全文获取类型
收费全文 | 3066篇 |
免费 | 113篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 66篇 |
综合类 | 2篇 |
化学工业 | 662篇 |
金属工艺 | 104篇 |
机械仪表 | 80篇 |
建筑科学 | 43篇 |
矿业工程 | 4篇 |
能源动力 | 115篇 |
轻工业 | 146篇 |
水利工程 | 27篇 |
石油天然气 | 30篇 |
无线电 | 318篇 |
一般工业技术 | 676篇 |
冶金工业 | 498篇 |
原子能技术 | 38篇 |
自动化技术 | 393篇 |
出版年
2024年 | 10篇 |
2023年 | 45篇 |
2022年 | 64篇 |
2021年 | 89篇 |
2020年 | 103篇 |
2019年 | 73篇 |
2018年 | 89篇 |
2017年 | 106篇 |
2016年 | 97篇 |
2015年 | 71篇 |
2014年 | 104篇 |
2013年 | 246篇 |
2012年 | 109篇 |
2011年 | 160篇 |
2010年 | 134篇 |
2009年 | 128篇 |
2008年 | 134篇 |
2007年 | 131篇 |
2006年 | 100篇 |
2005年 | 69篇 |
2004年 | 65篇 |
2003年 | 57篇 |
2002年 | 59篇 |
2001年 | 45篇 |
2000年 | 48篇 |
1999年 | 44篇 |
1998年 | 110篇 |
1997年 | 83篇 |
1996年 | 55篇 |
1995年 | 60篇 |
1994年 | 68篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 26篇 |
1990年 | 32篇 |
1989年 | 23篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 27篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 29篇 |
1975年 | 13篇 |
排序方式: 共有3202条查询结果,搜索用时 0 毫秒
31.
32.
Wei Huang Ghosh S. Velusamy S. Sankaranarayanan K. Skadron K. Stan M.R. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2006,14(5):501-513
This paper presents HotSpot-a modeling methodology for developing compact thermal models based on the popular stacked-layer packaging scheme in modern very large-scale integration systems. In addition to modeling silicon and packaging layers, HotSpot includes a high-level on-chip interconnect self-heating power and thermal model such that the thermal impacts on interconnects can also be considered during early design stages. The HotSpot compact thermal modeling approach is especially well suited for preregister transfer level (RTL) and presynthesis thermal analysis and is able to provide detailed static and transient temperature information across the die and the package, as it is also computationally efficient. 相似文献
33.
Shiqiang Hui Justin RollerSing Yick Xinge ZhangCyrille Decès-Petit Yongsong XieRadenka Maric Dave Ghosh 《Journal of power sources》2007
The advantages of lowering the operation temperature of SOFCs have attracted great interest worldwide. One of the major barriers to decreasing the operation temperature is the ohmic loss of the electrolyte. Maximizing the electrolyte ionic conductivity is of significant importance, especially in the absence of new electrolyte materials. The ionic conductivity of electrolytes can be influenced by many parameters. There has been an enormous effort in the literature for the improvement of the electrolyte ionic conductivity. From a practical point of view, this paper reviews various approaches to enhancing the ionic conductivity of polycrystalline zirconia- and ceria-based oxide electrolytes in the light of composition, microstructure, and processing. Suggestions are given for future work. 相似文献
34.
Wide band gap a-SiOx:H films have been prepared by the photochemical decomposition of a SiH4, CO2 and H2 gas mixture. Deposition parameters namely the CO2 to SiH4 gas flow ratio, H2 dilution and chamber pressure were optimized in order to achieve highly photoconducting (1 × 10-6 S cm-1) films with an optical gap of 1.99 eV. The optical gap was found to increase with an increase in the CO2 to SiH4 flow ratio. A decrease in the photoconductivity, refractive index, spin g-value and a simultaneous increase in the spin density are attributed to an incorporation of oxygen into the films. Upon hydrogen
dilution the photoconductivity of a-SiOx:H films was observed to improve along with an increase of the optical gap. The spin density of a-SiOx:H films was of the order of 1017 cm-9. The optoelectronic properties of the films have been correlated with the bonding configurations in the film, deposition
parameters and the growth kinetics.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
35.
36.
Pulse-current MIG welding of Al-Zn-Mg alloy was carried out using an extruded section of base material and Al-Mg (5183) filler wire. During welding the pulse parameters such as the mean current and pulse frequency were varied and their effect on the geometry and porosity content of weld deposit as well as the fatigue life of the weldment was studied. The pulse parameters were found to affect significantly the geometry and porosity content of weld deposit and consequently the fatigue life of the weldment. For a comparative study, weldments were also prepared by using conventional continuous current MIG-welding process, where welding currents equivalent to the mean currents of pulsed process were used. The fatigue life of the weldment was correlated with the geometry and porosity content of weld deposit. 相似文献
37.
BR Crane AS Arvai DK Ghosh C Wu ED Getzoff DJ Stuehr JA Tainer 《Canadian Metallurgical Quarterly》1998,279(5359):2121-2126
Crystal structures of the murine cytokine-inducible nitric oxide synthase oxygenase dimer with active-center water molecules, the substrate L-arginine (L-Arg), or product analog thiocitrulline reveal how dimerization, cofactor tetrahydrobiopterin, and L-Arg binding complete the catalytic center for synthesis of the essential biological signal and cytotoxin nitric oxide. Pterin binding refolds the central interface region, recruits new structural elements, creates a 30 angstrom deep active-center channel, and causes a 35 degrees helical tilt to expose a heme edge and the adjacent residue tryptophan-366 for likely reductase domain interactions and caveolin inhibition. Heme propionate interactions with pterin and L-Arg suggest that pterin has electronic influences on heme-bound oxygen. L-Arginine binds to glutamic acid-371 and stacks with heme in an otherwise hydrophobic pocket to aid activation of heme-bound oxygen by direct proton donation and thereby differentiate the two chemical steps of nitric oxide synthesis. 相似文献
38.
39.
40.
The solution to increasing traffic congestion is not to simply build new roads. Instead, researchers hope to use technology to make more efficient use of the highway network that already exists. Key efforts to date have fallen into two categories. One set of studies has looked at the use of a centralized traffic management center that collects traffic congestion information at a single point and relays it to on-board computers in vehicles or directly to the drivers. Another set of studies has looked at systems that would prescribe the routes for vehicles. The authors describe their Dicaf (distributed scalable architecture for IVHS using a continuous-function congestion measure) system, which envisions a network of distributed, independent traffic management centers that provide congestion and other information to on-board navigation systems in the automobiles themselves. The navigation system uses that information to help drivers avoid slower traffic and thus find the fastest route home or anywhere 相似文献