全文获取类型
收费全文 | 1009篇 |
免费 | 33篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 26篇 |
化学工业 | 226篇 |
金属工艺 | 30篇 |
机械仪表 | 27篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 30篇 |
轻工业 | 105篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 69篇 |
一般工业技术 | 218篇 |
冶金工业 | 163篇 |
原子能技术 | 28篇 |
自动化技术 | 84篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 19篇 |
2016年 | 25篇 |
2015年 | 17篇 |
2014年 | 38篇 |
2013年 | 49篇 |
2012年 | 32篇 |
2011年 | 74篇 |
2010年 | 52篇 |
2009年 | 40篇 |
2008年 | 40篇 |
2007年 | 60篇 |
2006年 | 39篇 |
2005年 | 32篇 |
2004年 | 27篇 |
2003年 | 40篇 |
2002年 | 18篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 57篇 |
1997年 | 40篇 |
1996年 | 28篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1044条查询结果,搜索用时 15 毫秒
81.
Kazunori Asano 《International Journal of Cast Metals Research》2018,31(1):29-36
Pure aluminium and high-silicon aluminium alloy were reinforced with the discontinuous pitch-based carbon fibres by squeeze casting, then the thermal conductivity and the mechanical properties of the composites were investigated. Optical microscopy revealed that the fibres were in a random planar arrangement, and the transmission electron microscopy revealed that there is no interfacial reaction between the matrices and the fibres. The random planar arrangement of the fibres leads to the anisotropy of the composite. The fibre-reinforcement increased the thermal conductivity in the parallel direction for both pure aluminium and its alloy matrices, while the thermal conductivity decreased in the vertical direction. The increase in the elastic modulus by the reinforcement was not observed for both matrices. The proof stress of the pure aluminium increased by the reinforcement especially in the parallel direction, while that of the high-silicon alloy decreased by the reinforcement. 相似文献
82.
Nitritation performance in membrane-aerated biofilm reactors differs from conventional biofilm systems 总被引:1,自引:0,他引:1
Susanne Lackner Akihiko Terada Harald Horn Mogens Henze Barth F. Smets 《Water research》2010,44(20):6073-6084
Nitrogen removal via nitrite has gained increasing attention in recent years due to its potential cost savings. Membrane-aerated biofilm reactors (MABRs) are one potential technology suitable to achieve nitritation. In this study we compared lab scale MABRs with conventional biofilm reactors to evaluate the influence of environmental conditions and operational parameters on nitritation performance. The oxygen mass transfer rate is postulated as a crucial parameter to control nitritation in the MABR: Clean water measurements showed significant underestimation of the total oxygen mass transfer, however, accurate determination of the oxygen mass transfer coefficient (km) of the system could be achieved by adjusting the liquid-phase mass transfer resistance in the constructed model. Batch experiments at different initial ammonium concentrations revealed that the conventional biofilm geometry was superior for nitritation compared to MABRs. These differences were reflected well in estimates of the oxygen affinity constants of the key microbial players, AOB and NOB (KO,AOB < KO,NOB (in both systems) and KO,NOB values smaller in the MABR vs. the conventional biofilm system). It also appeared that – in addition to oxygen limitation – the absolute and relative substrate concentrations in the biofilm (esp. of oxygen) are very important for successful nitritation. Initial biomass composition, furthermore, impacted reactor performance in the MABR systems indicating the need for appropriate inoculum choice. 相似文献
83.
84.
Kyoko Kofuji Yuzhou Huang Kazufumi Tsubaki Fumihiko Kokido Kazunori Nishikawa Takashi Isobe Yoshifumi Murata 《Reactive and Functional Polymers》2010,70(10):784-789
A transparent wound dressing sheet was obtained by forming a complex between β-glucan and chitosan (CS). These materials were chosen for their biocompatible, bioabsorbable, and biodegradable properties, and they were expected to promote the therapeutic efficacy of the dressing by increasing the wound healing response. The therapeutic efficacy of the β-glucan–CS complex sheet as a wound dressing was evaluated in wounds created on the dorsal surfaces of mice. β-glucan–CS complex sheets demonstrated therapeutic efficacies comparable or superior to that of Beschitin®W, a commercial wound dressing made from CS. Additionally, the β-glucan–CS complex sheet did not dissolve during the application period, did not adhere to wounds, and was easy to remove. Cumulatively, these results indicate that β-glucan–CS complex sheets are a promising new wound dressing product. 相似文献
85.
86.
H.F.-W. SadrozinskiC. Betancourt A. BieleckiZ. Butko V. FadeyevC. Parker N. PtakJ. Wright Y. UnnoS. Terada Y. IkegamiT. Kohriki S. MitsuiK. Hara N. HamasakiY. Takahashi A. ChilingarovH. Fox 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,658(1):46-50
We have tested the effectiveness of punch-through protection (PTP) structures on n-on-p AC-coupled Silicon strip detectors using pulses from an 1064 nm IR laser, which simulate beam accidents. The voltages on the strips are measured as a function of the bias voltage and compared with the results of DC I-V measurements, which are commonly used to characterize the PTP structures. We find that the PTP structures are only effective at very large currents (several mA), and clamp the strips to much larger voltages than assumed from the DC measurements. We also find that the finite resistance of the strip implant compromises the effectiveness of the PTP structures. 相似文献
87.
Hideaki Fujita Kazunori ShimizuYuki Morioka Eiji Nagamori 《Journal of Bioscience and Bioengineering》2010,110(3):359-362
We have studied the effect of enhanced oxygen delivery by perfluorocarbons on the differentiation of C2C12 cells. The extent of differentiation was assessed by means of phase contrast/fluorescence microscopy, active tension measurement and the glucose consumption/lactate production rates. We found that enhanced oxygen delivery is suitable for full differentiation of C2C12 cells. 相似文献
88.
Ferromagnetic stainless steels (SSs) have been investigated as potential candidates for dental prosthesis applications in replacement of magnetic attachments made of noble and expensive alloys. In order to be used as biomaterials, their corrosion resistance has to be appropriate. The corrosion resistance of passive materials is related to the characteristics of the passive film formed and their properties might be investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves, and Mott–Schottky approach. The corrosion resistance and the capacitance of the passive films formed on PM2000, DIN 1.4575, and 17‐4 PH advanced SSs during 2 days of immersion in a phosphate buffered saline solution (PBS), at 25 °C and pH 7.0 were studied by electrochemical techniques. A commercial alloy Dyna EFM was also analyzed for comparison reasons. The results showed that films on tested materials behave as both n‐type and p‐type semiconductors and the PM2000 presented the highest corrosion resistance among all of them. 相似文献
89.
Bifurcation mechanism underlying echelon-mode formation 总被引:1,自引:0,他引:1
Kazuo Murota Kiyohiro Ikeda Kenjiro Terada 《Computer Methods in Applied Mechanics and Engineering》1999,170(3-4):423-448
This paper presents a theory on the underlying mathematical mechanism of the echelon mode (a series of parallel short wrinkles that looks like a flight of stairs or wild geese arranged in formation) which has been observed ubiquitously with uniform materials, but which has long denied successful numerical simulations. It is shown by means of the group-theoretic bifurcation theory that the echelon mode formation can be explained as a recursive (secondary, tertiary, …) symmetry-breaking bifurcation if O(2) × O(2) is chosen as the underlying symmetry to model the local uniformity of materials. This implies, for example, that the use of periodic boundaries is essential to successfully realize the oblique stripe patterns and the subsequent echelon mode formation in numerical simulations. In fact, a recursive bifurcation analysis of a rectangular domain with periodic boundaries subject to uniform uniaxial compression yields various kinds of patterns, such as diamond, stripe and echelon modes, which are often observed for materials under shear. 相似文献
90.
Digital image-based modeling applied to the homogenization analysis of composite materials 总被引:4,自引:0,他引:4
Absract The systematic methodologies to derive accurate microstructural models are developed for studying the mechanical behaviors
of composite materials. Since the geometric information of a microstructure is often given by an image or a set of images,
the direct interpretation of the geometry is possibly by digitizing it. By identifying each pixel or voxel with a finite element
(FE) and accompanying appropriate image processing, an FE model can be automatically generated. It is also emphasized that
the digitized models can be suitable for solving the FE equations by utilizing the uniformity of the FE mesh. The finite element
analysis (FEA) with the homogenization method enables the prediction the thermo-mechanical behavior of the periodic microstructure
(unit cell) as well as the global mechanical response of a structural component, while we are taking into account the specific
effect of the geometric structural configuration of the microstructure through digitization. Several kinds of the digitizing
techniques are presented to illustrate the potential of digital image-based (DIB) FE modeling of the unit cell. Keeping the
microstructural design in mind, the modification of the plane image is introduced and the virtual realization of the unit
cell geometry is presented so that a microstructural analysis utilizing the homogenization method would be realistic. 相似文献