全文获取类型
收费全文 | 3914篇 |
免费 | 54篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 128篇 |
综合类 | 5篇 |
化学工业 | 597篇 |
金属工艺 | 1574篇 |
机械仪表 | 55篇 |
建筑科学 | 31篇 |
矿业工程 | 1篇 |
能源动力 | 97篇 |
轻工业 | 154篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 260篇 |
一般工业技术 | 415篇 |
冶金工业 | 458篇 |
原子能技术 | 71篇 |
自动化技术 | 121篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 28篇 |
2020年 | 18篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 26篇 |
2016年 | 40篇 |
2015年 | 21篇 |
2014年 | 52篇 |
2013年 | 146篇 |
2012年 | 110篇 |
2011年 | 127篇 |
2010年 | 93篇 |
2009年 | 147篇 |
2008年 | 148篇 |
2007年 | 132篇 |
2006年 | 126篇 |
2005年 | 106篇 |
2004年 | 100篇 |
2003年 | 129篇 |
2002年 | 154篇 |
2001年 | 142篇 |
2000年 | 113篇 |
1999年 | 139篇 |
1998年 | 254篇 |
1997年 | 219篇 |
1996年 | 171篇 |
1995年 | 112篇 |
1994年 | 113篇 |
1993年 | 164篇 |
1992年 | 160篇 |
1991年 | 148篇 |
1990年 | 59篇 |
1989年 | 49篇 |
1988年 | 40篇 |
1987年 | 32篇 |
1986年 | 44篇 |
1985年 | 37篇 |
1984年 | 44篇 |
1983年 | 29篇 |
1982年 | 16篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 18篇 |
1974年 | 4篇 |
1973年 | 7篇 |
排序方式: 共有3971条查询结果,搜索用时 15 毫秒
41.
42.
Two series of polypropylenes with different molecular weight distribution and tacticity characteristics were injection molded into flexural test specimens by varying cylinder temperature and the effects of the molecular weight distribution and tacticity on the structure and properties of the moldings were studied. Measured propertied were flexural modulus, flexural strength, heat distortion temperature, Izod impact strength, and mold shrinkage and structures studied were crystallinity, the thickness of skin layer, a*‐axis‐oriented component fraction and crystalline orientation functions. The relations between the structures and properties were also studied. It was found that the molecular weight distribution and tacticity characteristics affect the properties mainly through the molecular orientation and crystallinity, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2142–2156, 2002 相似文献
43.
Ti wire electrodes were immersed in acidic solutions containing H2SO4 and HCl of various concentrations at 353 K to evaluate corrosion rate by measurement of electric resistance change (resistometry). Addition of hydrochloric acid to sulphuric acid solution promoted depassivation of Ti. After depassivation, the immersion potential dropped to the hydrogen evolution potential and a hydride layer was formed on the surface. The hydride layer dissolved continuously in the acidic solution. SEM observation showed that Ti wires dissolved almost uniformly in the early stage and that the dissolution then trace became irregular due to nonuniform growth of the hydride layer. Dissolution rate of a Ti wire was estimated almost accurately by resistometry. 相似文献
44.
H Yasoshima K Uematsu K Sakurai Y Ueno K Hori N Kanazawa T Tanaka N Yamanaka E Okamoto 《Canadian Metallurgical Quarterly》1993,43(12):783-789
A case of primary carcinoid tumor arising in the liver of a 69 year old woman with no endocrine symptoms is reported. Histopathologically, the tumor was diagnosed initially as a hepatocellular carcinoma in the biopsy specimen, and was shown subsequently to be a carcinoid tumor, demonstrating diffuse positive staining with Grimelius method. Mucin stained with periodic acid-Schiff (PAS), alcian-blue, and mucicarmine, and was shown partially in the glandular structures. Immunohistochemically, most of the tumor cells stained positively for chromogranin-A, epithelial membrane antigen (EMA) and neuron specific enolase (NSE). Ultrastructural examination revealed electron-dense core granules, measuring 40-120 nm in diameter in some of the tumor cells. Intensive and careful searches pre- and post-operatively revealed no other primary source of tumor other than the liver. The patient was reported well with no symptoms 3 1/2 years after the operation. This case is considered to be a primary hepatic carcinoid tumor. The recent literature is reviewed, and the possible histogenesis of hepatic carcinoid tumor is discussed. 相似文献
45.
46.
Toyokura M. Kodama H. Miyagoshi E. Okamoto K. Gion M. Minemaru T. Ohtani A. Araki T. Takeno H. Akiyama T. Wilson B. Aono K. 《Solid-State Circuits, IEEE Journal of》1994,29(12):1474-1481
A video DSP with macroblock-level-pipeline and a SIMD type vector-pipeline architecture (VDSP2) has been developed, using 0.5 μm triple-layer-metal CMOS technology. This 17.00 mm×15.00 mm chip consists of 2.5 M transistors, and operates at 100 MHz. The real-time encoder and decoder specified in the MPEG2 main profile at the main level can be realized with two VDSP2's and a motion estimation (ME) unit, and one VDSP2 respectively, at an 80 MHz clock rate, with a total power dissipation of 4.2 W at 3.3 V 相似文献
47.
Masahito Matsubayashi Takashi Hibiki Kaichiro Mishima Koji Yoshii Koji Okamoto 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2003,510(3):325-333
A fluorescent converter for fast neutron radiography (FNR) comprising a scintillator and hydrogen-rich resin has been developed and applied to electronic imaging. The rate of the reaction between fast neutrons and the converter is increased by thickening the converter, but its opaqueness attenuates emitted light photons before they reach its surface. To improve the luminosity of a fluorescent converter for FNR, a novel type of converter was designed in which wavelength-shifting fibers were adopted to transport radiated light to the observation end face. The performance of the converter was compared with that of a polypropylene-based fluorescent converter in an experiment conducted at the fast-neutron-source reactor YAYOI in the University of Tokyo. 相似文献
48.
Hozumi N. Suzuki H. Okamoto T. Watanabe K. Watanabe A. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1994,1(6):1068-1076
Space charge distribution was measured, applying an electric field of >1 MV/cm to 3 mm thick XLPE cable insulation. Improving the conventional pulse electro-acoustic method, a new method was developed to measure space charge when applying HV to cables. Under high field, hetero charges were formed soon after voltage application, followed by an injection from the cathode. Then intermittent injections of charge packets from the anode took place. The space charge distribution kept changing without becoming stabilized. A simulation was done assuming hysteresis of the injection characteristics. The observed intermittent injection near the anode was qualitatively reproduced using computer simulation 相似文献
49.
H. Okamoto 《Journal of Phase Equilibria》1992,13(5):571-572
This work was supported by ASM International. Literature searched through 1987. Dr. Okamoto is the Alloy Phase Diagram Program
Category Editor for miscellaneos binary alloys. 相似文献
50.