全文获取类型
收费全文 | 151504篇 |
免费 | 7570篇 |
国内免费 | 3543篇 |
学科分类
工业技术 | 162617篇 |
出版年
2024年 | 144篇 |
2023年 | 1000篇 |
2022年 | 1540篇 |
2021年 | 2652篇 |
2020年 | 1988篇 |
2019年 | 1799篇 |
2018年 | 16266篇 |
2017年 | 15313篇 |
2016年 | 11987篇 |
2015年 | 3304篇 |
2014年 | 3825篇 |
2013年 | 4865篇 |
2012年 | 8225篇 |
2011年 | 15058篇 |
2010年 | 13109篇 |
2009年 | 10443篇 |
2008年 | 11381篇 |
2007年 | 11901篇 |
2006年 | 4030篇 |
2005年 | 4439篇 |
2004年 | 3582篇 |
2003年 | 3160篇 |
2002年 | 2460篇 |
2001年 | 1728篇 |
2000年 | 1475篇 |
1999年 | 1133篇 |
1998年 | 1151篇 |
1997年 | 764篇 |
1996年 | 684篇 |
1995年 | 474篇 |
1994年 | 357篇 |
1993年 | 312篇 |
1992年 | 233篇 |
1991年 | 214篇 |
1990年 | 144篇 |
1989年 | 142篇 |
1988年 | 127篇 |
1987年 | 101篇 |
1986年 | 81篇 |
1985年 | 58篇 |
1984年 | 47篇 |
1983年 | 39篇 |
1982年 | 46篇 |
1976年 | 46篇 |
1968年 | 45篇 |
1966年 | 44篇 |
1965年 | 44篇 |
1958年 | 37篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
3.
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
4.
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
5.
Yixuan ZHOU Huajie WANG Yi YU Yihang CHEN Rui KE Min XU Chijie XIAO Zhanhui WANG Jiquan LI Xuru DUAN Minyou YE 《等离子体科学和技术》2021,23(7):75105-52
In this article, we present the optical design of a novel diagnostic on the HL-2 A tokamak, i.e. the20-channel edge Lyman-alpha beam emission spectroscopy, which is a promising solution for edge density turbulence research on tokamaks, as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of1 μs. The optical path, including the reflective collection optics, the high-dispersion spectrometer, and the linear detector array, is carefully optimized to obtain a good image quality and a high throughput. The maximum root mean square radius of the collection optics is 64 μm.The detected photon flux is estimated to be about 10~(11) photons/s/channel. 相似文献
6.
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple... 相似文献
7.
8.
9.
10.
Zhenkun Ke Xin Cao Chuanli Shan Lifen Shi Pingping Wang Yong Yang Fengyang Zhao Jiedong Cui Jinwei Li Gang Zhou Min Guan Tao Yu 《Ceramics International》2021,47(14):19605-19613
The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R2O–CaO–B2O3–SiO2) systematically. Because the glass would emulsify when Li2O was added to the glass batch, this article did not discuss Li2O. The results showed that when the amount of Na2O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na2O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased. 相似文献