全文获取类型
收费全文 | 3327篇 |
免费 | 164篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 623篇 |
金属工艺 | 124篇 |
机械仪表 | 160篇 |
建筑科学 | 41篇 |
能源动力 | 139篇 |
轻工业 | 208篇 |
水利工程 | 21篇 |
石油天然气 | 6篇 |
武器工业 | 2篇 |
无线电 | 352篇 |
一般工业技术 | 481篇 |
冶金工业 | 988篇 |
原子能技术 | 54篇 |
自动化技术 | 274篇 |
出版年
2024年 | 3篇 |
2023年 | 33篇 |
2022年 | 62篇 |
2021年 | 97篇 |
2020年 | 60篇 |
2019年 | 62篇 |
2018年 | 83篇 |
2017年 | 80篇 |
2016年 | 84篇 |
2015年 | 78篇 |
2014年 | 117篇 |
2013年 | 164篇 |
2012年 | 215篇 |
2011年 | 247篇 |
2010年 | 158篇 |
2009年 | 180篇 |
2008年 | 127篇 |
2007年 | 87篇 |
2006年 | 96篇 |
2005年 | 85篇 |
2004年 | 74篇 |
2003年 | 60篇 |
2002年 | 48篇 |
2001年 | 52篇 |
2000年 | 53篇 |
1999年 | 74篇 |
1998年 | 353篇 |
1997年 | 192篇 |
1996年 | 130篇 |
1995年 | 76篇 |
1994年 | 73篇 |
1993年 | 51篇 |
1992年 | 11篇 |
1991年 | 18篇 |
1990年 | 10篇 |
1989年 | 22篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 15篇 |
1975年 | 1篇 |
排序方式: 共有3496条查询结果,搜索用时 31 毫秒
91.
In this letter, we propose a novel design scheme for an optimal non‐uniform planar array geometry in view of maximum side‐lobe reduction. This is implemented by a thinned array using a genetic algorithm. We show that the proposed method can maintain a low side‐lobe level without pattern distortion during beam steering. 相似文献
92.
Spectral shape tunable band-rejection filter using a long-period fiber grating with divided coil heaters 总被引:2,自引:0,他引:2
Jun Kye Bae Sang Hyuck Kim Jun Hee Kim Jinho Bae Sang Bae Lee Je-Myung Jeong 《Photonics Technology Letters, IEEE》2003,15(3):407-409
We have developed a new type of tunable band rejection filter, which provides high spectral-shaping flexibility in a wide tuning range. The filter consists of a long-period fiber grating (LPFG) with divided coil heaters. Each of the divided coil heaters is controlled individually to adjust a temperature distribution along the LPFG and to modify the spectral shape of the LPFG filter. The tunable band rejection filter is demonstrated to function properly when applied as an erbium-doped fiber amplifier gain-flattening filter. 相似文献
93.
Xuetao Shi Serge Ostrovidov Yihua Zhao Xiaobin Liang Motohiro Kasuya Kazue Kurihara Ken Nakajima Hojae Bae Hongkai Wu Ali Khademhosseini 《Advanced functional materials》2015,25(15):2250-2259
Engineering living tissues that simulate their natural counterparts is a dynamic area of research. Among the various models of biological tissues being developed, fiber‐shaped cellular architectures, which can be used as artificial blood vessels or muscle fibers, have drawn particular attention. However, the fabrication of continuous microfiber substrates for culturing cells is still limited to a restricted number of polymers (e.g., alginate) having easy processability but poor cell–material interaction properties. Moreover, the typical smooth surface of a synthetic fiber does not replicate the micro‐ and nanofeatures observed in vivo, which guide and regulate cell behavior. In this study, a method to fabricate photocrosslinkable cell‐responsive methacrylamide‐modified gelatin (GelMA) fibers with exquisite microstructured surfaces by using a microfluidic device is developed. These hydrogel fibers with microgrooved surfaces efficiently promote cell encapsulation and adhesion. GelMA fibers significantly promote the viability of cells encapsulated in/or grown on the fibers compared with similar grooved alginate fibers used as controls. Importantly, the grooves engraved on the GelMA fibers induce cell alignment. Furthermore, the GelMA fibers exhibit excellent processability and could be wound into various shapes. These microstructured GelMA fibers have great potential as templates for the creation of fiber‐shaped tissues or tissue microstructures. 相似文献
94.
Highly stable optical add/drop multiplexer using polarization beam splitters and fiber Bragg gratings 总被引:1,自引:0,他引:1
Se Yoon Kim Sang Bae Lee Joon Chung Sang Yong Kim Il Jong Park Jichai Jeong Sang Sam Choi 《Photonics Technology Letters, IEEE》1997,9(8):1119-1121
We demonstrate a novel wavelength-division add/drop multiplexer employing fiber Bragg gratings and polarization beam splitters. The multiplexer is easy to fabricate without any special technique such as UV trimming, and yet shows very stable performance with less than 0.3-dB crosstalk power penalty in a 0.8-nm-spaced, 2.5-Gb/s-per-channel wavelength-division multiplexing (WDM) transmission system. 相似文献
95.
Soojeong Choi Jihoon Jeon Yunsu Bae Yongsoon Hwang Seung-Woo Cho 《Advanced functional materials》2023,33(44):2303043
Oral disease is one of the most common conditions worldwide, negatively affecting general health, reducing the quality of life, and often developing into systemic illness. However, the design of therapeutic agents for oral diseases is challenging due to various unique features of the oral cavity, including its wet and dynamic environment and curved shape. Herein, the development of highly biocompatible mucoadhesive functional hydrogels for oral applications is reported, generated by introducing bio-inspired phenolic moieties into a pectin polymer. Pyrogallol-functionalized pectin (Pec-PG) can be crosslinked in situ via autoxidation without chemical agents and readily fabricated as various formulations. Sprayable Pec-PG hydrogel exhibits strong mucoadhesion and outstanding hydration ability ex vivo and in vivo, thus displaying significant potential as a novel saliva substitute for dry mouth. The authors further show that topical application of mucoadhesive Pec-PG patches pre-loaded with corticosteroid significantly promotes the repair of diabetic oral ulcer tissue via prolonged drug release, free radical scavenging, and physical barrier effects. Moreover, similar applications for oral ulcer treatment using a pectin hydrogel modified with catechol (Pec-CA), another phenolic moiety are demonstrated. Together, these findings suggest that mucoadhesive phenolic pectin derivatives can provide highly biocompatible, convenient, and effective hydrogel platforms for treating oral diseases. 相似文献
96.
Kwang‐Seong Choi Ki‐Jun Sung Byeong‐Ok Lim Hyun‐Cheol Bae Sunghae Jung Jong‐Tae Moon Yong‐Sung Eom 《ETRI Journal》2010,32(2):342-344
A novel, maskless, low‐volume bumping material, called solder bump maker, which is composed of a resin and low‐melting‐point solder powder, has been developed. The resin features no distinct chemical reactions preventing the rheological coalescence of the solder, a deoxidation of the oxide layer on the solder powder for wetting on the pad at the solder melting point, and no major weight loss caused by out‐gassing. With these characteristics, the solder was successfully wetted onto a metal pad and formed a uniform solder bump array with pitches of 120 µm and 150 µm. 相似文献
97.
Surface leakage current analysis of ion implanted ZnS-passivated n-on-p HgCdTe diodes in weak inversion 总被引:1,自引:0,他引:1
Young-Ho Kim Soo-Ho Bae Hee Chul Lee Choong Ki Kim 《Journal of Electronic Materials》2000,29(6):832-836
Effects of fixed charge on R0A value of ZnS-passivated x=0.3 HgCdTe n-on-p diode are explained as a shunt resistance that affects current-voltage (I-V)
and dynamic resistance-voltage (Rd-V) characteristics. The fixed charge of 1×1011/cm2 to 2 × 1011/cm2 which is usually obtained with ZnS passivation makes the surface weakly inverted and reduces HgCdTe diode R0A value owing to the short generation lifetime of HgCdTe substrate. The gate-controlled diode and specially fabricated diode
are used to explain the surface leakage current in the weak inversion and charge sheet model is used to explain the characteristics.
It is found that the surface leakage current by the inverted channel in the weak inversion can reduce R0A more than other currents such as the generation current and tunneling current which are usually used to explain the surface
leakage current of HgCdTe diode. 相似文献
98.
Jong Bum Hong Student Member IEEE Yeong Bae Yeo Byoung Yoon Kim Fellow IEEE 《战术导弹控制技术》2002,(2):55-58
通过采用锁相放大器,演示了一种性能明显提高的锁模光纤激光陀螺.结果表明锁相放大器的输出与转动速率之间具有理想的线性关系,并对两脉冲(在时间间隔测量过程中引起相位误差)之间的光强差不敏感.与以往报道的时间间隔测量相比,演示了长期稳定性提高了二个数量级. 相似文献
99.
Magnificent elongation of bridge span length, especially of recently constructed cable stayed bridges and suspension bridges, can be achieved by technological as well as new material development of orthotropic steel deck systems. One such effort is to install curved bulkhead plates inside longitudinal u-ribs, which was analytically and experimentally demonstrated to reduce significant amount of concentrated stresses without sacrificing self-weight of the whole structure. In this paper, the optimal shape of more effective bulkhead plates is characterized by computational analysis. And it is verified from fatigue tests of a 3-dimensional full-scale structure that the fatigue performance can be significantly improved by installing the optimal bulkhead plates and by fabricating the structure out of recently developed high performance steel for bridges. 相似文献
100.
Moon Jae-Sung Kim Choonghyun Youm Youngil Bae Joonbum 《Journal of Mechanical Science and Technology》2018,32(5):2289-2298
Journal of Mechanical Science and Technology - This paper presents the design and modeling of the UNI-Copter, a portable spherical unmanned aerial vehicle (UAV) that is powered by a single rotor.... 相似文献