全文获取类型
收费全文 | 271287篇 |
免费 | 5335篇 |
国内免费 | 2004篇 |
学科分类
工业技术 | 278626篇 |
出版年
2022年 | 1904篇 |
2021年 | 3120篇 |
2020年 | 2339篇 |
2019年 | 2603篇 |
2018年 | 3953篇 |
2017年 | 4129篇 |
2016年 | 4109篇 |
2015年 | 3290篇 |
2014年 | 5217篇 |
2013年 | 12992篇 |
2012年 | 7913篇 |
2011年 | 10298篇 |
2010年 | 8415篇 |
2009年 | 9290篇 |
2008年 | 9780篇 |
2007年 | 9496篇 |
2006年 | 8459篇 |
2005年 | 7372篇 |
2004年 | 6850篇 |
2003年 | 6943篇 |
2002年 | 6347篇 |
2001年 | 6797篇 |
2000年 | 6207篇 |
1999年 | 6566篇 |
1998年 | 16589篇 |
1997年 | 11488篇 |
1996年 | 8868篇 |
1995年 | 6668篇 |
1994年 | 5945篇 |
1993年 | 5879篇 |
1992年 | 4177篇 |
1991年 | 4038篇 |
1990年 | 3886篇 |
1989年 | 3667篇 |
1988年 | 3578篇 |
1987年 | 2979篇 |
1986年 | 2914篇 |
1985年 | 3166篇 |
1984年 | 2904篇 |
1983年 | 2790篇 |
1982年 | 2604篇 |
1981年 | 2500篇 |
1980年 | 2438篇 |
1979年 | 2274篇 |
1978年 | 2089篇 |
1977年 | 2570篇 |
1976年 | 3515篇 |
1975年 | 1734篇 |
1974年 | 1709篇 |
1973年 | 1638篇 |
排序方式: 共有10000条查询结果,搜索用时 997 毫秒
101.
102.
Jonathan K. Dozier Mark D. Distefano 《International journal of molecular sciences》2015,16(10):25831-25864
The use of proteins as therapeutics has a long history and is becoming ever more common in modern medicine. While the number of protein-based drugs is growing every year, significant problems still remain with their use. Among these problems are rapid degradation and excretion from patients, thus requiring frequent dosing, which in turn increases the chances for an immunological response as well as increasing the cost of therapy. One of the main strategies to alleviate these problems is to link a polyethylene glycol (PEG) group to the protein of interest. This process, called PEGylation, has grown dramatically in recent years resulting in several approved drugs. Installing a single PEG chain at a defined site in a protein is challenging. Recently, there is has been considerable research into various methods for the site-specific PEGylation of proteins. This review seeks to summarize that work and provide background and context for how site-specific PEGylation is performed. After introducing the topic of site-specific PEGylation, recent developments using chemical methods are described. That is followed by a more extensive discussion of bioorthogonal reactions and enzymatic labeling. 相似文献
103.
104.
105.
J. Grune K. Sempert M. Kuznetsov T. Jordan 《International Journal of Hydrogen Energy》2021,46(23):12487-12496
This paper presents results of experimental investigations on spherical and cylindrical flame propagation in pre-mixed H2/air-mixtures in unconfined and semi-confined geometries. The experiments were performed in a facility consisting of two transparent solid walls with 1 m2 area and four weak side walls made from thin plastic film. The gap size between the solid walls was varied stepwise from thin layer geometry (6 mm) to cube geometry (1 m). A wide range of H2/air-mixtures with volumetric hydrogen concentrations from 10% to 45% H2 was ignited between the transparent solid walls. The propagating flame front and its structure was observed with a large scale high speed shadow system. Results of spherical and cylindrical flame propagation up to a radius of 0.5 m were analyzed. The presented spherical burning velocity model is used to discuss the self-acceleration phenomena in unconfined and unobstructed pre-mixed H2/air flames. 相似文献
106.
Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid 下载免费PDF全文
Li Li Dan Wang Xihong Li Yu Wang Xiaofeng Ju 《International Journal of Food Science & Technology》2015,50(5):1083-1088
It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO2) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO2 atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO2 atmosphere packaging (80% CO2) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO2 gas atmosphere in package stored at low temperature could result in garlic greening as well. 相似文献
107.
108.
109.
110.