全文获取类型
收费全文 | 2057篇 |
免费 | 79篇 |
国内免费 | 28篇 |
专业分类
电工技术 | 2篇 |
综合类 | 56篇 |
化学工业 | 512篇 |
金属工艺 | 117篇 |
机械仪表 | 183篇 |
建筑科学 | 84篇 |
矿业工程 | 8篇 |
能源动力 | 41篇 |
轻工业 | 429篇 |
水利工程 | 2篇 |
石油天然气 | 69篇 |
无线电 | 137篇 |
一般工业技术 | 312篇 |
冶金工业 | 56篇 |
原子能技术 | 62篇 |
自动化技术 | 94篇 |
出版年
2024年 | 6篇 |
2023年 | 24篇 |
2022年 | 39篇 |
2021年 | 56篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 46篇 |
2017年 | 65篇 |
2016年 | 56篇 |
2015年 | 55篇 |
2014年 | 93篇 |
2013年 | 154篇 |
2012年 | 127篇 |
2011年 | 190篇 |
2010年 | 120篇 |
2009年 | 141篇 |
2008年 | 119篇 |
2007年 | 134篇 |
2006年 | 104篇 |
2005年 | 88篇 |
2004年 | 72篇 |
2003年 | 78篇 |
2002年 | 42篇 |
2001年 | 31篇 |
2000年 | 38篇 |
1999年 | 38篇 |
1998年 | 36篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有2164条查询结果,搜索用时 15 毫秒
101.
Monitoring the performance of systems installed to protect against/halt the corrosion of reinforcing steel in concrete is essential in ensuring that the reinforcing bar (rebar) is adequately protected and remains in a non‐corroding state. A chloride contaminated concrete test block containing a hybrid anode system has been periodically monitored over the past 4.5 years to assess the anode current output and thus, the protection offered to the steel. De‐polarisation and impedance analysis data have been acquired to calculate steel corrosion rates. Both tests indicated that the steel was passive in the concrete environment and that the anode was able to protect all of the embedded steel despite the difficult geometry of the sample. It was also found that after 2 years it was still possible to drive a high current from the installed anode. 相似文献
102.
Sir: A Fortran IV computer program is used to calculate absorbance at varying wavelengths in a UV-visible rapid scanning spectrophotometer. Using the program eliminates the necessity of calibrating the absorbance axis in the usual manner using standard solutions or filters and plotting calibration curves, because the voltage output of the computer is automatically identical to the actual absorbance of a sample. 相似文献
103.
The presence of two carboxylic acid groups and two hydroxyl groups within the novel dye, (E)-4-(4-bis(2-hydroxyethyl)amino)styryl)pyridine-2,6-dicarboxylic acid, resulted in good water solubility. The compound's UV absorption and photoluminescence spectra were each highly pH sensitive in acidic solutions and two isobestic points were observed. The TPA cross-section coefficient and two-photon fluorescence cell imaging of the dye were investigated. 相似文献
104.
This study reported the frequency characteristics of series photodetector frequency circuit system for detection of fluorescence dye concentration. In the condition of the same fluorescence intensity, the series photodetector frequency circuit system with higher responsivity of photodetector had higher frequency shift. The 100 MHz series photodetector frequency circuit system was applied to determine the fluorescence dye concentration of HEX by frequency shift. The correlation curve showed that the frequency shift was linearly related to the logarithm of fluorescence dye concentration from 100 pmol 3 μl−1 to 10 amol 3 μl−1. The proposed method can be applied simply and the detection limit of fluorescence dye concentration was lower than the conventional fluorescence technique by 2–3 orders. 相似文献
105.
Emission from Xe2* excimers exhibiting photon energies between 7 and 10 eV can be used to induce strong surface modification effects on polymeric materials in the top 100 nm layer. In order to identify suitable monomers for this VUV-based process, the photodegradation mechanism of different organosilanes of the general structure R-CH2-Si(OCH3)3 was elucidated by quantum chemical calculations. Herein, the photodegradation of 3-aminopropyltrimethoxysilane films by the use of a 172 nm excimer lamp under different irradiation conditions is described and completed by micropatterning experiments. The presence of 1000-5000 ppm oxygen was found to promote the transformation process to an inorganic-like surface. The films obtained were analyzed by X-ray photoelectron spectroscopy, contact angle measurements and fluorescence microscopy after covalent attachment of a fluorescent dye to the remaining amino groups. Complementary, silver staining was used to visualize photopatterning. 相似文献
106.
107.
108.
109.
The precipitation temperatures of sodium caseinate in H2O and D2O in the presence of Mg2+, Ca2+, Sr2+ and Ba2+ were investigated through fluorescence, turbidity and conductivity experiments. 相似文献
110.
《Food Control》2016
Contamination of food with pathogenic bacteria can lead to foodborne illnesses. Food processing surfaces can serve as a medium for cross-contamination if sanitization procedures are inadequate. Ensuring that food processing surfaces are correctly cleaned and sanitized is important in the food industry to reduce risks of foodborne illnesses and their related costs. A handheld fluorescence imaging device was assessed for detection of three types of food residues that have been associated with foodborne illness outbreaks, i.e. spinach leaf, milk, and bovine red meat, on two commonly used processing surfaces, i.e. high-density polyethylene and food grade stainless steel. Fluorescence excitation at 405 nm was supplied by 4 × 10 W light emitting diodes. Interchangeable optical filters were selected to optimise the contrast between the food residues and processing surfaces, using hyperspectral fluorescence imaging. The fluorescence imaging plus image analysis differentiated food residues from the processing surfaces more clearly than visual inspection in ambient lighting. This optical sensing device can be used to detect food fouling on food processing surfaces over relatively large areas, and has potential for use in the food industry as an aid for detection of specific food residues. 相似文献