全文获取类型
收费全文 | 42262篇 |
免费 | 4196篇 |
国内免费 | 1269篇 |
专业分类
电工技术 | 1279篇 |
综合类 | 3072篇 |
化学工业 | 12010篇 |
金属工艺 | 1217篇 |
机械仪表 | 1437篇 |
建筑科学 | 3891篇 |
矿业工程 | 408篇 |
能源动力 | 484篇 |
轻工业 | 7892篇 |
水利工程 | 477篇 |
石油天然气 | 458篇 |
武器工业 | 218篇 |
无线电 | 7844篇 |
一般工业技术 | 5181篇 |
冶金工业 | 411篇 |
原子能技术 | 143篇 |
自动化技术 | 1305篇 |
出版年
2024年 | 195篇 |
2023年 | 510篇 |
2022年 | 967篇 |
2021年 | 1120篇 |
2020年 | 1160篇 |
2019年 | 1023篇 |
2018年 | 1023篇 |
2017年 | 1475篇 |
2016年 | 1420篇 |
2015年 | 1571篇 |
2014年 | 2269篇 |
2013年 | 2603篇 |
2012年 | 2928篇 |
2011年 | 2872篇 |
2010年 | 2286篇 |
2009年 | 2418篇 |
2008年 | 2165篇 |
2007年 | 3001篇 |
2006年 | 2938篇 |
2005年 | 2553篇 |
2004年 | 2054篇 |
2003年 | 1676篇 |
2002年 | 1519篇 |
2001年 | 1242篇 |
2000年 | 1012篇 |
1999年 | 824篇 |
1998年 | 593篇 |
1997年 | 464篇 |
1996年 | 361篇 |
1995年 | 333篇 |
1994年 | 311篇 |
1993年 | 242篇 |
1992年 | 190篇 |
1991年 | 161篇 |
1990年 | 97篇 |
1989年 | 52篇 |
1988年 | 30篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1980年 | 9篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
腈纶纤维上油率的稳定控制 总被引:1,自引:0,他引:1
从油剂泵、皮辊和钢罗拉等设备构件运行状态考虑,探讨了腈纶纤维上油率的稳定控制问题。 相似文献
32.
33.
介绍一种新型光纤燃煤炉火焰检测器,阐述其系统组成及特点,并提出了基于模糊推理的多信号融合处理方法。 相似文献
34.
35.
研究结果表明 :水胶比、胶凝材料用量、钢纤维掺量、矿渣代水泥量对钢纤维砼强度影响显著。当矿渣取代水泥 10 %时 ,钢纤维砼强度最高。经试验选择出一个具有良好和易性和较高强度 (118MPa)的钢纤维砼配合比 ,为掺磨细矿渣的中含量超短异形钢纤维砼的设计和施工提供了试验依据 相似文献
36.
37.
This study describes a laboratory method for the estimation of emission from preservative-treated wood in the different situations where emissions could enter the environment for use classes 3 (not in contact with ground) and 4 and 5 (in contact with the ground, fresh water or sea water) according to OECD Guidelines. Samples of scotch pine sapwood (Pinus sylvestris L.) were treated with CCA (1% and 2%), ACQ-1900 (3% and 7%), ACQ-2200 (2%), Tanalith E 3491 (2% and 2.8%), and Wolmanit CX-8 (2%). 相似文献
38.
Interfacial hybridization kinetics of oligonucleotides immobilized onto fused silica surfaces 总被引:3,自引:0,他引:3
Jiang Zeng Amer Almadidy James Watterson Ulrich J. Krull 《Sensors and actuators. B, Chemical》2003,90(1-3):68-75
Fused silica optical fibers have been used in an intrinsic mode optical configuration as biosensors for fluorescence based detection of hybridization of nucleic acids. In this work, the kinetics of hybridization of single-stranded oligonucleotides that were covalently immobilized were studied. The probe DNA was dT20, and the target was Fluorescein-labeled non-complementary (dT20) or complementary (dA20) oligonucleotide. Chronofluorimetric monitoring of the adsorption and hybridization processes was used to investigate oligonucleotide films of different density, in different salt concentrations, at temperatures of 25 and 40 °C, with the concentration of the target DNA being 0.005–0.1 μM. Mathematical models based on first- and second-order Langmuir adsorption have been examined to describe both the adsorption and the hybridization processes. Experimental data were processed using the models, and the hybridization kinetics were calculated. Hybridization kinetics on these optical fiber DNA sensors was found to be up to three orders faster than results presented for a number of other experiments using different immobilization chemistries. 相似文献
39.
CHENSheng-ping LUKe-cheng LIYi-gang LIJia-fang ZHUJian-ping FENGMing LIJing 《半导体光子学与技术》2004,10(2):122-126
The effects of the variations in fiber length, fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs). The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated. By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port, the pump power dependent on MWS becomes independent of pumped EDF length. This is a novel phenomenon that hasn‘t been reported up to now,and should be helpful to SFS fabrication and theory analysis. By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ~20 channels (from 1542nm to 1559nm) is got. The MWFS has a channel spacing of ~0. 8 nm which satisfies ITUstandard. The intensity fluctuation among channels is less than 0.5dB,and the extinction ratio of all channels is above 14dB. This kind of MWFS should be useful to wavelength division multiplexing systems. 相似文献
40.