全文获取类型
收费全文 | 241573篇 |
免费 | 22570篇 |
国内免费 | 18112篇 |
专业分类
电工技术 | 19296篇 |
技术理论 | 7篇 |
综合类 | 22953篇 |
化学工业 | 32391篇 |
金属工艺 | 18036篇 |
机械仪表 | 15979篇 |
建筑科学 | 18824篇 |
矿业工程 | 7995篇 |
能源动力 | 6937篇 |
轻工业 | 17899篇 |
水利工程 | 5984篇 |
石油天然气 | 13670篇 |
武器工业 | 2634篇 |
无线电 | 28299篇 |
一般工业技术 | 23501篇 |
冶金工业 | 9763篇 |
原子能技术 | 3901篇 |
自动化技术 | 34186篇 |
出版年
2024年 | 1017篇 |
2023年 | 3341篇 |
2022年 | 6604篇 |
2021年 | 9117篇 |
2020年 | 6892篇 |
2019年 | 5451篇 |
2018年 | 6039篇 |
2017年 | 7168篇 |
2016年 | 6283篇 |
2015年 | 9260篇 |
2014年 | 11873篇 |
2013年 | 14001篇 |
2012年 | 16248篇 |
2011年 | 20069篇 |
2010年 | 17058篇 |
2009年 | 15268篇 |
2008年 | 15184篇 |
2007年 | 14126篇 |
2006年 | 13202篇 |
2005年 | 10876篇 |
2004年 | 11196篇 |
2003年 | 9133篇 |
2002年 | 9698篇 |
2001年 | 7936篇 |
2000年 | 5498篇 |
1999年 | 5317篇 |
1998年 | 3482篇 |
1997年 | 3096篇 |
1996年 | 2296篇 |
1995年 | 2007篇 |
1994年 | 1651篇 |
1993年 | 2739篇 |
1992年 | 2203篇 |
1991年 | 1583篇 |
1990年 | 1433篇 |
1989年 | 1126篇 |
1988年 | 731篇 |
1987年 | 443篇 |
1986年 | 333篇 |
1985年 | 181篇 |
1984年 | 128篇 |
1983年 | 84篇 |
1982年 | 88篇 |
1981年 | 83篇 |
1980年 | 137篇 |
1979年 | 98篇 |
1977年 | 34篇 |
1965年 | 60篇 |
1959年 | 44篇 |
1957年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach. 相似文献
2.
文章主要研究用水浸法提取落葵浆果天然染料及研究浸提液对羊毛织物的染色性能。以水为提取剂提取落葵浆果天然染料,探讨提取工艺中料液比、提取温度及时间等因素对落葵浆果天然染料提取效果的影响。研究结果表明,落葵浆果水浸提法优化工艺为:料液比1∶20、提取温度70℃、提取时间30 min。落葵浆果天然染料可以对羊毛织物进行染色,媒染染色与直接染色相比,染色深度深且会呈现不同的颜色。由于媒染剂的络合作用,媒染染色色牢度比直接染色普遍高1~2级。 相似文献
3.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
4.
5.
6.
The fracture behaviour and morphologies of high-strength boron steel were investigated at different temperatures at a constant strain rate of 0.1 s-1 based on isothermal tensile tests. Fracture mechanisms were also analyzed based on the relationship between microstructure transformation and continuous cooling transformation(CCT) curves. It is found that 1) fractures of the investigated steel at high temperatures are dimple fractures; 2) the deformation of high-strength boron steel at high temperatures accelerates diffusion transformations; thus, to obtain full martensite, a higher cooling rate is needed; and 3) the investigated steel has the best plasticity when the deformation temperature is 750 °C. 相似文献
7.
A contact layer element for large deformations 总被引:1,自引:0,他引:1
8.
9.
Rapid synthesis of silver nanowires(Ag NWs) with high quality and a broad processing window is challenging because of the low selectivity of the formation of multiply twinned particles at the nucleation stage for subsequent Ag NWs growth.Herein we report a systematic study of the water-involved heterogeneous nucleation of Ag NWs with high rate(less than 20 min) in a simple and scalable preparation method.Using glycerol as a reducing agent and a solvent with a high boiling point,the reaction is rapidly heated to 210 ℃ in air to synthesize Ag NWs with a very high yield in gram level.It is noted that the addition of a small dose of water plays a key role for obtaining highly pure Ag NWs in high yield,and the optimal water/glycerol ratio is0.25%.After investigating a series of forming factors including reaction temperature and dose of catalysts,the formation kinetics and mechanism of the Ag NWs are proposed.Compared to other preparation methods,our strategy is simple and reproducible.These Ag NWs show a strong Raman enhancement effect for organic molecules on their surface. 相似文献
10.