全文获取类型
收费全文 | 432573篇 |
免费 | 13983篇 |
国内免费 | 6379篇 |
专业分类
电工技术 | 13012篇 |
技术理论 | 9篇 |
综合类 | 8887篇 |
化学工业 | 68758篇 |
金属工艺 | 27705篇 |
机械仪表 | 20871篇 |
建筑科学 | 14620篇 |
矿业工程 | 7663篇 |
能源动力 | 7930篇 |
轻工业 | 20110篇 |
水利工程 | 7532篇 |
石油天然气 | 20738篇 |
武器工业 | 1073篇 |
无线电 | 39816篇 |
一般工业技术 | 93978篇 |
冶金工业 | 42798篇 |
原子能技术 | 13950篇 |
自动化技术 | 43485篇 |
出版年
2022年 | 6275篇 |
2021年 | 8513篇 |
2020年 | 6486篇 |
2019年 | 6269篇 |
2018年 | 14910篇 |
2017年 | 15761篇 |
2016年 | 13463篇 |
2015年 | 8521篇 |
2014年 | 11828篇 |
2013年 | 17880篇 |
2012年 | 17533篇 |
2011年 | 23197篇 |
2010年 | 20159篇 |
2009年 | 19564篇 |
2008年 | 19911篇 |
2007年 | 20433篇 |
2006年 | 12995篇 |
2005年 | 13242篇 |
2004年 | 11009篇 |
2003年 | 10711篇 |
2002年 | 9910篇 |
2001年 | 8800篇 |
2000年 | 8277篇 |
1999年 | 7170篇 |
1998年 | 9441篇 |
1997年 | 7676篇 |
1996年 | 6124篇 |
1995年 | 5132篇 |
1994年 | 4675篇 |
1993年 | 4561篇 |
1992年 | 4087篇 |
1991年 | 4060篇 |
1990年 | 4096篇 |
1989年 | 3937篇 |
1988年 | 3748篇 |
1987年 | 3681篇 |
1986年 | 3500篇 |
1985年 | 3617篇 |
1984年 | 3516篇 |
1983年 | 3409篇 |
1981年 | 3303篇 |
1980年 | 3336篇 |
1979年 | 3565篇 |
1978年 | 3783篇 |
1977年 | 3772篇 |
1976年 | 4225篇 |
1975年 | 3521篇 |
1974年 | 3591篇 |
1973年 | 3613篇 |
1972年 | 3305篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Measurement Techniques - A comparative analysis of the results of estimation of measurement uncertainty is conducted. The results are obtained by a method described in the Handbook on the... 相似文献
62.
Mobile Networks and Applications - Public cloud system offers Infrastructure-as-a-Service (IaaS) to deliver the computational resources on demand. Resource requirements of a cloud environment are... 相似文献
63.
Thermosetting materials are widely used as encapsulation in the electrical packaging to protect the core electronic components from external force, moisture, dust, and other factors. However, the spreading and curing behaviors of such kind of fluid on a heated surface have been rarely explored. In this study, we experimentally and numerically investigated the spreading and curing behaviors of the silicone(OE6550 A/B, which is widely used in the light-emitting diode packaging) droplet with diameter of ~2.2 mm on a heated surface with temperature ranging from 25 ℃ to 250 ℃. For the experiments, we established a setup with high-speed camera and heating unit to capture the fast spreading process of the silicone droplet on the heated surface. For the numerical simulation, we built a viscosity model of the silicone by using the Kiuna's model and combined the viscosity model with the Volume of Fluid(VOF) model by the User Defined Function(UDF) method. The results show that the surface temperature significantly affected the spreading behaviors of the silicone droplet since it determines the temperature and viscosity distribution inside the droplet. For surface temperature varied from 25 ℃ to 250 ℃, the final contact radius changed from ~2.95 mm to ~1.78 mm and the total spreading time changed from ~511 s to ~0.15 s. By further analyzing the viscosity evolution of the droplet, we found that the decreasing of the total spreading time was caused by the decrease of the viscosity under high surface temperature at initial spreading stage, while the reduction of the final contact radius was caused by the curing of the precursor film. This study supplies a strategy to tuning the spreading and curing behavior of silicone by imposing high surface temperature, which is of great importance to the electronic packaging. 相似文献
64.
Kozhitov L. V. Kiselev B. G. Raykova T. B. Popkova A. V. Kostishin V. G. Muratov D. G. Yakushko E. V. Kosushkin V. G. Bebenin V. G. 《Russian Microelectronics》2019,48(8):599-612
Russian Microelectronics - The recently developed nanomaterials and their production technologies as intellectual property objects (IPOs) are considered. The role of the informational-analytical... 相似文献
65.
Breslavs’kyi D. V. Metel’yov V. O. Morachkovs’kyi O. K. Tatarinova O. A. 《Strength of Materials》2019,51(5):753-760
Strength of Materials - Creep constitutive equations have been derived for the materials that exhibit the properties of orthotropy (transversal isotropy) and transient creep under cyclic loading. A... 相似文献
66.
Kazantsev Yu. N. Kraftmakher G. A. Mal’tsev V. P. 《Journal of Communications Technology and Electronics》2019,64(6):550-554
Journal of Communications Technology and Electronics - Approximate formulas for calculating the coefficient of reflection from an artificial magnetic conductor (AMC) based on a capacitive lattice... 相似文献
67.
Zakharov A. V. Rozenko S. A. 《Journal of Communications Technology and Electronics》2019,64(4):430-438
Journal of Communications Technology and Electronics - Microstrip band-pass filters (BPFs) containing quarter-wavelength resonators and a Π-shaped half-wavelength resonator placed next to each... 相似文献
68.
Geetha R. Madhusudhan V. Padmavathy T. Lallithasree A. 《Wireless Personal Communications》2019,108(3):1957-1976
Wireless Personal Communications - The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the... 相似文献
69.
Journal of Computer and Systems Sciences International - The problem of constructing a guaranteeing anticipating control for a shock isolator that protects an object on a movable base from impacts... 相似文献
70.
High Temperature - Experimental findings suggest that a strongly ionized, arc He plasma of atmospheric pressure does not exist in the state of the local thermodynamic equilibrium (LTE) expected for... 相似文献