge management perspective on IT outsourcing. Consequently, we induce insight
and a guideline on how to use knowledge management for effective outsourcing in one of the leading financial institutes in
Europe.
相似文献
Mehmet N. AydinEmail: |
47.
Mehmet Bozca Ata Muğan Hakan Temeltaş 《Structural and Multidisciplinary Optimization》2008,36(2):169-191
Integrated optimum design of structures and control systems is studied by using H
2 and robust control formulations. It is derived that conventional simultaneous optimization approach by using these robust control
laws can be approximated by a decoupled optimization approach in which the structures are optimized by shaping the structural
singular values and then the controllers can be designed, namely, decoupled, sequential or successive design approach. It
is shown that the proposed decoupled optimization approach can be used to design optimum robust structures and has certain
advantages over the conventional simultaneous optimization procedures such as it avoids the drawbacks of pure robust control
laws and faster, especially if the number of degrees of freedom (DOF) of the associated structure is large. The bounds for
achievable robustness measures are also obtained. Following, simultaneous and decoupled optimization approaches are applied
to active control of two structures. The optimization results are presented, and it is concluded that the proposed decoupled
optimization approach yields the achieved global minimum much faster than the simultaneous optimization approach. 相似文献
48.
This paper presents an incremental neural network (INeN) for the segmentation of tissues in ultrasound images. The performances of the INeN and the Kohonen network are investigated for ultrasound image segmentation. The elements of the feature vectors are individually formed by using discrete Fourier transform (DFT) and discrete cosine transform (DCT). The training set formed from blocks of 4x4 pixels (regions of interest, ROIs) on five different tissues designated by an expert is used for the training of the Kohonen network. The training set of the INeN is formed from randomly selected ROIs of 4x4 pixels in the image. Performances of both 2D-DFT and 2D-DCT are comparatively examined for the segmentation of ultrasound images. 相似文献
49.
A gantry-based tri-modality system that combines bioluminescence (BLT), diffuse optical (DOT), and x-ray computed tomography (XCT) into the same setting is presented here. The purpose of this system is to perform bioluminescence tomography using a multi-modality imaging approach. As parts of this hybrid system, XCT and DOT provide anatomical information and background optical property maps. This structural and functional a priori information is used to guide and restrain bioluminescence reconstruction algorithm and ultimately improve the BLT results. The performance of the combined system is evaluated using multi-modality phantoms. In particular, a cylindrical heterogeneous multi-modality phantom that contains regions with higher optical absorption and x-ray attenuation is constructed. We showed that a 1.5 mm diameter bioluminescence inclusion can be localized accurately with the functional a priori information while its source strength can be recovered more accurately using both structural and the functional a priori information. 相似文献
50.
Mehmet Emin Aydin 《Journal of Intelligent Manufacturing》2012,23(4):991-999
Coordination of multi agent systems remains as a problem since there is no prominent method suggests any universal solution. Metaheuristic agents are specific implementations of multi-agent systems, which imposes working together to solve optimisation problems using metaheuristic algorithms. An idea for coordinating metaheuristic agents borrowed from swarm intelligence is introduced in this paper. This swarm intelligence-based coordination framework has been implemented as swarms of simulated annealing agents collaborated with particle swarm optimization for multidimensional knapsack problem. A comparative performance analysis is also reported highlighting that the implementation has produced much better results than the previous works. 相似文献