全文获取类型
收费全文 | 1769篇 |
免费 | 80篇 |
国内免费 | 54篇 |
专业分类
电工技术 | 42篇 |
综合类 | 29篇 |
化学工业 | 161篇 |
金属工艺 | 44篇 |
机械仪表 | 48篇 |
建筑科学 | 59篇 |
矿业工程 | 21篇 |
能源动力 | 15篇 |
轻工业 | 77篇 |
水利工程 | 9篇 |
石油天然气 | 31篇 |
武器工业 | 2篇 |
无线电 | 121篇 |
一般工业技术 | 131篇 |
冶金工业 | 982篇 |
原子能技术 | 17篇 |
自动化技术 | 114篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 27篇 |
2021年 | 28篇 |
2020年 | 21篇 |
2019年 | 28篇 |
2018年 | 19篇 |
2017年 | 40篇 |
2016年 | 33篇 |
2015年 | 41篇 |
2014年 | 22篇 |
2013年 | 60篇 |
2012年 | 40篇 |
2011年 | 77篇 |
2010年 | 37篇 |
2009年 | 50篇 |
2008年 | 50篇 |
2007年 | 29篇 |
2006年 | 42篇 |
2005年 | 50篇 |
2004年 | 30篇 |
2003年 | 19篇 |
2002年 | 27篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 43篇 |
1998年 | 275篇 |
1997年 | 165篇 |
1996年 | 123篇 |
1995年 | 60篇 |
1994年 | 59篇 |
1993年 | 65篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 17篇 |
1987年 | 17篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 27篇 |
1976年 | 69篇 |
1975年 | 2篇 |
1974年 | 3篇 |
排序方式: 共有1903条查询结果,搜索用时 15 毫秒
1.
Combination of heat treatment and chitosan coating to improve postharvest quality of wolfberry (Lycium barbarum) 下载免费PDF全文
Zhaojun Ban Wenwen Wei Xiangzheng Yang Jianhua Feng Junfeng Guan Li Li 《International Journal of Food Science & Technology》2015,50(4):1019-1025
The synergistic application of hot water dip at 42 °C for 30 min and 1% chitosan coating on differentiation in postharvest quality traits, microstructure as well as microbiological evolution of wolfberry fruits was investigated. Fresh wolfberry fruits were stored at 2 ± 0.5 °C and 90% relative humidity (RH) for 28 days. Results indicated the combination of prestorage heat treatment and chitosan coating maintained higher levels of ascorbic acid, total phenolic contents and antioxidant capacity as well as lower decay, compared with untreated wolfberry fruits. The possible mechanism was that the heat treatment almost sealed open stomata to limit the sites of pathogen penetration into fruits independently, followed by the biofilm formed by chitosan which controlled secondary infections as well as slowed changes in fruit respiration and metabolic activity in wolfberries. The synergistically treated fruit also exhibited a higher acceptability obtained by sensory analysis after cold storage. In this sense, the integrated application of heat treatment and chitosan coating could be regarded as an effective strategy to extend storage life and maintain the postharvest quality of wolfberry fruits. 相似文献
2.
3.
4.
Osteomyelitis in uncommon locations can present unusual diagnostic difficulties. A patient with primary sternal osteomyelitis who presented with pain over the right supraclavicular area and a radiologic picture of a pleural-based right upper lung mass is discussed. A triple-phase bone scan was consistent with the diagnosis, and a needle aspiration of the mass revealed a staphylococcal abscess. Percutaneous drainage of the contiguous abscess and a prolonged course of antibiotic therapy cured the infection. 相似文献
5.
6.
7.
8.
9.
10.
D Jacob-Wilk EE Goldschmidt J Riov A Sadka D Holland 《Canadian Metallurgical Quarterly》1997,35(5):661-666
In response to a light pulse, hamsters normally generate phase advances that are positively correlated with the length of their circadian period (tau). To determine whether this is a general property of the phase-shifting oscillator, the present study looked for a correlation between tau and phase-advance size not only for photic but also for nonphotic shifts. Syrian hamsters, Mesocricetus auratus, were entrained to light-dark cycles with a periodicity of either 23.67 h (the short-T group) or 24.33 h (the long-T group); after release into constant darkness, the short-T and long-T groups exhibited short and long taus, respectively. These animals were then induced to run in a novel exercise wheel for 3 h, starting at circadian time (CT) 7, or were exposed to 20 min of light, starting at CT 19. The size of the ensuing phase advances did not differ between the short-T and long-T groups not only for the nonphotic stimulus but also for the photic one, an unexpected result for the photic stimulus. Within the short-T groups for photic and nonphotic stimuli, the shorter tau was, the larger the phase advances were, another unexpected relationship. Another experiment where phase delays were induced by light pulses at CT 15 also failed to yield significant differences between the short-T and long-T groups. Independently of their after-effects on tau, T cycles may influence the capacity of the pacemaker to phase shift in ways that are still unclear but at least similar for both photic and nonphotic shifts. 相似文献