全文获取类型
收费全文 | 1356篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 40篇 |
综合类 | 1篇 |
化学工业 | 238篇 |
金属工艺 | 21篇 |
机械仪表 | 27篇 |
建筑科学 | 25篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 119篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
武器工业 | 2篇 |
无线电 | 241篇 |
一般工业技术 | 182篇 |
冶金工业 | 290篇 |
原子能技术 | 3篇 |
自动化技术 | 172篇 |
出版年
2022年 | 24篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 21篇 |
2014年 | 30篇 |
2013年 | 50篇 |
2012年 | 41篇 |
2011年 | 51篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 43篇 |
2007年 | 56篇 |
2006年 | 38篇 |
2005年 | 48篇 |
2004年 | 31篇 |
2003年 | 47篇 |
2002年 | 42篇 |
2001年 | 43篇 |
2000年 | 32篇 |
1999年 | 42篇 |
1998年 | 126篇 |
1997年 | 72篇 |
1996年 | 45篇 |
1995年 | 41篇 |
1994年 | 38篇 |
1993年 | 41篇 |
1992年 | 27篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1977年 | 10篇 |
1976年 | 16篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 5篇 |
排序方式: 共有1393条查询结果,搜索用时 856 毫秒
11.
Schnepp H. Muller T. Luy J.-F. Russer P. 《Microwave and Wireless Components Letters, IEEE》2003,13(8):323-325
A novel channel diversity concept is proposed and demonstrated, which avoids receiving signal deterioration due to multipath fading in mobile receivers. The system is based on coherent superposition of the signals received from several transmitters supplying the same information at different frequencies. Based on a software radio architecture this concept may increase the quality of mobile reception in modern car receivers considerably. Compared with multiantenna-receivers which overcome the multipath fading problem by simultaneously receiving the same program with several antennas, the proposed solution is advantageous, since it requires only a single antenna. 相似文献
12.
Design aspects of MOS-controlled thyristor elements: technology,simulation, and experimental results
Bauer F. Halder E. Hofmann K. Haddon H. Roggwiller P. Stockmeier T. Burgler J. Fichtner W. Muller S. Westermann M. Moret J.-M. Vuilleumier R. 《Electron Devices, IEEE Transactions on》1991,38(7):1605-1611
2.5-kV thyristor devices have been fabricated with integrated MOS controlled n+-emitter shorts and a bipolar turn-on gate using a p-channel DMOS technology. Square-cell geometries with pitch variations ranging from 15 to 30 μm were implemented in one- and two-dimensional arrays with up to 20000 units. The impact of the cell pitch on the turn-off performance and the on-state voltage was studied for arrays with constant cathode area as well as for single-cell structures. By realizing MOS components with submicrometer channel lengths, scaled single cells are shown to turn off with current densities of several kiloamperes per square centimeter at a gate bias of 5 V. In the case of multi-cell ensembles, turn-off performance is limited due to inhomogeneous current distribution. Critical process parameters as well as the device behavior were optimized through multidimensional numerical simulation 相似文献
13.
Linear and nonlinear methods for brain-computer interfaces 总被引:7,自引:0,他引:7
Muller K.-R. Anderson C.W. Birch G.E. 《IEEE transactions on neural systems and rehabilitation engineering》2003,11(2):165-169
At the recent Second International Meeting on Brain-Computer Interfaces (BCIs) held in June 2002 in Rensselaerville, NY, a formal debate was held on the pros and cons of linear and nonlinear methods in BCI research. Specific examples applying EEG data sets to linear and nonlinear methods are given and an overview of the various pros and cons of each approach is summarized. Overall, it was agreed that simplicity is generally best and, therefore, the use of linear methods is recommended wherever possible. It was also agreed that nonlinear methods in some applications can provide better results, particularly with complex and/or other very large data sets. 相似文献
14.
ED Pisano R McLelland RL Clark K Dicke K Muller 《Canadian Metallurgical Quarterly》1993,28(8):762-766
RATIONAL AND OBJECTIVES: Training in breast imaging is highly variable among radiology programs. The authors have developed a standardized breast imaging curriculum for radiology residents. METHODS: This curriculum has been implemented within the residency program at the University of North Carolina at Chapel Hill. It includes nine standardized components: 1) the clinical activities of the service; 2) the study of breast imaging teaching file films and contribution of new cases; 3) selected readings; 4) formal discussion with faculty on the readings; 5) review of this material using an interactive computer program; 6) formal conferences; 7) technical and quality control activities; 8) research activities; and 9) an evaluation. The participating residents have been surveyed regarding their opinions of their educational experience. RESULTS AND CONCLUSION: The standardized curriculum has been well received by the participating residents. Conclusions about the educational efficacy of such a curriculum cannot be made until more residents have used it. 相似文献
15.
The initial stages of the deposition of nickel on vitreous carbon from aqueous NiCl2 (10–2M adjusted to 1 M in chloride) has been studied using voltammetric and potentiostatic methods. The morphology of the deposits was observed by scanning electron and optical microscopy. A discussion of the relation between the deposition mechanism and the morphology is presented. 相似文献
16.
D. Eckert A. Junod A. Bezinge T. Graf J. Muller 《Journal of Low Temperature Physics》1988,73(3-4):241-254
We have measured the low-temperature specific heat (1.3T20 K) and the dc magnetic susceptibility (100T250 K) of eight samples of the high-T
c
superconductor Y
x
Ba3–x
Cu3O7– (x=0.9, 1.0, 1.1) and of two samples of nonsuperconducting YBa2Cu3O6+. We have also performed specific heat measurements on the possible impurity phases: YBa3Cu2O7, Y2BaCuO5, CuO, and BaCuO2+x
. The superconducting samples all have a nonzero, sample-dependent linear term * and an upturn inC/T at very low temperature. We show that this anomalous behavior is at least partly due to the presence of a small amount (1%) of BaCuO2+x
impurity phase in the measured samples. This is evidenced by the correlation between * and the Curie component of the susceptibility, which is proportional to the amount of paramagnetic impurities. 相似文献
17.
18.
The influence of demineralisation and ammoxidation on the adsorption properties of an activated carbon prepared from a Polish lignite 总被引:1,自引:0,他引:1
Julien Starck Sebastien Muller Guy Furdin Cathie Vix_Guterl Pierre Faure 《Carbon》2006,44(12):2549-2557
The preparation of cheap nitrogen-enriched materials with large adsorptive capacities and selectivity towards volatile organic compounds remains a challenge. Ammoxidation has been used to prepare nitrogen-enriched activated carbons using a demineralised Polish lignite. The lignite samples were demineralised by two different methods before nitrogen-enrichment by ammoxidation and physical activation in steam. The surface chemistry was investigated by elemental analysis, Boehm titration, infrared and XPS spectroscopies and adsorptive properties by a linear solvation energy relationship approach. Results show a quasi-total demineralisation and a higher reactivity towards nitrogen for the demineralised samples. The BET surface is also higher than for the non-demineralised lignite. Active carbons previously ammoxidated and demineralised are more interesting in terms of selective removal of gaseous pollutants. 相似文献
19.
E. Stamatakis C. Chatzichristos A.K. Stubos J. Muller 《Chemical engineering science》2006,61(21):7057-7067
The applicability of a newly developed radiotracer technique as a reliable laboratory procedure for the evaluation of scale inhibitors performance to prevent mineral precipitation is demonstrated. The performance of two new environmentally friendly inhibitors to prevent calcite and barite scale was evaluated experimentally in connection with a standard phosphonate-type scale inhibitor using the radioactive tracer technology. The radiotracers 47Ca and 131Ba were employed in order to monitor at real-time calcite and barite scale formation, respectively. The results show that the developed radiotracer technique can be established as a novel method for the determination of the minimum inhibitor concentration (MIC) under dynamic, reservoir conditions. In addition, the radioactive tritiated water (HTO) was used as a reference water tracer to identify the inhibitors’ properties, such as adsorption/desorption characteristics, in sandpack-flooding tests. Further issues regarding the implementation of the radiotracer technology for the laboratory evaluation of scale inhibitors performance are also discussed. 相似文献
20.
Interactions between the antioxidant Santonox (4,4′-thiobis(6-tert-butyl-m-cresol)) and the LCST polymer blend of polystyrene (PS) and polyvinylmethylether (PVME) were examined. The presence of the antioxidant caused inhomogeneities in blend films cast from toluene solutions at antioxidant compositions greater than 0.25 wt% of the PVME. Also, the cloud-point of the blend decreased linearly with antioxidant content with a slope of 21 °C/wt%. As expected, the ability of the antioxidant to prevent degradation of the PVME within the blend was found to increase with increasing Santonox composition. Based on these results, an antioxidant composition of no more than 0.10 wt% is recommended in the studies of PS/PVME blends. 相似文献