全文获取类型
收费全文 | 1992篇 |
免费 | 30篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 118篇 |
综合类 | 10篇 |
化学工业 | 395篇 |
金属工艺 | 73篇 |
机械仪表 | 51篇 |
建筑科学 | 30篇 |
矿业工程 | 1篇 |
能源动力 | 59篇 |
轻工业 | 123篇 |
水利工程 | 7篇 |
石油天然气 | 5篇 |
无线电 | 236篇 |
一般工业技术 | 338篇 |
冶金工业 | 422篇 |
原子能技术 | 59篇 |
自动化技术 | 101篇 |
出版年
2023年 | 4篇 |
2022年 | 16篇 |
2021年 | 23篇 |
2020年 | 14篇 |
2019年 | 17篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 14篇 |
2014年 | 37篇 |
2013年 | 77篇 |
2012年 | 73篇 |
2011年 | 92篇 |
2010年 | 59篇 |
2009年 | 58篇 |
2008年 | 77篇 |
2007年 | 71篇 |
2006年 | 54篇 |
2005年 | 63篇 |
2004年 | 62篇 |
2003年 | 59篇 |
2002年 | 64篇 |
2001年 | 52篇 |
2000年 | 55篇 |
1999年 | 52篇 |
1998年 | 151篇 |
1997年 | 104篇 |
1996年 | 87篇 |
1995年 | 71篇 |
1994年 | 54篇 |
1993年 | 52篇 |
1992年 | 18篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 34篇 |
1988年 | 20篇 |
1987年 | 17篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 21篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 21篇 |
1976年 | 17篇 |
1975年 | 7篇 |
1973年 | 9篇 |
排序方式: 共有2028条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ken Kanazawa Shoji Yoshida Hidemi Shigekawa Shinji Kuroda 《Science and Technology of Advanced Materials》2015,16(1)
The reconstructed surface structure of the II–VI semiconductor ZnTe (110), which is a promising material in the research field of semiconductor spintronics, was studied by scanning tunneling microscopy/spectroscopy (STM/STS). First, the surface states formed by reconstruction by the charge transfer of dangling bond electrons from cationic Zn to anionic Te atoms, which are similar to those of IV and III–V semiconductors, were confirmed in real space. Secondly, oscillation in tunneling current between binary states, which is considered to reflect a conformational change in the topmost Zn–Te structure between the reconstructed and bulk-like ideal structures, was directly observed by STM. Third, using the technique of charge injection, a surface atomic structure was successfully fabricated, suggesting the possibility of atomic-scale manipulation of this widely applicable surface of ZnTe. 相似文献
4.
Shohei Minagawa Shoji Fujiwara Takeshi Hashimoto Takashi Hayashita 《International journal of molecular sciences》2021,22(9)
Cyclodextrins (CyDs) are water-soluble host molecules possessing a nanosized hydrophobic cavity. In the realm of molecular recognition, this cavity is used not only as a recognition site but also as a reaction medium, where a hydrophobic sensor recognizes a guest molecule. Based on the latter concept, we have designed a novel supramolecular sensing system composed of Zn(II)-dipicolylamine metal complex-based azobenzene (1-Zn) and 3A-amino-3A-deoxy-(2AS,3AS)-γ-cyclodextrin (3-NH2-γ-CyD) for sensing adenosine-5′-triphosphate (ATP). 1-Zn showed redshifts in the UV-Vis spectra and induced circular dichroism (ICD) only when both ATP and 3-NH2-γ-CyD were present. Calculations of equilibrium constants indicated that the amino group of 3-NH2-γ-CyD was involved in the formation of supramolecular 1-Zn/3-NH2-γ-CyD/ATP. The Job plot of the ICD spectral response revealed that the stoichiometry of 1-Zn/3-NH2-γ-CyD/ATP was 2:1:1. The pH effect was examined and 1-Zn/3-NH2-γ-CyD/ATP was most stable in the neutral condition. The NOESY spectrum suggested the localization of 1-Zn in the 3-NH2-γ-CyD cavity. Based on the obtained results, the metal coordination interaction of 1-Zn and the electrostatic interaction of 3-NH2-γ-CyD were found to take place for ATP recognition. The “reaction medium approach” enabled us to develop a supramolecular sensing system that undergoes multi-point interactions in water. This study is the first step in the design of a selective sensing system based on a good understanding of supramolecular structures. 相似文献
5.
D. Li K. Imasaki S. Miyamoto S. Amano T. Mochizuki 《Journal of Infrared, Millimeter and Terahertz Waves》2004,25(7):1069-1073
We studied on realization of short pulse gamma ray and X-ray simultaneously induced by a femtosecond laser on NewSUBARU storage ring. Based on the fact that the transverse dimensions of electron beam are much shorter than the longitudinal one, the laser light is arranged to collide the electron beam at a right angle to generate femtosecond pulse gamma ray, furthermore, the modulated part of the electron bunch gives rise to short pulse X-ray by synchrotron radiation from a downstream bending magnet. The temporal characteristic of the radiation is analyzed in this paper, as well as the performances are estimated. 相似文献
6.
N Manabe Y Imai H Ohno Y Takahagi M Sugimoto H Miyamoto 《Canadian Metallurgical Quarterly》1996,52(7):647-651
The porcine antral follicles, 3-6 mm in diameter, were dissected from the ovaries of mature pigs, and then granulosa and cumulus cells were isolated from each follicle. In atretic follicles, high activity of neutral Ca2+/Mg2+-dependent endonuclease and DNA ladder formation, estimated by electrophoresis, were noted in granulosa cells but not in cumulus cells. Extremely low activity of the endonuclease and no DNA ladder formation were observed in both types of cells obtained from healthy follicles. Moreover, apoptotic cells were observed histochemically among granulosa cells only. A good correlation (r = 0.987) between the endonuclease activity of granulosa cells and the progesterone/estradiol ratio of follicular fluid in each follicle was found. These results suggest that apoptosis occurs in granulosa cells but not cumulus cells in the atretic antral follicles in pigs. 相似文献
7.
Takashi Itoh Hitoe Habuchi Shoji Nitta Shuichi Nonomura 《Fullerenes, Nanotubes and Carbon Nanostructures》1994,2(2):181-187
Gas effusion spectra of fullerenes are studied. Three peaks of toluene are found in gas effusion spectra dp/dT-T. Two peaks of oxygen are found in gas effusion spectra dN/dt-T of samples kept in the air after annealing to avoid the toluene. These phenomena confirmed to be reversible are discussed by treating fullerenes as intercalated materials. 相似文献
8.
液闪效率示踪法校正效果的评价 总被引:1,自引:0,他引:1
本文评价了Aloka商品液闪仪效率示踪法dpm校正的效果。轻,中度猝灭校正效果理想,具有简便、实用和适用性广泛的特点。严重化学和颜色猝灭样品的校正结果分别随猝灭增加而向增大和减小的方向偏离,形成喇叭状曲线,文中对这一现象给出初步解释。 相似文献
9.
10.
Tsujimura T. Tokuhiro O. Morooka M. Miyamoto T. Miwa K. Yoshimura Y. Andry P. Libsch F. 《Electron Devices, IEEE Transactions on》2002,49(4):576-583
The leakage mechanism for a top-gate thin-film transistor (TFT) produced using the fewest process steps in the industry is analyzed in order to achieve a high-contrast liquid crystal display (LCD). Using a T-shaped TFT structure, the OFF and ON channel lengths are defined independently, so that the leakage can be reduced with no ON current decrease 相似文献