全文获取类型
收费全文 | 47篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 10篇 |
金属工艺 | 3篇 |
能源动力 | 12篇 |
无线电 | 1篇 |
一般工业技术 | 14篇 |
冶金工业 | 4篇 |
原子能技术 | 2篇 |
自动化技术 | 2篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2004年 | 2篇 |
2003年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有48条查询结果,搜索用时 15 毫秒
1.
Starting from plysical laws a four-dimensional nonlinear model for mecano-hydraulic servomechanisms is deduced. The stability of its equilibria is analysed using a theorem of Lyapunov and Malkin to handle the critical case due to the presence of zero in the spectrum of the matrix of the linear part around equilibria. Stability diagrams are drawn and simulation results are presented through phase diagrams. 相似文献
2.
3.
4.
5.
Nanocrystalline Fe-doped ZnO films were obtained by spin coating, using zinc acetate and iron acetate as starting materials and N,N-dimethylformamide as solvent. Characteristic XRD patterns indicate that the films under study are single phase with the ZnO-like wurtzite structure. There are not any secondary phases and Fe2+ as well as Fe3+ substitutes for Zn2+ of ZnO host. Atomic force microscopy analysis revealed that the studied films are characterized by high-density columnar structure and the incorporation of Fe atoms into the ZnO lattice modified the surface morphology. The sensitivity, at three different gases, was investigated and it was observed that acetone is the test gas that produces the most significant changes in the electrical resistance of all studied samples. Experimental results indicate that the optimum operating temperature increases for Fe-doped ZnO films by comparison with the undoped one. Also, the values of sensitivity were found to depend on the dopant concentration in ZnO films. 相似文献
6.
7.
The output parameters of an experimental fission electric cell (FEC) operating in the current generator mode have been estimated for the values of the neutron flux existing in the nuclear reactors. The estimation has been performed on the basis of the experimental values obtained in an investigation carried out at the Central Institute of Physcis (CIP) in Bucharest, Romania, concentrating on direct nuclear fission energy conversion into electrical energy. These experimental values are higher by orders of magnitude than those reported by other laboratories. The results of the estimation indicate that hundreds of microamperes, hundreds of kilovolts and hundreds of watts could be delivered by an FEC containing 1g of 235U and irradiated in a thermal neutron flux of 1.4 × 1013 neutron cm?2s?1. The research demonstrates the feasibility of efficient fission electric cells as potentially usable components in nuclear reactors. 相似文献
8.
A nonlinear programming optimization problem is considered for the case in which the decision vector is the vector of zonal irradiation while the objective function is the equilibrium fuel feed rate with a CANDU-600 reactor subject to certain restrictions regarding the reactivity excess and the maximum powers per channel and bundle. The objective and restriction functions of the system are estimated within a time average approximation of a three-dimensional two-group diffusion type, with the control systems uniformly immersed within the reactor, and also considering the newest increments of the parasitic absorbents using FMDP program. The optimization problem is solved by means of the SUMT method, modified so as to become a technique of sequential solving for certain subproblems of linear optimization through the application of LPROG program. The results are presented as optimal vectors of zonal irradiation and as optimal values of fuel feed rate, with some two-zone cases, which establish the best zonal configuration. This configuration is then extended to a four-zone case which is analysed in a similar manner, evidencing a saving potential which gives the possibiliy of increasing the reactor performance. 相似文献
9.
Doug Williams Marian F. Ursu Joshan Meenowa Pablo Cesar Ian Kegel Karl Bergström 《Telematics and Informatics》2011
This paper discusses results from research related to the use of television as a device that supports social interaction between close-knit groups in settings that include more than two locations, each location being potentially equipped with more than one camera. The paper introduces the notion of a framing experience, as a specific scenario or situation within which social communication takes place. It reports on the evaluation of some of the key attributes of social communication through semi-structured interviews, with 16 families across four European countries. The inferences drawn from this study are reduced to four system capabilities including the ability to support: excitement, engagement and entertainment; high quality, reliable audiovisual communications; flexibility and adaptability sufficient to support the unpredictable and reactive nature of human interaction and discourse. These system requirements are, in turn, reduced to a number of technology challenges which if solved will help enable effective social communications between groups, mediated by the television. These technology challenges include: high quality reliable audio visual communication; interaction orchestration, multimedia interpretation and multimedia composition. Finally the paper reflects on the impact the use of framing experiences, such as those described here, could have on strategy and policy for service providers and regulators. 相似文献
10.
The 20Fe2O3 80[3B2O3·PbO] glasses equilibrated at 1250°C, for times ranging between 0.5 and 10 hrs are studied by X-rays, electron-microscope, Mössbauer effect, electron paramagnetic resonance and magnetic measurements. The iron valence states as well as the distribution of iron ions in the glass matrix are analysed. 相似文献