全文获取类型
收费全文 | 1935篇 |
免费 | 42篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 147篇 |
综合类 | 2篇 |
化学工业 | 475篇 |
金属工艺 | 64篇 |
机械仪表 | 49篇 |
建筑科学 | 49篇 |
矿业工程 | 1篇 |
能源动力 | 77篇 |
轻工业 | 179篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 168篇 |
一般工业技术 | 291篇 |
冶金工业 | 261篇 |
原子能技术 | 50篇 |
自动化技术 | 165篇 |
出版年
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 23篇 |
2020年 | 14篇 |
2019年 | 21篇 |
2018年 | 30篇 |
2017年 | 24篇 |
2016年 | 25篇 |
2015年 | 21篇 |
2014年 | 41篇 |
2013年 | 112篇 |
2012年 | 71篇 |
2011年 | 107篇 |
2010年 | 71篇 |
2009年 | 104篇 |
2008年 | 102篇 |
2007年 | 68篇 |
2006年 | 65篇 |
2005年 | 66篇 |
2004年 | 65篇 |
2003年 | 77篇 |
2002年 | 54篇 |
2001年 | 41篇 |
2000年 | 29篇 |
1999年 | 44篇 |
1998年 | 109篇 |
1997年 | 68篇 |
1996年 | 61篇 |
1995年 | 51篇 |
1994年 | 41篇 |
1993年 | 43篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 26篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 21篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 16篇 |
1975年 | 5篇 |
1970年 | 7篇 |
排序方式: 共有1986条查询结果,搜索用时 15 毫秒
1.
To enhance chemical stability and suppress of aggregation of magnetite nanoparticles (MNPs), which are used as a support for thermoresponsive copolymer immobilization, silica coating of the MNPs is applied via the electrooxidation method. Although the resulting silica coated-MNPs also formed aggregates, the size distribution of the aggregate shifted to smaller size range. Because of that, the surface area available for copolymer immobilization increased approximately 6.7 times at maximum as compared with that of the uncoated MNPs. It contributed to the increase of the amount of the immobilized copolymer on the silica-coated MNPs, which is approximately four times larger than that on the uncoated MNPs. Fe3O4 dissolution test confirmed enhancement of chemical stability of MNPs. The thermoresponsive copolymer immobilized on the silica-coated MNPs shows the ability to recycle Cu(II) ion from Cu(II) containing solution by changing temperature with significantly shorter time than those in other thermoresponsive adsorbents in gel form. 相似文献
2.
Hitoshi Muta 《Journal of Nuclear Science and Technology》2019,56(5):367-368
Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering, the studies related to risk analysis methodology, design, and operational management, physical phenomena, and emergency preparedness and nuclear security, have been progressed. Especially, ‘risk analysis methodology’ and ‘design and operational management’ are the main categories of the field, in which more than half of published articles on Journal of Nuclear Science and Technology are related to these categories. 相似文献
3.
The effect of humidity during storage on the crosslinking reactions of isocyanate groups was investigated with attenuated total reflectance Fourier transform infrared spectroscopy with pressure‐sensitive adhesives composed of poly[ethyl acrylate‐co‐(2‐ethylhexyl acrylate)‐co‐(2‐hydroxyethyl methacrylate)] as a base resin and polyisocyanate as a crosslinker. A peak‐resolving analysis of the amide II region revealed four bands. According to an analysis of the Fourier transform infrared spectra of the model compounds, these four bands were assigned to free urethane linkages, hydrogen‐bonded urethane linkages, free urea linkages, and hydrogen‐bonded urea linkages. As expected, storage under humid conditions led to the formation of free and hydrogen‐bonded urea linkages corresponding to the promotion of isocyanate consumption. Peak resolution of the amide II region was found to be a reasonable way of monitoring urethane and urea linkages during crosslinking reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3039–3045, 2003 相似文献
4.
In order to investigate the reduction mechanism of thioglycolic acid (TG) on the keratin fibers, cross-sectional samples of white human hair treated with TG were prepared. The heterogeneous reaction between TG and keratin fibers involving the diffusion of TG into human hair was analyzed at the molecular level using microspectrophotometry and FT-Raman spectroscopy. The diffusion of TG into human hair clearly increased by increasing the treatment time and by raising pH. The TG relative concentration and the disconnected relative concentration of disulfide (–SS–) groups at various depths of the hair samples with pH 9.0 were in good agreement, indicating that the reaction rate (the disconnection of –SS– groups) was faster than the diffusion rate of TG into human hair. From these experiments, we demonstrated that TG diffuses gradually beyond the cuticle region, and toward the inside of the cortex region along with the disconnection of –SS– groups. 相似文献
5.
This paper proposes a method to reduce the vibration of the three-phase HB-type stepping motor with cogging torque by the feedforward compensation control. The compensation signal to suppress the vibration of the motor frame is obtained by the repetitive controller installing an online Fourier transformer and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor such as a microphone placed close to the frame. The sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation data obtained by the repetitive controller is applied to the operating point changed by reference frequency and load condition in steady state. The compensation signal for the new operating point will be generated from compensation data utilizing polynomial equation approximation and linear interpolation method. The effectiveness of this proposed method is confirmed by the experimental results. 相似文献
6.
Mamiko Hori Cécile Pagnoux Jean-François Baumard Masayuki Nogami 《Journal of Materials Science》2007,42(1):80-86
A new method is proposed to produce gold nanoparticles (GNP) by in situ reduction of a gold salt dissolved in water. The reducing
agent used is Tiron instead of the citrate anion most often mentioned in literature. The influence of various parameters has
been investigated, such as the content of Tiron with respect to that of the precursor of gold HAuCl4, or the initial pH of the solution after mixing of reactants. It is shown that Tiron also exerts a positive influence as
a dispersant, which impedes agglomeration of gold nanoparticles. The typical average size of GNP synthesized in the present
work is close to 7 nm. 相似文献
7.
Iwao Shimizu Yuji Naito Iwao Yamaguchi Katsuyuki Kaiho Hitoshi Mizoguchi Satoru Yanabu 《Electrical Engineering in Japan》2008,164(1):52-61
Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315 相似文献
8.
A molecular far-infrared (FIR) laser optically pumped by a high-power CO2 laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 20~30m W by pumping power of 35~81W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller. As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes. 相似文献
9.
A case of small epithelioid hemangioendothelioma encapsulated by an egg-shaped bony shell composed of newly formed mature lamellar bone is presented. A nodule measuring 10 x 5 x 5 mm was excised from inside of the right cheek muscle of a 46-year-old man. Histopathologically, the nodule consisted mainly of round-to-short spindled epithelioid cells with round nuclei and occasional cytoplasmic vacuoles associated with some foci of osseous metaplasia. Characteristically, egg shell-like lamellar bone enclosed this lesion showing well-circumscribed appearance. The main component cells were immunohistochemically stained positive for factor VIII-related antigen, CD 34, UEA-1, and vimentin, and proved to be vascular endothelial cells. The term ossifying epithelioid hemangioendothelioma is proposed for this unique lesion. This type of epithelioid hemangioendothelioma has not been previously reported to our knowledge, and differentiation from ossifying fibromyxoid tumor of soft parts is considered to be important. 相似文献
10.
Hitoshi Furuta Jianhong He Eiichi Watanabe 《Computer-Aided Civil and Infrastructure Engineering》1996,11(1):37-45
Abstract: An efficient knowledge-acquisition support method is required for improvement and maintenance of the knowledge base in durability evaluation of an RC bridge deck. Such a method is proposed in this paper to automatically acquire fuzzy production rules. This method makes joint use of genetic algorithms and a neural network. Using a neural network as a subsystem, the evaluation function of genetic algorithms can be provided with the weights of the neural network. Introducing a neural network into genetic algorithms, it is possible to acquire new knowledge so that the method is useful when it is difficult to acquire knowledge in the field. 相似文献