全文获取类型
收费全文 | 569171篇 |
免费 | 6804篇 |
国内免费 | 1005篇 |
专业分类
电工技术 | 10528篇 |
综合类 | 469篇 |
化学工业 | 90684篇 |
金属工艺 | 23372篇 |
机械仪表 | 18522篇 |
建筑科学 | 12681篇 |
矿业工程 | 4318篇 |
能源动力 | 14496篇 |
轻工业 | 46281篇 |
水利工程 | 6957篇 |
石油天然气 | 15001篇 |
武器工业 | 39篇 |
无线电 | 60411篇 |
一般工业技术 | 116628篇 |
冶金工业 | 96194篇 |
原子能技术 | 14691篇 |
自动化技术 | 45708篇 |
出版年
2021年 | 5559篇 |
2020年 | 4051篇 |
2019年 | 5303篇 |
2018年 | 9262篇 |
2017年 | 9459篇 |
2016年 | 9897篇 |
2015年 | 6067篇 |
2014年 | 10317篇 |
2013年 | 26288篇 |
2012年 | 15938篇 |
2011年 | 21254篇 |
2010年 | 17122篇 |
2009年 | 18967篇 |
2008年 | 19215篇 |
2007年 | 18917篇 |
2006年 | 16392篇 |
2005年 | 14867篇 |
2004年 | 14102篇 |
2003年 | 13785篇 |
2002年 | 13328篇 |
2001年 | 12902篇 |
2000年 | 12364篇 |
1999年 | 12061篇 |
1998年 | 27715篇 |
1997年 | 20111篇 |
1996年 | 15689篇 |
1995年 | 12047篇 |
1994年 | 10896篇 |
1993年 | 10641篇 |
1992年 | 8365篇 |
1991年 | 8124篇 |
1990年 | 8021篇 |
1989年 | 7789篇 |
1988年 | 7495篇 |
1987年 | 6769篇 |
1986年 | 6555篇 |
1985年 | 7412篇 |
1984年 | 6724篇 |
1983年 | 6454篇 |
1982年 | 5793篇 |
1981年 | 5903篇 |
1980年 | 5640篇 |
1979年 | 5744篇 |
1978年 | 5675篇 |
1977年 | 6194篇 |
1976年 | 7702篇 |
1975年 | 5125篇 |
1974年 | 4908篇 |
1973年 | 4992篇 |
1972年 | 4286篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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
72.
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
73.
74.
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
75.
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
76.
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
77.
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
78.
Dreissenid mussel veligers compose a substantial component of pelagic biomass in the Great Lakes, yet their dynamics are poorly understood. To evaluate seasonal, spatial, and inter-annual variation in veliger density, we used a 64-μm mesh plankton net (2008, 2013–2016) and a 153-μm mesh plankton net (2007–2016) to collect dreissenid veligers at nearshore (15–25?m depth), transitional (45?m) and offshore (93–110?m) sites in southeast Lake Michigan during March–December. We also evaluated trends in density of recently settled mussels relative to veliger abundance and the density of the standing stock of adult mussels. Veliger density peaked during both summer and fall at all sites, but peak densities in summer were generally higher nearshore, whereas peak densities in the fall were generally higher offshore. The density of veligers in the 153-μm net was overall 28% of that in the 64-μm net, but there was high variability in this comparison among months. Smaller veligers were much more abundant in the 64-μm net, but there was little difference in the size distribution and abundance between nets for the 210–300?μm size classes. Thus, the 153-μm net could still be a useful tool for assessing density trends of larger veligers just prior to their settlement. Newly settled mussels (≤2?mm) were most abundant in summer or fall at the nearshore and offshore sites but were nearly absent at the transitional site despite the high density of veligers there. Factors other than veliger density must play an important role in mussel recruitment. 相似文献
79.
Byakova O. V. Stepanov G. V. Vlasov A. O. Danylyuk V. E. Semenov N. V. Berezovs’kyi O. M. Gnyloskurenko S. V. 《Strength of Materials》2019,51(5):726-734
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to... 相似文献
80.
Measurement Techniques - The article is devoted to the issues of conceptual development of a new generation of electrocardiogram imitators. A mathematical model is proposed for simulating ECG... 相似文献