全文获取类型
收费全文 | 775031篇 |
免费 | 63823篇 |
国内免费 | 35135篇 |
专业分类
电工技术 | 48961篇 |
技术理论 | 78篇 |
综合类 | 53105篇 |
化学工业 | 122942篇 |
金属工艺 | 42856篇 |
机械仪表 | 49721篇 |
建筑科学 | 63637篇 |
矿业工程 | 24052篇 |
能源动力 | 22012篇 |
轻工业 | 52597篇 |
水利工程 | 15103篇 |
石油天然气 | 44416篇 |
武器工业 | 6882篇 |
无线电 | 87790篇 |
一般工业技术 | 86256篇 |
冶金工业 | 39179篇 |
原子能技术 | 8479篇 |
自动化技术 | 105923篇 |
出版年
2024年 | 3174篇 |
2023年 | 11000篇 |
2022年 | 21176篇 |
2021年 | 29126篇 |
2020年 | 22156篇 |
2019年 | 17778篇 |
2018年 | 20212篇 |
2017年 | 23402篇 |
2016年 | 20925篇 |
2015年 | 29250篇 |
2014年 | 38142篇 |
2013年 | 46402篇 |
2012年 | 50178篇 |
2011年 | 55551篇 |
2010年 | 49263篇 |
2009年 | 47280篇 |
2008年 | 46471篇 |
2007年 | 44768篇 |
2006年 | 44446篇 |
2005年 | 38418篇 |
2004年 | 26106篇 |
2003年 | 22325篇 |
2002年 | 20661篇 |
2001年 | 18519篇 |
2000年 | 18064篇 |
1999年 | 19360篇 |
1998年 | 16170篇 |
1997年 | 13435篇 |
1996年 | 12344篇 |
1995年 | 10441篇 |
1994年 | 8512篇 |
1993年 | 6276篇 |
1992年 | 4993篇 |
1991年 | 3862篇 |
1990年 | 3011篇 |
1989年 | 2557篇 |
1988年 | 2017篇 |
1987年 | 1398篇 |
1986年 | 1082篇 |
1985年 | 751篇 |
1984年 | 528篇 |
1983年 | 462篇 |
1982年 | 411篇 |
1981年 | 331篇 |
1980年 | 325篇 |
1979年 | 180篇 |
1978年 | 98篇 |
1977年 | 110篇 |
1976年 | 139篇 |
1975年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films are attracting famous applications in antistatic coating, energy storage and conversion, printed electronics, and biomedical fields due to their conductivity, optical transparency and flexibility. However, PEDOT:PSS has poor dispersion stability during long-term storage and transport. Moreover, the dried PEDOT:PSS films are insoluble in any solvent and cannot be redispersed again. In comparison to bake drying, here, a feasible strategy to achieve mechanically redispersed PEDOT:PSS with the help of freeze-drying process was reported. The redispersed PEDOT:PSS can recover not only the initial characters such as pH, chemical composition, viscosity, and particle size under similar solid contents, but also conductivity and surface morphology of treated films. In addition, the treated film exhibits self-healing properties similar to pristine film in terms of mechanical and electrical properties. This technology enables reuse and overcomes the technical problems of PEDOT:PSS dispersion, realizing real-time processing to meet variable applications. 相似文献
62.
Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs. 相似文献
63.
64.
65.
Scientometrics - Examining the relationships among scientific disciplines is important today, but existing methods are limited by the contents and structure of their bibliographic databases. We... 相似文献
66.
Xuejie Li Yaqing Wen Jian Zhang Dongyun Ma Jie Zhang Yanxia An Xiaoyan Song Xiujuan Ren Weifeng Zhang 《International Journal of Food Science & Technology》2022,57(3):1544-1553
The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products. 相似文献
67.
Sumeng Wei Yining Xu Baohua Kong Meijuan Wang Jingming Zhang Qian Liu Yuling Yang 《International Journal of Food Science & Technology》2022,57(8):5024-5035
The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties. 相似文献
68.
Xiaojun Chen Hongyang Liu Dechao Hu Huaqing Liu Wenshi Ma 《Ceramics International》2021,47(17):23749-23761
With the blossom of information industry, electromagnetic wave technology shows increasingly potential in many fields. Nevertheless, the trouble caused by electromagnetic waves has also drawn extensive attention. For instance, electromagnetic pollution can threaten information safety in vital fields and the normal function of delicate electronic devices. Consequently, electromagnetic pollution and interference become an urgent issue that needs to be addressed. Carbon nanotubes (CNTs) have become a potential candidate to deal with these problems due to many advantages, such as high dielectric loss, remarkable thermodynamic stability, and low density. With the appearance of climbing demands, however, the carbon nanotubes combining various composites have shown greater prospects than the single CNTs in microwave absorbing materials. In this short review, recent advances in CNTs-based microwave absorbing materials were comprehensively discussed. Typically, we introduced the electromagnetic wave absorption mechanism of CNTs-based microwave absorbing materials and generalized the development of CNTs-based microwave absorbers, including CNTs-based magnetic metal composites, CNTs-based ferrite composites, and CNTs-based polymer composites. Ultimately, the growing trend and bottleneck of CNTs-based composites for microwave absorption were analyzed to provide some available ideas to more scientific workers. 相似文献
69.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献
70.
Yujie Chen Yiping Song Zhen Zhang Yali Chen Qiliang Deng Shuo Wang 《Advanced functional materials》2021,31(41):2104885
Various products, including foods and pharmaceuticals, are sensitive to temperature fluctuations. Thus, temperature monitoring during production, transportation, and storage is critical. Facile indicators are required to monitor temperature conditions via color changes in real time. This study aimed to prepare and apply thiol-functionalized covalent organic frameworks (COFs) as a novel indicator for monitoring thermal history and temperature abuse. The COFs underwent obvious color changes from bright yellow to purple after exposure to different temperatures for varying durations. The reaction kinetics are analyzed under isothermal conditions, which reveal that the order of reaction rates is k−20°C < k4°C < k20°C < k35°C < k55°C. The activation energy (Ea) of the COFs is calculated using the Arrhenius equation as 50.71 kJ moL−1. The COFs are capable of sensitive color changes and offer a broad temperature tracking range, thereby demonstrating their application potential for the monitoring of temperature and time exposure history during production, transportation, and storage. This excellent performance thermal history indicator also shows promise for expanding the application field of COFs. 相似文献