全文获取类型
收费全文 | 4228篇 |
免费 | 428篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 74篇 |
综合类 | 3篇 |
化学工业 | 1162篇 |
金属工艺 | 168篇 |
机械仪表 | 289篇 |
建筑科学 | 51篇 |
矿业工程 | 2篇 |
能源动力 | 166篇 |
轻工业 | 241篇 |
水利工程 | 11篇 |
无线电 | 752篇 |
一般工业技术 | 1117篇 |
冶金工业 | 219篇 |
原子能技术 | 58篇 |
自动化技术 | 347篇 |
出版年
2023年 | 50篇 |
2022年 | 56篇 |
2021年 | 121篇 |
2020年 | 89篇 |
2019年 | 135篇 |
2018年 | 126篇 |
2017年 | 160篇 |
2016年 | 187篇 |
2015年 | 150篇 |
2014年 | 226篇 |
2013年 | 277篇 |
2012年 | 325篇 |
2011年 | 371篇 |
2010年 | 226篇 |
2009年 | 280篇 |
2008年 | 226篇 |
2007年 | 178篇 |
2006年 | 136篇 |
2005年 | 120篇 |
2004年 | 131篇 |
2003年 | 137篇 |
2002年 | 118篇 |
2001年 | 79篇 |
2000年 | 85篇 |
1999年 | 73篇 |
1998年 | 91篇 |
1997年 | 72篇 |
1996年 | 64篇 |
1995年 | 39篇 |
1994年 | 41篇 |
1993年 | 43篇 |
1992年 | 35篇 |
1991年 | 37篇 |
1990年 | 21篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 26篇 |
1984年 | 11篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1970年 | 4篇 |
排序方式: 共有4660条查询结果,搜索用时 288 毫秒
101.
Jiabin Liu Jiawei Deng Yangyang Zhu Xiaokang Geng Lifu Zhang Sang Young Jeong Dan Zhou Han Young Woo Dong Chen Feiyan Wu Lie Chen 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2208008
With the great potential of the all-polymer solar cells for large-area wearable devices, both large-area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX-A and PYTX-B (X = Cl or H) are developed. The configuration difference caused by the replacement of non-conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film-forming of the active materials and the technically slow film-forming of the blade-coating process, the toluene-processed large-area (1.21 cm2) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl-A and PM6:PYTCl-B yield significantly higher ESF than PM6:PY-IT. Further blending with non-conjugated polymer donor PM6-A, the best ESF of 3.12% is achieved for PM6-A:PYTCl-A, which is among the highest comprehensive performances. 相似文献
102.
Jae-Duk Moon Jin-Gyu Kim Dae-Hee Lee 《Industry Applications, IEEE Transactions on》1998,34(6):1212-1217
Some interesting electrophysicochemical characteristics of waterpen point-to-plate discharges with DC and AC power have been investigated in a room atmosphere. The metal point electrode of a conventional point-to-plate air gap is severely bombarded by energetic ions from the discharge region near the point. Concurrently, the temperature of the point is greatly increased. There are different characteristics for the waterpen point discharge, because the surface temperature of the waterpen point stays low due to the evaporation of the moisture from the waterpen point. In this paper, the discharges and electrophysicochemical characteristics of a waterpen point and a Pt metal point have been studied to evaluate the differences. It was found that mists and sprays are dispersed from the waterpen point due to the bombardment of ions. Also, a positive corona is effective for mist dispersion, a negative corona disperses sprays, and AC corona disperses both mists and sprays. The AC discharge of the waterpen point generated more ozone of 56 ppm, while it was the negative DC discharge of the Pt point that produced more ozone of 30 ppm. The AC discharge of the waterpen point produced 0.11 ppm at 10 kV, and the Pt point produced 0.10 ppm at 15 kV. The DC discharge of the both points showed no NO formation 相似文献
103.
Study on the solidification cracking behaviour of high strength aluminum alloy welds: Effects of alloying elements and solidification behaviours 总被引:1,自引:0,他引:1
The solidification cracking susceptibility of the 7000 series Al-Zn-Mg high strength aluminum alloy has been studied. The cracking behaviour of the specimens were evaluated by a Tig-a-Ma-Jig Varestraint test process under various augmented strain conditions. It has been experimentally observed that the addition of copper decreased the solidification cracking resistivity of the high strength aluminum alloy weld metal by increasing the total crack length (TCL). The effect of the addition of manganese on the solidification cracking behaviour is found to be beneficial by markedly decreasing the solidification cracking susceptibility as the manganese content increases from 0.3 to 0.7%. This enhancement by manganese is understood to be attributed to the reduction of the mushy zone size during the solidification process. The effects of chromium and zirconium additions are also investigated. The weld metal containing zirconium is less sensitive to the solidification cracking than the weld metal containing chromium. In addition, the solidification behaviours of the tested alloys are also investigated and it is found that as the solidification temperature range (T) becomes narrow, the solidified structure becomes more dendritic in its features which is believed to create higher solidification cracking resistance. 相似文献
104.
Woo Young Kwon Il Hong Suh Sanghoon Lee 《International Journal of Control, Automation and Systems》2011,9(2):328-338
Reinforcement learning (RL) has been widely used as a mechanism for autonomous robots to learn state-action pairs by interacting
with their environment. However, most RL methods usually suffer from slow convergence when deriving an optimum policy in practical
applications. To solve this problem, a stochastic shortest path-based Q-learning (SSPQL) is proposed, combining a stochastic
shortest path-finding method with Q-learning, a well-known model-free RL method. The rationale is, if a robot has an internal
state-transition model which is incrementally learnt, then the robot can infer the local optimum policy by using a stochastic
shortest path-finding method. By increasing state-action pair values comprising of these local optimum policies, a robot can
then reach a goal quickly and as a result, this process can enhance convergence speed. To demonstrate the validity of this
proposed learning approach, several experimental results are presented in this paper. 相似文献
105.
Yong‐Kyu Jang Seong Jun Lee Jae Young Lee Yi Li Jae Hoon Hwang Sang Woo Kim Chang Woo Shim Ju Yeon Seo Nam Jin Kim Yi Joon Ahn Nam Hee Kim Seon Hong Ahn Seong Ryong Lee Dae Hee Park Chi Woo Kim 《Journal of the Society for Information Display》2011,19(3):253-257
Abstract— A novel pixel design for vertical‐alignment LCDs with superior transmittance has been developed. The new liquid‐crystal mode, refered to as the hole‐induced vertical‐alignment mode (Hi‐VA), uses a via hole of an organic layer on a TFT substrate to achieve multi‐domain alignment. Compared to the conventional design, the Hi‐VA mode has a transmittance of up to 135% with a contrast ratio of 2000:1. Moreover, the new structure is free from ITO patterning or protrusion on the color‐filter side, which makes the fabrication process simple and low cost. 相似文献
106.
Kim S Lee Y Lazar P Son M Baek A Thangapandian S Jeong NY Yoo YH Lee KW 《Journal of molecular graphics & modelling》2011,29(8):996-1005
The acetylcholinesterase (AChE) is important to terminate acetylcholine-mediated neurotransmission at cholinergic synapses. The pivotal role of AChE in apoptosome formation through the interactions with cytochrome c (Cyt c) was demonstrated in recent study. In order to investigate the proper binding conformation between the human AChE (hAChE) and human Cyt c (hCyt c), macro-molecular docking simulation was performed using DOT 2.0 program. The hCyt c was bound to peripheral anionic site (PAS) on hAChE and binding mode of the docked conformation was very similar to the reported crystal structure of the AChE and fasciculin-II (Fas-II) complex. Two 10ns molecular dynamics (MD) simulations were carried out to refine the binding mode of docked structure and to observe the differences of the binding conformations between the absent (Apo) and presence (Holo) of heme group. The key hydrogen bonding residues between hAChE and hCyt c proteins were found in Apo and Holo systems, as well as each Tyr341 and Trp286 residue of hAChE was participated in cation-pi (π) interactions with Lys79 of hCyt c in Apo and Holo systems, respectively. From the present study, although the final structures of the Apo and Holo systems have similar binding pattern, several differences were investigated in flexibilities, interface interactions, and interface accessible surface areas. Based on these results, we were able to predict the reasonable binding conformation which is indispensable for apoptosome formation. 相似文献
107.
This paper considers ‘two-stage’ call centers where some incoming calls are completed by first service while others require an additional second service. Although this type of call center is not uncommon, it has not been dealt with, if any, in the call center literature. In this paper, we introduce the concept of the ‘two-stage’ call center and discuss its features. Furthermore, we develop an effective outsourcing strategy in ‘two-stage’ call centers. To this end, we model ‘two-stage’ service system and propose several call routing structures. The structures are compared through numerical test and conventional queueing theories form the theoretical basis of our study. 相似文献
108.
Tomoko Watanabe Traphagan Yueh-hui Vanessa Chiang Hyeseung Maria Chang Benjaporn Wattanawaha Haekyung Lee Michael Charles Mayrath Jeongwon Woo Hyo-Jin Yoon Min Jung Jee Paul E. Resta 《Computers & Education》2010
Using a framework of cognitive, social, and teaching presence, the nature of learning experiences in a three-dimensional virtual world environment (Second Life) and a text-chat learning environment without visuals (TeachNet) were investigated. A mixed method of code frequencies, coherence graphs, interviews, and a survey was used. The results revealed that the TeachNet debates included more cognitive presence codes that indicate higher levels of cognitive processing than in SL debates. The teams were significantly different from each other in the collaboration style for developing arguments and in the ways to use utterances associated with cognitive, social, and teaching presences, and the groups’ collaboration style became more established with more experience with the tasks. The three critical factors–tool, tasks and group cohesion–that affect cognitive, teaching, and social presence are discussed. 相似文献
109.
Ganbat Baasantseren Jae‐Hyeung Park Munkh‐Uchral Erdenebat Seung‐Woo Seo Nam Kim 《Journal of the Society for Information Display》2010,18(7):519-526
Abstract— An integral floating display (IFD) with a long depth range without floating lens distortion is proposed. Two lenses were used to reduce barrel distortion of the floating lens and three‐dimensional (3‐D) image deformation from object‐dependent longitudinal and lateral magnifications in the floating‐display system, combined with an integral imaging display. The distance between the floating lenses is the sum of their focal lengths. In the proposed configuration, lateral and longitudinal magnifications are constant regardless of the distance of the integrated 3‐D images, so the distortions from the distant‐dependent magnifications of the floating lens do not occur with the proposed method. In addition, the proposed floating system expands the depth range of the integral imaging display. As a result, the display can show a correct 3‐D floating image with a large depth range. Experimental results demonstrate that the proposed method successfully displays a 3‐D image without floating lens distortions across a large depth range. 相似文献
110.
In financial service industry, service improvement should be considered from process viewpoint and customer viewpoint because the value creation is ultimately linked with internal business processes on the back office and customers are involved as a co-producer of value. In this perspective, customer complaints through call centers are adequate to support the analysis for service improvement in financial service industry. In this study, we propose a web-based decision support system for business process management employing customer complaints, namely Voice of the Customer (VOC), and its handling data for service improvement. It involves VOC conversion for data enrichment and includes analysis of summarization, exception and comparison. The proposed system is evaluated on a major credit card company in South Korea. 相似文献