全文获取类型
收费全文 | 1018篇 |
免费 | 27篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 310篇 |
金属工艺 | 38篇 |
机械仪表 | 20篇 |
建筑科学 | 25篇 |
矿业工程 | 1篇 |
能源动力 | 36篇 |
轻工业 | 51篇 |
水利工程 | 7篇 |
无线电 | 75篇 |
一般工业技术 | 196篇 |
冶金工业 | 127篇 |
原子能技术 | 9篇 |
自动化技术 | 142篇 |
出版年
2024年 | 4篇 |
2023年 | 5篇 |
2022年 | 26篇 |
2021年 | 42篇 |
2020年 | 27篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 19篇 |
2016年 | 40篇 |
2015年 | 16篇 |
2014年 | 36篇 |
2013年 | 64篇 |
2012年 | 36篇 |
2011年 | 55篇 |
2010年 | 37篇 |
2009年 | 56篇 |
2008年 | 40篇 |
2007年 | 32篇 |
2006年 | 36篇 |
2005年 | 28篇 |
2004年 | 18篇 |
2003年 | 23篇 |
2002年 | 27篇 |
2001年 | 25篇 |
2000年 | 27篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 12篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1959年 | 2篇 |
排序方式: 共有1050条查询结果,搜索用时 15 毫秒
1.
Kumar S. Ganesh Sridhar S. S. Hussain Azham Manikanthan S. V. Padmapriya T. 《Multimedia Tools and Applications》2022,81(7):9091-9109
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many... 相似文献
2.
Kalai Selvan Ramalingam Karmegam Karuppiah Shiamala Devi Ramaiya Vivien How Enoch Kumar Perimal Hassan Sadeghi Naeini Sivasankar Sambasivam Kulanthayan KC Mani 《人机工程学与制造业中的人性因素》2019,29(5):426-434
Many occupations require workers to stand for long periods of time without proper interventions, which causes discomfort in the back and lower limbs. Therefore, this study aims to assess the effectiveness in alleviating body muscle discomfort during prolonged standing through the use of a calf massager. This study was conducted among male workers at a manufacturer with production line workers and the list was obtained from the HR Department and simple random sampling was done by number categorization. A total of 100 respondents (50 respondents for both the control and the experimental groups) participated in this study. The experiment took place in a room with a similar setup for the production line. Each respondent was requested to perform the simulated task for 2 hr. For the experimental group, the calf massager was turned on every 15 min. At every 15‐min interval after turning on the calf massager, respondents from both groups were required to evaluate their discomfort level on a Borg's scale CR‐10 questionnaire. The results showed that the level of body discomfort among respondents in the experimental group reduced (20–30%) compared with that of the control group. Multivariate analysis results revealed that the discomfort rating for the lower back, knees, thighs, calves, and feet was significantly lower (p < .05) among the experimental group compared with the control group. For lower body parts, the lower back region was statistically significant (p < .05) at the 90th, 105th, and 120th min; the thigh region was statistically significant (p < .05) at the 120th min; the knee region was statistically significant (p < .05) at the 105th and 120th min; the calf region was statistically significant (p < .05) at all minute intervals except the 15th and 45th min, while the feet region, was statistically significant at the 105th and 120th min. Therefore, this study indicates that calf massage treatment is capable of reducing body muscle discomfort during prolonged standing and highlights the significance of calf massage. 相似文献
3.
In this paper two problems on the class of k -trees, a subclass of the class of chordal graphs, are considered: the fast reordering problem and the isomorphism problem. An O(log 2 n) time parallel algorithm for the fast reordering problem is described that uses O(nk(n-k)/\kern -1ptlog n) processors on a CRCW PRAM proving membership in the class NC for fixed k . An O(nk(k+1)!) time sequential algorithm for the isomorphism problem is obtained representing an improvement over the O(n 2 k(k+1)!) algorithm of Sekharan (the second author) [10]. A parallel version of this sequential algorithm is presented that runs in O(log 2 n) time using O((nk((k+1)!+n-k))/log n) processors improving on a parallel algorithm of Sekharan for the isomorphism problem [10]. Both the sequential and parallel algorithms use a concept introduced in this paper called the kernel of a k -tree. 相似文献
4.
A Confocal Scanning Laser Microscope equipped with a gold image furnace was used to directly observe the precipitation of MnS during solidification of high sulphur steels under isothermal conditions in the temperature region 1440 to 1480°C on the free surface of the steel melt. For the case of Al‐killed steels, below 1480°C MnS particles were found to precipitate with Fe forming simultaneously around them. This MnS containing structure continued to grow rapidly (264 μm/s) as a surface film. The film gradually changed, as the level of S in the melt decreased, into a eutectic structure (with lamella spacing of 2 μm) as predicted by thermodynamics. In Si‐ killed steels there was significantly lower tendency to form MnS both in terms of time until precipitation occurred and growth rate. 相似文献
5.
6.
B. Sridhar H.R.D. Sunak B.R. Strauss S.P. Bastien 《Photonics Technology Letters, IEEE》1996,8(2):215-217
In this letter, we report an efficient single-mode Er/sup 3+/ doped fluoride fiber amplifier (EDFFA) in the 850 mn signal band. The Ti-sapphire laser was used to pump the EDFFA at 792 mm with an estimated absorbed pump power of 35 mW. The EDFFA used a 4.2 meter long NA=0.39, /spl lambda//sub c/=850 nm fluoride fiber as the active medium. A peak gain of 25 dB was observed at 852 mm. The gain was measured for a 10 nm region between 847.5 mn and 857.5 nm. The 3 dB gain bandwidth is less than 3 nm. However, the gain exceeded 20 dB over wavelength region of at least 7.5 nm. The gain and the gain bandwidth can be further increased by optimizing the length of the active fiber. 相似文献
7.
Observation of calcium aluminate inclusions at interfaces between Ca-treated,Al-killed steels and slags 总被引:1,自引:0,他引:1
B. Coletti B. Blanpain S. Vantilt S. Sridhar 《Metallurgical and Materials Transactions B》2003,34(5):533-538
The evolution of Al2O3-CaO inclusions on molten steel surfaces and at molten steel/slag interfaces was observed in-situ through a confocal scanning laser microscope (CSLM) equipped with a gold-image furnace. Depending on the slag chemistry,
some of the initially liquid inclusions evolved into irregular Al2O3 or SiO2-enriched inclusions during the separation across the interface. Inclusions were found to cluster at specific locations at
the steel/slag interface. Unlike capillary-depression-driven clustering, which is observed on molten steel surfaces, a weak
repulsive force opposes fluid-flow-driven clustering at the steel/slag interface. After clustering, the irregular solid inclusions
were observed to agglomerate to form large aggregates.
This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties
& Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002. 相似文献
8.
We address the problem of determining the topology and bridge-capacity assignments for a network connecting a number of token rings via source-routing bridges. The objective is to minimize the cost of bridge installations while meeting the network users' performance requirements. The problem is modeled as a mixed 0–1 integer program. A comparison is given between two solution algorithms: a simulated annealing algorithm using the flow-deviation algorithm for each routing subproblem, and a drop algorithm using the simplex method for the same subproblems to provide benchmark solutions. In the former algorithm, the routing subproblem is formulated as a nonlinear program with penalty functions to model node and link capacity constraints, and in the latter as a multicommodity flow model with the same capacity constraints. Computational results show that the simulated-annealing/flow-deviation algorithm produced substantially better solutions than the LP-based drop algorithm. 相似文献
9.
The ability of rotorcraft to fly at low altitude is hindered by the high pilot workload required to avoid obstacles. The development of automation tools that can detect obstacles in the rotorcraft flight path, warn the crew, and interact with the guidance system to avoid detected obstacles would significantly reduce pilot workload and increase safety. This article describes an obstacle detection approach based on feature tracking and recursive range estimation that takes into account the characteristics of rotorcraft flight. The merits and weaknesses of the approach are discussed using image sequences from the laboratory and from flight. © 1992 John Wiley & Sons, Inc. 相似文献
10.
Recent Advances in Hierarchical Reinforcement Learning 总被引:16,自引:0,他引:16
Reinforcement learning is bedeviled by the curse of dimensionality: the number of parameters to be learned grows exponentially with the size of any compact encoding of a state. Recent attempts to combat the curse of dimensionality have turned to principled ways of exploiting temporal abstraction, where decisions are not required at each step, but rather invoke the execution of temporally-extended activities which follow their own policies until termination. This leads naturally to hierarchical control architectures and associated learning algorithms. We review several approaches to temporal abstraction and hierarchical organization that machine learning researchers have recently developed. Common to these approaches is a reliance on the theory of semi-Markov decision processes, which we emphasize in our review. We then discuss extensions of these ideas to concurrent activities, multiagent coordination, and hierarchical memory for addressing partial observability. Concluding remarks address open challenges facing the further development of reinforcement learning in a hierarchical setting. 相似文献