全文获取类型
收费全文 | 5196篇 |
免费 | 410篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 69篇 |
综合类 | 3篇 |
化学工业 | 1180篇 |
金属工艺 | 171篇 |
机械仪表 | 294篇 |
建筑科学 | 54篇 |
矿业工程 | 2篇 |
能源动力 | 167篇 |
轻工业 | 246篇 |
水利工程 | 11篇 |
无线电 | 757篇 |
一般工业技术 | 1132篇 |
冶金工业 | 1102篇 |
原子能技术 | 58篇 |
自动化技术 | 365篇 |
出版年
2023年 | 50篇 |
2022年 | 71篇 |
2021年 | 121篇 |
2020年 | 89篇 |
2019年 | 133篇 |
2018年 | 128篇 |
2017年 | 160篇 |
2016年 | 187篇 |
2015年 | 150篇 |
2014年 | 227篇 |
2013年 | 286篇 |
2012年 | 326篇 |
2011年 | 369篇 |
2010年 | 225篇 |
2009年 | 278篇 |
2008年 | 225篇 |
2007年 | 179篇 |
2006年 | 135篇 |
2005年 | 121篇 |
2004年 | 130篇 |
2003年 | 138篇 |
2002年 | 121篇 |
2001年 | 85篇 |
2000年 | 85篇 |
1999年 | 110篇 |
1998年 | 383篇 |
1997年 | 233篇 |
1996年 | 160篇 |
1995年 | 94篇 |
1994年 | 88篇 |
1993年 | 95篇 |
1992年 | 38篇 |
1991年 | 48篇 |
1990年 | 31篇 |
1989年 | 18篇 |
1988年 | 28篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 31篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1977年 | 28篇 |
1976年 | 61篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1970年 | 4篇 |
排序方式: 共有5611条查询结果,搜索用时 15 毫秒
81.
Younggeun Lee Jinhyeong Kwon Jaemook Lim Wooseop Shin Sewoong Park Eunseung Hwang Jaeho Shin Hyunmin Cho Jinwook Jung Hyun-Jong Kim Seungyong Han Habeom Lee Yong Son Cheol Woo Ha Prem Prabhakaran Junyeob Yeo Seung Hwan Ko Sukjoon Hong 《Advanced functional materials》2021,31(1):2006854
Structural coloration is closely related to the progress of innovative optoelectronic applications, but the absence of direct, on-demand, and rewritable coloration schemes has impeded advances in the relevant area, particularly including the development of customized, reprogrammable optoelectronic devices. To overcome these limitations, a digital laser micropainting technique, based on controlled thin-film interference, is proposed through direct growth of the absorbing metal oxide layer on a metallic reflector in the solution environment via a laser. A continuous-wave laser simultaneously performs two functions—a photothermal reaction for site-selective metal oxide layer growth and in situ real-time monitoring of its thickness—while the reflection spectrum is tuned in a broad visible spectrum according to the laser fluence. The scalability and controllability of the proposed scheme is verified by laser-printed painting, while altering the thickness via supplementary irradiation of the identical laser in the homogeneous and heterogeneous solutions facilitates the modification of the original coloration. Finally, the proof-of-concept bolometer device verifies that specific wavelength-dependent photoresponsivity can be assigned, erased, and reassigned by the successive application of the proposed digital laser micropainting technique, which substantiates its potential to offer a new route for reprogrammable optoelectronic applications. 相似文献
82.
The high-field mobility behavior of silicon MOSFETs fabricated with reoxidized nitrided oxide (ONO) gate dielectrics has been investigated. Measurements have been performed at both room temperature and 77 K on both n- an p-channel FETs, for both ONO and conventional SiO 2 films. While the peak electron mobility is much higher for standard SiO2, a crossover occurs in the high-field region beyond which ONO transistors exhibit higher mobility. The crossover voltage is reduced at 77 K. Measurements intended to gain further insight into this phenomenon suggest that differences in surface roughness scattering, or the buried-channel nature of an ONO NMOS transistor, are the most likely explanations for the high-field mobility behavior observed 相似文献
83.
84.
Various simulation applications for hair, clothing, and makeup of a 3D avatar can provide more useful information to users before they select a hairstyle, clothes, or cosmetics. To enhance their reality, the shapes, textures, and colors of the avatars should be similar to those found in the real world. For a more realistic 3D avatar color reproduction, this paper proposes a spectrum‐based color reproduction algorithm and color management process with respect to the implementation of the algorithm. First, a makeup color reproduction model is estimated by analyzing the measured spectral reflectance of the skin samples before and after applying the makeup. To implement the model for a makeup simulation system, the color management process controls all color information of the 3D facial avatar during the 3D scanning, modeling, and rendering stages. During 3D scanning with a multicamera system, spectrum‐based camera calibration and characterization are performed to estimate the spectrum data. During the virtual makeup process, the spectrum data of the 3D facial avatar is modified based on the makeup color reproduction model. Finally, during 3D rendering, the estimated spectrum is converted into RGB data through gamut mapping and display characterization. 相似文献
85.
Vivek Chidambaram Eric Phua Jian Rong Gan Chee Lip Rhee Min Woo Daniel 《Journal of Electronic Materials》2013,42(9):2803-2812
Cyanate ester resin-based composite materials have been proposed as potential encapsulants for high-temperature applications. The objective of this study is to develop a cyanate ester-based encapsulant, which can also serve as a flip-chip underfill as well as for traditional encapsulation. Two different materials, quartz and alumina fillers, have been studied. The impact of shapes and sizes of the fillers on the overall thermomechanical properties has been investigated. The adhesion strengths of the materials to the ceramic substrate, Kovar lid, and silicon die have also been characterized. The modulus of the resin and the shape of the fillers play a pivotal role in minimizing thermal stress, generated by coefficient of thermal expansion mismatches. Smaller filler particles were found to have better adhesion to the cyanate ester resin. The high-temperature performance of the cyanate ester-based encapsulants was evaluated by thermal aging at 300°C for up to 500 h. 相似文献
86.
Woo Sik Jeon Jung Soo Park Ling Li Dae Chul Lim Young Hoon Son Min Chul Suh Jang Hyuk Kwon 《Organic Electronics》2012,13(6):939-944
We report a unique non-radiative p-n-p junction structure to provide high current conduction with high mobility in organic semiconductor devices. The current conduction was improved by increasing p-n junctions made with intrinsic p-type hole transport layer and n-type electron transport layer. The excellent hole mobility of 5.3 × 10?1 cm2/V s in this p-n-p device configuration is measured by the space charge limited current method with an electric field of 0.3 MV/cm. Enhanced current conduction of 248% at 4.0 V was observed in fluorescent blue organic light-emitting diodes with introduction of non-radiative p-n-p-n-p junction interfaces. Thereupon, the power efficiency at 1000 cd/m2 was improved by 22% and the driving voltage also was reduced by 17%, compared to that of no interface device. Such high current conduction with high mobility is attributed to the carrier recombination at p-n-p interfaces through coulombic interaction. This non-radiative p-n-p junction structure suggested in this report can be very useful for many practical organic semiconductor device applications. 相似文献
87.
Yeong-Taek Lee Dong-Soo Woo Jong Duk Lee Byung-Gook Park 《Electron Devices, IEEE Transactions on》2000,47(12):2326-2333
A quasi-two-dimensional (2-D) threshold voltage reduction model for buried channel pMOSFETs is derived. In order to account for the coexistence of isoand anisotype junctions in a buried channel structure, we have incorporated charge sharing effect in the quasi-2-D Poisson model. The proposed model correctly predicts the effects of drain bias (V/sub DS/), counter doping layer thickness (x/sub CD/), counter doping concentration (N/sub CD/), substrate doping concentration (N/sub sub/) and source/drain junction depth (x/sub j/), and the new model performs satisfactorily in the sub-0.1 /spl mu/m regime. By using the proposed model on the threshold voltage reduction and subthreshold swing, we have obtained the process windows of the counter doping thickness and the substrate concentration. These process windows are very useful for predicting the scaling limit of the buried channel pMOSFET with known process conditions or systematic design of the buried channel pMOSFET. 相似文献
88.
Jung Woo Lee Ravindranath Viswan Yoon Jeong Choi Yeob Lee Se Yun Kim Jaehun Cho Younghun Jo Jeung Ku Kang 《Advanced functional materials》2009,19(14):2213-2218
Using conventional methods to synthesize magnetic nanoparticles (NPs) with uniform size is a challenging task. Moreover, the degradation of magnetic NPs is an obstacle to practical applications. The fabrication of silica‐shielded magnetite NPs on carbon nitride nanotubes (CNNTs) provides a possible route to overcome these problems. While the nitrogen atoms of CNNTs provide selective nucleation sites for NPs of a particular size, the silica layer protects the NPs from oxidation. The morphology and crystal structure of NP–CNNT hybrid material is investigated by transmission electron microscopy (TEM) and X‐ray diffraction. In addition, the atomic nature of the N atoms in the NP–CNNT system is studied by near‐edge X‐ray absorption fine structure spectroscopy (nitrogen K‐edge) and calculations of the partial density of states based on first principles. The structure of the silica‐shielded NP–CNNT system is analyzed by TEM and energy dispersive X‐ray spectroscopy mapping, and their magnetism is measured by vibrating sample and superconducting quantum interference device magnetometers. The silica shielding helps maintain the superparamagnetism of the NPs; without the silica layer, the magnetic properties of NP–CNNT materials significantly degrade over time. 相似文献
89.
Bo Ram Kang Woo Jong Yu Ki Kang Kim Hyeon Ki Park Soo Min Kim Yongjin Park Gunn Kim Hyeon‐Jin Shin Un Jeong Kim Eun‐Hong Lee Jae‐Young Choi Young Hee Lee 《Advanced functional materials》2009,19(16):2553-2559
Here, a pyrolytically controlled antioxidizing photosynthesis coenzyme, β‐Nicotinamide adenine dinucleotide, reduced dipotassium salt (NADH) for a stable n‐type dopant for carbon nanotube (CNT) transistors is proposed. A strong electron transfer from NADH, mainly nicotinamide, to CNTs takes place during pyrolysis so that not only the type conversion from p‐type to n‐type is realized with 100% of reproducibility but also the on/off ratio of the transistor is significantly improved by increasing on‐current and/or decreasing off‐current. The device was stable up to a few months with negligible current changes under ambient conditions. The n‐type characteristics were completely recovered to an initial doping level after reheat treatment of the device. 相似文献