全文获取类型
收费全文 | 306566篇 |
免费 | 19109篇 |
国内免费 | 9505篇 |
专业分类
电工技术 | 13173篇 |
技术理论 | 24篇 |
综合类 | 16028篇 |
化学工业 | 49430篇 |
金属工艺 | 17557篇 |
机械仪表 | 17290篇 |
建筑科学 | 19652篇 |
矿业工程 | 8003篇 |
能源动力 | 7446篇 |
轻工业 | 16887篇 |
水利工程 | 4802篇 |
石油天然气 | 16904篇 |
武器工业 | 1648篇 |
无线电 | 33766篇 |
一般工业技术 | 42523篇 |
冶金工业 | 15298篇 |
原子能技术 | 2482篇 |
自动化技术 | 52267篇 |
出版年
2024年 | 994篇 |
2023年 | 3804篇 |
2022年 | 6482篇 |
2021年 | 9053篇 |
2020年 | 7083篇 |
2019年 | 6016篇 |
2018年 | 20077篇 |
2017年 | 19913篇 |
2016年 | 15968篇 |
2015年 | 9423篇 |
2014年 | 11471篇 |
2013年 | 13465篇 |
2012年 | 17184篇 |
2011年 | 24325篇 |
2010年 | 21279篇 |
2009年 | 17879篇 |
2008年 | 18771篇 |
2007年 | 19285篇 |
2006年 | 12450篇 |
2005年 | 11901篇 |
2004年 | 8319篇 |
2003年 | 7336篇 |
2002年 | 5982篇 |
2001年 | 4977篇 |
2000年 | 5603篇 |
1999年 | 6495篇 |
1998年 | 5482篇 |
1997年 | 4477篇 |
1996年 | 4230篇 |
1995年 | 3506篇 |
1994年 | 2823篇 |
1993年 | 1973篇 |
1992年 | 1548篇 |
1991年 | 1249篇 |
1990年 | 933篇 |
1989年 | 740篇 |
1988年 | 546篇 |
1987年 | 336篇 |
1986年 | 278篇 |
1985年 | 196篇 |
1984年 | 139篇 |
1983年 | 114篇 |
1982年 | 124篇 |
1981年 | 98篇 |
1980年 | 70篇 |
1968年 | 47篇 |
1966年 | 43篇 |
1965年 | 48篇 |
1955年 | 64篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
Neural Machine Translation (NMT) is an end-to-end learning approach for
automated translation, overcoming the weaknesses of conventional phrase-based translation
systems. Although NMT based systems have gained their popularity in commercial
translation applications, there is still plenty of room for improvement. Being the most
popular search algorithm in NMT, beam search is vital to the translation result. However,
traditional beam search can produce duplicate or missing translation due to its target
sequence selection strategy. Aiming to alleviate this problem, this paper proposed neural
machine translation improvements based on a novel beam search evaluation function. And
we use reinforcement learning to train a translation evaluation system to select better
candidate words for generating translations. In the experiments, we conducted extensive
experiments to evaluate our methods. CASIA corpus and the 1,000,000 pairs of bilingual
corpora of NiuTrans are used in our experiments. The experiment results prove that the
proposed methods can effectively improve the English to Chinese translation quality. 相似文献
193.
Shuang Shao Yong Liu Chun-Shui Xu Ying-Xuan Xu Bin Wu Xiao-Shu Zeng Xian-Feng Lu Xiang-Jie Yang 《金属学报(英文版)》2015,(1):7-14
The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y(wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing(SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates(Rc) from 10.2 to 23 K/s, which can be predicted using a empirical model of SDAS=68 R 0:45:45cand SDAS=73 R 0c, respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction(Vf) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory. 相似文献
194.
195.
Hong Wei Li Li Ya‐Li Ma Ru‐Xue Liu Shuang‐Yan Meng Li‐Tong Niu Zhe Zhang Zhi‐Wang Yang 《火与材料》2019,43(7):868-879
Through the simple precipitation of palygorskite (PGS) by zinc borate (ZB) (to make PGS@ZB) and the decoration of PGS@ZB by dodecylamine (N), a novel organic‐inorganic@inorganic hybrid flame retardant of PGS@ZB‐N was prepared and was incorporated with ethylene vinyl acetate copolymer (EVA) to improve its flame retardance. The structure and morphology of PGS@ZB‐N were characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM), and it was confirmed that the PGS@ZB‐N hybrid had been successfully prepared. The flame retardancy and burning behavior of EVA/PGS@ZB‐N/EG (EG = expandable graphite) composite were studied through thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL‐94 (by the vertical burning test), and cone calorimeter test (CCT) characterizations. The prepared EVA/PGS@ZB‐N/EG composite obtained an LOI value of 41.2% with the addition of 30 wt% PGS@ZB‐N/EG. It was found that EVA/PGS@ZB‐N/EG was protected through a gas phase and condensed phase alternating synergistic effect mechanism. 相似文献
196.
197.
198.
Multimedia Tools and Applications - Understanding human emotions through facial expressions is key enabling technology for interactive robots. Most approaches of facial expression recognition are... 相似文献
199.
Wan Huan Wang Hui Scotney Bryan Liu Jun Ng Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is... 相似文献
200.
Pavel Strunz Debashis Mukherji Přemysl Beran Ralph Gilles Lukas Karge Michael Hofmann Markus Hoelzel Joachim Rösler Gergely Farkas 《Metals and Materials International》2018,24(5):934-944
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献