全文获取类型
收费全文 | 3977篇 |
免费 | 98篇 |
国内免费 | 101篇 |
专业分类
电工技术 | 53篇 |
技术理论 | 1篇 |
综合类 | 133篇 |
化学工业 | 1979篇 |
金属工艺 | 340篇 |
机械仪表 | 82篇 |
建筑科学 | 103篇 |
矿业工程 | 113篇 |
能源动力 | 133篇 |
轻工业 | 143篇 |
水利工程 | 12篇 |
石油天然气 | 40篇 |
武器工业 | 7篇 |
无线电 | 115篇 |
一般工业技术 | 553篇 |
冶金工业 | 247篇 |
原子能技术 | 7篇 |
自动化技术 | 115篇 |
出版年
2024年 | 8篇 |
2023年 | 103篇 |
2022年 | 132篇 |
2021年 | 145篇 |
2020年 | 131篇 |
2019年 | 132篇 |
2018年 | 156篇 |
2017年 | 175篇 |
2016年 | 147篇 |
2015年 | 87篇 |
2014年 | 190篇 |
2013年 | 267篇 |
2012年 | 204篇 |
2011年 | 402篇 |
2010年 | 165篇 |
2009年 | 215篇 |
2008年 | 208篇 |
2007年 | 186篇 |
2006年 | 169篇 |
2005年 | 142篇 |
2004年 | 118篇 |
2003年 | 113篇 |
2002年 | 99篇 |
2001年 | 93篇 |
2000年 | 57篇 |
1999年 | 81篇 |
1998年 | 54篇 |
1997年 | 41篇 |
1996年 | 30篇 |
1995年 | 40篇 |
1994年 | 32篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 13篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1976年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有4176条查询结果,搜索用时 15 毫秒
991.
Thomas D. Weddell Yury M. Yarin Markus Drexl Ian J. Russell Stephen J. Elliott Andrei N. Lukashkin 《Journal of the Royal Society Interface》2014,11(93)
The round window (RW) membrane provides pressure relief when the cochlea is excited by sound. Here, we report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Maximum cochlear sensitivity, corresponding to subnanometre magnet displacements at neural thresholds, was observed for frequencies around 20 kHz, which is similar to that for acoustic stimulation. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those owing to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex pressure field, which is generated by the magnetically vibrated RW. Outcomes of research described here are theoretical and practical design principles for the development of new types of hearing aids, which use near-field, RW excitation of the cochlea. 相似文献
992.
993.
994.
This paper investigates densification and grain growth evolutions during gas pressure sintering of alumina. Isothermal sintering runs are performed under different nitrogen pressures: atmospheric pressure and 2 MPa. Experimental data are fitted thanks to constitutive laws in order to understand nitrogen pressure effect on densification and grain growth mechanisms of a fine-grained alumina. An optimal run of densification is proposed as an application of these results. 相似文献
995.
Websites nowadays are an important and popular source of publicly available information. However, due to their exploding scale and complexity, overcoming information overload to find relevant information is a major challenge. In addition to website maps and search engines, self-adaptive websites or websites with intelligent navigation aid are very useful tools in addressing this issue. In this paper, a navigation graph-based recommendation system is proposed, in which the navigation patterns of previous website visitors are utilized to provide recommendations for newcomers. The performance of the proposed recommendation algorithm is tested using the data collected from a real world website. Experimental results reveal that the proposed system can yield satisfactory recommendations, especially to the visitors in their early navigation steps. 相似文献
996.
Polycrystalline BaTi2O5 (BT2) was prepared by solid state sintering in air using BaCO3 and TiO2 as starting materials. A rod-like BT2 sintered bodies in a single phase were obtained above 1025 °C by adding 5 wt.% B2O3. The densification of BT2 sintered bodies decreased with increasing sintering temperature. The maximum permittivity of BT2 sintered body was 640 at the Curie temperature (Tc) of 461 °C and the frequency of 100 kHz. The addition of B2O3 was effective to obtain BT2 in a single phase at low temperatures with elongated microstructure and to improve the permittivity, indicating the formation of preferred orientation at low temperature was related with liquid-phase sintering mechanism. 相似文献
997.
998.
In this study we have prepared three zirconia–ceria compositions, namely 12, 50 and 80 mole% CeO2. Along with each pure ceria–zirconia composition we have prepared two parallel erbia- or europia-doped materials in which 0.5 mole% of each of the two starting oxides is replaced by 1 mole erbia or europia. 相似文献
999.
Indium-tin oxide (ITO) ceramic sputtering targets are widely used in formation of electrically conductive transparent thin films for electrodes in flat panel displays, solar cells, antistatic films and others, and which are commonly produced by a conventional dc magnetron sputtering process. The ceramic targets should be of high purity with a uniform microcrystalline structure and should possess high density and high electrical conductivity. In the present work, the challenges of the ceramic composition (e.g. the ratio of In2O3 and SnO2) and manufacturing are considered; they include the use of high quality starting materials, particularly In2O3 powders with respect to purity, morphology and sinterability, manufacturing routes and sintering process. Positive experience in the development and manufacturing of ITO ceramic planar sputtering targets using in-house prepared In2O3 powders is reported. ITO ceramic tiles with areas up to 1500–1700 cm2 and densities of 99+% of TD are manufactured. Physical properties of the ITO ceramics and sputtered films have been studied. 相似文献
1000.
Paolo Tripodi Daniele Di Gioacchino Jenny Darja Vinko 《Journal of Alloys and Compounds》2009,470(1-2):L6-L8
In this paper, the effect of heating rate on the microwave sintered 90W–7Ni–3Fe heavy alloys was investigated, with the heating rate in the range from 10 to 112 °C/min. When the alloys were sintered at the heating rate from 20 to 105 °C/min, they exhibit excellent properties with the relative density over 99%, tensile strength between 850 and 922 MPa and elongation around 20%. It has been shown that a faster heating rate results in smaller W grain size and larger W–W contiguity. The heating rate of 80 °C/min has the best combination of the microstructure and mechanical performance. Sintering under an optimized condition leads to the enhanced mechanical properties of 1020 MPa in tensile strength and 21% in elongation. 相似文献