全文获取类型
收费全文 | 561篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 189篇 |
金属工艺 | 23篇 |
机械仪表 | 17篇 |
建筑科学 | 17篇 |
能源动力 | 21篇 |
轻工业 | 50篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 16篇 |
一般工业技术 | 130篇 |
冶金工业 | 31篇 |
原子能技术 | 20篇 |
自动化技术 | 55篇 |
出版年
2023年 | 4篇 |
2022年 | 22篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 8篇 |
2014年 | 27篇 |
2013年 | 38篇 |
2012年 | 42篇 |
2011年 | 47篇 |
2010年 | 31篇 |
2009年 | 34篇 |
2008年 | 37篇 |
2007年 | 42篇 |
2006年 | 26篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 16篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有589条查询结果,搜索用时 31 毫秒
151.
Yomi?Watanabe Yoshie?Yamauchi-Sato Toshihiro?Nagao Takaya?Yamamoto Kentaro?Tsutsumi Akio?Sugihara Yuji?ShimadaEmail author 《Journal of the American Oil Chemists' Society》2003,80(9):909-914
We attempted to produce MAG of CLA through lipase-catalyzed esterification of a FFA mixture containing CLA (referred to as
FFA-CLA) with glycerol. Screening of lipases showed that MAG-CLA was produced efficiently at 5°C with Penicillium camembertii, Rhizopus oryzae, and Candida rugosa lipases. Among them, C. rugosa lipase was selected because the lipase is widely used as a catalyst for oils and fats processing. The reaction was conducted
with agitation of a 300-g mixture of FFA-CLA/glycerol (1∶5, mol/mol), a 200-U/g mixture of C. rugosa lipase, and 2% water. When the reaction was conducted at 30°C, the esterification scarcely proceeded, owing to inhibition
of the reaction by glycerol. But the reaction at 5°C eliminated the inhibition and produced MAG efficiently: The degree of
esterification reached 93.8% after 58 h, and MAG content in the reaction mixture was 88.4 wt%. To reduce the reaction time,
the reactor was connected with a vacuum pump after 24 h, and the reaction was continued with dehydration at 5 mm Hg. The degree
of esterification reached 94.7% after 24 h of dehydration (48 h in total), and MAG content increased to 93.0 wt%. Candida rugosa lipase acted a little more strongly on cis-9, trans-11 CLA than on trans-10,cis-12 CLA, but the contents of the two isomers in MAG obtained from a 48-h reaction were the same as the contents in FFA-CLA. 相似文献
152.
Kentaro Fukuda Teiichi Hanada Setsuhisa Tanabe Takeshi Yao 《Journal of the American Ceramic Society》2002,85(4):915-920
Amorphous films in the system Al2 O3 –Y2 O3 were prepared by the rf sputtering method in the range of 0–76 mol% Y2 O3 , and their density, refractive index, and elastic constants were measured. All of the physical properties of the amorphous Al2 O3 –Y2 O3 films had a similar compositional dependence; that is, they increased continuously, but not linearly with increasing Y2 O3 content. To confirm the coordination states of aluminum and yttrium ions in the amorphous Al2 O3 –Y2 O3 films, the Al K α X-ray emission spectra and the X-ray absorption near edge structures (XANES) were measured. The average coordination number of aluminum ions in the amorphous films containing up to about 40 mol% Y2 O3 content was 5, that is a mixture of 4-fold- and 6-fold-coordinated states. In the region of more than about 50 mol% Y2 O3 , the fraction of the 6-fold-coordinated aluminum ions increased with increasing Y2 O3 content, while the results led to the conclusion that the coordination number of yttrium ions was always 6, regardless of composition. These results indicate that, in amorphous films in the system Al2 O3 –Y2 O3 , the change of the coordination state of aluminum ions has an important effect on physical properties. 相似文献
153.
Hoshino M Uesugi K Takeuchi A Suzuki Y Yagi N 《The Review of scientific instruments》2011,82(7):073706
An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatial resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique. 相似文献
154.
介绍了一种结构简单、价格低、带有反射率和亮度补偿的光纤振动计。该光纤式振动计由发光二极管、光纤探头和两个光子探测器组成。光纤探头的光纤束分为三部分:一根发射光纤、第一邻近接收光纤组(组A)、第二邻近接收光纤组(组B)。光纤组A和光纤组B的输出信号平均值的比值取决于光纤探头和被测表面之间的平均距离,而与被测表面的反射率及亮度无关。根据这一比值可以实现探头与被测表面间距离的估计。然后根据光纤组A和B的标定曲线,对振动计的灵敏度进行了补偿。因为在比值运算中使用的是平均值,所以振动频率的提高不会限制这一技术的使用。实验结果表明,这一方法适宜于动态测量,可以实现被测表面反射率、入射亮度及探头与被测表面间平均距离的补偿。 相似文献
155.
Factors influencing species diversity of ferns and fern allies in fragmented forest patches in the Kyoto city area 总被引:4,自引:0,他引:4
We investigated the relationship between species diversity of pteridophytes and the environmental factors of 39 fragmented forest patches in the Kyoto city area. There was a significant correlation between the number of species and the micro-landform diversity, artificial habitat diversity, and logarithm of the area of the forest patch. When we performed a multiple regression analysis to identify the best-fit model so as to optimize the amount of variation in species diversity explained by using stepwise selection, three species diversity indices (species richness or Shannon’s diversity index, logarithm of inverse Simpson index) had significant positive partial correlations with the logarithm of area of the forest patch, and negative correlations with the logarithm of isolation distance from mountain forest. Therefore, we conclude that pteridophyte species diversity depends on patch size and isolation distance from mountain forests. Comparison of the woody plant species–area curve with the pteridophyte species–area curve showed that the rate of increase of species number (inclination) with area was the same, but the Y-intercept of the pteridophyte species–area curve was lower than that of the woody plant curve. Therefore, the minimum conservation area required for ferns and fern allies is greater than that for woody plant species. 相似文献
156.
Katsuhiro Hirata Kentaro Hamamoto Yoshio Mitsutake Tomohiro Ota Masahito Yamana 《Electrical Engineering in Japan》2010,173(4):38-45
The transmission characteristics of the electromagnetic induction RFID systems are greatly influenced by the distance between the primary and secondary antenna coils and by the materials used in their design. In this paper the induced current of the secondary antenna coil is calculated by the 3D finite element method when both the primary and secondary antenna coils are operated in resonant circuits. The influences of the analyzed parameters on the transmission characteristics are demonstrated. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 38–45, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21019 相似文献
157.
158.
159.
Ryota Yuge Takashi Manako Kentaro Nakahara Motoharu Yasui Shigeyuki Iwasa Tsutomu Yoshitake 《Carbon》2012,50(15):5569-5573
We prepared single-wall carbon nanohorns (SWCNHs) with a high specific surface area and fabricated an electrochemical capacitor electrode with good performance from them. Carbon impurities involved in the as-grown SWCNHs were thoroughly removed and the purified SWCNHs were oxidized to produce holes in them (SWCNHox). The specific surface area was estimated as 1720 m2/g, the largest surface area of SWCNHs ever reported. Capacitive properties were also investigated using the obtained SWCNHox. We found that an electrochemical device with SWCNHox showed an excellent specific capacitance of about 100 F/g, accelerating industrial progress for their uses in energy and environmental fields. 相似文献
160.
Ju-Hyeon Shin Seong-Hwan Lee Kyeong-Jae Byeon Kang-Soo Han Heon Lee Kentaro Tsunozaki 《Nanoscale research letters》2011,6(1):458
UV curing nanoimprint lithography is one of the most promising techniques for the fabrication of micro- to nano-sized patterns on various substrates with high throughput and a low production cost. The UV nanoimprint process requires a transparent template with micro- to nano-sized surface protrusions, having a low surface energy and good flexibility. Therefore, the development of low-cost, transparent, and flexible templates is essential. In this study, a flexible polyethylene terephthalate (PET) film coated with a fluorinated polymer material was used as an imprinting mold. Micro- and nano-sized surface protrusion patterns were formed on the fluorinated polymer layer by the hot embossing process from a Si master template. Then, the replicated pattern of the fluorinated polymer, coated on the flexible PET film, was used as a template for the UV nanoimprint process without any anti-stiction coating process. In this way, the micro- to nano-sized patterns of the original master Si template were replicated on various substrates, including a flat Si substrate and curved acryl substrate, with high fidelity using UV nanoimprint lithography. 相似文献