全文获取类型
收费全文 | 1895篇 |
免费 | 49篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 113篇 |
综合类 | 5篇 |
化学工业 | 471篇 |
金属工艺 | 57篇 |
机械仪表 | 63篇 |
建筑科学 | 49篇 |
能源动力 | 85篇 |
轻工业 | 176篇 |
水利工程 | 4篇 |
石油天然气 | 5篇 |
无线电 | 115篇 |
一般工业技术 | 347篇 |
冶金工业 | 252篇 |
原子能技术 | 40篇 |
自动化技术 | 171篇 |
出版年
2023年 | 6篇 |
2022年 | 18篇 |
2021年 | 43篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 32篇 |
2017年 | 21篇 |
2016年 | 37篇 |
2015年 | 31篇 |
2014年 | 64篇 |
2013年 | 111篇 |
2012年 | 94篇 |
2011年 | 136篇 |
2010年 | 65篇 |
2009年 | 89篇 |
2008年 | 102篇 |
2007年 | 87篇 |
2006年 | 67篇 |
2005年 | 75篇 |
2004年 | 65篇 |
2003年 | 53篇 |
2002年 | 48篇 |
2001年 | 57篇 |
2000年 | 35篇 |
1999年 | 44篇 |
1998年 | 92篇 |
1997年 | 47篇 |
1996年 | 49篇 |
1995年 | 31篇 |
1994年 | 36篇 |
1993年 | 37篇 |
1992年 | 21篇 |
1991年 | 20篇 |
1990年 | 24篇 |
1989年 | 24篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 22篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有1953条查询结果,搜索用时 0 毫秒
101.
Christian Gentzsch Dr. Matthias Hoffmann Dr. Yasuhiro Ohshima Naoko Nose Dr. Xinyu Chen Prof. Dr. Takahiro Higuchi Prof. Dr. Michael Decker 《ChemMedChem》2021,16(9):1427-1437
The enzyme butyrylcholinesterase (BChE) represents a promising target for imaging probes to potentially enable early diagnosis of neurodegenerative diseases like Alzheimer's disease (AD) and to monitor disease progression in some forms of cancer. In this study, we present the design, facile synthesis, in vitro and preliminary ex vivo and in vivo evaluation of a morpholine-based, selective inhibitor of human BChE as a positron emission tomography (PET) tracer with a pseudo-irreversible binding mode. We demonstrate a novel protecting group strategy for 18F radiolabeling of carbamate precursors and show that the inhibitory potency as well as kinetic properties of our unlabeled reference compound were retained in comparison to the parent compound. In particular, the prolonged duration of enzyme inhibition of such a morpholinocarbamate motivated us to design a PET tracer, possibly enabling a precise mapping of BChE distribution. 相似文献
102.
Repeatable change in electrical resistance of Si surface by mechanical and electrical nanoprocessing
The properties of mechanically and electrically processed silicon surfaces were evaluated by atomic force microscopy (AFM). Silicon specimens were processed using an electrically conductive diamond tip with and without vibration. After the electrical processing, protuberances were generated and the electric current through the silicon surface decreased because of local anodic oxidation. Grooves were formed by mechanical processing without vibration, and the electric current increased. In contrast, mechanical processing with vibration caused the surface to protuberate and the electrical resistance increased similar to that observed for electrical processing. With sequential processing, the local oxide layer formed by electrical processing can be removed by mechanical processing using the same tip without vibration. Although the electrical resistance is decreased by the mechanical processing without vibration, additional electrical processing on the mechanically processed area further increases the electrical resistance of the surface. 相似文献
103.
Shuichi Nakamura Ayaka Toda Masahide Sano Tsubasa Hatanaka Yasuhiro Funahashi 《Advanced Synthesis \u0026amp; Catalysis》2016,358(7):1029-1034
We disclose herein an efficient enantioselective conjugate addition reaction between coumarin‐3‐carboxylic acids and malonic acid half thioesters (MAHTs). The reaction was catalyzed by N‐heteroarenesulfonyl Cinchona alkaloid amides to afford double‐decarboxylative conjugate addition products in good yield with high enantioselectivity. The reaction of various coumarin‐3‐carboxylic acids with MAHTs gave products in high yield with high enantioselectivity.
104.
105.
Thermal Stability,Optical Transmittance,and Refractive Index Dispersion of La2O3–Nb2O5–Al2O3 Glasses 下载免费PDF全文
Kohei Yoshimoto Atsunobu Masuno Hiroyuki Inoue Yasuhiro Watanabe 《Journal of the American Ceramic Society》2015,98(2):402-407
La2O3–Nb2O5–Al2O3 high‐refractive‐index glasses were fabricated by containerless processing, and the glass‐forming region was determined. The thermal stability, density, optical transmittance, and the refractive index dispersion of these glasses were investigated. All the glasses were colorless and transparent in the visible to near infrared (NIR) region and had high refractive index with low wavelength dispersion. Some of these glasses were found to have significantly high glass‐forming ability. These results indicate that the ternary glasses are suitable for optical applications in the visible to NIR region. The effects of the substitution of Al2O3 for Nb2O5 on optical properties were discussed on the basis of the Drude–Voigt equation. It was suggested that the substitution of Al2O3 for Nb2O5 increased the molecular density and suppressed a decrease in the refractive index, even when both the average oscillator strength and inherent absorption wavelength decreased in La2O3–Nb2O5–Al2O3 glasses. These results are helpful for designing new optical glasses controlled to have a higher refractive index and lower wavelength dispersion. 相似文献
106.
Copolymerization is a useful way of modifying the physical properties of a material to meet specific needs, but it can result in a significant light scattering loss due to dielectric fluctuations in the material. Ideal random copolymers are known to be more transparent; however, the light-scattering properties of such copolymers in bulk have not been fully studied. In this paper, two representative ideal random copolymers were synthesized: methyl methacrylate (MMA)/benzyl methacrylate (BzMA) and MMA/2,2,2-trifluoroethyl methacrylate (TFEMA). The effects of copolymer composition and polymerization temperature on the light-scattering properties were investigated. Polarized light scattering (VV) in copolymers was more sensitive to the polymerization temperature. Higher temperatures were necessary to homogenize the dielectric fluctuations and minimize excess light scattering. However, once the heterogeneous structures vanished, the copolymer bulk exhibited low scattering losses, which are comparable with homopolymers, over the entire range of copolymer compositions. 相似文献
107.
Mio Yamaguchi Kiyoshi Takagi Koki Narita Yasuhiro Miki Yoshiaki Onodera Minoru Miyashita Hironobu Sasano Takashi Suzuki 《International journal of molecular sciences》2021,22(4)
Chemokines secreted from stromal cells have important roles for interactions with carcinoma cells and regulating tumor progression. C-C motif chemokine ligand (CCL) 5 is expressed in various types of stromal cells and associated with tumor progression, interacting with C-C chemokine receptor (CCR) 1, 3 and 5 expressed in tumor cells. However, the expression on CCL5 and its receptors have so far not been well-examined in human breast carcinoma tissues. We therefore immunolocalized CCL5, as well as CCR1, 3 and 5, in 111 human breast carcinoma tissues and correlated them with clinicopathological characteristics. Stromal CCL5 immunoreactivity was significantly correlated with the aggressive phenotype of breast carcinomas. Importantly, this tendency was observed especially in the CCR3-positive group. Furthermore, the risk of recurrence was significantly higher in the patients with breast carcinomas positive for CCL5 and CCR3 but negative for CCR1 and CCR5, as compared with other patients. In summary, the CCL5-CCR3 axis might contribute to a worse prognosis in breast cancer patients, and these findings will contribute to a better understanding of the significance of the CCL5/CCRs axis in breast carcinoma microenvironment. 相似文献
108.
Jinhua She Xin Xin Yasuhiro Ohyama 《IEEJ Transactions on Electrical and Electronic Engineering》2011,6(6):585-593
This paper explains how to use an arm robot experiment system to teach sampled‐data H∞ control theory. A design procedure is presented for a digital tracking control system for a continuous plant with structured uncertainties; the target is the positioning control of an arm robot. To guarantee the robust stability of the closed‐loop system and provide the desired closed‐loop performance, the design problem is first formulated as a sampled‐data H∞ control problem, and is then transformed into an equivalent discrete‐time H∞ control problem. Finally, linear matrix inequalities are used to obtain a reduced‐order output‐feedback controller and a static state‐feedback controller. In a course, the design procedure is explained and practice is provided through simulations and experiments. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
109.
Chienru Lung Shota Miyake Hiroaki Kakigano Yushi Miura Toshifumi Ise Toshinari Momose Hideki Hayakawa 《Electrical Engineering in Japan》2013,182(4):29-46
For the past few years, hybrid generation systems including solar panel and gas cogeneration have been used for residential houses. Solar panels can generate electronic power at daytime but not at night. But the power consumption of residential houses usually peaks in the evening. The gas engine cogeneration system can generate electronic power without such a restriction, and it also can generate heat power to warm up a house or to produce hot water. In this paper we propose a solar panel and gas engine cogeneration hybrid system with an energy storage device, combined by a DC bus. If a blackout occurs, the system still can supply electronic power for special house loads. We propose a control scheme for the system related to the charging level of the energy storage device and the voltage of the utility grid, which can be applied to both grid‐connected and standalone operation. Finally, we report experiments designed to demonstrate system operation and calculations for loss estimation. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(4): 29–46, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ).DOI 10.1002/eej.22321 相似文献
110.
Hiroko Ohuchi-Yoshida Yuji Hatano Yasushi Kino Yasuhiro Kondo 《Fusion Engineering and Design》2012,87(5-6):423-426
A method to detect tritium non-destructively in regions deeper than the escape depth of beta rays is being developed using bremsstrahlung induced by beta rays with an imaging plate (IP). An IP made of europium-doped BaFBr(I), a photostimulated luminescence (PSL) material, is a two-dimensional radiation sensor. The bremsstrahlung energy spectrum is a continuum with photon energies, varying based on the atomic number and thickness of the target (or absorbing) material. When tritium migrates into matter, the bremsstrahlung energy spectrum distribution would change. The PSL intensity of the IP is affected by this energy spectrum variation. In order to quantify the amount of tritium in deeper regions with the IP technique, a tritium depth profile is required.In this study, a new method of obtaining a tritium depth profileusing the combined technique of the IP and thin absorbers is presented. 相似文献