全文获取类型
收费全文 | 3674篇 |
免费 | 167篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 41篇 |
综合类 | 11篇 |
化学工业 | 937篇 |
金属工艺 | 79篇 |
机械仪表 | 38篇 |
建筑科学 | 197篇 |
矿业工程 | 9篇 |
能源动力 | 93篇 |
轻工业 | 252篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
无线电 | 355篇 |
一般工业技术 | 882篇 |
冶金工业 | 403篇 |
原子能技术 | 30篇 |
自动化技术 | 493篇 |
出版年
2023年 | 49篇 |
2022年 | 64篇 |
2021年 | 121篇 |
2020年 | 73篇 |
2019年 | 74篇 |
2018年 | 78篇 |
2017年 | 70篇 |
2016年 | 114篇 |
2015年 | 80篇 |
2014年 | 146篇 |
2013年 | 180篇 |
2012年 | 184篇 |
2011年 | 239篇 |
2010年 | 149篇 |
2009年 | 165篇 |
2008年 | 169篇 |
2007年 | 163篇 |
2006年 | 169篇 |
2005年 | 138篇 |
2004年 | 123篇 |
2003年 | 100篇 |
2002年 | 90篇 |
2001年 | 72篇 |
2000年 | 63篇 |
1999年 | 66篇 |
1998年 | 105篇 |
1997年 | 77篇 |
1996年 | 73篇 |
1995年 | 55篇 |
1994年 | 55篇 |
1993年 | 36篇 |
1992年 | 28篇 |
1991年 | 37篇 |
1990年 | 39篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 22篇 |
1986年 | 15篇 |
1985年 | 20篇 |
1984年 | 21篇 |
1983年 | 24篇 |
1982年 | 20篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1977年 | 21篇 |
1976年 | 31篇 |
1973年 | 12篇 |
1969年 | 13篇 |
排序方式: 共有3845条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
J Macas J Dolezel G Gualberti U Pich I Schubert S Lucretti 《Canadian Metallurgical Quarterly》1995,19(3):402-4; 407-8
A protocol for primed in situ DNA labeling (PRINS) was optimized for pea (Pisum sativum L.) and field bean (Vicia faba L.) chromosomes attached to coverslips. Cloned DNA or synthetic oligonucleotides were used as probes for repetitive DNA sequences (rDNA, Fok-element) and different reaction conditions were tested to achieve the highest specific signal-to-background ratio. A procedure based on direct labeling by fluorescein-dUTP was compared with an indirect one using digoxigenin detected by fluorescently labeled antibody. Under optimal conditions, strong and specific signals were obtained exclusively on chromosome regions known to contain respective DNA sequences. Compared to the direct labeling, significantly stronger signals were obtained when the indirect procedure was used. Both types of labeling were successfully applied to chromosomes in suspension and were shown to produce signals comparable to that obtained with chromosomes attached to coverslips. It is expected that primed in situ DNA labeling en suspension (PRINSES) will provide a basis for flow-cytometric discrimination and sorting of otherwise indistinguishable chromosomes according to their specific fluorescent labeling. 相似文献
7.
Schubert E.F. Hunt N.E.J. Malik R.J. Micovic M. Miller D.L. 《Lightwave Technology, Journal of》1996,14(7):1721-1729
Resonant-cavity light-emitting diodes (RCLED) are novel, high-efficiency light-emitting diodes which employ optical microcavities. These diodes have higher intensities and higher spectral purity as compared to conventional LEDs. Analytical formulas are derived for the enhancement of the spontaneous emission along the optical axis of the cavity. The design rules for high-efficiency operation of RCLEDs are established. The temperature dependence of the emission intensity is analyzed in the range 20-80° and it is described by an exponential dependence with a characteristic temperature of 112 K. The modulation characteristics of RCLEDs exhibit 3 dB frequencies of 580 MHz. Eye diagrams at transmission rates of 622 Mb/s are wide open indicating the suitability of RCLEDs for high-speed data transmission 相似文献
8.
9.
10.