全文获取类型
收费全文 | 584篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 145篇 |
金属工艺 | 22篇 |
机械仪表 | 17篇 |
建筑科学 | 14篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 49篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 82篇 |
一般工业技术 | 102篇 |
冶金工业 | 66篇 |
原子能技术 | 6篇 |
自动化技术 | 63篇 |
出版年
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 26篇 |
2014年 | 21篇 |
2013年 | 43篇 |
2012年 | 26篇 |
2011年 | 28篇 |
2010年 | 24篇 |
2009年 | 23篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 34篇 |
2003年 | 29篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 20篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1956年 | 1篇 |
排序方式: 共有603条查询结果,搜索用时 15 毫秒
51.
On the existence of chaos in the electronically adjustable structures of the state variable filters 下载免费PDF全文
Jiri Petrzela 《International Journal of Circuit Theory and Applications》2016,44(10):1779-1797
As demonstrated in the paper, chaotic motion can appear in state variable filters, that is, common network structures dedicated for analog signal processing. In particular, two Kerwin–Huelsman–Newcomb biquadratic filtering sections are considered for theoretical, numerical and experimental analysis. Mathematical models are designed, and conditions for evolution of typical strange attractors are provided. The corresponding largest Lyapunov exponent is calculated and visualized as a function of internal system parameters and the shape of input harmonic waveform. Mutual connection between the mathematical model and the real lumped electronic circuit is discussed in detail. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
52.
The effect of alumina particulates on a thermoplastic matrix is investigated, in particular the effect altering the alumina particle size and morphology has on the mechanical properties. Different grades of alumina are used and two thermoplastic matrices; namely poly(propylene) and poly(ethylene-co-vinyl acetate). Investigations showed that optimum properties were achieved with the alumina of smallest particle size and lowest aspect ratio. Preliminary work has also been performed on the use of silane coupling agents and they have proved effective in increasing the tensile properties of the composites. 相似文献
53.
Jiri Hajek Tomas Jurena Bernhard Baier Arash Bagherzadeh Tom Schnick Quido Smejkal 《化学,工程师,技术》2015,87(7):991-997
Calcination of diatomite is an expensive process frequently resulting in products with unpredictable structure. Alternatively, calcination in swirling flow is an energy‐saving option. Computational fluid dynamics modeling of an experimental calcination process unit is presented. Experimental results and systematic collection of process data were used to define boundary condition for steady‐state and transient simulation runs. The comparison of experimental and simulation results shows the complexity of the calcination process. The results can be used for further process optimization. 相似文献
54.
Emily H. Kuhns Xavier Martini Yolani Tribuiani Monique Coy Christopher Gibbard Jorge Peña Jiri Hulcr Lukasz L. Stelinski 《Journal of chemical ecology》2014,40(4):355-362
The redbay ambrosia beetle, Xyleborus glabratus, is an invasive wood-boring beetle that has become established in the southeastern United States. The beetle transmits the causal pathogen of lethal laurel wilt to susceptible host trees, which include redbay, an important forest community species, and avocado, a valuable food crop. By examining odors of redbay wood, we developed an artificial lure that captured X. glabratus in redbay forests. Eucalyptol was a critical component of the blend for beetle attraction, and eucalyptol alone in large quantities attracted X. glabratus. Furthermore, eucalyptol stimulated boring by X. glabratus into paper arenas. The results suggest that eucalyptol contributes to host selection behavior of X. glabratus and may be useful for management of this pathogen vector. 相似文献
55.
Synn?ve Nymark Aasen Aneta Pospisilova Tilo Wolf Eichler Jiri Panek Martin Hruby Petr Stepanek Endy Spriet Daniel Jirak Kai Ove Skaftnesmo Frits Thorsen 《International journal of molecular sciences》2015,16(9):21658-21680
To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T1 relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/μL of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe. 相似文献
56.
Granular bed filter (GBF) technology can be applied for high-temperature gas cleanup in integrated gasification combined-cycle (IGCC) and pressurized fluidized-bed combustion (PFBC) advanced coal-fired power plants. The design of the gas inlet component of the granular bed filter is important to achieve a uniform gas distribution and higher usage rate of the filter media. Previous studies show that the gas velocity at the inlet is not uniformly distributed. This non-uniformity may lead to a lower usage rate of the filter media. In this study a baffle device is introduced to the inlet system in order to achieve a more uniform gas velocity distribution. A more uniform gas inlet distribution can be obtained by adjustment of the lengths and angles of the baffles. The gas velocities along the inlet and filtration surfaces are measured using a pitot tube. The uniformity of the gas velocity distribution can be characterized by looking at the distributions of the standard deviation of the gas velocity and the differences in the mean velocities between the two filtration surfaces. 相似文献
57.
Cheng He Jim Wood Jiri Marsalek Quintin Rochfort 《Canadian Metallurgical Quarterly》2008,134(9):722-730
The feasibility of high-rate treatment of storm water achieving total suspended solids (TSS) removals in the range from 60 to 80% was studied using an available clarifier. The clarifier (3?m long, 1.4?m wide, and 2?m deep) was fitted with a removable lamella pack and had a limited flow capacity (surface load rate of 35?m/h). To achieve the desired removals of TSS, the clarifier required polymer feed (4?mg/L), which caused maintenance problems during intermittent storm-water treatment—laborious and costly cleaning of lamella plates after individual storm events. This problem posed the following challenge: was it feasible to avoid costly maintenance by removing the lamella pack and at the same time to retain the high TSS removals by improving the clarifier hydraulics by internal structural changes? The purpose of the paper is to evaluate such changes by focusing on different inlet configurations designed using computational fluid dynamics (CFD) simulations. This analysis resulted in adopting a U-tube duct inlet (inserted into the outer box of the original clarifier) with two special features: (1) three horizontal slot openings (width = 0.1?m) releasing flow into the clarifier and (2) a narrow slot opening in the bottom U bend allowing removal of grit. The flow release slots in the rising leg of the U tube were fitted, along the upper edge, with horizontal trailing plates protruding 0.15?m into the clarifier and forcing the flow to move horizontally. This clarifier design performed well, but storm-water grit accumulated at the bottom of the U tube, which had to be cleaned out after individual storms to avoid plugging. This issue was resolved by allowing grit to move into the sludge storage compartment of the clarifier through a narrow tilted slot opening in the U-tube bottom. The final clarifier design with polymer feed, without lamellas, produced TSS removals comparable to those in the original lamella clarifier (almost 80%), but at a higher surface loading rate (43?m/h, which was limited by the feed pump capacity). CFD modeling, in comparison to conventional methods of hydraulic design, served as a flexible and powerful tool providing distinct advantages with respect to the speed, efficiency and reduced cost of analysis, and a better understanding of the clarifier operation. 相似文献
58.
Michal Hoznedl Ladislav Tajc Jaroslav Krejcik Lukas Bednar Kamil Sedlak Jiri Linhart 《Frontiers of Energy and Power Engineering in China》2009,3(3):321-329
In the past, increased attention was given to the development of an optimal shape for the inlet part of LP turbine casings
in SKODA POWER. A double-flow design is typically used for high power output turbines. An optimized shape for the internal
diffuser has been found, which transforms the kinetic energy of steam into increased pressure, thus effectively increasing
the thermodynamic efficiency of the stage. Some conclusions have been drawn from laboratory experiments, others derived directly
from on-site measurements at power plants. The conclusions from the development of double-flow turbines form the basis for
the design of the single-flow turbine arrangement. Single-flow design is typically used for lower output turbines. There are
still some limitations in applying this arrangement. The designer needs to resolve the bearing position and how to ensure
access to them. Reinforcing the ribs and supports are used, therefore, to ensure the rigidity of the entire casing. The optimization
of the single-flow diffuser shape is therefore the subject of the study presented below. 相似文献
59.
We use a surface impedance formulation to enable the MoM‐based full‐wave layered interconnect simulator, UA‐FWLIS, to handle conductor losses for stripline interconnects. Because these approaches are fully compatible with the previously developed analytical calculations for the reaction matrix elements, the computational efficiency of UA‐FWLIS is not affected by including conductor losses. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. 相似文献
60.
Panagiotis Dallas Jiri Tucek Dalibor Jancik Milan Kolar Ales Panacek Radek Zboril 《Advanced functional materials》2010,20(14):2347-2354
A recently developed multi‐functional phosphotriazine‐based polymer is used as a matrix for embedding γ‐Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4‐phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum‐inhibition concentrations are below 100 mg L?1, which is comparable to their equivalent minimum‐inhibition concentrations in colloidal silver systems. 相似文献