全文获取类型
收费全文 | 1421篇 |
免费 | 150篇 |
国内免费 | 67篇 |
专业分类
电工技术 | 54篇 |
综合类 | 109篇 |
化学工业 | 605篇 |
金属工艺 | 18篇 |
机械仪表 | 19篇 |
建筑科学 | 167篇 |
矿业工程 | 13篇 |
能源动力 | 24篇 |
轻工业 | 330篇 |
水利工程 | 16篇 |
石油天然气 | 35篇 |
武器工业 | 10篇 |
无线电 | 64篇 |
一般工业技术 | 92篇 |
冶金工业 | 24篇 |
原子能技术 | 28篇 |
自动化技术 | 30篇 |
出版年
2024年 | 4篇 |
2023年 | 14篇 |
2022年 | 44篇 |
2021年 | 75篇 |
2020年 | 67篇 |
2019年 | 51篇 |
2018年 | 44篇 |
2017年 | 50篇 |
2016年 | 59篇 |
2015年 | 55篇 |
2014年 | 70篇 |
2013年 | 83篇 |
2012年 | 99篇 |
2011年 | 89篇 |
2010年 | 65篇 |
2009年 | 87篇 |
2008年 | 77篇 |
2007年 | 90篇 |
2006年 | 98篇 |
2005年 | 69篇 |
2004年 | 55篇 |
2003年 | 44篇 |
2002年 | 42篇 |
2001年 | 32篇 |
2000年 | 26篇 |
1999年 | 26篇 |
1998年 | 14篇 |
1997年 | 19篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有1638条查询结果,搜索用时 15 毫秒
91.
以黄瓜为例 ,研究了其切割后经臭氧、涂膜、低温等处理后的物理、生理变化 .结果表明 ,黄瓜经过 4 .2mg/m3质量浓度的臭氧水以及涂膜配方C处理后具有较好的保鲜效果 ,能抑制最小加工黄瓜的呼吸作用 ,阻止可溶性固形物的分解 ,以及营养成分的损失 ,并有效地抑制酶促褐变 . 相似文献
92.
前途光明的臭氧漂白技术 总被引:2,自引:1,他引:2
本文介绍了臭氧漂白的漂白原理、发展过程及世界臭氧漂白的最新发展,展望了臭氧漂白的光明前景. 相似文献
93.
94.
95.
96.
Abstract: Durum wheat grain from the field is naturally contaminated with bacteria, yeast, and mold. The reduction in aerobic plate count (APC) and yeast and mold count (YMC) is often necessary before processing wheat. Gaseous ozone, ozonated water, and acetic acid solution are nontraditional antimicrobial agents for grains and are safe for humans and the environment. Better disinfection may be possible by applying antimicrobial agents to grain in a fluidized state. Fluidization increases the exposure of grain surfaces, resulting in uniform and quick contact of grain with antimicrobial agents. Therefore, a fluidized bed was developed with automated spraying system (to spray treatment waters), and a port for gaseous ozone injection. The pressures and velocities within the fluidized bed system were measured to characterize the system. The treatments used on fluidized grain were: distilled water (control), gaseous ozone (6 ppm), ozonated water (23 mg/L), gaseous ozone + ozonated water (6 ppm, 23 mg/L), acetic acid solution (0.5%), acetic acid + ozonated water (0.5%, 26 mg/L), and gaseous ozone + acetic acid + ozonated water (6 ppm, 0.5%, 26 mg/L). The last of these treatments was most effective with 1.7 and 3.3 log reduction in APC and YMC, respectively. This combined treatment can be used to replace the chlorinated water that industry uses during tempering of grain. Ozonated water alone resulted in a 0.3 log reduction in both APC and YMC. Gaseous ozone alone did not cause a significant reduction in APC and YMC. 相似文献
97.
Daniel Cassidy Abraham Northup Duane Hampton 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(6):820-826
BACKGROUND: Recent studies indicate that chemical oxidation may be compatible with subsequent biodegradation in contaminated soils. To test this, soil contaminated with 2,4‐dinintrotoluene (2,4‐DNT) was treated in batch slurry reactors with (1) ozone, (2) modified Fenton chemistry (MFC), and (3) iron‐activated sodium persulfate (SPS). Chemical and subsequent biological oxidation were monitored, and compared with biodegradation alone. Release of nitrite and nitrate distinguished biological from chemical oxidation of 2,4‐DNT, respectively. DNT‐degrading microorganisms were enumerated. The disappearance of volatile fatty acids (VFAs) accumulated during chemical oxidation was also monitored. RESULTS: In the biological reactor 66% of the 2,4‐DNT was degraded, but further biodegradation was inhibited by nitrite concentrations approaching 18 mmol L?1. At the doses tested, all oxidants achieved chemical oxidation followed by biodegradation, resulting in 98% DNT removal overall. Ozone achieved the greatest DNT removal (70%), but also caused the greatest reduction in DNT degraders and the longest rebound time (60 days) before biodegradation of the remaining DNT and VFAs. SPS resulted in the least DNT removal by chemical oxidation (37%), but showed no obvious rebound period for DNT degraders, and even signs of co‐existing chemical and biological oxidation. By releasing nitrate, which is less toxic than nitrite, the oxidants kept nitrite levels below 18 mmol L?1, enabling the follow‐on biodegradation step to attain lower concentrations of 2,4‐DNT than biodegradation alone. CONCLUSIONS: All three chemical oxidants were compatible with biodegradation of residual 2,4‐DNT. Post‐oxidation bioremediation should be included in remedial designs. Copyright © 2009 Society of Chemical Industry 相似文献
98.
A life cycle optimization model intended to potentially reduce the environmental impacts of energy use in commercial buildings is presented. A combination of energy simulation, life cycle assessment, and operations research techniques are used to develop the model. In addition to conventional energy systems, such as the electric grid and a gas boiler, cogeneration systems which concurrently generate power and heat are investigated as an alternative source of energy. Cogeneration systems appeared to be an attractive alternative to conventional systems when considering life cycle environmental criteria. Internal combustion engine and microturbine (MT) cogeneration systems resulted in a reduction of up to 38% in global warming potential compared with conventional systems, while solid oxide fuel cell and MT cogeneration systems resulted in a reduction of up to 94% in tropospheric ozone precursor potential (TOPP). Results include a Pareto-optimal frontier between reducing costs and reducing the selected environmental indicators. 相似文献
99.
通过臭氧氧化改性方法制备含有大量含氧官能团的改性碳纳米管(CNT)。采用有机元素分析、X射线光电子能谱(XPS)元素分析以及Boehm滴定法分别测得样品的表面含氧量、总含氧量以及不同含氧官能团含量,并对产物的比表面积、孔体积和孔径进行测定。结果表明,改性后含氧功能团数量增加了3~7倍,并且这种臭氧改性技术受温度影响显著。然后,考察了改性CNT对铀的吸附性能,对吸附条件进行优化。结果表明,未经改性的CNT样品的吸附效果较差,铀去除率仅为78.0%,而改性后的CNT对铀的吸附效果有显著提高,铀去除率高达95.0%以上,表明含氧量的增加显著提高了改性物对铀的吸附效果。 相似文献
100.
It is shown to be theoretically possible to balance out almost completely the total error in measurements with a three-wave
ozone meter used to determine the total ozone content in the atmosphere. The working algorithm is given together with the
theoretical basis for the compensation condition.
__________
Translated from Izmeritel'naya Tekhnika, No. 8, pp. 66–68, August, 2005. 相似文献