全文获取类型
收费全文 | 299450篇 |
免费 | 4335篇 |
国内免费 | 999篇 |
专业分类
电工技术 | 5642篇 |
综合类 | 960篇 |
化学工业 | 41537篇 |
金属工艺 | 10808篇 |
机械仪表 | 9359篇 |
建筑科学 | 6909篇 |
矿业工程 | 1456篇 |
能源动力 | 6785篇 |
轻工业 | 24789篇 |
水利工程 | 3129篇 |
石油天然气 | 3957篇 |
武器工业 | 73篇 |
无线电 | 36455篇 |
一般工业技术 | 53246篇 |
冶金工业 | 65612篇 |
原子能技术 | 5592篇 |
自动化技术 | 28475篇 |
出版年
2021年 | 2143篇 |
2019年 | 2084篇 |
2018年 | 3925篇 |
2017年 | 4199篇 |
2016年 | 4752篇 |
2015年 | 3088篇 |
2014年 | 4466篇 |
2013年 | 11684篇 |
2012年 | 8547篇 |
2011年 | 11161篇 |
2010年 | 7614篇 |
2009年 | 8583篇 |
2008年 | 9251篇 |
2007年 | 9189篇 |
2006年 | 8342篇 |
2005年 | 10374篇 |
2004年 | 9380篇 |
2003年 | 8741篇 |
2002年 | 7193篇 |
2001年 | 7199篇 |
2000年 | 6443篇 |
1999年 | 6806篇 |
1998年 | 19652篇 |
1997年 | 13655篇 |
1996年 | 10317篇 |
1995年 | 7700篇 |
1994年 | 6668篇 |
1993年 | 6548篇 |
1992年 | 4758篇 |
1991年 | 4464篇 |
1990年 | 4304篇 |
1989年 | 4016篇 |
1988年 | 3873篇 |
1987年 | 3359篇 |
1986年 | 3235篇 |
1985年 | 3753篇 |
1984年 | 3442篇 |
1983年 | 3099篇 |
1982年 | 2964篇 |
1981年 | 3107篇 |
1980年 | 2934篇 |
1979年 | 2698篇 |
1978年 | 2583篇 |
1977年 | 3514篇 |
1976年 | 4781篇 |
1975年 | 2400篇 |
1974年 | 2348篇 |
1973年 | 2355篇 |
1972年 | 1888篇 |
1971年 | 1793篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
21.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
22.
23.
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
24.
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
25.
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
26.
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
27.
28.
Hypoxia formation and breakdown were tracked during 2015 in Muskegon Lake estuary at multiple locations, and five years (2011–2015) of time-series buoy observatory data were evaluated for the effect of episodic wind-events on lake mixing. Bi-weekly water temperature and dissolved oxygen (DO) profiles at four locations revealed that hypoxia occurred at all sites and persisted for 2–3 months during summer 2015. On one date in late-summer, up to 24% of the lake’s volume was estimated to be mildly hypoxic (DO < 4 mg L?1) as defined by lake sturgeon requirements. Patterns of wind speed and water column stability in late spring indicated that high winds and low stability delayed the onset of hypoxia while in late summer low winds and high stability delayed degradation of hypoxia. Wind speeds appear to play a great role in the interannual variability of stratification and subsequent hypoxia. Water temperature and DO profiles taken before and after one mid-summer mixing event (wind speed >7.7 m s?1 for 10 h), indicated that while the wind was unable to completely mix the entire water column, it deepened the epilimnion by ~1.5 m and sheared a thin layer from the upper hypolimnion. By entraining internally loaded nutrients, such episodic wind-events may initiate and sustain algal blooms in nutrient limited surface waters. Quantifying the variable role of wind and mixing events will be key to integrating limnological processes into climate models of the future. 相似文献
29.
C. G. Prosgolitis S. G. Lambrakos A. D. Zervaki 《Journal of Materials Engineering and Performance》2018,27(10):5102-5113
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size. 相似文献
30.
Buryakov A. M. Khusyainov D. I. Mishina E. D. Khabibullin R. A. Yachmenev A. E. Ponomarev D. S. 《Technical Physics Letters》2018,44(12):1115-1119
Technical Physics Letters - The influence of excitation photons energy on the relaxation times of photoexcited carriers is studied. The involved relaxation mechanisms are evaluated and the... 相似文献