全文获取类型
收费全文 | 14587篇 |
免费 | 1059篇 |
国内免费 | 59篇 |
专业分类
电工技术 | 220篇 |
综合类 | 21篇 |
化学工业 | 3253篇 |
金属工艺 | 361篇 |
机械仪表 | 517篇 |
建筑科学 | 425篇 |
矿业工程 | 13篇 |
能源动力 | 583篇 |
轻工业 | 1070篇 |
水利工程 | 67篇 |
石油天然气 | 26篇 |
武器工业 | 1篇 |
无线电 | 2725篇 |
一般工业技术 | 2974篇 |
冶金工业 | 1236篇 |
原子能技术 | 157篇 |
自动化技术 | 2056篇 |
出版年
2024年 | 22篇 |
2023年 | 186篇 |
2022年 | 328篇 |
2021年 | 509篇 |
2020年 | 416篇 |
2019年 | 430篇 |
2018年 | 542篇 |
2017年 | 439篇 |
2016年 | 648篇 |
2015年 | 468篇 |
2014年 | 648篇 |
2013年 | 1026篇 |
2012年 | 770篇 |
2011年 | 967篇 |
2010年 | 734篇 |
2009年 | 747篇 |
2008年 | 733篇 |
2007年 | 605篇 |
2006年 | 527篇 |
2005年 | 448篇 |
2004年 | 408篇 |
2003年 | 355篇 |
2002年 | 324篇 |
2001年 | 303篇 |
2000年 | 248篇 |
1999年 | 269篇 |
1998年 | 518篇 |
1997年 | 329篇 |
1996年 | 262篇 |
1995年 | 209篇 |
1994年 | 160篇 |
1993年 | 150篇 |
1992年 | 98篇 |
1991年 | 96篇 |
1990年 | 85篇 |
1989年 | 89篇 |
1988年 | 59篇 |
1987年 | 68篇 |
1986年 | 71篇 |
1985年 | 54篇 |
1984年 | 52篇 |
1983年 | 43篇 |
1982年 | 22篇 |
1981年 | 32篇 |
1980年 | 32篇 |
1979年 | 22篇 |
1978年 | 25篇 |
1977年 | 30篇 |
1976年 | 31篇 |
1975年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Huynh Nguyen Simran Sangha Michelle Pan Dong Ha Shin Hayoung Park Ali I. Mohammed Nicola Cirillo 《International journal of molecular sciences》2022,23(9)
Chemoradiation-induced mucositis is a debilitating condition of the gastrointestinal tract eventuating from antineoplastic treatment. It is believed to occur primarily due to oxidative stress mechanisms, which generate Reactive Oxygen Species (ROS). The aim of this scoping review was to assess the role of oxidative stress in the development of Oral Mucositis (OM). Studies from the literature, published in MEDLINE and SCOPUS, that evaluated the oxidative stress pathways or antioxidant interventions for OM, were retrieved to elucidate the current understanding of their relationship. Studies failing inclusion criteria were excluded, and those suitable underwent data extraction, using a predefined data extraction table. Eighty-nine articles fulfilled criteria, and these were sub-stratified into models of study (in vitro, in vivo, or clinical) for evaluation. Thirty-five clinical studies evaluated antioxidant interventions on OM’s severity, duration, and pain, amongst other attributes. A number of clinical studies sought to elucidate the protective or therapeutic effects of compounds that had been pre-determined to have antioxidant properties, without directly assessing oxidative stress parameters (these were deemed “indirect evidence”). Forty-seven in vivo studies assessed the capacity of various compounds to prevent OM. Findings were mostly consistent, reporting reduced OM severity associated with a reduction in ROS, malondialdehyde (MDA), myeloperoxidase (MPO), but higher glutathione (GSH) and superoxide dismutase (SOD) activity or expression. Twenty-one in vitro studies assessed potential OM therapeutic interventions. The majority demonstrated successful a reduction in ROS, and in select studies, secondary molecules were assessed to identify the mechanism. In summary, this review highlighted numerous oxidative stress pathways involved in OM pathogenesis, which may inform the development of novel therapeutic targets. 相似文献
82.
Shoji Seki Mami Iwasaki Hiroto Makino Yasuhito Yahara Miho Kondo Katsuhiko Kamei Hayato Futakawa Makiko Nogami Kenta Watanabe Nguyen Tran Canh Tung Tatsuro Hirokawa Mamiko Tsuji Yoshiharu Kawaguchi 《International journal of molecular sciences》2022,23(9)
The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm2, respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis. 相似文献
83.
84.
We investigated the cantilevered carbon-nanotube-resonator including electromigratively movable nanoparticle via classical molecular dynamics simulations and continuum model. The change of the effective mass value, which was closely correlated with the position change of the encapsulated nanoparticle, could be regressed by a power function, the resonance frequency of the carbon-nanotube-resonator could be tuned by controlling the nanoparticle’s position, and the possible frequency-shift-ranges then reached 18–85%. The suggested device could be served as a data-storage-media for electromechanical nonvolatile-memory as well as a frequency-tuner. 相似文献
85.
86.
The paper aims at the development of the wavelet neural network (WNN) based conservative meta-model that satisfies the constraint feasibility of approximate optimal solution. The WNN based constraint-feasible meta-model is formulated via exterior penalty method to optimally determine interconnection weights and dilation and translation coefficients in the network. Using Ackley’s path function, the approximation performance of WNN is first tested in comparison with BPN. The proposed approach of constraint feasibility is then verified through a ten-bar planar truss problem. For constrained approximate optimization, the structural design of a composite rotor blade is explored to support the proposed strategies. 相似文献
87.
Yung Ho Chang 《Frontiers of Architecture and Civil Engineering in China》2010,4(4):519-521
New technologies are becoming today’s basic building blocks. This paper presents a case study of the Shanghai Corporate Pavilion for the 2010World Expo in Shanghai. From the shape of the building to the use of solar energy, the Shanghai Corporate Pavilion incorporates the state-of-art technologies to convey the spirit of the architecture. It addresses the pressing issue of energy, environment, and sustainability and reflects the spirit of Shanghai as a historically progressive yet still fast moving international metropolis. 相似文献
88.
Jong-Yul Kim Kyeong-Jun MunHyung-Su Kim June Ho Park 《International Journal of Electrical Power & Energy Systems》2011,33(8):1457-1461
In recent studies, PSO algorithm is applied to solve OPF problem. However, population based optimization method requires higher computing time to find optimal point. This shortcoming is overcome by a straightforward parallelization of PSO algorithm. The developed parallel PSO algorithm is implemented on a PC-cluster system with 8 Intel Pentium IV 2 GHz processors. The proposed approach has been tested on the test systems. The results showed that computing time of parallelized PSO algorithm can be reduced by parallel processing without losing the quality of solution. 相似文献
89.
Chae-Seon Hong Hyeong-Ho Park Hyung-Ho Park Ho Jung Chang 《Journal of Electroceramics》2009,22(4):353-356
Low-temperature crystallized ZnO thin film was achieved by sol–gel process using zinc acetate dihydrate and 2-methoxyethanol
as starting precursor and solvent, respectively. Ag nanoparticles were prepared with uniform size at 4.4 nm by spontaneous
reduction method of Ag 2-ethylhexanoate in dimethyl sulfoxide (DMSO). The optical and electrical properties of ZnO thin films
containing various contents of Ag-nanoparticles were monitored. Light scattering and charge emission and scattering behaviors
of Ag nanoparticles in ZnO film were found. The incorporation of Ag nanoparticles into Al-doped ZnO film was also investigated.
The optical transmittance was not degraded but the increase of electrical sheet resistance was found. The effect of Al-dopant
on the transmittance and electrical sheet resistance of ZnO film was found too great to distinguish the positive effect of
the incorporation of Ag nanoparticles into Al-doped ZnO thin films. 相似文献
90.
Yang Li Xi Tian Si‐Ping Gao Lin Jing Kerui Li Haitao Yang Fanfan Fu Jim Yang Lee Yong‐Xin Guo John S. Ho Po‐Yen Chen 《Advanced functional materials》2020,30(5)
In the emerging Internet of Things, stretchable antennas can facilitate wireless communication between wearable and mobile electronic devices around the body. The proliferation of wireless devices transmitting near the human body also raises interference and safety concerns that demand stretchable materials capable of shielding electromagnetic interference (EMI). Here, an ultrastretchable conductor is fabricated by depositing a crumple‐textured coating composed of 2D Ti3C2Tx nanosheets (MXene) and single‐walled carbon nanotubes (SWNTs) onto latex, which can be fashioned into high‐performance wearable antennas and EMI shields. The resulting MXene‐SWNT (S‐MXene)/latex devices are able to sustain up to an 800% areal strain and exhibit strain‐insensitive resistance profiles during a 500‐cycle fatigue test. A single layer of stretchable S‐MXene conductors demonstrate a strain‐invariant EMI shielding performance of ≈30 dB up to 800% areal strain, and the shielding performance is further improved to ≈47 and ≈52 dB by stacking 5 and 10 layers of S‐MXene conductors, respectively. Additionally, a stretchable S‐MXene dipole antenna is fabricated, which can be uniaxially stretched to 150% with unaffected reflected power <0.1%. By integrating S‐MXene EMI shields with stretchable S‐MXene antennas, a wearable wireless system is finally demonstrated that provides mechanically stable wireless transmission while attenuating EM absorption by the human body. 相似文献