全文获取类型
收费全文 | 540篇 |
免费 | 14篇 |
专业分类
综合类 | 1篇 |
化学工业 | 211篇 |
金属工艺 | 8篇 |
机械仪表 | 10篇 |
建筑科学 | 18篇 |
能源动力 | 15篇 |
轻工业 | 116篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 79篇 |
冶金工业 | 39篇 |
原子能技术 | 10篇 |
自动化技术 | 29篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 34篇 |
2012年 | 31篇 |
2011年 | 30篇 |
2010年 | 16篇 |
2009年 | 25篇 |
2008年 | 35篇 |
2007年 | 30篇 |
2006年 | 30篇 |
2005年 | 27篇 |
2004年 | 33篇 |
2003年 | 24篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有554条查询结果,搜索用时 187 毫秒
551.
The quantitative analysis of amino acids by terahertz (THz) time-domain absorption spectroscopy is demonstrated. The optical densities of the amino acids were found to be linearly proportional to the concentration. The molar absorption coefficients of L-glutamic acid (L-Glu), L-glutamic acid sodium salt (Na-L-Glu), L-glutamic acid hydrochloric salt (HCl-L-Glu), L-cysteine (L-Cys), and L-histidine (L-His) were calculated by averaging the THz spectra of the amino acids at several different concentrations in approximately the 0.2-1.0 mol L(-1) range. The concentrations of L-Glu, L-Cys, and L-His mixed samples were successfully calculated with errors of less than 11% and 20% when their concentrations were higher than 0.45 and 0.22 mol L(-1), respectively, by using the obtained molar absorption coefficient. 相似文献
552.
Arisa Kawamukai Ayana Iwano Momoka Shibata Yuko Kishi Akira Matsuura 《Yeast (Chichester, England)》2023,40(2):59-67
Changes in extracellular pH affect the homeostasis and survival of unicellular organisms. Supplementation of culture media with amino acids can extend the lifespan of budding yeast, Saccharomyces cerevisiae, by alleviating the decrease in pH. However, the optimal amino acids to use to achieve this end, and the underlying mechanisms involved, remain unclear. Here, we describe the specific role of serine metabolism in the regulation of pH in a medium. The addition of serine to synthetic minimal medium suppressed acidification, and at higher doses increased the pH. CHA1, which encodes a catabolic serine hydratase that degrades serine into ammonium and pyruvate, is essential for serine-mediated alleviation of acidification. Moreover, serine metabolism supports extra growth after glucose depletion. Therefore, medium supplementation with serine can play a prominent role in the batch culture of budding yeast, controlling extracellular pH through catabolism into ammonium and acting as an energy source after glucose exhaustion. 相似文献
553.
Phosphate diesters of waxy maize starch were prepared by crossbonding reactions using various concentrations of phosphorus oxychloride (POCl3) under conditions of controlled pH and temperature in order to have the modified starch with better functional properties. The waxy maize starch treated with 350 ppm POCl3 (D. B.) showed higher paste viscosity and better heat resistance and acid proofing at a range of pH 3.0–4.0 than the unmodified starch and the other diesters prepared using 250–1,000 ppm POCl3. The viscosity at 25°C of 4% pastes, added salt, sugar and acid simulating a kind of brown sauce and cooked at 95°C for 10 min, containing the diester prepared by either 350 or 1,000 ppm POCl3, was higher and more stable in a refrigerator up to 4 months than that of the unmodified waxy maize starch. Application of the diester (1,000 ppm POCl3) to an effective thickener for “instant Miso soup” was also investigated. 相似文献
554.