首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   120篇
  免费   12篇
  国内免费   2篇
电工技术   6篇
综合类   1篇
化学工业   18篇
金属工艺   2篇
机械仪表   4篇
建筑科学   9篇
能源动力   7篇
轻工业   27篇
石油天然气   1篇
无线电   16篇
一般工业技术   8篇
冶金工业   6篇
原子能技术   2篇
自动化技术   27篇
  2023年   1篇
  2022年   2篇
  2021年   9篇
  2020年   9篇
  2019年   8篇
  2018年   10篇
  2017年   12篇
  2016年   6篇
  2015年   6篇
  2014年   7篇
  2013年   12篇
  2012年   2篇
  2011年   5篇
  2010年   7篇
  2009年   5篇
  2008年   6篇
  2007年   2篇
  2006年   2篇
  2005年   3篇
  2004年   3篇
  2001年   2篇
  1999年   1篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1995年   2篇
  1992年   2篇
  1991年   2篇
  1984年   1篇
  1982年   1篇
  1967年   1篇
排序方式: 共有134条查询结果,搜索用时 228 毫秒
1.
Strategy Logic (SL) is a very expressive temporal logic for specifying and verifying properties of multi-agent systems: in SL, one can quantify over strategies, assign them to agents, and express LTL properties of the resulting plays. Such a powerful framework has two drawbacks: first, model checking SL has non-elementary complexity; second, the exact semantics of SL is rather intricate, and may not correspond to what is expected. In this paper, we focus on strategy dependences in SL, by tracking how existentially-quantified strategies in a formula may (or may not) depend on other strategies selected in the formula, revisiting the approach of [Mogavero et al., Reasoning about strategies: On the model-checking problem, 2014]. We explain why elementary dependences, as defined by Mogavero et al., do not exactly capture the intended concept of behavioral strategies. We address this discrepancy by introducing timeline dependences, and exhibit a large fragment of SL for which model checking can be performed in 2-EXPTIME under this new semantics.  相似文献   
2.
Because of heat amount is different from peripheral to central of friction welding interface, which is leaded to vary the characterizations along that interface. Current study, respectively, focused on the effect of different friction pressure on micro-structural and mechanical properties of that friction welding joint interface. Presently, these friction pressures are 110, 130, 150 and 170 MPa while kept all other conditions constant. The effects of different friction pressure on welding interface characterization were investigated by EDX, SEM, tensile, compression, impact and hardness tests. The tensile tests carried out on the standardized test piece with diameter 6 mm and 8 mm, thus, compression tests were extracted from the positions of 0°, 45° 90° with test specimen of 4 mm diameter and 6.5 mm length at weld center. Whereas, the impact test pieces were picked up in two positions, the first one is symmetrical, which it obtained to the respect of the rotation axis and the interface, on the other hand, the second one is non-symmetrical with the axis of rotation and symmetrical to the interface, for making the notch head coincide with the center of the welded joint, The obtained results showed that with reducing of friction pressure will present lack of bonding increasing from peripheral toward the welding center, which will responsible on reducing of the mechanical properties such as tensile, compression and impact strength.  相似文献   
3.
This work aims to improve the rheological properties and stability of multiwalled carbon nanotubes (MWCNTs)/acrylamide (AA) base skeleton polymer blends at harsh environment of high salinity-high temperature (HS-HT) or various pH. Different co/terpolymers have been accomplished to modify the structure of AA polymer by free-radical copolymerization of AA-based monomers. Anionic, cationic, and hydrophobic functional groups were used for the synthesis of polyelectrolyte, polyampholytic, and partially hydrophobic AA polymer types. The conversion, molecular weight, and poly dispersity of co/terpolymers have been evaluated by nuclear magnetic resonance (1H-NMR), gel permeation chromatography, and differential scanning calorimetry analysis. The effects of sonication power, concentration of polymer, and concentration of MWCNTs were also investigated on rheological behavior of co/terpolymers. The results show that negative polyelectrolyte and polyampholytic polymers are the best candidates for the improvement of MWCNTs/polymer stability and viscosity at HS-HT and alkali environment, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47205.  相似文献   
4.
Multimedia Tools and Applications - Accurate food image classification is often critical to accurately monitor the dietary assessment to reduce the risk of different heart-related diseases,...  相似文献   
5.
In this work, highly-pure silicon oxide nanostructures were prepared by a closed-field unbalanced magnetron plasma sputtering technique. These nanostructures were characterized by Fourier-transform infrared spectroscopy, UV-visible spectroscopy, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy and atomic force microscopy in order to determine the optimum preparation conditions. Minimum particle size of 20 nm was determined for the samples prepared at an inter-electrode distance of 4 cm, Ar:O2 gas mixing ratio of 70:30, total gas pressure of 0.08 torr, discharge voltage of 2.5 kV, discharge current of 35 mA, anode temperature of 27 °C (room temperature) and cathode temperature of about 40 °C. These conditions are optimized to control the structural characteristics of such nanostructures and hence to satisfy certain requirements and purposes in spectroscopic and photonic applications of SiO2 nanostructures.  相似文献   
6.
The Internet has become essential to all aspects of modern life, and thus the consequences of network disruption have become increasingly severe. It is widely recognised that the Internet is not sufficiently resilient, survivable, and dependable, and that significant research, development, and engineering is necessary to improve the situation. This paper provides an architectural framework for resilience and survivability in communication networks and provides a survey of the disciplines that resilience encompasses, along with significant past failures of the network infrastructure. A resilience strategy is presented to defend against, detect, and remediate challenges, a set of principles for designing resilient networks is presented, and techniques are described to analyse network resilience.  相似文献   
7.
Many experimental and numerical studies have been done on different configurations of solar stills to optimize the design by examining the effect of climatic, operational and design parameters on its performance. The majority of the investigators presented their results in scatter diagrams rather than correlations. One of the most important of the operational parameters that has received a considerable attention in the literature is the brine depth. A good number of the investigations on the effect of brine depth are cited in this study. For each of these studies, a correlation was developed from the data reported by each study. A concluding correlation from all brine depth data was developed. The correlation showed a decreasing trend in the productivity with the increase in the brine depth. An experimental study was subsequently conducted to verify this trend by an experimental investigation on a solar still that was constructed and tested with five different brine depths, namely 1, 4, 6, 8 and 10 cm. The present study validated the decreasing trend in productivity with the increase of brine depth and showed that the still productivity could be influenced by the brine depth by up to 48%.  相似文献   
8.
This work aims at identifying, by coupled scanning and transmission electron microscopy (SEM and TEM) observations, the densification mechanisms occurring when an atomized Ti-47Al-1W-1Re-0.2Si powder is densified by spark plasma sintering (SPS). For this purpose, interruptions of the SPS cycle have been performed to follow the evolution of the microstructure step by step. The powder particles exhibit a classical dendritic microstructure containing a large amount of out-of-equilibrium α phase. During heating-up, the microstructure undergoes successive transformations. At T = 525-875 °C the α phase transforms into γ. The γ phase formed is supersaturated in W and Re. It de-saturates for T above 875 °C by discontinuous precipitation of W and Re-rich B2 phase. Densification takes place for T between 900 °C and 1150 °C by plastic deformation of the powder particles. TEM observations show that the repartition of the plastic deformation is correlated to the dendritic microstructure, and that dynamic recrystallization mechanisms occur. Microstructural phenomena directly resulting from the high currents involved in the SPS process have not been observed.  相似文献   
9.
Atmospheric concentrations of many elements have been significantly increased by human activities. The quantification of these changes and their effect on the terrestrial and aquatic ecosystems is important because of their potentially adverse effects. The human nuclear activities, especially releases from the spent nuclear fuel reprocessing plants, are presently the main source of 129I in the environment.In this work, the concentration of 129I and the ratios of 129I/127I in aerosols weekly collected in Vienna, Austria (202 m a.s.l) during the year 2001 are presented. Iodine was extracted from the aerosol filters using a strong basic solution and separated from the matrix elements by anion exchange. The chemical yield of the procedure, determined by ICP-MS, ranges from 70% to 95%. The AMS results indicated that the 129I/127I isotopic ratios were of the order 10−8 to 10−7. The 129I originated from gaseous emissions from the Sellafield reprocessing plant. The measured 129I concentrations were compared with those of 7Be, a cosmogenic radionuclide. Although, both radionuclides exhibit nearly the same distribution pattern (higher levels in summer and lower in winter) their different origins can clearly be deduced from short term variations.  相似文献   
10.
For a sequence ofm urns we investigate how the number of urns satisfying a certain condition (e.g., being empty) evolves in time when after each time unit a ball is thrown. We show for a variety of urn models that this process (suitably normalized) converges weakly to a Gaussian process. The first and third authors’ work was supported by the Austrian Science Foundation FWF, Grant P10187-MAT. The second author was also supported by the Austrian-French project AMADEUS No. 97049. Online publication September 22, 2000.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号