全文获取类型
收费全文 | 86484篇 |
免费 | 4912篇 |
国内免费 | 2187篇 |
专业分类
电工技术 | 3005篇 |
技术理论 | 2篇 |
综合类 | 3120篇 |
化学工业 | 12140篇 |
金属工艺 | 3177篇 |
机械仪表 | 3770篇 |
建筑科学 | 3839篇 |
矿业工程 | 1686篇 |
能源动力 | 1674篇 |
轻工业 | 4881篇 |
水利工程 | 1249篇 |
石油天然气 | 2526篇 |
武器工业 | 341篇 |
无线电 | 7200篇 |
一般工业技术 | 9272篇 |
冶金工业 | 23847篇 |
原子能技术 | 673篇 |
自动化技术 | 11181篇 |
出版年
2024年 | 299篇 |
2023年 | 1058篇 |
2022年 | 1623篇 |
2021年 | 2263篇 |
2020年 | 1583篇 |
2019年 | 1503篇 |
2018年 | 1954篇 |
2017年 | 2212篇 |
2016年 | 2484篇 |
2015年 | 2666篇 |
2014年 | 2672篇 |
2013年 | 3089篇 |
2012年 | 4895篇 |
2011年 | 5563篇 |
2010年 | 3135篇 |
2009年 | 3183篇 |
2008年 | 3042篇 |
2007年 | 2799篇 |
2006年 | 2844篇 |
2005年 | 5145篇 |
2004年 | 3863篇 |
2003年 | 3209篇 |
2002年 | 1954篇 |
2001年 | 1707篇 |
2000年 | 1219篇 |
1999年 | 1608篇 |
1998年 | 6971篇 |
1997年 | 4510篇 |
1996年 | 3125篇 |
1995年 | 1971篇 |
1994年 | 1471篇 |
1993年 | 1371篇 |
1992年 | 470篇 |
1991年 | 506篇 |
1990年 | 470篇 |
1989年 | 428篇 |
1988年 | 391篇 |
1987年 | 307篇 |
1986年 | 254篇 |
1985年 | 217篇 |
1984年 | 105篇 |
1983年 | 117篇 |
1982年 | 156篇 |
1981年 | 198篇 |
1980年 | 216篇 |
1979年 | 76篇 |
1978年 | 112篇 |
1977年 | 615篇 |
1976年 | 1337篇 |
1975年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Klimis?S.?NtalianisEmail author Anastasios?D.?Doulamis Nikolaos?D.?Doulamis Nikos?E.?Mastorakis Athanasios?S.?Drigas 《Journal of Signal Processing Systems》2015,80(2):153-161
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation. 相似文献
2.
Peer-to-Peer Networking and Applications - 相似文献
3.
4.
Klaus Reinhardt Hans Georg Breunig Aisada Uchugonova Karsten K?nig 《Journal of the Royal Society Interface》2015,12(110)
We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius, was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τm = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τm = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype. 相似文献
5.
6.
7.
8.
9.
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
10.
From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank (PST), fully aerobic or N removal activated sludge (AS) and anaerobic and aerobic sludge digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through primary sludge anaerobic digestion, activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant (WWTP) unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organisms (OHO) biomass contributes to the ISS flux by differing amounts depending on the active fraction of the VSS solids at that stage. 相似文献