全文获取类型
收费全文 | 5277篇 |
免费 | 136篇 |
国内免费 | 88篇 |
专业分类
电工技术 | 94篇 |
综合类 | 7篇 |
化学工业 | 1018篇 |
金属工艺 | 125篇 |
机械仪表 | 204篇 |
建筑科学 | 101篇 |
矿业工程 | 3篇 |
能源动力 | 197篇 |
轻工业 | 304篇 |
水利工程 | 28篇 |
石油天然气 | 7篇 |
武器工业 | 1篇 |
无线电 | 920篇 |
一般工业技术 | 919篇 |
冶金工业 | 565篇 |
原子能技术 | 26篇 |
自动化技术 | 982篇 |
出版年
2024年 | 12篇 |
2023年 | 46篇 |
2022年 | 124篇 |
2021年 | 139篇 |
2020年 | 57篇 |
2019年 | 69篇 |
2018年 | 80篇 |
2017年 | 89篇 |
2016年 | 106篇 |
2015年 | 106篇 |
2014年 | 188篇 |
2013年 | 384篇 |
2012年 | 277篇 |
2011年 | 330篇 |
2010年 | 236篇 |
2009年 | 271篇 |
2008年 | 277篇 |
2007年 | 245篇 |
2006年 | 230篇 |
2005年 | 202篇 |
2004年 | 163篇 |
2003年 | 158篇 |
2002年 | 129篇 |
2001年 | 117篇 |
2000年 | 87篇 |
1999年 | 99篇 |
1998年 | 250篇 |
1997年 | 151篇 |
1996年 | 115篇 |
1995年 | 72篇 |
1994年 | 97篇 |
1993年 | 61篇 |
1992年 | 45篇 |
1991年 | 54篇 |
1990年 | 36篇 |
1989年 | 45篇 |
1988年 | 53篇 |
1987年 | 39篇 |
1986年 | 32篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 18篇 |
1976年 | 34篇 |
1974年 | 7篇 |
排序方式: 共有5501条查询结果,搜索用时 15 毫秒
101.
Guo Y Hsu S Sawhney HS Kumar R Shan Y 《IEEE transactions on pattern analysis and machine intelligence》2007,29(5):824-839
This paper addresses the problem of matching vehicles across multiple sightings under variations in illumination and camera poses. Since multiple observations of a vehicle are separated in large temporal and/or spatial gaps, thus prohibiting the use of standard frame-to-frame data association, we employ features extracted over a sequence during one time interval as a vehicle fingerprint that is used to compute the likelihood that two or more sequence observations are from the same or different vehicles. Furthermore, since our domain is aerial video tracking, in order to deal with poor image quality and large resolution and quality variations, our approach employs robust alignment and match measures for different stages of vehicle matching. Most notably, we employ a heterogeneous collection of features such as lines, points, and regions in an integrated matching framework. Heterogeneous features are shown to be important. Line and point features provide accurate localization and are employed for robust alignment across disparate views. The challenges of change in pose, aspect, and appearances across two disparate observations are handled by combining a novel feature-based quasi-rigid alignment with flexible matching between two or more sequences. However, since lines and points are relatively sparse, they are not adequate to delineate the object and provide a comprehensive matching set that covers the complete object. Region features provide a high degree of coverage and are employed for continuous frames to provide a delineation of the vehicle region for subsequent generation of a match measure. Our approach reliably delineates objects by representing regions as robust blob features and matching multiple regions to multiple regions using Earth Mover's Distance (EMD). Extensive experimentation under a variety of real-world scenarios and over hundreds of thousands of Confirmatory Identification (CID) trails has demonstrated about 95 percent accuracy in vehicle reacquisition with both visible and Infrared (IR) imaging cameras. 相似文献
102.
103.
104.
105.
Mechanical behaviour of particulate composites of cadmium containing 0.6 to 3 m size particles of boron and tungsten (up to 30 vol %) were studied from –196 to 260° C (0.13 to 0.9T
m). The marked strengthening of cadmium by the presence of fine particles is attributed to significant grain size and texture strengthening effects as well as to dispersion hardening effects. 相似文献
106.
107.
A modified circular harmonic filter may be used for the rotation-invariant discrimination of a target from another object which contains the same pattern as the target. The method is illustrated by the experimental rotation-invariant detection of the letter F in the presence of the letter E. 相似文献
108.
Chopsticks are one of the most simple and popular hand tools ever invented by humans, but have not previously been investigated by ergonomists. Two laboratory studies were conducted in this research, using a randomised complete block design, to evaluate the effects of the length of the chopsticks on the food-serving performance of adults and children. Thirty-one male junior college students and 21 primary school pupils served as subjects for the experiment. The results showed that the food-pinching performance was significantly affected by the length of the chopsticks, and that chopsticks of about 240 and 180 mm long were optimal for adults and pupils, respectively. Based on these findings, the researchers suggested that families with children should provide both 240 and 180 mm long chopsticks. In addition, restaurants could provide 210 mm long chopsticks, considering the trade-offs between ergonomics and cost. 相似文献
109.
Hsu YC Huang HH Huang YD Chu CP Chung YJ Huang YT 《Water science and technology》2012,66(10):2185-2193
Water shortage has become an emerging environmental issue. Reclamation of the effluent from municipal wastewater treatment plant (WWTP) is feasible for meeting the growth of water requirement from industries. In this study, the results of a pilot-plant setting in Futian wastewater treatment plant (Taichung, Taiwan) were presented. Two processes, sand filter - ultrafiltration - reverse osmosis (SF-UF-RO) and sand filter - electrodialysis reversal (SF-EDR), were operated in parallel to evaluate their stability and filtrate quality. It has been noticed that EDR could accept inflow with worse quality and thus required less pretreatment compared with RO. During the operation, EDR required more frequent chemical cleaning (every 3 weeks) than RO did (every 3 months). For the filtrate quality, the desalination efficiency of SF-EDR ranged from 75 to 80% in continuous operation mode, while the conductivity ranged from 100 to 120 μS/cm, with turbidity at 0.8 NTU and total organic carbon at 1.3 mg/L. SF-EDR was less efficient in desalinating the multivalent ions than SF-UF-RO was. However for the monovalent ions, the performances of the two processes were similar to each other. Noticeably, total trihalomethanes in SF-EDR filtrate was lower than that of SF-UF-RO, probably because the polarization effects formed on the concentrated side of the EDR membrane were not significant. At the end of this study, cost analysis was also conducted to compare the capital requirement of building a full-scale wastewater reclamation plant using the two processes. The results showed that using SF-EDR may cost less than using SF-UF-RO, if the users were to accept the filtrate quality of SF-EDR. 相似文献
110.
In this note, we prove that both problems studied by Cheng et al. [Cheng, T. C. E., Hsu, C.-J., & Yang, D.-L. (2011). Unrelated parallel-machine scheduling with deteriorating maintenance activities. Computers and Industrial Engineering, 60, 602–605] can be solved in O(nm+3) time no matter what the processing time of a job after a maintenance activity is greater or less than its processing time before the maintenance activity, where m is the number of machines and n is the number of jobs. 相似文献