全文获取类型
收费全文 | 2181篇 |
免费 | 57篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 119篇 |
综合类 | 1篇 |
化学工业 | 728篇 |
金属工艺 | 67篇 |
机械仪表 | 98篇 |
建筑科学 | 31篇 |
能源动力 | 110篇 |
轻工业 | 151篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 130篇 |
一般工业技术 | 450篇 |
冶金工业 | 102篇 |
原子能技术 | 93篇 |
自动化技术 | 159篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 26篇 |
2021年 | 47篇 |
2020年 | 21篇 |
2019年 | 20篇 |
2018年 | 42篇 |
2017年 | 23篇 |
2016年 | 55篇 |
2015年 | 35篇 |
2014年 | 66篇 |
2013年 | 137篇 |
2012年 | 99篇 |
2011年 | 122篇 |
2010年 | 99篇 |
2009年 | 139篇 |
2008年 | 131篇 |
2007年 | 125篇 |
2006年 | 112篇 |
2005年 | 87篇 |
2004年 | 64篇 |
2003年 | 87篇 |
2002年 | 67篇 |
2001年 | 44篇 |
2000年 | 47篇 |
1999年 | 59篇 |
1998年 | 51篇 |
1997年 | 36篇 |
1996年 | 46篇 |
1995年 | 26篇 |
1994年 | 21篇 |
1993年 | 28篇 |
1992年 | 20篇 |
1991年 | 22篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 28篇 |
1984年 | 28篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有2246条查询结果,搜索用时 15 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.
4.
Electromechanical transducers for sensing and actuating disturbances or vibrations have been used in many fields of applications. There have been transducers of different configuration developed for the unidirectional transduction. This paper demonstrates a single element transducer for tri-axial components made of a piezoelectric cylindrical shell. The separation of the tri-axial transductions is achieved by devising a proper electrode arrangement. The structure and the fundamental idea are first presented, and then the numerical analysis by means of the finite element modeling follows, and their characteristics and behaviors are then experimentally verified. 相似文献
5.
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
6.
7.
Zhishen Wu Yixin Shao Kentaro Iwashita Koji Sakamoto 《Canadian Metallurgical Quarterly》2007,11(3):299-307
Reinforced concrete (RC) beams subject to service loads of 40 or 60% of steel yielding were strengthened using hybrid continuous carbon fiber sheets. The hybrid systems were made of high-strength and high-modulus carbon sheets, and compared with systems using only high-strength carbon. It was found that the use of high-modulus carbon sheets in hybrid systems could increase the yielding load, the flexural stiffness, the postyielding ductility, and reduce the crack opening in concrete. The slope changes on load-deflection curves at steel yielding are not noticeable in hybrid systems. The tensile strains developed in hybrid sheets after the fracture of high-modulus carbon are higher in magnitude and distributed in a larger area, leading to an ultimate carbon fracture with concrete crushing. These unique features are attributed to the high stiffness and low ultimate tensile strain of the high-modulus carbon fibers which stiffen the structures, avoid or delay the fiber-reinforced polymer debonding, and facilitate the deformability during their subsequent breakdown. 相似文献
8.
E Kobayashi Y Yoshida A Fujimura T Yamanaka H Endo T Hamamoto Y Kagawa 《Canadian Metallurgical Quarterly》1997,24(12):1775-1777
We studied the in vivo gene transfusion using a gene gun, formerly used in plants and culture cells. The hand-held type gene gun (Helios Gene Gun System) is simple and convenient for effective gene transfection in living animals. This method has some advantages in that there is no need for use of viral vector, independence on the cell cycle and local inducement of plural genes. There is a great possibility for application to local-regional cancer. 相似文献
9.
Analoni M. Kagawa Y. Kagami Y. Nishimura F. 《Electromagnetic Compatibility, IEEE Transactions on》1995,37(3):443-448
High-frequency (HF) operated lamps, such as HF fluorescent lamps, have several advantages over conventional ones but they contaminate the environment with their EM field emissions. The shielding of the electromagnetic emission should be realized without much effect on the emission of the light. Enclosing the lamps in a housing made of widely spaced thin wires could be an appropriate way to shield the electromagnetic field. The paper studies the effectiveness of some wire structures for shielding the electromagnetic emission from HF fluorescent lamps. An analytical study, method of moments (MoM), and measurements have been carried out to evaluate the strength of the near-field and the shielding effectiveness of the structures 相似文献
10.
Koji Kamei Kunihiko Fujita Eva Jettmar Sen Yoshida Kazuhiro Kuwabara 《Interacting with computers》2002,14(6):438-759
In this paper, we present and discuss Community Organizer, a system designed to support network communities. The main characteristic of Community Organizer is the use of spatial representations for the relationships among community members including the communications exchanged among these members. These spatial representations reflect the degree of closeness of interests and concerns among the members, and are intended to provide users with clues on how to form network communities. In order to investigate the effectiveness of the proposed spatial representations, we conducted experiments with two different versions of the software. One version offered meaningful spatial representations while the other version did not. The subjects who used the former software version felt a greater sense of ‘community’, enjoyed using the software more, and actively used it longer than the subjects using the latter software version (control condition). These results indicated that the proposed spatial representations are effective in supporting network community formation. 相似文献