全文获取类型
收费全文 | 110412篇 |
免费 | 9943篇 |
国内免费 | 5845篇 |
专业分类
电工技术 | 6374篇 |
技术理论 | 7篇 |
综合类 | 7975篇 |
化学工业 | 18022篇 |
金属工艺 | 6630篇 |
机械仪表 | 6950篇 |
建筑科学 | 8086篇 |
矿业工程 | 3481篇 |
能源动力 | 3087篇 |
轻工业 | 8933篇 |
水利工程 | 2183篇 |
石油天然气 | 6486篇 |
武器工业 | 910篇 |
无线电 | 12144篇 |
一般工业技术 | 12720篇 |
冶金工业 | 5283篇 |
原子能技术 | 1294篇 |
自动化技术 | 15635篇 |
出版年
2024年 | 519篇 |
2023年 | 1772篇 |
2022年 | 3252篇 |
2021年 | 4433篇 |
2020年 | 3342篇 |
2019年 | 2945篇 |
2018年 | 3333篇 |
2017年 | 3668篇 |
2016年 | 3389篇 |
2015年 | 4475篇 |
2014年 | 5674篇 |
2013年 | 6721篇 |
2012年 | 7371篇 |
2011年 | 8136篇 |
2010年 | 7430篇 |
2009年 | 6979篇 |
2008年 | 6792篇 |
2007年 | 6510篇 |
2006年 | 6233篇 |
2005年 | 5273篇 |
2004年 | 3845篇 |
2003年 | 3524篇 |
2002年 | 3760篇 |
2001年 | 3172篇 |
2000年 | 2436篇 |
1999年 | 2328篇 |
1998年 | 1630篇 |
1997年 | 1388篇 |
1996年 | 1368篇 |
1995年 | 1051篇 |
1994年 | 803篇 |
1993年 | 617篇 |
1992年 | 472篇 |
1991年 | 365篇 |
1990年 | 268篇 |
1989年 | 217篇 |
1988年 | 191篇 |
1987年 | 123篇 |
1986年 | 94篇 |
1985年 | 50篇 |
1984年 | 49篇 |
1983年 | 38篇 |
1982年 | 42篇 |
1981年 | 16篇 |
1980年 | 28篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Zhi‐Long Ye Min Lu Yan Zheng Ya‐Hong Li Wei‐Min Cai 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(11):1541-1550
BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO3 had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g?1 dried food waste, a protease activity of 2.12 U g?1 dried food waste, a temperature of 29.31 °C and a CaCO3 concentration of 62.67 g L?1, which resulted in a maximum lactic acid concentration of 98.51 g L?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry 相似文献
82.
In this research, Ni/SiO2 catalyst was modified with different amount of Gd2O3 and characterized with temperature-programmed desorption of CO2 (CO2-TPD) and NH3 (NH3-TPD), temperature-programmed reduction with H2 (H2-TPR) and X-ray diffraction (XRD). It was found that Gd2O3-modified Ni/SiO2 catalysts possessed higher CO2 adsorption and activation ability due to the formation of surface carbonate species. H2-TPR and XRD characterizations found that the strong interaction among nickel, Gd2O3 and SiO2 took place, which improved the dispersion of Ni. Gd2O3-modified Ni/SiO2 catalysts exhibited higher activity and stability for the combined oxy-CO2 reforming of methane in fluidized-bed reactor. The H2/CO ratio in produced syngas could be controlled via controlling reaction temperature and CO2/O2 ratio in feed. 相似文献
83.
84.
85.
86.
现场总线控制系统浅谈 总被引:1,自引:0,他引:1
简述了现场总线控制系统的结构及其显优点。现场总线控制系统的结构包括:主控器、总线接口、电源、输入/输出接点、总线电揽和终端电阻。另外对其显优点做了逐一介绍。现场总线控制系统可在工业自动化控制系统中推广应用。 相似文献
87.
Woo Yong Sung Seung Min Lee Wal Jun Kim Jong Girl Ok Ho Young Lee Yong Hyup Kim 《Diamond and Related Materials》2008,17(6):1003-1007
Complementary electroplating combined with electrophoresis enhanced the field emission characteristics of emitters by improving the adhesions between CNT emitters and substrate. The emitting current of the CNT emitters prepared by our combined method increased nine times higher than that of CNT emitters prepared by electrophoresis only, since electroplating improved the adhesion of CNT emitters. During the life-time measurement for 10 h, the emitting current of CNT emitters fabricated by electrophoresis only was drastically decreased to 13% of the initial current, while that prepared by the combination of electrophoresis and successive electroplating decreased to 64% of the initial current. We suggest that our method is a promising approach for the efficient fabrication of reliable CNT emitters. 相似文献
88.
In this work the synergistic effects of microwave (MW) irradiation induced oxidation processes and CoFe2O4 were studied for the degradation of brilliant green (BG) from aqueous solutions. Under the optimum condition, the ratio of solid to liquid was 1:167 (0.3 g CoFe2O4 mixed with 50 mL of 20 mg L−1 BG solution), MW power 600 W, and the time of the irradiation 2 min. And the decolorization rate could reach up to 100%. Further investigation showed that BG was degraded by MW-induced oxidation combined with CoFe2O4 surface adsorption. The CoFe2O4 could increase the efficiencies of MW degradation and be used repeatedly. The experimental results indicated that the method of MW degradation BG in the presence of CoFe2O4 could reduce reaction time and increase product yield. 相似文献
89.
分析了湿法成形薄型陶瓷砖干燥的特点.具体讨论了微波干燥和少空气干燥方式在湿法薄形陶瓷砖干燥上中应用及干燥过程中坯体传动方式的选择。 相似文献
90.