全文获取类型
收费全文 | 8595篇 |
免费 | 526篇 |
国内免费 | 28篇 |
专业分类
电工技术 | 132篇 |
综合类 | 6篇 |
化学工业 | 1780篇 |
金属工艺 | 322篇 |
机械仪表 | 584篇 |
建筑科学 | 166篇 |
能源动力 | 370篇 |
轻工业 | 626篇 |
水利工程 | 32篇 |
石油天然气 | 11篇 |
无线电 | 1739篇 |
一般工业技术 | 1819篇 |
冶金工业 | 625篇 |
原子能技术 | 149篇 |
自动化技术 | 788篇 |
出版年
2024年 | 5篇 |
2023年 | 113篇 |
2022年 | 152篇 |
2021年 | 277篇 |
2020年 | 211篇 |
2019年 | 179篇 |
2018年 | 239篇 |
2017年 | 266篇 |
2016年 | 312篇 |
2015年 | 223篇 |
2014年 | 335篇 |
2013年 | 540篇 |
2012年 | 552篇 |
2011年 | 664篇 |
2010年 | 482篇 |
2009年 | 497篇 |
2008年 | 471篇 |
2007年 | 369篇 |
2006年 | 330篇 |
2005年 | 303篇 |
2004年 | 276篇 |
2003年 | 236篇 |
2002年 | 251篇 |
2001年 | 211篇 |
2000年 | 203篇 |
1999年 | 197篇 |
1998年 | 307篇 |
1997年 | 182篇 |
1996年 | 141篇 |
1995年 | 94篇 |
1994年 | 99篇 |
1993年 | 79篇 |
1992年 | 43篇 |
1991年 | 55篇 |
1990年 | 38篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 29篇 |
1986年 | 17篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1974年 | 5篇 |
排序方式: 共有9149条查询结果,搜索用时 15 毫秒
61.
Ahn Kyu-Hong Hwang Jong-Hyuk Song Kyung-Guen Jung Yong-Ho Cho Eul-Saeng Lim Byung-Ran Kim Kwang-Soo 《Metals and Materials International》2004,10(2):167-170
The performance of an attached growth wastewater treatment process was investigated in an effort to improve nitrogen removal
efficiency. Recycled Yakult (lactic acid fermentation drink) bottles made of polystyrene were used as a biofilm media. The
use of Yakult bottles as a biofilm media has been attempted by numerous researchers in Japan for the removal of solids and
organics. However, these studies focused only on the removal of solids and organics. This study extended their application
to the removal of nitrogen for domestic sewage treatment. Yakult media was placed in a reactor with 70% apparent reactor volume
in a conventional A/O process. The bottom of the Yakult media was removed, and randomly filled Yakult media were effectively
able to reduce the flow in tanks, resulting in an increase in the contact time between pollutants and microorganisms. With
higher HRT, the nitrogen removal efficiency was increased by up to 83% with 12 hr of HRT. Nitrification appeared to be the
limiting factor of nitrogen removal at an HRT that is less than 12 hr, indicating that the Yakult process requires more retention
time to achieve nitrification compared to other biofilm processes. The removal efficiencies of organics and solids were high
regardless of the change of operational parameters.
This article is based on a presentation in “The 7th Korea-China Workshop On Advanced Materials” organized by the Korea-China
Advanced Materials Cooperation Center and the China-Korea Advanced Materials Cooperation Center, held at Ramada Plaza Jeju
Hotel, Jeju Island, Korea on August 24–27, 2003. 相似文献
62.
Workers in grocery stores are exposed to numerous musculoskeletal risks that can be reduced using assistive devices while performing stocking tasks. A regional grocery store has recently deployed a mobile cart without comprehension of its ergonomic impact on workers, which this article investigates using normalized electromyography data (%MVC). This article studies not only ergonomic impact based on %MVC values but also work performance represented by a muscle force metric (MFM). The results from this study showed highest muscle groups in %MVC and MFM were the erector spinae and triceps. Interestingly, muscle activations on erector spinae were reduced when mobile cart is used. %MVC and MFM distribution for value‐added‐ and non‐value‐added subtasks were slightly different, with larger differences observed for non‐value‐added tasks. Video recordings revealed higher work performance when the mobile cart is used. In future research, the number of participants will be increased to further validate the results from this study. 相似文献
63.
Da-Jung Cho Yo-Sub Han Shin-Dong Kang Hwee Kim Sang-Ki Ko Kai Salomaa 《Natural computing》2016,15(1):31-39
We consider a pseudo-inversion operation inspired by biological events, such as DNA sequence transformations, where only parts of a string are reversed. We define the pseudo-inversion of a string \(w = uxv\) to be the set of all strings \(v^Rxu^R\), where \(uv \ne \lambda \) and consider the operation from a formal language theoretic viewpoint. We show that regular languages are closed under the pseudo-inversion operation whereas context-free languages are not. Furthermore, we study the iterated pseudo-inversion operation and show that the iterated pseudo-inversion of a context-free language is recognized by a nondeterministic reversal-bounded multicounter machine. Finally, we introduce the notion of pseudo-inversion-freeness and examine closure properties and decidability problems for regular and context-free languages. We demonstrate that pseudo-inversion-freeness is decidable in polynomial time for regular languages and undecidable for context-free languages. 相似文献
64.
Su-gil Cho Junyong Jang Shinyu Kim Sanghyun Park Tae Hee Lee Minuk Lee Jong-Su Choi Hyung-Woo Kim Sup Hong 《Structural and Multidisciplinary Optimization》2016,54(6):1671-1688
Uncertainty-based multidisciplinary design optimization (UMDO) has been widely acknowledged as an advanced methodology to address competing objectives and reliable constraints of complex systems by coupling relationship of disciplines involved in the system. UMDO process consists of three parts. Two parts are to define the system with uncertainty and to formulate the design optimization problem. The third part is to quantitatively analyze the uncertainty of the system output considering the uncertainty propagation in the multidiscipline analysis. One of the major issues in the UMDO research is that the uncertainty propagation makes uncertainty analysis difficult in the complex system. The conventional methods are based on the parametric approach could possibly cause the error when the parametric approach has ill-estimated distribution because data is often insufficient or limited. Therefore, it is required to develop a nonparametric approach to directly use data. In this work, the nonparametric approach for uncertainty-based multidisciplinary design optimization considering limited data is proposed. To handle limited data, three processes are also adopted. To verify the performance of the proposed method, mathematical and engineering examples are illustrated. 相似文献
65.
66.
Suehye Park Edward Namkyu Cho Ilgu Yun 《Journal of the Society for Information Display》2013,21(8):333-338
Amorphous In–Ga–Zn–O thin‐film transistors (TFTs) have attracted increasing attention due to their electrical performance and their potential for use in transparent and flexible devices. Because TFTs are exposed to illumination through red, green, and blue color filters, wavelength‐varied light illumination tests are required to ensure stable TFT characteristics. In this paper, the effects of different light wavelengths under both positive and negative VGS stresses on amorphous In–Ga–Zn–O TFTs are investigated. The TFT instability that is dependent on optical and electrical stresses can be explained by the charge trapping mechanism and interface modification. 相似文献
67.
Jungchan Cho Minsik Lee Chong-Ho Choi Songhwai Oh 《Computer Vision and Image Understanding》2013,117(11):1549-1559
Aligning shapes is essential in many computer vision problems and generalized Procrustes analysis (GPA) is one of the most popular algorithms to align shapes. However, if some of the shape data are missing, GPA cannot be applied. In this paper, we propose EM-GPA, which extends GPA to handle shapes with hidden (missing) variables by using the expectation-maximization (EM) algorithm. For example, 2D shapes can be considered as 3D shapes with missing depth information due to the projection of 3D shapes into the image plane. For a set of 2D shapes, EM-GPA finds scales, rotations and 3D shapes along with their mean and covariance matrix for 3D shape modeling. A distinctive characteristic of EM-GPA is that it does not enforce any rank constraint often appeared in other work and instead uses GPA constraints to resolve the ambiguity in finding scales, rotations, and 3D shapes. The experimental results show that EM-GPA can recover depth information accurately even when the noise level is high and there are a large number of missing variables. By using the images from the FRGC database, we show that EM-GPA can successfully align 2D shapes by taking the missing information into consideration. We also demonstrate that the 3D mean shape and its covariance matrix are accurately estimated. As an application of EM-GPA, we construct a 2D + 3D AAM (active appearance model) using the 3D shapes obtained by EM-GPA, and it gives a similar success rate in model fitting compared to the method using real 3D shapes. EM-GPA is not limited to the case of missing depth information, but it can be easily extended to more general cases. 相似文献
68.
Video conferencing provides an environment for multiple users linked on a network to have meetings. Since a large quantity of audio and video data are transferred to multiple users in real time, research into reducing the quantity of data to be transferred has been drawing attention. Such methods extract and transfer only the features of a user from video data and then reconstruct a video conference using virtual humans. The disadvantage of such an approach is that only the positions and features of hands and heads are extracted and reconstructed, whilst the other virtual body parts do not follow the user. In order to enable a virtual human to accurately mimic the entire body of the user in a 3D virtual conference, we examined what features should be extracted to express a user more clearly and how they can be reproduced by a virtual human. This 3D video conferencing estimates the user’s pose by comparing predefined images with a photographed user’s image and generates a virtual human that takes the estimated pose. However, this requires predefining a diverse set of images for pose estimation and, moreover, it is difficult to define behaviors that can express poses correctly. This paper proposes a framework to automatically generate the pose-images used to estimate a user’s pose and the behaviors required to present a user using a virtual human in a 3D video conference. The method for applying this framework to a 3D video conference on the basis of the automatically generated data is also described. In the experiment, the framework proposed in this paper was implemented in a mobile device. The generation process of poses and behaviors of virtual human was verified. Finally, by applying programming by demonstration, we developed a system that can automatically collect the various data necessary for a video conference directly without any prior knowledge of the video conference system. 相似文献
69.
Tae Hyun Fang Deuk Jae Cho Jae Weon Choi 《International Journal of Control, Automation and Systems》2013,11(4):752-760
This paper proposes an off-line optimal channel scheduling algorithm for an interconnected vehicle control system. The optimal sequence obtained through the scheduling algorithm provides a switching controller with the best switching order if the controller can access only one plant at each time slot over the shared communication medium. Interconnected systems require the string stability as well as the dynamic stability of each unit. This paper shows that integrating the simple string stable control law with the approximately optimal linear-quadratic (LQ) tracker gives the optimal channel scheduling algorithm. 相似文献
70.
Using simulation and multi-criteria methods to provide robust solutions to dispatching problems in a flow shop with multiple processors 总被引:1,自引:0,他引:1
Yiyo Kuo Taho Yang Chiwoon Cho Yao-Ching Tseng 《Mathematics and computers in simulation》2008,78(1):40-56
Dispatching rules are important to the performance of a manufacturing system. Selective applications of different priority rules at different processing stages in a multiple workstation manufacturing system have a positive impact on shop performance. This type of problem is a combinatorial dispatching decision. However, no dispatching rule can consistently produce better performance than all other rules under a variety of operating conditions and criteria. It is the purpose of this study to provide a robust solution for a dispatching decision that will have ‘good’ performance under different operating scenarios. In this paper a simulation case of a flow shop with multiple processors is proposed, specifically a multi-layer ceramic capacitor manufacturing system. Two multiple criteria decision-making methods – techniques for order preference by similarity to ideal solution (TOPSIS) and an analytic hierarchy process (AHP) – in combination with Taguchi orthogonal array are used to find the most suitable dispatching rule for every workstation. The results show that for 15 production scenarios and 4 criteria this combinatorial dispatching rule is robust, in the sense that it outperforms other commonly employed strategies. 相似文献