全文获取类型
收费全文 | 3804篇 |
免费 | 435篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 41篇 |
综合类 | 1篇 |
化学工业 | 946篇 |
金属工艺 | 139篇 |
机械仪表 | 280篇 |
建筑科学 | 30篇 |
矿业工程 | 1篇 |
能源动力 | 167篇 |
轻工业 | 319篇 |
水利工程 | 11篇 |
石油天然气 | 2篇 |
无线电 | 762篇 |
一般工业技术 | 939篇 |
冶金工业 | 151篇 |
原子能技术 | 97篇 |
自动化技术 | 358篇 |
出版年
2024年 | 2篇 |
2023年 | 52篇 |
2022年 | 63篇 |
2021年 | 112篇 |
2020年 | 105篇 |
2019年 | 121篇 |
2018年 | 135篇 |
2017年 | 145篇 |
2016年 | 203篇 |
2015年 | 170篇 |
2014年 | 242篇 |
2013年 | 274篇 |
2012年 | 315篇 |
2011年 | 365篇 |
2010年 | 236篇 |
2009年 | 213篇 |
2008年 | 249篇 |
2007年 | 136篇 |
2006年 | 149篇 |
2005年 | 125篇 |
2004年 | 112篇 |
2003年 | 100篇 |
2002年 | 92篇 |
2001年 | 77篇 |
2000年 | 72篇 |
1999年 | 70篇 |
1998年 | 59篇 |
1997年 | 47篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 23篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 8篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 7篇 |
排序方式: 共有4244条查询结果,搜索用时 15 毫秒
51.
It has already been recognized that looking for a positive definite Lyapunov function such that a high-order linear differential inequality with respect to the Lyapunov function holds along the trajectories of a nonlinear system can be utilized to assess asymptotic stability when the standard Lyapunov approach examining only the first derivative fails. In this context, the main purpose of this paper is, on one hand, to theoretically unveil deeper connections among existing stability conditions especially for linear time-invariant (LTI) systems, and from the other hand to examine the effect of the higher-order time-derivatives approach on the stability results for uncertain polytopic LTI systems in terms of conservativeness. To this end, new linear matrix inequality (LMI) stability conditions are derived by generalizing the concept mentioned above, and through the development, relations among some existing stability conditions are revealed. Examples illustrate the improvement over the quadratic approach. 相似文献
52.
Chulwoo KimCheol Lee Mark R. LehtoMyung Hwan Yun 《International Journal of Industrial Ergonomics》2011,41(2):118-127
This study aims to investigate a cost effective and efficient way of analyzing customer impressions on design alternatives by incorporating the benefits of virtual prototyping into the Internet-based experimental environment. It is hypothesized that the results of the Internet-based experiment using the images of virtual prototypes are comparable to those of the virtual reality-based environment using virtual prototypes. Two experiments were conducted. In the virtual reality environment, participants were employed to evaluate virtual prototypes while in the Internet environment participants evaluated images of the same virtual prototypes from their own places. For each experiment, 16 male participants were employed to evaluate 32 different virtual prototypes generated from the combination of 17 design elements of automobile interior. The results of the experiments indicated that there were no significant differences between the two experimental methods while the Internet environment-based method could save considerable time and efforts for experimentation. This study concludes that the Internet-based evaluation method using the images of virtual prototypes could be a cost effective and efficient way of analyzing customer impressions on design alternatives.
Relevance to Industry
This study showed that the results of the Internet-based evaluation method using the images of virtual prototypes are comparable to those of the virtual reality-based method using real virtual prototypes. The Internet-based evaluation method could be used as a cost effective and efficient way of collecting and analyzing various customers’ impressions on design alternatives at the early stage of product development process. 相似文献53.
When multimedia information is transported over a packet-switched network, the quality of presentation can be degraded due
to network delay variation or jitter. This paper presents a dejittering scheme that can be used in the transport of MPEG-4
and MPEG-2 video to absorb any introduced network jitter, thus preserving the presentation quality of transported media streams.
The dejittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets
carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4
system is presented. 相似文献
54.
J. B. Noh K. C. Lee J. K. Kim J. K. Lee S. H. Kim 《Expert systems with applications》2000,19(4):249-259
Knowledge is at the heart of knowledge management. In literature, a lot of studies have been suggested covering the role of knowledge in improving the performance of management. However, there are few studies about investigating knowledge itself in the arena of knowledge management. Knowledge circulating in an organization may be explicit or tacit. Until now, literature in knowledge management shows that it has mainly focused on explicit knowledge. On the other hand, tacit knowledge plays an important role in the success of knowledge management. It is relatively hard to formalize and reuse tacit knowledge. Therefore, research proposing the explication and reuse of tacit knowledge would contribute significantly to knowledge management research. In this sense, we propose using cognitive map (CM) as a main vehicle of formalizing tacit knowledge, and case-based reasoning as a tool for storing CM-driven tacit knowledge in the form of frame-typed cases, and retrieving appropriate tacit knowledge from the case base according to a new problem. Our proposed methodology was applied to a credit analysis problem in which decision-makers need tacit knowledge to assess whether a firm under consideration is healthy or not. Experiment results showed that our methodology for tacit knowledge management can provide decision makers with robust knowledge-based support. 相似文献
55.
Hyung Rim Reference to Choi Hyun Soo Reference to Kim Young Jae Reference to Park Kyoung Hwan Reference to Kim Myung Ho Reference to Joo Hyung Soo Reference to Sohn 《Decision Support Systems》2000,28(4):333
The sales activity of most parts manufacturing companies is based on orders of buyers. The process of promotion, receipt and selection of orders of the parts manufacturers is closely coupled with the load status of the production lines. On deciding whether to accept an order or not, as well as negotiating with buyers, sales persons need information such as load and schedule of production lines, and manufacturability of the order. Manufacturability analysis, process planning, and scheduling are therefore key features in developing an agent of sales activity for the parts manufacturing business. In this paper, an intelligent agent, a virtual manufacturing-based sales agent (VMSA) with multi-agent architecture is proposed to support the sales activity for the parts manufacturers in the Internet environment. A VMSA has an integrated architecture of agent and virtual manufacturing. The prototype of VMSA has been developed for a machine parts manufacturing company that has lathe machines, drilling machines, cutting machines, and milling machines. 相似文献
56.
Se Hwan Kim Eung Bum Kim Jae Hwan Oh Ji Ho Hur Jin Jang 《Journal of the Society for Information Display》2008,16(3):415-419
Abstract— A 2.0‐in. a‐Si:H TFT‐LCD with embedded TFT sensors for the control of the backlight intensity according to the ambient light intensity has been developed. Two types of a‐Si:H TFT sensors with various channel widths were embedded into a TFT backplane with bottom‐ and top‐gate structures for measuring the ambient light and backlight illumination, respectively. The output signal, measured by a readout IC, increased with backlight intensity until 20,000 lux. 相似文献
57.
Indicating that CBMC does not satisfy the monotonic property in terms of the number of interactions, Xu and Zhou proposed an augmented definition of CBMC by adopting cut set instead of glue methods. The augmented CBMC clearly satisfies the monotonic property. However, CBMC is designed to overcome the problem with respect to the number of interactions and, therefore, focuses on the interaction pattern, especially, member connectivity. Consequently, it does not make sense to mention the monotonic property of CBMC with respect to interaction number. Moreover, the notion of glue methods allows several interpretations on the design quality of a class. However, that meaningful interpretation is not possible for the augmented definition due to the removal of the notion of glue methods. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
58.
Kyeong Bock Lee Choon Mahn Park Hyun Sik Noh Chul Koo Kim Kyun Nahm 《Journal of Materials Science》1993,28(24):6545-6548
Measurements of electrical resistivity. X-ray diffraction patterns, magnetic susceptibility and thermoelectric power of the Er1-x
Pr
x
Ba2Cu3O7- system have been made. The superconducting transition temperature was found to decrease monotonically with praseodymium concentration, x. From the susceptibility data, it was determined that the valence of praseodymium lies between +3 and +4. The thermoelectric power was found to increase with x, and the slopes of dS/dT were negative except for the case x= 0. The. tendency of the thermopower to change with increasing praseodymium concentration has been qualitatively explained using the theory for strongly correlated systems. 相似文献
59.
Accurate depth estimation is a challenging, yet essential step in the conversion of a 2D image sequence to a 3D stereo sequence. We present a novel approach to construct a temporally coherent depth map for each image in a sequence. The quality of the estimated depth is high enough for the purpose of2D to 3D stereo conversion. Our approach first combines the video sequence into a panoramic image. A user can scribble on this single panoramic image to specify depth information. The depth is then propagated to the remainder of the panoramic image. This depth map is then remapped to the original sequence and used as the initial guess for each individual depth map in the sequence. Our approach greatly simplifies the required user interaction during the assignment of the depth and allows for relatively free camera movement during the generation of a panoramic image. We demonstrate the effectiveness of our method by showing stereo converted sequences with various camera motions. 相似文献
60.
Recently many statistical learning techniques have been applied to the prediction of financial variables. The aim of this paper is to conduct a comprehensive study of the applications of statistical learning techniques to predict the trend of the return of high-frequency Korea composite stock price index (KOSPI) 200 index data using the information from the one-minute time series of spot index, futures index, and foreign exchange rate. Through experiments, it is observed that the spot index change is better predictable with high-frequency time series data and the futures index information significantly improves the prediction accuracy of the return trends of the spot index for high-frequency index data, while the information of exchange rate does not. Also, dimension reduction process before training helps to increase the accuracy and dramatically for some classifiers. In addition, the trained classifiers with which a virtual trading strategy is applied to, noticeable better profits can be achieved than just a buy-and-hold-like strategy. 相似文献