全文获取类型
收费全文 | 121216篇 |
免费 | 9636篇 |
国内免费 | 4006篇 |
专业分类
电工技术 | 5049篇 |
技术理论 | 8篇 |
综合类 | 5408篇 |
化学工业 | 21617篇 |
金属工艺 | 6378篇 |
机械仪表 | 7865篇 |
建筑科学 | 6658篇 |
矿业工程 | 2316篇 |
能源动力 | 4276篇 |
轻工业 | 9106篇 |
水利工程 | 1716篇 |
石油天然气 | 4312篇 |
武器工业 | 732篇 |
无线电 | 16280篇 |
一般工业技术 | 19048篇 |
冶金工业 | 7122篇 |
原子能技术 | 1661篇 |
自动化技术 | 15306篇 |
出版年
2024年 | 303篇 |
2023年 | 1708篇 |
2022年 | 2468篇 |
2021年 | 4536篇 |
2020年 | 3437篇 |
2019年 | 3098篇 |
2018年 | 3618篇 |
2017年 | 3868篇 |
2016年 | 4014篇 |
2015年 | 4287篇 |
2014年 | 5900篇 |
2013年 | 7710篇 |
2012年 | 8266篇 |
2011年 | 9097篇 |
2010年 | 7520篇 |
2009年 | 7401篇 |
2008年 | 7210篇 |
2007年 | 6465篇 |
2006年 | 6044篇 |
2005年 | 5089篇 |
2004年 | 4032篇 |
2003年 | 3735篇 |
2002年 | 3653篇 |
2001年 | 3173篇 |
2000年 | 2660篇 |
1999年 | 2420篇 |
1998年 | 2713篇 |
1997年 | 1969篇 |
1996年 | 1723篇 |
1995年 | 1263篇 |
1994年 | 1045篇 |
1993年 | 800篇 |
1992年 | 628篇 |
1991年 | 515篇 |
1990年 | 456篇 |
1989年 | 414篇 |
1988年 | 328篇 |
1987年 | 242篇 |
1986年 | 181篇 |
1985年 | 156篇 |
1984年 | 127篇 |
1983年 | 94篇 |
1982年 | 66篇 |
1981年 | 57篇 |
1980年 | 42篇 |
1979年 | 41篇 |
1978年 | 33篇 |
1977年 | 43篇 |
1976年 | 68篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
53.
54.
55.
56.
Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior... 相似文献
57.
Microsystem Technologies - A color-laser printing system consisting of a tandem laser scanning unit uses four laser diodes and a single polygonal mirror (PM) to expose light onto four... 相似文献
58.
Yong Xu Yun Li Songlin Li Francis Balestra Gerard Ghibaudo Wenwu Li Yen‐Fu Lin Huabin Sun Jing Wan Xinran Wang Yufeng Guo Yi Shi Yong‐Young Noh 《Advanced functional materials》2020,30(20)
Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research. 相似文献
59.
Bing Yang Yu Zhou Wenjie Yu Song Zhang Hongxiang Chen Ju Ye 《Polymer International》2019,68(4):675-683
In order to improve the dispersity and stability of the nano‐SiO2 aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590‐PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3‐mercaptopropyl)trimethoxysilane (KH590). After adding KH590‐PAA into the nano‐SiO2 aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured with a rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590‐PAA for the nano‐SiO2 aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of the nanoparticles with a conductivity meter, dynamic light scattering, SEM and TEM, respectively. The results showed that the methoxysilicon groups in KH590‐PAA could react with hydroxyl groups on the surface of nano‐SiO2 in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between the SiO2 nanoparticles could be further enhanced by adding the KH590‐PAA dispersant, and then the nano‐SiO2 aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO2 nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590‐PAA dispersant. © 2018 Society of Chemical Industry 相似文献
60.