全文获取类型
收费全文 | 1914篇 |
免费 | 72篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 32篇 |
综合类 | 4篇 |
化学工业 | 324篇 |
金属工艺 | 87篇 |
机械仪表 | 174篇 |
建筑科学 | 11篇 |
能源动力 | 33篇 |
轻工业 | 124篇 |
水利工程 | 2篇 |
无线电 | 196篇 |
一般工业技术 | 274篇 |
冶金工业 | 552篇 |
原子能技术 | 34篇 |
自动化技术 | 146篇 |
出版年
2023年 | 14篇 |
2022年 | 9篇 |
2021年 | 46篇 |
2020年 | 20篇 |
2019年 | 32篇 |
2018年 | 31篇 |
2017年 | 48篇 |
2016年 | 44篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 85篇 |
2012年 | 94篇 |
2011年 | 95篇 |
2010年 | 59篇 |
2009年 | 69篇 |
2008年 | 70篇 |
2007年 | 60篇 |
2006年 | 71篇 |
2005年 | 59篇 |
2004年 | 41篇 |
2003年 | 51篇 |
2002年 | 51篇 |
2001年 | 33篇 |
2000年 | 46篇 |
1999年 | 51篇 |
1998年 | 185篇 |
1997年 | 111篇 |
1996年 | 108篇 |
1995年 | 52篇 |
1994年 | 50篇 |
1993年 | 37篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1977年 | 25篇 |
1976年 | 32篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有1993条查询结果,搜索用时 21 毫秒
11.
Suh K.S. Damon D. Tanaka J. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1995,2(1):1-11
Measurements of thermally stimulated currents were made on ionomer/polyethylene blends. The objective of this work was to study space charge formation in these materials. Two ionomers were compared; both ionomers contained methacrylic acid, neutralized by zinc in one and by sodium in the other. A large current peak centered near 60°C was observed in all blends and associated with the motion of space charges injected into the blends during poling. All blends accumulated large negative space charge concentrations. The approach to the equilibrium space charge distribution (negative and spatially uniform in all blends) is much more rapid in the blends containing the sodium ionomer than in the blends containing the zinc ionomer 相似文献
12.
13.
A rotating disk air distribution (RDAD) system consisting of a rotating disk with an air supply hole was fabricated to solve the nonuniform freezing problem of a freezer that supplies air through a duct at a fixed location. The RDAD system was installed in a freezer to supply freezing air in various directions by controlling the position of the air supply hole. An equation estimating air velocity in the freezer was developed based on heat balance between a brass block thermocouple (BBT) probe and ambient air stream. The equation was applied to the analysis of airflow patterns developed through the RDAD and the fixed duct system. For control of the RDAD system, a fuzzy matrix was constructed with the measured nodal temperature at 3D locations in the freezer and used to search for the optimum direction of air supply. Uniform cooling was accomplished with the RDAD system using fuzzy and expert algorithms leading to temperature deviation σ=0.666, compared with 0.289 of the fixed air supply system. Cooling rate of model food (BBT) was 1.75 times faster than that of the fixed system. 相似文献
14.
LW Didenko IB Buchwalow W Schulze K Augsten M Susa E Unger 《Canadian Metallurgical Quarterly》1996,98(4):399-409
Heterotrimeric GTP-binding proteins (G-proteins) have been shown to play an important role in cellular signalling. However, G-protein involvement in the intracellular spreading of bacterial pathogens is still poorly understood. In this study, antibodies, that recognize G-protein alpha-subunits (anti-G alpha), were used to investigate the localization of G-proteins in the macrophage-like cell line P388D1 and E. coli, also in their L-forms, during phagocytosis. In E. coli, anti-G alpha-binding sites were detected preferably in the cell wall and septa of the whole bacterial forms as well as in the cytoplasm of L-forms. Western blotting of bacterial lysates demonstrated protein bands with positive immunoreaction to antibodies against Gs alpha, Gi alpha, and Gcommon alpha with a higher affinity to the antibody against Gs alpha. Immunoreaction with the anti-Gs alpha-antibody was markedly higher in pathogenic strains of E. coli. Because of the conserved structure in all GTP-binding proteins which seem to derive from a single primordial protein involved in signal transduction mechanisms, it is reasonable to assume that some anti-Ga-positive proteins in E. coli might be related to G-proteins of higher organisms. A putative candidate for bacterial G-proteins seems to be a 36 kDa protein. Enhancement in G-protein immunostaining in the cytoplasm of macrophages around the internalized bacteria testifies to the involvement of G-proteins in mediation of endocytosis responses of phagocytes. 相似文献
15.
16.
JP Grass IB Dockendorff VA Soto PH Araya CM Henriquez 《Canadian Metallurgical Quarterly》1993,18(3):336-338
A case report of a 10-year old girl with a herniated disc is presented. The most significant symptoms were progressive scoliosis with a flat back and paravertebral muscle spasm. An absent H reflex on the left and an increased latency of the somatosensory-evoked potentials of the left posterior tibial nerve were found. The computed tomographic scan of the lumbar spine showed a large central left-sided disc protrusion at the L5-S1 level. Our case presents the youngest patient with documented intervertebral disc herniation and the only one with severe scoliosis and vertebral rotation. The curve was not structural because it improved with surgery and an orthosis was not necessary. 相似文献
17.
Kyeong Joong Kim Jong-Yeul Suh Moon Gi Kang Kyu Tae Park 《Electronics letters》1998,34(13):1302-1303
The boundary is approximated by a polygon which can be encoded with the smallest number of bits for maximum distortion. The temporal redundancy between two successive frames is efficiently removed with the proposed scheme, resulting in a lower bit rate than the conventional algorithms 相似文献
18.
19.
Chang-Kyo Suh Eui-Ho Suh Kwang-Churn Baek 《Engineering Management, IEEE Transactions on》1994,41(3):264-275
This paper concerns telecommunications technologies prioritization for long-range R&D planning at the Korea Telecommunication Authority (KTA), which is the primary common carrier in Korea. Criteria weighting and technological importance ranking were determined by means of the Analytic Hierarchy Process as a decision aid, along with hierarchical representation and pairwise comparisons. The opinions derived from three divisions of KTA were analyzed and aggregated. Such aggregated prioritization weighting of technologies allows the corporation management to use it for funding decisions about technological aspects of its long-range planning for R&D projects during the period from 1992 to 2006; especially those concerning baseline budget level selection and the scope of research activities.<> 相似文献
20.