全文获取类型
收费全文 | 1152篇 |
免费 | 27篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 104篇 |
综合类 | 1篇 |
化学工业 | 434篇 |
金属工艺 | 26篇 |
机械仪表 | 18篇 |
建筑科学 | 17篇 |
能源动力 | 44篇 |
轻工业 | 95篇 |
水利工程 | 1篇 |
无线电 | 68篇 |
一般工业技术 | 236篇 |
冶金工业 | 39篇 |
原子能技术 | 32篇 |
自动化技术 | 67篇 |
出版年
2022年 | 13篇 |
2021年 | 25篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 47篇 |
2011年 | 45篇 |
2010年 | 41篇 |
2009年 | 40篇 |
2008年 | 57篇 |
2007年 | 62篇 |
2006年 | 40篇 |
2005年 | 32篇 |
2004年 | 32篇 |
2003年 | 38篇 |
2002年 | 32篇 |
2001年 | 26篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 43篇 |
1997年 | 32篇 |
1996年 | 33篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 21篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 17篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 21篇 |
1986年 | 20篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 21篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有1182条查询结果,搜索用时 46 毫秒
1.
2.
3.
Si3N4 ceramic was jointed to itself using a filler alloy of Cu76.5Pd8.5Ti15, and the mechanical properties of the jointwere measured and analyzed. By using a filler alloy of Cu76.5Pd8.5Ti15, the SisN4/SisN4 joints were obtained bybrazing at 1373~1473 K f 相似文献
4.
5.
Hideaki Katayama Tsutomu Tawa Shinzaburo Ito Masahide Yamamoto Yoshio Wada 《Polymer Bulletin》1992,29(3-4):365-367
Summary The effect of side chain length on intramolecular triplet energy migration of naphthalene containing polymers was investigated by a delayed fluorescence (DF) spectroscopy for the solid solution of the polymers. The degree of triplet energy migration depends strongly on whether the chromophores are directly attached to the main chain or not. 相似文献
6.
Group-velocity dispersion (GVD) compensation in in-line amplifier systems is evaluated from the viewpoint of improving the transmission distance. The nonlinear Schrodinger equation, which simulates signal propagation in optical fibers, is numerically evaluated to clarify the optimum configuration for GVD compensation. It is shown that the optimum amount of GVD compensation is about 100% of the GVD experienced by the transmitted signal. The optimum compensation interval is found to be a function of the bit rate, signal power, and dispersion parameter. For dispersion parameter values ranging from about -0.1 ps/nm/km to -10 ps/nm/km, and an amplifier noise figure of about 6 dB, the optimum compensation configuration can eliminate the GVD from in-line amplifier systems, thus improving transmission distances to those limited by self-phase modulation and higher-order GVD 相似文献
7.
Bhupesh C. Roy Motonobu Goto & Tsutomu Hirose 《International Journal of Food Science & Technology》1996,31(2):137-141
Tomato seed oil was extracted with supercritical carbon dioxide in a semibatch-flow extractor within the temperature range 313–343 K and the pressure range 10.8–24.5MPa. The extraction rates increased with pressure, but decreased with temperature increase because of the variation in solvent density and resultant differences in oil solubility. The fatty acid composition of the extracted oil was similar to that of soybean oil. 相似文献
8.
Numerical analysis of IM signal propagation in an optical fibre is carried out taking selfphase modulation and group-velocity dispersion into account. The transmission distance yielding a prescribed eye opening penalty, in the normal dispersion region, is shown to be inversely proportional to the square root of the signal power.<> 相似文献
9.
Hydrothermal synthesis and in situ surface modification of boehmite nanoparticles in supercritical water 总被引:2,自引:1,他引:1
T. Mousavand S. Ohara M. Umetsu J. Zhang S. Takami T. Naka T. Adschiri 《The Journal of Supercritical Fluids》2007,40(3):397-401
In situ surface modification of boehmite (AlOOH) nanoparticles during hydrothermal synthesis in supercritical water was examined by adding CH3(CH2)4CHO and CH3(CH2)5NH2 as modifier reagents to the reactants. Changes in surface properties of the nanoparticles by surface modification was observed by FTIR, dispersion in solvents and TEM analyses, which demonstrated that reagents chemically binded onto the surface of the AlOOH nanoparticles. The results of SEM and TEM pictures show that the surface modification affects crystal growth and reduces the particle size and changes the morphology of the particles. 相似文献
10.
Tsutomu Takeichi Yuki Saito Tarek Agag Hiroyuki Muto Takehiro Kawauchi 《Polymer》2008,49(5):1173-1179
Two series of high-performance polymer alloys were prepared by mixing typical benzoxine monomers, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (P-a) or 6,6-(1-methylethyliden)-bis-(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) (B-a), with a typical bismaleimide, 4,4-bismaleimidodiphenyl methane by various ratios followed by thermal treatment up to 240 °C. DSC and IR of the alloys were examined to follow the curing reaction. These analyses showed that the obtained polymer alloys are AB co-cross-linked polymer networks through the formation of ether linkage between the hydroxyl group of polybenoxazine and the double bond of bismaleimide. Viscoelastic analysis and softening temperature measurement revealed that the polymer alloys have much higher glass transition temperatures than those of each homopolymer. The thermal stability also increased with the increase of bismaleimide content as evidenced by TGA. 相似文献