全文获取类型
收费全文 | 91篇 |
免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 2篇 |
化学工业 | 9篇 |
金属工艺 | 6篇 |
机械仪表 | 5篇 |
建筑科学 | 9篇 |
能源动力 | 7篇 |
轻工业 | 11篇 |
无线电 | 14篇 |
一般工业技术 | 17篇 |
原子能技术 | 2篇 |
自动化技术 | 12篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 19篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有96条查询结果,搜索用时 15 毫秒
71.
72.
Hyun Do NAM 《浙江大学学报:C卷英文版》2012,(11):840-849
Ball grid arrays (BGAs) have been used in the production of electronic devices/assemblies because of their advantages of small size, high I/O port density, etc. However, BGA voids can degrade the performance of the board and cause failure. In this paper, a novel blob filter is proposed to automatically detect BGA voids presented in X-ray images. The proposed blob filter uses the local image gradient magnitude and thus is not influenced by image brightness, void position, or component interference. Different sized average box filters are employed to analyze the image in multi-scale, and as a result, the proposed blob filter is robust to void size. Experimental results show that the proposed method obtains void detection accuracy of up to 93.47% while maintaining a low false ratio. It outperforms another recent algorithm based on edge detection by 40.69% with respect to the average detection accuracy, and by 16.91% with respect to the average false ratio. 相似文献
73.
Entransy has been applied and studied in a broad range of heat transfer optimizations recently. Current study proposes the entransy of evaporators to conduct the optimization of heat exchangers in heating, ventilation, air conditioning and refrigeration systems. A novel finless bare tube heat exchanger was studied using a validated heat exchanger modeling tool. The capacity based optimization and entransy dissipation based thermal resistance were used and compared. The applicability of using entransy dissipation based thermal resistance in this type of heat exchanger optimization has been discussed. It has been demonstrated that minimizing entransy dissipation and maximizing capacity are equivalent to optimizing evaporators with fixed flow rates and different when optimizing evaporators with variable flow rates and the deviation is negligible when heat exchanger capacity is small (~1 kW) and more obvious as heat exchanger capacity increases. Thus entransy dissipation based thermal resistance could be used as an alternative optimization index to capacity for evaporators with fixed flow rate and small capacity evaporators with variable flow rates and should be used individually with capacity as an optimization index for evaporators with large capacity and variable flow rates. 相似文献
74.
Recent drive for high-throughput microfluidic systems has triggered tremendous research effort to develop efficient, high-throughput microfluidic mixers. In particular, inducing a fluid–fluid collision at high flow rate in microfluidic channel has been suggested as an effective strategy to enhance mixing. However, previous studies using T-shaped microfluidic mixers showed that, in addition to fluid–fluid collision, the confluence angle of fluid stream in microfluidic channel also has a dramatic effect on mixing. This study suggests the possibility to enhance mixing by simply changing the inlet confluence angle of the streams. In this work, we assess the mixing behaviour of microfluidic mixers with variable inlet confluence angle with the Reynolds number (Re) range of 2.83–566. It is shown that the increase in inlet confluence angle enables the reduction of Re required for complete mixing. Simulation results demonstrate that increasing the confluence angle facilitates the interaction of vortices in mixers to induce an enhanced mixing. We further demonstrate that the increased interaction of vortices also prompts the turbulent emulsification where a significant reduction in emulsion size is observed for each mixer with increased inlet confluence angle at same Re. 相似文献
75.
Image analysis is an important tool for characterizing nano/micro network structures. To understand the connection, organization and proper alignment of network structures, the knowledge of the segments that represent the materials inside the image is very necessary. Image segmentation is generally carried out using statistical methods. In this study, we developed a simple and reliable masking method that improves the performance of the indicator kriging method by using entropy. This method selectively chooses important pixels in an image (optical or electron microscopy image) depending on the degree of information required to assist the thresholding step. Reasonable threshold values can be obtained by selectively choosing important pixels in a complex network image composed of extremely large numbers of thin and narrow objects. Thus, the overall image segmentation can be improved as the number of disconnected objects in the network is minimized. Moreover, we also proposed a new method for analyzing high‐pixel resolution images on a large scale and optimized the time‐consuming steps such as covariance estimation of low‐pixel resolution image, which is rescaled by performing the affine transformation on high‐pixel resolution images. Herein, image segmentation is executed in the original high‐pixel resolution image. This entropy‐based masking method of low‐pixel resolution significantly decreases the analysis time without sacrificing accuracy. 相似文献
76.
Seung Jung Yu Kwanyong Pak Moo Jin Kwak Munkyu Joo Bong Jun Kim Myung Seok Oh Jieung Baek Hongkeun Park Goro Choi Do Heung Kim Junhwan Choi Yunho Choi Jihye Shin Heeyeon Moon Eunjung Lee Sung Gap Im 《Advanced Engineering Materials》2018,20(3)
77.
Yunho Hwang Reinhard Radermacher Toshio Hirata 《International Journal of Refrigeration》2008,31(2):256-261
In this study, a method of using a capacitance sensor was investigated as a means to measure the mass fraction of a type of PAG oil flowing with CO2 in a transcritical cycle. The test facility equipped with the capacitance sensor was fabricated to establish and maintain a known oil mass fraction and to measure the capacitance of the CO2/oil mixture. By using this facility, the relationship among three parameters (reduced CO2 density (CO2 density divided by the critical density of CO2), oil mass fraction, and relative dielectric constant of the CO2/PAG oil mixture) was developed. For the range of oil mass fraction 0–0.07, the error of new measurement method was within 0.005 for a wide range of pressures and temperatures tested. This study established the method of measuring the oil mass fraction continuously in the transcritical CO2 cycle without affecting the cycle performance. Through this method, the effect of oil mass fraction on the characteristics of the oil circulation behavior and the performance of the transcritical CO2 cycle can be investigated. 相似文献
78.
Jae-Woo Lim Yunho Choi Hee-Seung Yoon Young-Kwon Park Jin-Heong Yim Jong-Ki Jeon 《Journal of Industrial and Engineering Chemistry》2010,16(1):51-56
A facile preparation method of activated carbon (AC) honeycomb monoliths is suggested in this work. A composite consisting of activated carbon, organic polymer binder (LDPE), and organic lubricant was effectively extruded above the melting temperature of the organic polymer in the shape of a honeycomb monoliths (dimensions: 256 cells in 4 cm × 4 cm). Three types of AC powders are investigated to elucidate the relationships between the processibility of the honeycomb monoliths and the size of their AC particles. The surface area of activated carbon filters increases as the size of the AC particle increases. This may be due to pore blocking by organic polymer binder on the surface of the AC particle. The mechanical properties of the honeycomb monolith are enhanced drastically when extrusion molding is used as compared to the use of a conventional press-molding process. 相似文献
79.
Multichip on Aluminum Metal Plate(MOAMP) technology with simple structure and low thermal resistance is developed for effective heat removal of Light Emitting Diode(LED) p-n junction and LED lighting module to have high reliability. The thermal resistance of LED modules was numerical and experimental. Thermal resistance from the junction to aluminum metal plate, considering input power of LED module using MOAMP technology, is 3.02 K/W, 3.23 K/W for the measured and calculated, respectively. We expect that the reported MOAMP technology with low thermal resistance will be a promising solution for high power LED lighting modules. 相似文献
80.
Despite their potential carcinogenicity and probable formation during water disinfection processes, little is known about the occurrence of other nitro(so) compounds than a few specific N-nitroso compounds such as N-nitrosodimethylamine (NDMA). An analytical method was developed to monitor various nitro(so) compounds including N-nitrosamines based on the Griess colorimetric determination of nitrite generated by UV-254 nm photolysis of nitro(so) compounds after separation by HPLC (HPLC-Post Column UV photolysis/Griess reaction (HPLC-PCUV)). To differentiate N-nitro(so) compounds (i.e. UV-labile) from other nitro(so) and N-containing compounds (i.e. UV-resistant), a pre-treatment was established by photolyzing solid-phase extracted samples at 254 nm (1000 mJ/cm2) and thus removing N-nitro(so) compounds selectively. Considering a 1000-fold concentration factor and extraction efficiencies (57–83%) during solid phase extraction, the method detection limits ranged from 4 to 28 ng/L for dimethylnitramine and eight N-nitrosamines (EPA 8270 nine nitrosamines mixture except for N-nitrosodiphenylamine). For four pool waters, the UV-resistant groups accounted for more than 78% of the estimated total concentration of nitro(so) and other N-containing compounds (6.1–48.6 nM). Only one unknown UV-labile compound was detected in one pool water (2.0–7.9 nM). NDMA was most frequently detected and N-nitrosodipropylamine (NDPA) and N-nitrosodibutylamine (NDBA) were additionally detected in one pool water. Chloramination of a secondary wastewater effluent with NDMA (0.2 nM) and UV-resistant compounds (7.9 nM) from a pilot-scale municipal wastewater treatment plant led to a significant formation of not only unidentified UV-resistant compounds (67.8 nM) and UV-labile compounds (14.6 nM), but also identified nitrosamines such as NDMA (4.3 nM), N-nitrosopiperidine (1.8 nM), NDPA (0.5 nM), and NDBA (0.5 nM). Overall, the novel HPLC-PCUV system is a powerful screening tool for the detection of (un)known N-nitro(so) as well as other nitro(so) and UV-induced nitrite-producing compounds. 相似文献