全文获取类型
收费全文 | 179769篇 |
免费 | 19213篇 |
国内免费 | 11357篇 |
专业分类
电工技术 | 15091篇 |
技术理论 | 4篇 |
综合类 | 15163篇 |
化学工业 | 24996篇 |
金属工艺 | 11004篇 |
机械仪表 | 12205篇 |
建筑科学 | 15191篇 |
矿业工程 | 5976篇 |
能源动力 | 5440篇 |
轻工业 | 13703篇 |
水利工程 | 4494篇 |
石油天然气 | 8741篇 |
武器工业 | 2168篇 |
无线电 | 21968篇 |
一般工业技术 | 18126篇 |
冶金工业 | 7232篇 |
原子能技术 | 2039篇 |
自动化技术 | 26798篇 |
出版年
2024年 | 887篇 |
2023年 | 2928篇 |
2022年 | 5891篇 |
2021年 | 8058篇 |
2020年 | 6068篇 |
2019年 | 4715篇 |
2018年 | 5243篇 |
2017年 | 6256篇 |
2016年 | 5417篇 |
2015年 | 8138篇 |
2014年 | 10193篇 |
2013年 | 11978篇 |
2012年 | 14005篇 |
2011年 | 14627篇 |
2010年 | 13604篇 |
2009年 | 12780篇 |
2008年 | 12631篇 |
2007年 | 11957篇 |
2006年 | 10905篇 |
2005年 | 8555篇 |
2004年 | 5979篇 |
2003年 | 5002篇 |
2002年 | 4899篇 |
2001年 | 4365篇 |
2000年 | 3404篇 |
1999年 | 2688篇 |
1998年 | 1716篇 |
1997年 | 1441篇 |
1996年 | 1327篇 |
1995年 | 1134篇 |
1994年 | 920篇 |
1993年 | 586篇 |
1992年 | 456篇 |
1991年 | 329篇 |
1990年 | 266篇 |
1989年 | 229篇 |
1988年 | 164篇 |
1987年 | 106篇 |
1986年 | 99篇 |
1985年 | 44篇 |
1984年 | 40篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 42篇 |
1980年 | 43篇 |
1979年 | 28篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1959年 | 10篇 |
1951年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Wei Shaowei Yu Guoxian Wang Jun Domeniconi Carlotta Zhang Xiangliang 《Machine Learning》2021,110(6):1505-1526
Machine Learning - Traditional clustering algorithms focus on a single clustering result; as such, they cannot explore potential diverse patterns of complex real world data. To deal with this... 相似文献
32.
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
33.
To overcome the drawbacks of solid microporous materials for CO2 capture, this proof‐of‐concept study demonstrates a low‐cost and rapid method for producing composites consisting of hypercrosslinked polymers (HCP) with a polyethyleneimine (PEI) binder. The resulting materials capture CO2 through physical and chemical absorption simultaneously. Compared with HCP, the composites exhibit higher CO2 uptake, higher volumetric density, and improved tolerance to water which is attributed to the PEI binder. 相似文献
34.
Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration. 相似文献
35.
36.
Qi Yang Qilong Wu Yang Liu Shuiping Luo Xiaotong Wu Xixia Zhao Haiyuan Zou Baihua Long Wen Chen Yujia Liao Lanxi Li Pei Kang Shen Lele Duan Zewei Quan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(36):2002822
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO. 相似文献
37.
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
38.
39.
40.
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