全文获取类型
收费全文 | 4943篇 |
免费 | 85篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 178篇 |
综合类 | 1篇 |
化学工业 | 993篇 |
金属工艺 | 1618篇 |
机械仪表 | 111篇 |
建筑科学 | 42篇 |
矿业工程 | 1篇 |
能源动力 | 148篇 |
轻工业 | 206篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 352篇 |
一般工业技术 | 570篇 |
冶金工业 | 465篇 |
原子能技术 | 119篇 |
自动化技术 | 225篇 |
出版年
2023年 | 24篇 |
2022年 | 41篇 |
2021年 | 56篇 |
2020年 | 30篇 |
2019年 | 29篇 |
2018年 | 49篇 |
2017年 | 33篇 |
2016年 | 74篇 |
2015年 | 43篇 |
2014年 | 93篇 |
2013年 | 222篇 |
2012年 | 170篇 |
2011年 | 195篇 |
2010年 | 136篇 |
2009年 | 206篇 |
2008年 | 228篇 |
2007年 | 200篇 |
2006年 | 191篇 |
2005年 | 154篇 |
2004年 | 117篇 |
2003年 | 161篇 |
2002年 | 183篇 |
2001年 | 156篇 |
2000年 | 128篇 |
1999年 | 161篇 |
1998年 | 271篇 |
1997年 | 230篇 |
1996年 | 185篇 |
1995年 | 117篇 |
1994年 | 115篇 |
1993年 | 176篇 |
1992年 | 164篇 |
1991年 | 150篇 |
1990年 | 56篇 |
1989年 | 47篇 |
1988年 | 36篇 |
1987年 | 39篇 |
1986年 | 43篇 |
1985年 | 55篇 |
1984年 | 61篇 |
1983年 | 34篇 |
1982年 | 25篇 |
1981年 | 30篇 |
1980年 | 21篇 |
1979年 | 24篇 |
1978年 | 18篇 |
1977年 | 8篇 |
1976年 | 20篇 |
1974年 | 6篇 |
1973年 | 10篇 |
排序方式: 共有5037条查询结果,搜索用时 31 毫秒
1.
Joon‐Young Jun Sosuke Nakajima Koji Yamazaki Yuji Kawai Hajime Yasui Yasuyuki Konishi 《International Journal of Food Science & Technology》2015,50(4):871-877
Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria. 相似文献
2.
3.
Koji Morita Byung-Nam Kim Hidehiro Yoshida Keijiro Hiraga Yoshio Sakka 《Journal of the European Ceramic Society》2018,38(6):2588-2595
Carbon contamination from the carbon paper/dies during spark-plasma-sintering (SPS) processing was examined in the MgAl2O4 spinel. The carbon contamination sensitively changes with the heating rate during the SPS processing. At the high heating rate of 100 °C/min, the carbon contamination having organized structures occurred over almost the entire area from the surface to deep inside the SPSed spinel disk. In contrast, at the slow heating rate of 10 °C/min, the carbon contamination having disordered structures occurred only around the surface area. The carbon phases transform into high pressure CO/CO2 gases by post-annealing in air and lead to pore formation along the grain junctions. The pore formation significantly occurs at the high heating rate due to the large amount of the contaminant carbon phases. This suggests that if once the carbon contamination was formed in the materials, it is very difficult to remove the carbon phases from the materials. 相似文献
4.
5.
6.
K Takeda K Saito K Makino Y Saito S Aoki T Koji K Matsumura Y Nomura T Kitano T Nakagawa 《Canadian Metallurgical Quarterly》1997,38(4):559-563
Due to the changes in the frequency of penicillin-resistant strains of S. pneumoniae, it is necessary to perform surveillance studies of bacterial resistance. Isolates from the upper respiratory tract of asymptomatic children have been useful. There is no information about the difference between isolates from children with and without upper respiratory tract infection (URTI). The objective of the authors in this paper is to establish the prevalence of carrier-state, serotype and antimicrobial resistance of S. pneumoniae isolates from children with and without acute upper respiratory tract infection (URTI) in a rural area in Mexico. A cross-sectional comparative study was performed in Tlaxcala, Mexico. Children from one month 5 years of age were included. Nasopharyngeal swabs were obtained. Identification was done by international microbiology standards. Serotyping was done by the capsular Quellung test. The susceptibility testing was performed by the agar dilution method. Four-hundred and fifty patients were included. S. pneumoniae was isolated in 134 children (29.7%). Frequency of carriers was greater in patients with URTI (107/323) than without URTI (27/127) (33.1% vs. 21.1% p = 0.012, OR 1.84, IC 95% 1.1-3.08). The six most frequent serotypes were: 6B (16.4%); 19F (11.9%); 19A (6.7%); 14, 23F, and 35 (5.2% each), with no difference among the groups. Only 3% of the strains had high level resistance to penicillin, and 12.6% had intermediate resistance, and for ampicillin 4%, amoxicillin 4%, amoxicillin-clavulanate 4%, ceftriaxone 3%, cefotaxime 1.5%, erythromycin 6%, miocamycin 3%, chloramphenicol 4%, and vancomycin 0%. Trimethoprim-sulfamethoxazole resistance was very high (42%). In conclusion, colonization is higher in children with URTI. Five of the most frequent serotypes identified in this study were the same as those identified in patients with S. pneumoniae invasive diseases in Mexico City. In Tlaxcala, Mexico, beta-lactams could be the drug of choice for the treatment of S. pneumoniae lower respiratory tract infections. It is necessary to perform clinical assays to evaluate the efficacy of trimethoprim-sulfamethoxazole due to the high resistance in vitro. 相似文献
7.
8.
9.
10.
H. Okamoto 《Journal of Phase Equilibria and Diffusion》2002,23(4):384-385