全文获取类型
收费全文 | 747篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 130篇 |
金属工艺 | 14篇 |
机械仪表 | 9篇 |
建筑科学 | 17篇 |
能源动力 | 39篇 |
轻工业 | 61篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 101篇 |
一般工业技术 | 189篇 |
冶金工业 | 67篇 |
原子能技术 | 5篇 |
自动化技术 | 121篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 24篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 26篇 |
2017年 | 17篇 |
2016年 | 17篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 44篇 |
2012年 | 27篇 |
2011年 | 37篇 |
2010年 | 33篇 |
2009年 | 38篇 |
2008年 | 36篇 |
2007年 | 37篇 |
2006年 | 18篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有772条查询结果,搜索用时 0 毫秒
1.
A Gopal G Li Mandri DL King C Marboe S Homma 《Canadian Metallurgical Quarterly》1994,105(6):1885-1887
Cardiac papillary fibroelastomas are unusual, frond-like growths typically found on cardiac valves, diagnosed incidentally on autopsy or cardiac surgery, but rarely during life. We report a rare case of an aortic valve papillary fibroelastoma detected by transthoracic echocardiography and confirmed by histologic study. 相似文献
2.
Room temperature synthesis of crystalline metal oxides 总被引:6,自引:0,他引:6
Crystalline titanium dioxide powders have been synthesized as either rutile or anatase from aqueous solutions at low temperatures
(T≤100°C) and atmospheric pressure. First, a sol is prepared by the hydrolysis of a titanium alkoxide in an acidic solution.
The sol is subsequently heated at different rates to produce the different crystalline phases of titanium dioxide. Powder
characterization was carried out using X-ray diffraction, scanning electron microscopy and high resolution transmission electron
microscopy. In general, the precipitate size was observed to be between 50 and 100 nm. Possible mechanisms involved in determining
the crystal variants are discussed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
3.
Satya Gopal Rao P. Venkatehwarlu K. Siripuram Rajesh Sripada Suresh 《Glass Physics and Chemistry》2021,47(4):308-320
Glass Physics and Chemistry - The growth of nanocrystalization in TeO2–SeO2–Na2O glasses is achieved by the conventional heat treatment method. The influence of Na2O concentration on... 相似文献
4.
Silicon - This research aims at optimum utilization of waste recycled submerged arc welding slag along with virgin flux in place of pure virgin flux without compromising the quality of welding and... 相似文献
5.
This paper reports fabrication of 2-DOF vibratory gyroscope using SU-8 based UV-LIGA process. The device structure is designed to be symmetrical in order to match the resonance frequencies of drive and sense mode oscillators and also to minimize their relative temperature dependent drift. The overall arrangement is such that the two vibration modes do not affect each other and therefore, mechanical decoupling is achieved which helps in minimizing bias drift. The design is optimized to be compatible with the UV-LIGA process having 10 μm thick electroformed nickel as structural layer. Photolithography to create 11 μm thick SU-8 molds for electroforming sacrificial copper and structural nickel layer is optimized using multiple exposure technique that ensures near vertical side walls. Since the highly cross-linked SU-8 remaining after development is difficult to remove reliably from high aspect ratio structures without damage or alteration to the electroformed metals, a 2.45 GHz MW plasma etching process is developed with CF4/O2 mixes. The fabricated device is checked for off-plane misalignment between the stationary and movable comb fingers using white light interferometry and it is found to be almost negligible. Also, the prototype device is characterized for amplitude and phase spectral responses using Polytec MSA-500 Micro System Analyzer. The drive and sense mode resonance frequencies are observed at 7.3 and 7.1 kHz respectively against the mode matched designed frequency of 7.5 kHz. 相似文献
6.
Two unusual lipid classes were detected by thin-layer chromatography in the neutral lipids derived from goat cauda-epididymal
sperm plasma membrane. The lipids were identified as wax esters and 1-O-alkyl-2,3-diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/1H nuclear magnetic resonance spectral evidence. The membrane containedca. 3 and 5 μg/mg protein of wax esters and alkyldiacylglycerols, respectively. The relative proportions of wax esters and alkyldiacylglycerols
in the total neutral lipids were 1.5% and 2.4%, respectively. The lipids contained fatty acids with chain lengths of C14 to C22. The major fatty acids of the wax esters were 14∶0, 16∶0, 16∶1ω7, 18∶0 and 18∶1ω9. The fatty acids in alkyldiacylglycerol
were 16∶0, 18∶0, 22∶5ω3 and 22∶6ω3. Alkyldiacylglycerol was particularly rich in docosahexaenoic acid 22∶6ω3) representing
30% of the total fatty acids. The alcohols of wax ester were all saturated with C20–C29 carbon chains. The deacylated products derived from alkyldiacylglycerols were identified as hexadecyl, octadecyl and octadec-9′-enyl
glycerol ethers. 相似文献
7.
Gopal P. Khanal Ichiro Fujii Shintaro Ueno Satoshi Wada 《Journal of the American Ceramic Society》2021,104(9):4649-4658
The <110>-oriented BaTiO3 ceramics were fabricated using BaCO3 matrix and H1.08Ti1.73O4.nH2O (HTO) template particles, and the mechanism of BaTiO3 phase formation was investigated. The dielectric, ferroelectric, and piezoelectric properties were also investigated. The transformation of the HTO phase into the TiO2 bronze or TiO2 (B) phase was observed at 600°C, where the BaTiO3 nucleation was accompanied by the formation of a Ba2TiO4 phase. The TiO2 phase reacted with the Ba2TiO4 phase at 800°C to give a BaTiO3 phase, whereas its reaction with the BaTiO3 resulted in the formation of BaTi2O5 phase that got decomposed into BaTiO3 and Ba6Ti17O40 phase at sintering temperature ≥1300°C. Sintering with samples’ embedding in BaTiO3 powders prevented the formation of the Ba6Ti17O40 secondary phase. The crystallographic orientation along the <110> direction (F110) was developed by the epitaxial grain growth mechanism. In addition to the contribution of the grain-size increment for enhancing the F110, the preservation of the platelike structure was also found to have a significant impact. The ceramics prepared by the embedded sintering (grain size ≈12.4 µm and F110 = 83%) exhibited the room-temperature dielectric constant of 1708 and piezoelectric strain constant of 445 pm/V, which are higher than those of the BaTiO3 ceramics with randomly oriented grains. 相似文献
8.
9.
Judy Gopal Sechul Chun Mukesh Doble 《Journal of materials science. Materials in medicine》2016,27(8):135
Titanium is widely used as medical implant material and as condenser material in the nuclear industry where its integrity is questioned due to its susceptibility to bacterial adhesion. A systematic investigation on the influence of thermally (50–800 °C) stabilized titanium (TS-Ti) nano oxide towards bacterial adhesion was carried out. The results showed that below 350 °C significant bacterio-phobicity was observed, while above 500 °C significant affinity towards bacterial cells was recorded. Conventional characterization tools such as HR-TEM and XRD did not provide much insight on the changes occurring on the oxide film with heat treatment, however, attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) of the surface showed significant changes in the spectral pattern as a function of increasing heat treatment. It was observed that elevated OH, N–H and C=O groups and rutile titania on the TS-Ti oxide films led to higher affinity for bacterial adhesion. On the other hand low temperature TS-Ti nanooxide films (<350 °C) showed high C–H groups and decreased OH groups on their surface, which possibly contributed towards their bacterio-phobicity. The TS-Ti nanooxide film grown at 50 °C was observed to be the most efficient anti-bacterial adhesion interface, while the 800 °C interface was the one showing highest affinity towards bacterial adhesion. This study confirms the successful application of ATR-FTIR technique for nano-oxide film characterization and towards understanding the variations in bacterial interaction of such nano interfaces. 相似文献
10.
We present an improved version of one-against-all method for multiclass SVM classification based on subset sample selection, named reduced one-against-all, to achieve high performance in large multiclass problems. Reduced one-against-all drastically decreases the computing effort involved in training one-against-all classifiers, without any compromise in classification accuracy. Computational comparisons on publicly available datasets indicate that the proposed method has comparable accuracy to that of conventional one-against-all method, but with an order of magnitude faster. On the largest dataset considered, reduced one-against-all method achieved 50% reduction in computing time over one-against-all method for almost the same classification accuracy. We further investigated reduced one-against-all with linear kernel for multi-label text categorization applications. Computational results demonstrate the effectiveness of the proposed method on both the text corpuses considered. 相似文献