全文获取类型
收费全文 | 289478篇 |
免费 | 21486篇 |
国内免费 | 11100篇 |
专业分类
电工技术 | 15392篇 |
技术理论 | 31篇 |
综合类 | 17435篇 |
化学工业 | 50190篇 |
金属工艺 | 16873篇 |
机械仪表 | 18428篇 |
建筑科学 | 22869篇 |
矿业工程 | 9524篇 |
能源动力 | 7956篇 |
轻工业 | 16663篇 |
水利工程 | 4781篇 |
石油天然气 | 20256篇 |
武器工业 | 2234篇 |
无线电 | 31465篇 |
一般工业技术 | 34400篇 |
冶金工业 | 15268篇 |
原子能技术 | 2860篇 |
自动化技术 | 35439篇 |
出版年
2024年 | 1217篇 |
2023年 | 4677篇 |
2022年 | 7918篇 |
2021年 | 11473篇 |
2020年 | 8528篇 |
2019年 | 7274篇 |
2018年 | 8168篇 |
2017年 | 9216篇 |
2016年 | 8023篇 |
2015年 | 11168篇 |
2014年 | 13769篇 |
2013年 | 16443篇 |
2012年 | 17749篇 |
2011年 | 19400篇 |
2010年 | 16749篇 |
2009年 | 15901篇 |
2008年 | 15437篇 |
2007年 | 15085篇 |
2006年 | 15973篇 |
2005年 | 14146篇 |
2004年 | 9049篇 |
2003年 | 7906篇 |
2002年 | 7304篇 |
2001年 | 6484篇 |
2000年 | 7099篇 |
1999年 | 8499篇 |
1998年 | 6845篇 |
1997年 | 5823篇 |
1996年 | 5450篇 |
1995年 | 4507篇 |
1994年 | 3757篇 |
1993年 | 2629篇 |
1992年 | 2136篇 |
1991年 | 1601篇 |
1990年 | 1173篇 |
1989年 | 933篇 |
1988年 | 759篇 |
1987年 | 523篇 |
1986年 | 390篇 |
1985年 | 266篇 |
1984年 | 183篇 |
1983年 | 120篇 |
1982年 | 130篇 |
1981年 | 86篇 |
1980年 | 70篇 |
1979年 | 24篇 |
1978年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
991.
992.
Hao Long Yang Wei Tongjun Yu Zhe Wang Chuanyu Jia Zhijian Yang Guoyi Zhang Shoushan Fan 《Nano Research》2012,5(9):646-653
A novel carbon nanotube-patterned sapphire substrate (CPSS) has been utilized for the growth of GaN material and fabrication of a InGaN/GaN light emitting diode (LED) by metal-organic vapor phase epitaxy. Different lateral strain distributions and stress reductions were observed in a GaN thin film on CPSS compared with those on a conventional sapphire substrate. Nanoheteroepitaxy induced by small size nucleation islands of about 50 nm is ascribed to this significant strain modulation. The crystalline quality of the GaN thin film was also improved, as illustrated by X-ray diffraction. Performances of 1 mm × 1 mm LEDs on CPSS were also enhanced, with an operational power increase of 37.5% and higher saturation current. 相似文献
993.
Fei Li Heqiu Zhang Lizhong Hu Yingmin Luo Yu Zhao Yu Qiu Jiuyu Ji Lunlun Yue 《Journal of Materials Science: Materials in Electronics》2013,24(12):4812-4816
One-dimensional (1D) ZnO microwires were successfully synthesized by chemical vapor deposition and their structural and morphological properties were analyzed by X-ray diffraction and scanning electron microscopy, demonstrating that the microwires were single crystalline with perfect hexagonal structure and smooth surface. Using these 1D microstructures, we fabricated a novel ZnO-based ethanol gas sensor. Operating at room temperature, the sensor was found to have good sensing characteristics. The reliability and stability of the sensor could be improved by connecting multiple 1-wire devices (1-WD) in parallel into a multi-wires device. In interior natural lighting environment and under 3 V bias, the response and recovery time of the 1-WD to 200 ppm ethanol gas were <10 s and about 300 s, respectively, and the minimum and maximum detection limit were about 2 and 200 ppm, respectively. A sensing model was proposed for discussing the performance of the sensor. The simplicity in fabrication, low power consumption and low cost make the sensor suitable for practical application in many fields, especially in identifying driving under the influence and chemical industry monitoring. 相似文献
994.
超声波流量测量技术及发展 总被引:1,自引:0,他引:1
本文叙述了超声波流量测量的原理、基本测量方法以及传统的多普勒和时差法超声波流量计的缺陷和测量局限性,分析了超声波流量测量最新进展所采取的新的测量技术和方法,并介绍了超声波相关流量计的原理和技术特点. 相似文献
995.
Lithium‐Ion Batteries: Excimer Ultraviolet‐Irradiated Carbon Nanofibers as Advanced Anodes for Long Cycle Life Lithium‐Ion Batteries (Small 38/2016) 下载免费PDF全文
996.
Artificial Protection Film on Lithium Metal Anode toward Long‐Cycle‐Life Lithium‐Oxygen Batteries 下载免费PDF全文
997.
On the basis of a novel phase modulation method by in-plane diffraction processes, a well-designed nanoarray on metal surface is proposed to realize a broad band focusing (bandwidth ~100 nm) and a demultiplexing element (resolution ~12 nm) of surface plasmon polariton (SPP) waves. Moreover, sublattice arrays are developed to achieve an improved demultiplexer and confocal SPP beams. The proposed scheme with implemented functionalities is designed totally in planar dimension, which is free of the SPP coupling process and indicates more practical application in photonic integrations. 相似文献
998.
999.
1000.
Feng Wang Frank Stappenbeck Liu-Ya Tang Ying E. Zhang Simon T. Hui Aldons J. Lusis Farhad Parhami 《International journal of molecular sciences》2022,23(10)
Inflammatory responses by the innate and adaptive immune systems protect against infections and are essential to health and survival. Many diseases including atherosclerosis, osteoarthritis, rheumatoid arthritis, psoriasis, and obesity involve persistent chronic inflammation. Currently available anti-inflammatory agents, including non-steroidal anti-inflammatory drugs, steroids, and biologics, are often unsafe for chronic use due to adverse effects. The development of effective non-toxic anti-inflammatory agents for chronic use remains an important research arena. We previously reported that oral administration of Oxy210, a semi-synthetic oxysterol, ameliorates non-alcoholic steatohepatitis (NASH) induced by a high-fat diet in APOE*3-Leiden.CETP humanized mouse model of NASH and inhibits expression of hepatic and circulating levels of inflammatory cytokines. Here, we show that Oxy210 also inhibits diet-induced white adipose tissue inflammation in APOE*3-Leiden.CETP mice, evidenced by the inhibition of adipose tissue expression of IL-6, MCP-1, and CD68 macrophage marker. Oxy210 and related analogs exhibit anti-inflammatory effects in macrophages treated with lipopolysaccharide in vitro, mediated through inhibition of toll-like receptor 4 (TLR4), TLR2, and AP-1 signaling, independent of cyclooxygenase enzymes or steroid receptors. The anti-inflammatory effects of Oxy210 are correlated with the inhibition of macrophage polarization. We propose that Oxy210 and its structural analogs may be attractive candidates for future therapeutic development for targeting inflammatory diseases. 相似文献