全文获取类型
收费全文 | 1390篇 |
免费 | 133篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 403篇 |
金属工艺 | 40篇 |
机械仪表 | 89篇 |
建筑科学 | 37篇 |
能源动力 | 56篇 |
轻工业 | 83篇 |
石油天然气 | 9篇 |
无线电 | 264篇 |
一般工业技术 | 307篇 |
冶金工业 | 23篇 |
原子能技术 | 23篇 |
自动化技术 | 168篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 29篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 41篇 |
2017年 | 58篇 |
2016年 | 47篇 |
2015年 | 57篇 |
2014年 | 68篇 |
2013年 | 119篇 |
2012年 | 111篇 |
2011年 | 117篇 |
2010年 | 85篇 |
2009年 | 86篇 |
2008年 | 90篇 |
2007年 | 50篇 |
2006年 | 59篇 |
2005年 | 51篇 |
2004年 | 67篇 |
2003年 | 38篇 |
2002年 | 49篇 |
2001年 | 30篇 |
2000年 | 37篇 |
1999年 | 23篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1523条查询结果,搜索用时 15 毫秒
101.
Arun Pandian Chandrasekaran Sang Hyeon Woo Neha Sarodaya Byung Ho Rhie Apoorvi Tyagi Soumyadip Das Bharathi Suresh Na Re Ko Seung Jun Oh Kye-Seong Kim Suresh Ramakrishna 《International journal of molecular sciences》2021,22(11)
Cell division cycle 25A (Cdc25A) is a dual-specificity phosphatase that is overexpressed in several cancer cells and promotes tumorigenesis. In normal cells, Cdc25A expression is regulated tightly, but the changes in expression patterns in cancer cells that lead to tumorigenesis are unknown. In this study, we showed that ubiquitin-specific protease 29 (USP29) stabilized Cdc25A protein expression in cancer cell lines by protecting it from ubiquitin-mediated proteasomal degradation. The presence of USP29 effectively blocked polyubiquitination of Cdc25A and extended its half-life. CRISPR-Cas9-mediated knockdown of USP29 in HeLa cells resulted in cell cycle arrest at the G0/G1 phase. We also showed that USP29 knockdown hampered Cdc25A-mediated cell proliferation, migration, and invasion of cancer cells in vitro. Moreover, NSG nude mice transplanted with USP29-depleted cells significantly reduced the size of the tumors, whereas the reconstitution of Cdc25A in USP29-depleted cells significantly increased the tumor size. Altogether, our results implied that USP29 promoted cell cycle progression and oncogenic transformation by regulating protein turnover of Cdc25A. 相似文献
102.
The rich‐hydrogen generation from ethanol steam reforming over NiZr, which is used as an anode material in solid oxide fuel cells, ‐loaded MCM‐48 (NiZr/MCM‐48) catalyst was investigated in this study. We used an impregnation approach to synthesize an MCM‐48 (70.0 wt‐%) support loaded with bimetallic NiZr (30.0‐wt%, Ni:Zr atomic ratio = 4:6, 5:5, and 6:4), and the prepared catalysts were applied to the steam‐reforming reactions of ethanol. These three bimetallic NiZr/MCM‐48 catalysts exhibited significantly higher reforming reactivity than the mono‐metal, Ni‐loaded MCM‐48 (Ni/MCM‐48) catalyst. The hydrogen production was started from 350°C over the three NiZr/MCM‐48 catalysts, compared to above 550°C over the Ni/MCM‐48 catalyst. The catalytic performance was affected by the Zr content. The H2 production and ethanol conversion were maximized at 85% and 95%, respectively, over Ni4Zr6/MCM‐48 at 750°C for 1 h at CH3CH2OH:H2O = 1:1 and a gas hourly space velocity of 4000 h‐1. This high performance was maintained for up to 60 h. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
103.
Accumulating evidence strongly suggests that oxidative stress underlies aging processes. Research provides consistent evidence that calorie restriction (CR) reduces age-related oxidative stress and has anti-inflammatory properties. However, information is lacking on the molecular mechanism that would better define the interrelation of reactive oxygen species and nitrogen species and the pro-inflammatory states of the aging process. In this review, the biochemical and molecular bases of the inflammatory process in the aging process are analyzed to delineate the molecular inflammation hypothesis of aging. The key players involved in the proposed hypothesis are the age-related upregulation of NF-kappa B, IL-1 beta, IL-6, TNFalpha, cyclooxygenase-2, and inducible NO synthase, all of which are attenuated by CR. Furthermore, age-related NF kappa B activation is associated with phosphorylation by I kappa B kinase/NIK and MAPKs, while CR blocked these activation processes. The modulation of these factors provides molecular insights of the anti-inflammatory action of CR in relation to the aging process. Based on available finding and our recent supporting evidence, we prefer to use "molecular inflammation" to emphasize the importance of the molecular reaction mechanisms and their aberrance, predisposing to fully expressed chronic inflammatory phenomena. It was further proposed that CR's major force of the regulation of redox-sensitive inflammation may well be its life-prolonging action. 相似文献
104.
Monolithic integration of tensile-strained Si/ Germanium (Ge)-channel n-MOS and tensile-strained Ge p-MOS with ultrathin (equivalent oxide thickness ~14 Aring) HfO2 gate dielectric and TaN gate stack on Si substrate is demonstrated. Defect-free Ge layer (279 nm) grown by ultrahigh vacuum chemical-vapor deposition is achieved using a two-step Ge-growth technique coupled with compliant Si/SiGe buffer layers. The epi-Ge layer experiences tensile strain of up to ~0.67% and exhibits a peak hole mobility of 250 cm2/V ldr s which is 100% higher than the universal Si hole mobility. The gate leakage current is two orders of magnitude lower compared to the reported results on Ge bulk. 相似文献
105.
Dae Hun Lee Ui Seong Kim Chee Burm Shin Baek Haeng Lee Byung Woo Kim Young-Ho Kim 《Journal of power sources》2008
A three-dimensional modelling approach is used to study the effects of operating and ambient conditions on the thermal behaviour of a NESSCAP 2.7 V/3500 F ultracapacitor cell for a 42-V automotive electrical system. The rate of heat generation of the ultracapacitor during charge and discharge is measured with a calorimeter. The transient temperature distribution of the ultracapacitor during cycling is obtained by using the finite element method with an implicit predictor-multicorrector algorithm. The results show that the temperature of the ultracapacitor cell increases during the first 50 cycles after which it reaches a periodic steady-state value that increases with increasing ambient temperature. 相似文献
106.
107.
108.
109.
110.
Dae Chul Ha Ha Young Lee Yeo Won Son Soon Hong Yuk Youn Woong Choi Byung Kook Kwak Byung Cheol Shin Cheong-Weon Cho Sun Hang Cho 《Nanoscale research letters》2014,9(1):38
The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C16-iron oxide (PHEA-C16-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C16-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C16-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C16. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C16-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C16-iron oxide nanoparticles. Therefore, PHEA-C16-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes. 相似文献