全文获取类型
收费全文 | 753篇 |
免费 | 17篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 24篇 |
综合类 | 2篇 |
化学工业 | 116篇 |
金属工艺 | 14篇 |
机械仪表 | 24篇 |
建筑科学 | 18篇 |
能源动力 | 33篇 |
轻工业 | 80篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 67篇 |
一般工业技术 | 119篇 |
冶金工业 | 187篇 |
原子能技术 | 16篇 |
自动化技术 | 71篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 5篇 |
2014年 | 25篇 |
2013年 | 43篇 |
2012年 | 34篇 |
2011年 | 41篇 |
2010年 | 18篇 |
2009年 | 26篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 25篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 24篇 |
1998年 | 76篇 |
1997年 | 30篇 |
1996年 | 35篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 19篇 |
1992年 | 13篇 |
1991年 | 4篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 10篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 11篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有774条查询结果,搜索用时 0 毫秒
771.
Eiichi Kusagawa Chiharu Okuda Rikako Yamaguchi Kaori Nakano Yasunobu Miyake Takao Kataoka 《International journal of molecular sciences》2022,23(13)
Pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), induce the expression of intracellular adhesion molecule-1 (ICAM-1) by activating the nuclear factor κB (NF-κB) signaling pathway. In the present study, we found that cucurbitacin B decreased the expression of ICAM-1 in human lung adenocarcinoma A549 cells stimulated with TNF-α or interleukin-1α. We further investigated the mechanisms by which cucurbitacin B down-regulates TNF-α-induced ICAM-1 expression. Cucurbitacin B inhibited the nuclear translocation of the NF-κB subunit RelA and the phosphorylation of IκBα in A549 cells stimulated with TNF-α. Cucurbitacin B selectively down-regulated the expression of TNF receptor 1 (TNF-R1) without affecting three adaptor proteins (i.e., TRADD, RIPK1, and TRAF2). The TNF-α-converting enzyme inhibitor suppressed the down-regulation of TNF-R1 expression by cucurbitacin B. Glutathione, N-acetyl-L-cysteine, and, to a lesser extent, L-cysteine attenuated the inhibitory effects of cucurbitacin B on the TNF-α-induced expression of ICAM-1, suggesting that an α,β-unsaturated carbonyl moiety is essential for anti-inflammatory activity. The present results revealed that cucurbitacin B down-regulated the expression of TNF-R1 at the initial step in the TNF-α-dependent NF-κB signaling pathway. 相似文献
772.
Kamiyama S. Iida K. Kawashima T. Kasugai H. Mishima S. Honshio A. Miyake Y. Iwaya M. Amano H. Akasaki I. 《IEEE journal of selected topics in quantum electronics》2005,11(5):1069-1073
We have demonstrated a UV-laser diode with a lasing wavelength of 350.9 nm, which has a GaN-AlGaN multiquantum-well (MQW) active layer and was grown on low-dislocation-density Al/sub 0.18/Ga/sub 0.82/N template. The Al/sub 0.18/Ga/sub 0.82/N template was produced by the hetero-epitaxial lateral overgrowth technology on the low-cost sapphire substrate, and has partially low-dislocation density of approximately 2/spl times/10/sup 7/ cm/sup -2/. The lasing operation under pulsed current injection was achieved with the threshold current density of 7.3 kA/cm/sup 2/ and the operating voltage of 10.4 V. 相似文献
773.
Kazuki Kanehara Shingo Urata Sou Yasuhara Takaaki Tsurumi Takuya Hoshina 《Journal of the American Ceramic Society》2023,106(9):5341-5350
Oxide glasses are dielectric materials with potential applications in high-frequency communications; hence, their dielectric properties in the gigahertz to terahertz frequency range should be investigated. In this study, the dielectric properties of silica glass and five single alkali silicate glasses were measured at 0.5–10 THz using terahertz time-domain spectroscopy and far-infrared spectroscopic ellipsometry. At 0.5–10 THz, the silica glass exhibited low dielectric dispersion with a low dielectric constant and loss. By contrast, the alkali silicate glasses exhibited high dielectric dispersion, and the dielectric constant and loss were higher than those of the silica glass. The shape of the dielectric dispersion profile depended on the alkali-metal ions; it was broader for lighter ions such as Li ions and sharper for heavier ions such as Cs ions. The peak dielectric loss shifted toward a lower frequency as the weight of the alkali-metal ions in the alkali-silicate glass increased. To understand the dielectric dispersion, the complex permittivity was calculated using molecular dynamics simulations. The theoretical results qualitatively agreed with the experimental data. Ion dynamics analysis revealed that alkali-metal ions vibrate and migrate under an applied electric field, which affects the dielectric constant and loss of alkali-silicate glasses at gigahertz to terahertz frequencies. To fabricate filter devices at low temperatures, alkali metals should be added to silicate glass; therefore, a minimum amount of light alkali metals should be used to minimize the dielectric loss of the glass materials while maintaining productivity. 相似文献
774.