全文获取类型
收费全文 | 133556篇 |
免费 | 12799篇 |
国内免费 | 8124篇 |
专业分类
电工技术 | 9183篇 |
技术理论 | 5篇 |
综合类 | 12352篇 |
化学工业 | 20030篇 |
金属工艺 | 7776篇 |
机械仪表 | 8564篇 |
建筑科学 | 9866篇 |
矿业工程 | 3505篇 |
能源动力 | 3558篇 |
轻工业 | 13570篇 |
水利工程 | 3031篇 |
石油天然气 | 5598篇 |
武器工业 | 1319篇 |
无线电 | 15484篇 |
一般工业技术 | 13543篇 |
冶金工业 | 5436篇 |
原子能技术 | 1686篇 |
自动化技术 | 19973篇 |
出版年
2024年 | 543篇 |
2023年 | 1785篇 |
2022年 | 3618篇 |
2021年 | 4804篇 |
2020年 | 3744篇 |
2019年 | 3070篇 |
2018年 | 3436篇 |
2017年 | 3905篇 |
2016年 | 3708篇 |
2015年 | 5390篇 |
2014年 | 6887篇 |
2013年 | 8237篇 |
2012年 | 9812篇 |
2011年 | 10545篇 |
2010年 | 9791篇 |
2009年 | 9478篇 |
2008年 | 9568篇 |
2007年 | 8974篇 |
2006年 | 8367篇 |
2005年 | 6862篇 |
2004年 | 5348篇 |
2003年 | 4633篇 |
2002年 | 5117篇 |
2001年 | 4410篇 |
2000年 | 3034篇 |
1999年 | 2182篇 |
1998年 | 1401篇 |
1997年 | 1172篇 |
1996年 | 1001篇 |
1995年 | 873篇 |
1994年 | 630篇 |
1993年 | 470篇 |
1992年 | 356篇 |
1991年 | 299篇 |
1990年 | 245篇 |
1989年 | 147篇 |
1988年 | 130篇 |
1987年 | 98篇 |
1986年 | 54篇 |
1985年 | 60篇 |
1984年 | 50篇 |
1983年 | 35篇 |
1982年 | 23篇 |
1981年 | 29篇 |
1980年 | 39篇 |
1979年 | 19篇 |
1977年 | 14篇 |
1976年 | 19篇 |
1959年 | 16篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 185 毫秒
1.
Pengfei Liang Jie Zhu Di Wu Hui Peng Xiaolian Chao Zupei Yang 《Journal of the American Ceramic Society》2021,104(6):2702-2710
Due to the demand of miniaturization and integration for ceramic capacitors in electronic components market, TiO2-based ceramics with colossal permittivity has become a research hotspot in recent years. In this work, we report that Ag+/Nb5+ co-doped (Ag1/4Nb3/4)xTi1−xO2 (ANTOx) ceramics with colossal permittivity over a wide frequency and temperature range were successfully prepared by a traditional solid–state method. Notably, compositions of ANTO0.005 and ANTO0.01 respectively exhibit both low dielectric loss (0.040 and 0.050 at 1 kHz), high dielectric permittivity (9.2 × 103 and 1.6 × 104 at 1 kHz), and good thermal stability, which satisfy the requirements for the temperature range of application of X9R and X8R ceramic capacitors, respectively. The origin of the dielectric behavior was attributed to five dielectric relaxation phenomena, i.e., localized carriers' hopping, electron–pinned defect–dipoles, interfacial polarization, and oxygen vacancies ionization and diffusion, as suggested by dielectric temperature spectra and valence state analysis via XPS; wherein, electron-pinned defect–dipoles and internal barrier layer capacitance are believed to be the main causes for the giant dielectric permittivity in ANTOx ceramics. 相似文献
3.
Fan Deng-Ping Huang Ziling Zheng Peng Liu Hong Qin Xuebin Van Gool Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a... 相似文献
4.
Hong Sae Jin Park Nam Il Hwang Dae Keun Yi Tae Gyu Eum Hyang Lan 《Food science and biotechnology》2022,31(6):669-679
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex... 相似文献
5.
International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of... 相似文献
6.
Hui Liu Yaohui Fu Jinhai Yuan Lei Yu Zhefei Wang Quan Liu Bo Wei Xuhong Wang 《Ceramics International》2021,47(12):16570-16578
To provide a basis for the high-temperature oxidation of ultra-high temperature ceramics (UHTCs), the oxidation behavior of Zr3[Al(Si)]4C6 and a novel Zr3[Al(Si)]4C6-ZrB2-SiC composite at 1500 °C were investigated for the first time. From the calculation results, the oxidation kinetics of the two specimens follow the oxidation dynamic parabolic law. Zr3[Al(Si)]4C6 exhibited a thinner oxide scale and lower oxidation rate than those of the composite under the same conditions. The oxide scale of Zr3[Al(Si)]4C6 exhibited a two-layer structure, while that of the composite exhibited a three-layer structure. Owing to the volatilization of B2O3 and the active oxidation of SiC, a porous oxide layer formed in the oxide scale of the composite, resulting in the degradation of its oxidation performance. Furthermore, the cracks and defects in the oxide scale of the composite indicate that the reliability of the oxide scale was poor. The results support the service temperature of the obtained ceramics. 相似文献
7.
8.
盾构隧道施工物料无人运输有助于提升运输效率、降低运输成本、减少运输安全事故率。与公路汽车无人驾驶、港口车辆无人驾驶、轨道交通无人驾驶等逐步成熟的无人驾驶技术不同,在隧道场景下实施施工物料无人运输存在运输物料种类繁多、运输调度困难、地下定位信号拒止、狭窄车道频繁会车、行车路面工况复杂、地上地下联动响应慢等诸多挑战。从实现盾构隧道施工物料无人运输的关键问题分析入手,综述当前盾构隧道施工物料运输方式、运输需求、无人运输发展现状及存在的挑战,提出盾构隧道施工物料无人运输的五大关键技术:多种类物料智能货控能效管理技术,无人化垂直装卸门机控制技术,多传感器融合同步定位与地图构建技术,隧道复杂环境路径规划与自主避障技术,隧-地一体化联动响应的高可靠性无线通信技术。 相似文献
9.
Zhen Hong Mingshan Xue Yidan Luo Zuozhu Yin Chan Xie Junfei Ou Fajun Wang 《应用聚合物科学杂志》2021,138(2):49657
With the continuous development of bionics, such as, geckos and virginia creeper with both superhydrophobic and super-adhesive, the surface wetting and super-adhesive properties of various porous materials have attracted extensive attention of the scientific and medical communities. Here, the honeycomb polyurethane (PU) porous films with strong adhesion were successfully prepared by microphase separation method and the effects of growth parameters on their microstructure and adhesive strength to ice were investigated. It was found that a high relative humidity (e.g., 100%) and a low solution concentration (e.g., 2%) facilitated the formation of ordered honeycomb PU porous films, and as-prepared PU pores with average pore diameter as small as 5 μm are better ordered and more uniform than these in related documents. Although the contact angle of water droplets on the surface of PU porous films increased from the premodification value of 85–130° to more than 160° after surface modification with polydopamine (PDA), the corresponding rolling angle remained approximately constant (180°), indicating that the surface of PU porous films has strong adhesion similar to geckos and virginia creeper. Furthermore, at lower temperature, the PU porous films exhibited the high adhesive strength of 142.13 kPa on ice, which was strongly dependent on the porous microstructures and surface compositions. The improved adhesive behavior to ice of honeycomb PU porous films modified with PDA provides new strategies for surface modification of materials and potential applications in medical domain. 相似文献
10.
Shuang Chen Chao Yu Zhanfang Cao Xiaoping Huang Shuai Wang Hong Zhong 《International Journal of Hydrogen Energy》2021,46(10):7037-7046
The development of efficient and stable oxygen evolution reaction (OER) catalysts is an ongoing challenge. In order to solve the problem of low oxygen evolution efficiency of the current OER catalysts, a novel material was synthesized by the incorporation of NiFeCr-LDH and MoS2, and its structural and electrochemical properties were also investigated. The introduction of MoS2 improves the electrochemical performance of NiFeCr-LDH. The polarization curve shows that the potential of composite material is only 1.50 V at a current density of 10 mA cm?2, which is far superior to commercial precious metal catalysts. In addition, the stability experiment shows that the composite material has excellent stability, and the current density has little change after 500 cycles. Furthermore, we found that some metal ions, such as Ni, Cr and Mo, exist in the form of high valence on the surface of NiFeCr-LDH@MoS2, which is also conducive to the occurrence of oxygen evolution reaction. 相似文献