全文获取类型
收费全文 | 486篇 |
免费 | 4篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 169篇 |
金属工艺 | 10篇 |
机械仪表 | 10篇 |
建筑科学 | 7篇 |
能源动力 | 17篇 |
轻工业 | 41篇 |
石油天然气 | 1篇 |
无线电 | 63篇 |
一般工业技术 | 88篇 |
冶金工业 | 26篇 |
原子能技术 | 17篇 |
自动化技术 | 35篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 28篇 |
2012年 | 22篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 15篇 |
2002年 | 24篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有490条查询结果,搜索用时 15 毫秒
51.
52.
Shock compaction experiments for diamond powder with an initial size of 2 to 4 μm, respectively. The difference in the mechanical properties of SiC and diamond improves the densification, and Si is available to join diamond particles via chemical reaction. The difference of the constituent particle radii, however, causes serious problems with the distribution of shock energy. 相似文献
53.
Natural circulation characteristics of a marine reactor in rolling motion and heat transfer in the core 总被引:5,自引:0,他引:5
A series of single-phase natural circulation tests in a model reactor with rolling motion was performed in order to investigate effects of the rolling motion on its thermal-hydraulic behavior. The loop flow rate in each leg changes cyclically with the rolling angle due to the inertial force of the rolling motion. As the rolling period becomes shorter, the amplitude of the loop flow rate oscillations becomes larger, and the phase lag between the rolling angle and loop flow rate oscillations becomes larger. On the other hand, the core flow rate does not oscillate, though its value changes with the rolling period. Its change correlates well with both the Reynolds number for rolling motion and the Rayleigh number, and it is considered to be caused by the change of the thermal driving head and the pressure loss through the loop. In order to simulate core flow rate change with the rolling period, a simple one-dimensional analytical model was proposed, and its verification was demonstrated. Heat transfer in the core is enhanced by the rolling motion and the enhancement is thought to be caused by the internal flow due to the rolling motion. Heat transfer coefficient in the core is well correlated with the Richardson number for rolling motion and is classified into three regimes. 相似文献
54.
Atsuko Takita Katsuhiko Sasaki Ken-ichi Ohguchi 《Journal of Electronic Materials》2014,43(7):2530-2539
For the design of high-density electronic packages, finite element method (FEM) analyses to evaluate strength reliabilities of solder joints should be conducted by employing the material parameters which can precisely reflect the creep properties of solder joints in actual electronic equipment. To obtain accurate results of the structural analyses of the solder joints, a method to evaluate the steady-state creep deformation in situ must be developed. The indentation creep test is an effective method to evaluate the creep properties of the solder joints in situ; however, the creep properties obtained by this method do not give the same results as those obtained by tensile creep tests using bulk specimens. In this paper, the indentation creep test at 1 N loading for 9,000 s duration was experimentally conducted to confirm that the steady-state creep deformation obtained by the indentation creep test did not coincide with that by the tensile creep tests using bulk specimens. To identify the reason, the indentation creep simulation was conducted by FEM analysis. As a result, it was found that the reference area used to obtain the creep strain from the indentation creep test should be modified. A method to obtain the new reference area is proposed from comparisons of experiments with simulations. Finally, this paper shows that the creep properties obtained by the indentation creep test using the new reference area coincided with those obtained by tensile creep tests using bulk specimens. 相似文献
55.
Ryota Masumoto Ken-ichi Ueno Hirofumi Matsuda Ryuji Nomura Yuichi Okuda 《Journal of Low Temperature Physics》2011,162(5-6):399-406
Crystallization of 4He in aerogels of 90 and 96% porosities shows a dynamical phase transition at around 600 mK due to the competition between thermal fluctuation and disorder: crystals grow via creep at high temperatures and via avalanche at low temperatures. In a very high porosity 99.5% aerogel, however, the transition had not been observed in our previous publication (Nomura et al. in Phys. Rev. Lett. 101:175703, 2008). We improved the spatial resolution of the video image and found that the 99.5% aerogel did have the transition at around 200 mK, which is much lower than those of the lower porosities. The avalanche size is significantly smaller in the 99.5% aerogel. The reduction in the transition temperature and avalanche size may be the consequence of weaker disorder for the crystallization in the very high porosity aerogel. 相似文献
56.
Ken-ichi?KatsumataEmail author Takeshi?Wada Akihisa?Inoue Munetoshi?Sakai Akira?Nakajima Akira?Fujishima Nobuhiro?Matsushita Kiyoshi?Okada 《Journal of Materials Science》2011,46(10):3430-3435
The surfaces of the Ti-based bulk metallic glasses (Ti50Ni20Cu25Sn5) were modified by a hydrothermal method using sodium hydroxide (NaOH) solution, and the surface wettability was investigated.
No reflections were observed in the XRD patterns of the NaOH-treated samples even though there was a clear change of the color,
indicating formation of amorphous oxide phases. The Raman spectra showed peaks attributed to sodium titanate compounds (Na–O–Ti)
and titanium oxide. Some of the samples were observed to have a very rough surface microstructure such as a “house-of-cards”
or leaf-like structure. The water contact angle of the treated samples decreased with increasing treatment temperature and
time. These results indicate that the wettability of the sample surface was able to be controlled from hydrophobic to hydrophilic
by changing the conditions of the hydrothermal treatment. 相似文献
57.
A generalised Elmore delay (GED) expression is proposed which can be applied directly to distributed RC tree networks. Using this expression, the signal delay caused by interconnects such as those in LSIs can be estimated more simply and accurately than using the conventional Elmore delay model.<> 相似文献
58.
Masaru Yamashita Hiroshi Yamanaka Ken-ichi Sasage 《Journal of the American Ceramic Society》2004,87(5):967-969
The behavior of ruthenium oxide (RuO2 ) in aluminoborosilicate glass used for the stabilization of nuclear waste was investigated. It was found that 0.025 mass% RuO2 dissolved as Ru4+ in the glass at 1400°C, which caused the glass to turn yellow. When the RuO2 amount was 0.05 mass%, needle-shaped crystals formed in the glass during slow cooling. If the added amount exceeded 0.1 mass% and the cooling rate was slow, it separated rapidly and the glass became pale after cooling. No dissolution of ruthenium was detectable after melting at 1200°C. 相似文献
59.
Hidetoshi Kita Masanobu Shigekuni Isao Kawafune Kazuhiro Tanaka Ken-ichi Okamoto 《Polymer Bulletin》1989,21(4):371-376
Summary Plasma-polymerized membranes were prepared from fluoroalkyl acrylates and methacrylates by two different directions of monomer injection and the permeation rates of O2 and n2 through the membranes were investigated. The chemical structure and composition of the plasmapolymerized membranes varied significantly by the direction of monomer injection. The optimum plasma conditions to yield maximum gas separation characteristics was obtained by the remote plasma excitation at the W/FM value of 20 J/mg, where W is the discharge power, F is the monomer flow rate and M is the molecular weight of the monomer. 相似文献
60.
Ishikawa H. Soda H. Wakao K. Kihara K. Kamite K. Kotaki Y. Matsuda M. Sudo H. Yamakoshi S. Isozumi S. Imai H. 《Lightwave Technology, Journal of》1987,5(6):848-855
A distributed feedback (DFB) laser emitting at 1.3 μm for gigabit lightwave communication systems has been developed. The distributed feedback structure has been introduced in a newly developed buried heterostructure and designs for stable single-mode operation, high speed modulation, and low noise have been done. Threshold current of 10-15 mA, differential efficiency of around 0.28 mW/mA, low noise, small signal modulation bandwidth of 13.9 GHz, and satisfactory modulation waveform at 5-Gbit/s NRZ modulation have been attained with high single-mode operation yield. 相似文献