全文获取类型
收费全文 | 1171篇 |
免费 | 64篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 292篇 |
金属工艺 | 12篇 |
机械仪表 | 33篇 |
建筑科学 | 19篇 |
矿业工程 | 2篇 |
能源动力 | 26篇 |
轻工业 | 125篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 205篇 |
一般工业技术 | 244篇 |
冶金工业 | 168篇 |
原子能技术 | 6篇 |
自动化技术 | 94篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 31篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 34篇 |
2017年 | 30篇 |
2016年 | 32篇 |
2015年 | 21篇 |
2014年 | 41篇 |
2013年 | 59篇 |
2012年 | 54篇 |
2011年 | 97篇 |
2010年 | 55篇 |
2009年 | 49篇 |
2008年 | 65篇 |
2007年 | 56篇 |
2006年 | 47篇 |
2005年 | 31篇 |
2004年 | 28篇 |
2003年 | 37篇 |
2002年 | 37篇 |
2001年 | 26篇 |
2000年 | 35篇 |
1999年 | 31篇 |
1998年 | 51篇 |
1997年 | 47篇 |
1996年 | 33篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1243条查询结果,搜索用时 15 毫秒
21.
Wong E. H. Koh S. W. Lee K. H. Lim K.-M. Lim T. B. Mai Y.-W. 《Advanced Packaging, IEEE Transactions on》2006,29(4):751-759
Two advanced techniques have been developed for modeling vapor pressure within the plastic IC packages during solder reflow. The first involves the extension of the "wetness" technique to delamination along multimaterial interface and during dynamic solder reflow. Despite its simplicity, this technique is capable of offering reliable and accurate prediction for packages with high flexural rigidity. For packages with low flexural rigidity, the new "decoupling" technique that integrates thermodynamics, moisture diffusion, and structural analysis into a unified procedure has been shown to be more useful. The rigorous technique has been validated on both leadframe-based as well as laminate-based packages. With high accuracy and computational efficiency, these dynamic modeling tools will be valuable for optimization of package construction, materials, and solder reflow profile against popcorn cracking for both SnPb and Pb-free solders 相似文献
22.
Indium tin oxide (ITO) films with a smooth surface (root-mean-square roughness; Rrms=0.40 nm) were made using a combination of the deposition conditions in the ion beam-sputtering method. Sheet resistance was 13.8 Ω/sq for a 150-nm-thick film grown at 150 °C. Oxygen was fed into the growth chamber during film growth up to 15 nm, after which, the oxygen was turned off throughout the rest of the deposition. The surface of the films became smooth with the addition of ambient oxygen but electrical resistance increased. In films grown at 150 °C with no oxygen present, a rough surface (Rrms=2.1 nm) and low sheet resistance (14.4 Ω/sq) were observed. A flat surface (Rrms=0.5 nm) with high sheet resistance (41 Ω/sq) was obtained in the films grown with ambient oxygen throughout the film growth. Surface morphology and microstructure of the films were determined by the deposition conditions at the beginning of the growth. Therefore, fabrication of ITO films with a smooth surface and high electrical conductivity was possible by combining experimental conditions. 相似文献
23.
24.
Naixue Xiong Jong Hyuk Park Laurence T. Yang Byoung-Soo Koh Yingshu Li 《Journal of Intelligent Manufacturing》2011,22(2):333-342
Information security management has become an important research issue in distributed systems, and the detection of failures
is a fundamental issue for fault tolerance in large distributed systems. Recently, many people have come to realize that failure
detection ought to be provided as some form of generic service, similar to IP address lookup. However, this has not been successful
so far; one of the reasons being the fact that classical failure detectors were not designed to satisfy several application
requirements simultaneously. More specifically, traditional implementations of failure detectors are often tuned for running
over local networks and fail to address some important problems found in wide-area distributed systems with a large number
of monitored components, such as Grid systems. In this paper, we study the security management scheme for failure detector
distributed systems. We first identify some of the most important QoS problems raised in the context of large wide-area distributed
systems. Then we present a novel failure detector scheme combined with self-tuning control theory that can help in solving
or optimizing some of these problems. Furthermore, this paper discusses the design and analysis of implementing a scalable
failure detection service for such large wide-area distributed systems considering dynamically adjusting the heartbeat streams,
so that it satisfies the bottleneck router requirements. The basic z-transformation stability test is used to achieve the stability criterion, which ensures the bounded rate allocation without
steady state oscillation. We further show how the online failure detector control algorithm can be used to design a controller,
analyze the theoretical aspects of the proposed algorithm and verify its agreement with the simulations in the LAN and WAN
case. Simulation results show the efficiency of our scheme in terms of high utilization of the bottleneck link, fast response
and good stability of the bottleneck router buffer occupancy as well as of the controlled sending rates. In conclusion, the
new security management failure detector algorithm provides a better QoS than an algorithm that is proposed by Stelling et al.
(Proceedings of 7th IEEE symposium on high performance distributed computing, pp. 268–278, 1998), Foster et al. (Int J Supercomput
Appl, 2001). 相似文献
25.
26.
Mild functionalization of carbon nanotubes filled epoxy composites: Effect on electromagnetic interferences shielding effectiveness 下载免费PDF全文
The effect of nitric acid mild functionalized multiwalled carbon nanotubes (MWCNTs) on electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites was examined. MWCNTs were oxidized by concentrated nitric acid under reflux conditions, with different reaction times. The dispersion of MWCNTs after functionalization was improved due to the presence of oxygen functional groups on the nanotubes surface. Functionalization at 2 h exhibits the highest EMI SE and electrical conductivity of MWCNTs filled epoxy composites. However, EMI shielding performance of MWCNTs filled epoxy composite declined when the functionalization reaction time was prolonged. This was due to extensive damage on the MWCNT structure, as verified by a Raman spectroscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42557. 相似文献
27.
M. Luo C. G. Koh M. Gao W. Bai 《International journal for numerical methods in engineering》2015,103(4):235-255
A new numerical approach for solving incompressible two‐phase flows is presented in the framework of the recently developed Consistent Particle Method (CPM). In the context of the Lagrangian particle formulation, the CPM computes spatial derivatives based on the generalized finite difference scheme and produces good results for single‐phase flow problems. Nevertheless, for two‐phase flows, the method cannot be directly applied near the fluid interface because of the abrupt discontinuity of fluid density resulting in large change in pressure gradient. This problem is resolved by dealing with the pressure gradient normalized by density, leading to a two‐phase CPM of which the original singlephase CPM is a special case. In addition, a new adaptive particle selection scheme is proposed to overcome the problem of ill‐conditioned coefficient matrix of pressure Poisson equation when particles are sparse and non‐uniformly spaced. Numerical examples of Rayleigh–Taylor instability, gravity current flow, water‐air sloshing and dam break are presented to demonstrate the accuracy of the proposed method in wave profile and pressure solution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
28.
Younghun Sung Jaehoon Lim Jai Hyun Koh Byoung Koun Min Jeffrey Pyun Kookheon Char 《Korean Journal of Chemical Engineering》2016,33(8):2287-2290
Pt-decorated CdSe tetrapods with different arm lengths were tested for the photocatalytic hydrogen generation reaction. Well-defined CdSe tetrapods with controlled wurtzite arm lengths were synthesized by the continuous precursor injection (CPI) approach. Pt nanocrystals with an extremely small size of ~1 nm were directly decorated on the overall surfaces of CdSe tetrapods. Ligand-exchanged Pt-decorated CdSe tetrapods with different arm lengths were employed as photocatalysts for photocatalytic hydrogen generation reaction in the presence of hole scavengers. Pt-decorated CdSe tetrapods with shorter arm length showed the highest photocatalytic efficiency, which is due to higher probability of charge separation. 相似文献
29.
Stephen Buckman Mara Latorre M. Martin Bosman Neveen Nawawy Bomin Koh 《Papers in Regional Science》2019,98(2):679-699
As cities are compelled to compete for new sources of investment and revenue, arts-based economic development strategies have become the norm. The purpose of this paper is to revisit and reevaluate some of the conventional claims about the arts as an important economic development strategy by exploring a case study called “The Space at 2106 Main” in a rapidly gentrifying neighbourhood called West Tampa. The results of this study suggest that the arts are indeed assuming a greater role in economic policy under the auspices of West Tampa community redevelopment areas (CRA) and the direct actions of various arts related entrepreneurs. The results however, point to a mixed picture that raises difficult questions about the medium to long-term effects of this urban redevelopment strategy, especially on the poor and mostly minority residents of West Tampa. 相似文献
30.
Adam Alemayehu Dominika Zákutná Soňa Kohúteková Václav Tyrpekl 《Journal of the American Ceramic Society》2022,105(7):4621-4631
Ceria, pure or doped, is an important electrolyte material in solid oxide fuel cells, catalysts, and plutonium surrogates. Even though ceria is a widely studied material, its coprecipitation with the most common doping element, gadolinium, remains mostly overlooked. Here, we present a comprehensive study of gadolinium–cerium oxalates prepared by coprecipitation of gadolinium (III) and cerium (III) salts by oxalic acid under different reaction conditions and element ratios. For this purpose, we assessed the effects of basic precipitation conditions on the final oxalate size, shape, and conversion into the corresponding oxides. The results showed that coprecipitation with oxalic acid yields and ideal solid solution, which translates into the oxides. This low-cost and straightforward synthetic route provides then high-quality solid solutions of Ge–Gd in the oxide lattice. Thus, this approach has a high industrialization potential, with significant advantages over hydrolysis or hydrothermal techniques. 相似文献