全文获取类型
收费全文 | 4207篇 |
免费 | 346篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 64篇 |
综合类 | 4篇 |
化学工业 | 1047篇 |
金属工艺 | 182篇 |
机械仪表 | 219篇 |
建筑科学 | 46篇 |
能源动力 | 140篇 |
轻工业 | 334篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 599篇 |
一般工业技术 | 785篇 |
冶金工业 | 774篇 |
原子能技术 | 75篇 |
自动化技术 | 286篇 |
出版年
2024年 | 5篇 |
2023年 | 30篇 |
2022年 | 57篇 |
2021年 | 98篇 |
2020年 | 90篇 |
2019年 | 110篇 |
2018年 | 122篇 |
2017年 | 121篇 |
2016年 | 161篇 |
2015年 | 110篇 |
2014年 | 176篇 |
2013年 | 271篇 |
2012年 | 267篇 |
2011年 | 323篇 |
2010年 | 234篇 |
2009年 | 251篇 |
2008年 | 197篇 |
2007年 | 145篇 |
2006年 | 154篇 |
2005年 | 131篇 |
2004年 | 109篇 |
2003年 | 122篇 |
2002年 | 78篇 |
2001年 | 80篇 |
2000年 | 72篇 |
1999年 | 90篇 |
1998年 | 254篇 |
1997年 | 137篇 |
1996年 | 97篇 |
1995年 | 61篇 |
1994年 | 69篇 |
1993年 | 53篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 26篇 |
1989年 | 28篇 |
1988年 | 23篇 |
1987年 | 16篇 |
1986年 | 22篇 |
1985年 | 16篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 12篇 |
1977年 | 28篇 |
1976年 | 55篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有4562条查询结果,搜索用时 38 毫秒
81.
Young Suk Kim Sang Bok Ahn Dong Joon Oh Sung Soo Kim Yong Moo Cheong 《Metals and Materials International》2002,8(3):241-246
With the aim of assessing the degradation of Zr−2.5Nb pressure tubes operating in the Wolsong unit-1 nuclear power plant, characterization tests are being conducted on irradiated Zr−2.5Nb tubes removed after 10-year operation. The examined tube had been exposed to temperatures ranging from 264 to 306°C and a neutron fluence of 8.9×1021 n/cm2 (E>1 MeV) at the maximum. Tensile tests were carried out at temperatures ranging from RT to 300°C. The density of a-type and c-type dislocations was examined on the irradiated Zr-2.5Nb tube using a transmission electron microscope. Neutron irradiation up to 8.9×1021 n/cm2 (E>1 MeV) yielded an increase in a-type dislocation density of the Zr−2.5Nb pressure tube to 7.5×1014 m−2, which was highest at the inlet of the tube exposed to the low temperature of 275°C. In contranst, the c-component dislocation density did not change with irradiation, keeping an initial dislocation density of 0.8×1014 m−2 over the whole length of the tube. As expected, the neutron irradiation increased mechanical strength by about 17–26% in the transverse direction and by 34–39% in the longitudinal direction compared to that of the unirradiated tube at 300°C. The change in the mechanical properties with irradiation is discussed in association with the microstructural change as a function of temperature and neutron fluence. 相似文献
82.
Tuan Anh Tran In Seop Na Soo Hyung Kim 《International Journal on Document Analysis and Recognition》2016,19(3):191-209
Document layout analysis or page segmentation is the task of decomposing document images into many different regions such as texts, images, separators, and tables. It is still a challenging problem due to the variety of document layouts. In this paper, we propose a novel hybrid method, which includes three main stages to deal with this problem. In the first stage, the text and non-text elements are classified by using minimum homogeneity algorithm. This method is the combination of connected component analysis and multilevel homogeneity structure. Then, in the second stage, a new homogeneity structure is combined with an adaptive mathematical morphology in the text document to get a set of text regions. Besides, on the non-text document, further classification of non-text elements is applied to get separator regions, table regions, image regions, etc. The final stage, in refinement region and noise detection process, all regions both in the text document and non-text document are refined to eliminate noises and get the geometric layout of each region. The proposed method has been tested with the dataset of ICDAR2009 page segmentation competition and many other databases with different languages. The results of these tests showed that our proposed method achieves a higher accuracy compared to other methods. This proves the effectiveness and superiority of our method. 相似文献
83.
Sam Dong Jung Jeong Soo Kim Jung Won Park Jong Hwa Won Moon Kyum Kim 《Multimedia Tools and Applications》2015,74(20):9017-9029
A technique is developed to clearly establish the shear resistance of a cellular structure, retaining wall composed of a steel frame and fill materials with both continuous and discontinuous characteristics. To overcome the limitation of the existing analysis approach based on continuum mechanics, in which the shear behavior and interaction between the frames and fill material of this type of structure are difficult to describe, this paper introduces displacement incremental analysis into the distinct element method. The results obtained by using the proposed approach are compared with experimental results to verify its accuracy. The results show an internal friction angle of fill materials and overburdening load are major factor determining the shear resistance of a retaining wall with a cellular structure type. From the results of the parametric study on the shear behavior of this type of structure, this paper also proposes a shear resistance moment-shear displacement formula for designing a retaining wall with a cellular structure type. 相似文献
84.
A noteworthy thing in desktop PCs is that they can provide a great opportunity to increase the performance of processing multimedia data by exploiting task- and data-parallelism with multi-core CPU and many-core GPU. This paper presents a high performance parallel implementation of 2D DCT on this heterogeneous computing environment. For this purpose, Intel TBB (threading building blocks) and OpenCL (Open Compute Language) are utilized for task- and data-parallelism, respectively. The simulation result shows that the parallel DCT implementations far the serial ones in processing speed. Especially, OpenCL implementation shows a linear speedup, a typical SIMD characteristic as the increase of 2D data sets. 相似文献
85.
Pyung Soo Kim 《International Journal of Control, Automation and Systems》2013,11(1):206-210
In this paper, a finite memory filter is proposed to estimate the available bandwidth through real-time tracking unknown parameters of the sloping straight line while removing undesired system and measurement noises. The finite memory filter is developed under a weighted least square criterion using only the most recent finite probe-packet measurements on the window. The proposed finite memory filtering based available bandwidth estimate is shown to have several inherent properties such as unbiasedness, deadbeat, and robustness. A guideline for choosing appropriate window length is described as it can significantly affect the estimation performance. Finally, computer simulations show that the proposed finite memory filtering based approach can be comparable with the Kalman filtering based approach with infinite memory structure for constantly or slowly changing available bandwidth and outperform that for dynamically changing available bandwidth. 相似文献
86.
Hye Jung Choi Yeon Soo Kim Doo Soon Park Hyun Joo Kang 《Personal and Ubiquitous Computing》2013,17(7):1365-1372
The purpose of this study was to investigate the effect of wheelchair-based rehabilitation on the physical functions, health perception, and blood lipids according to the length of time since the stroke. Wheelchair-based rehabilitation progressed for 60 min per session, five times per week for 6 weeks. Physical functions, health perception (SF-36), and blood lipids were measured before and after rehabilitation. Physical fitness for physical function such as agility, grip strength, lower-body muscular endurance, flexibility, and posture control significantly improved after 6 weeks of rehabilitation. Health perception improved significantly with physical and mental health according to time since the stroke occurred. Overall, 6 weeks of wheelchair-based rehabilitation had a positive effect on the physical function and health perception regardless of stroke duration. Wheelchair-based rehabilitation had a more positive effect on the physical functions and health perception on the patients who suffered their stroke most recently. We suggested that wheelchair-based rehabilitation is necessary even through wheelchair based for chronic stroke patients, and it was useful their improved of quality of life. 相似文献
87.
It is foreseen that more and more music objects in symbolic format and multimedia objects, such as audio, video, or lyrics,
integrated with symbolic music representation (SMR) will be published and broadcasted via the Internet. The SMRs of the flowing songs or multimedia objects will form a
music stream. Many interesting applications based on music streams, such as interactive music tutorials, distance music education, and
similar theme searching, make the research of content-based retrieval over music streams much important. We consider multiple
queries with error tolerances over music streams and address the issue of approximate matching in this environment. We propose
a novel approach to continuously process multiple queries over the music streams for finding all the music segments that are
similar to the queries. Our approach is based on the concept of n-grams, and two mechanisms are designed to reduce the heavy
computation of approximate matching. One mechanism uses the clustering of query n-grams to prune the query n-grams that are
irrelevant to the incoming data n-gram. The other mechanism records the data n-gram that matches a query n-gram as a partial
answer and incrementally merges the partial answers of the same query. We implement a prototype system for experiments in
which songs in the MIDI format are continuously broadcasted, and the user can specify musical segments as queries to monitor
the music streams. Experiment results show the effectiveness and efficiency of the proposed approach. 相似文献
88.
Hyun‐Sang Park Seon‐Beom Ji Min‐Koo Han Jae‐Sic Lee Chi‐Woo Kim Kwang‐Soo Choi 《Journal of the Society for Information Display》2009,17(8):681-686
Abstract— A new digital ambient‐light sensor system is presented which employs two linear light sensors with different sensitivities and automatically adjusts the sensitivity based on the illumination condition. The adaptation mechanism allows a very wide range of light intensity to be detected, and the input dynamic range of the system is substantially improved from 22.5 to 45.1 dB. The proposed method does not require any additional precision bits for output data. Due to the small number of the output bits and the simple conversion process, the system can be easily integrated on the display panel. 相似文献
89.
Bong Hyun You Byoung Jun Lee Sang Youn Han Seiki Takahashi Brian H. Berkeley Nam Deog Kim Sang Soo Kim 《Journal of the Society for Information Display》2009,17(2):87-94
Abstract— A touch‐screen‐panel (TSP) embedded 12.1‐in. LCD employing a standard existing a‐Si:H TFT‐LCD process has been successfully developed. Compared with conventional external touch‐screen panels, which use additional components to detect touch events, the new internal TSP exhibits a clearer image and improved touch feeling, as well as increased sensing speed using discrete sensing lines to enable higher‐speed sensing functions including handwriting. The new internal digital switching TSP can be fabricated with low cost because it does not require any additional process steps compared to a standard a‐Si:H TFT‐LCD. 相似文献
90.
Z. V. Djordjevic X. Feng Li Won Soo Shin S. L. Wunder G. R. Baran 《Journal of Materials Science》1995,30(11):2968-2980
The branching patterns formed as a result of crack growth in dimethacrylate resins below their glass transition temperatures looked similar to fractal trees. The skeletons of the patterns were analysed numerically for their topological and geometrical properties. The number of branches, N
i
, mean branch lengths, N
i
, and branch angles of a particular order, defined according to the Strahler and inverted Weibel schemes, followed exponential scaling behaviour: N
i
(R
b
)–i
and L
i
(R
l
)
i
. Using the relationship for the fractal dimension D=In R
B
/In R
L
, a value of D=1.4 was obtained for the fracture pattern. Fractal behaviour was also examined by the box-counting method which indicated a power-law dependence of the mass on the box size with fractal dimension exponent D=1.4 in the case of the fracture pattern. However, the mass-shell method for both the fracture pattern and the fractal trees gave an exponential increase of mass with distance from the origin, rather than the power-law behaviour expected for fractals. This was attributed to the fact that branches of different sizes were distributed in restricted regions of space closer to the periphery, rather than uniformly over the whole pattern. 相似文献