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排序方式: 共有338条查询结果,搜索用时 19 毫秒
1.
微电子组装的大部份工艺开发都要求将元件做到更小,以便在尺寸日益缩小的便携式设备上实现更多功能。阐述了大元件的底部填充,即一侧的尺寸超过15mm,底部填充的胶量介于30~50mg。大尺寸晶元的制造工艺要求比现有生产线更大的产能,这就给底部填充点胶带来更大的挑战。大元件的产能超过3000个/h时,需要点胶机点出非常多的胶水。如此多的胶水在出胶前通过点胶阀,这将会带来加热的问题-某些工艺要求出胶前胶水必须要加热。这会对胶点尺寸有影响,因为随着温度的变化,底部填充的胶水黏度也会随之变化,从而轻微影响点出的胶量。从而将影响晶元相邻的“非沾染区”。稳定的温度是点胶稳定性的保证,并且能帮助胶水流进晶元下方同时也有助胶水分离从而更容易喷射出来。从研究中可以观察到:系统温度环境(点胶机内部)对点胶的胶水质量有影响。  相似文献   
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In this paper, we present a method for the sensitive detection of microRNAs (miRNAs) utilizing an antibody that specifically recognizes DNA:RNA heteroduplexes and a silicon photonic microring resonator array transduction platform. Microring resonator arrays are covalently functionalized with DNA capture probes that are complementary to solution phase miRNA targets. Following hybridization on the sensor, the anti-DNA:RNA antibody is introduced and binds selectively to the heteroduplexes, giving a larger signal than the original miRNA hybridization due to the increased mass of the antibody, as compared to the 22-mer oligoribonucleotide. Furthermore, the secondary recognition step is performed in neat buffer solution and at relatively higher antibody concentrations, facilitating the detection of miRNAs of interest. The intrinsic sensitivity of the microring resonator platform coupled with the amplification provided by the anti-DNA:RNA antibodies allows for the detection of microRNAs at concentrations as low as 10 pM (350 amol). The simplicity and sequence generality of this amplification method position it as a promising tool for high-throughput, multiplexed miRNA analysis as well as a range of other RNA based detection applications.  相似文献   
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We introduce the marriage of two technologies: digital microfluidics (DMF), a technique in which droplets are manipulated by application of electrostatic forces on an array of electrodes coated by an insulator, and porous polymer monoliths (PPMs), a class of materials that is popular for use for solid-phase extraction and chromatography. In this work, circular PPM discs were formed in situ by dispensing and manipulating droplets of monomer solutions to designated spots on a DMF device followed by UV-initiated polymerization. We used PPM discs formed in this manner to develop a digital microfluidic solid-phase extraction (DMF-SPE) method, in which PPM discs are activated and equilibrated, samples are loaded, PPM discs are washed, and the samples are eluted, all using microliter droplets of samples and reagents. The new method has extraction efficiency (93%) comparable to that of pipet-based ZipTips and is compatible with preparative sample extraction and recovery for on-chip desalting, removal of surfactants, and preconcentration. We anticipate that DMF-SPE may be useful for a wide range of applications requiring preparative sample cleanup and concentration.  相似文献   
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An evolutionary psychological perspective has much to offer the study of Internet behavior. However, cyber-psychologists have hitherto neglected this rich theoretical tradition and evolutionary psychologists have been slow to apply their perspective to computer-mediated behavior. This paper applies an evolutionary perspective to the study of Internet behavior in four relevant domains: (1) mating and sexual competition, (2) parenting and kinship, (3) trust and social exchange, and (4) personal information management. Both general and specific evolutionary theories are explored in relation to online behavior in each domain, with an emphasis on generating testable hypotheses for future research.  相似文献   
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Although negotiation experiences can affect a negotiator's ensuing attitudes and behavior, little is known about their long-term consequences. Using a longitudinal survey design, the authors tested the degree to which economic and subjective value achieved in job offer negotiations predicts employees' subsequent job attitudes and intentions concerning turnover. Results indicate that subjective value predicts greater compensation satisfaction and job satisfaction and lower turnover intention measured 1 year later. Surprisingly, the economic outcomes that negotiators achieved had no apparent effects on these factors. Implications, limitations, and future directions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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Despite decades of progress, developing minimally invasive bone-specific drug delivery systems (DDS) to improve fracture healing remains a significant clinical challenge. To address this critical therapeutic need, nanoparticle (NP) DDS comprised of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (PSMA-b-PS) functionalized with a peptide that targets tartrate-resistant acid phosphatase (TRAP) and achieves preferential fracture accumulation has been developed. The delivery of AR28, a glycogen synthase kinase-3 beta (GSK3β) inhibitor, via the TRAP binding peptide-NP (TBP-NP) expedites fracture healing. Interestingly, however, NPs are predominantly taken up by fracture-associated macrophages rather than cells typically associated with fracture healing. Therefore, the underlying mechanism of healing via TBP-NP is comprehensively investigated herein. TBP-NPAR28 promotes M2 macrophage polarization and enhances osteogenesis in preosteoblast-macrophage co-cultures in vitro. Longitudinal analysis of TBP-NPAR28-mediated fracture healing reveals distinct spatial distributions of M2 macrophages, an increased M2/M1 ratio, and upregulation of anti-inflammatory and downregulated pro-inflammatory genes compared to controls. This work demonstrates the underlying therapeutic mechanism of bone-targeted NP DDS, which leverages macrophages as druggable targets and modulates M2 macrophage polarization to enhance fracture healing, highlighting the therapeutic benefit of this approach for fractures and bone-associated diseases.  相似文献   
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Highly accurate real‐time localization is of fundamental importance for the safety and efficiency of planetary rovers exploring the surface of Mars. Mars rover operations rely on vision‐based systems to avoid hazards as well as plan safe routes. However, vision‐based systems operate on the assumption that sufficient visual texture is visible in the scene. This poses a challenge for vision‐based navigation on Mars where regions lacking visual texture are prevalent. To overcome this, we make use of the ability of the rover to actively steer the visual sensor to improve fault tolerance and maximize the perception performance. This paper answers the question of where and when to look by presenting a method for predicting the sensor trajectory that maximizes the localization performance of the rover. This is accomplished by an online assessment of possible trajectories using synthetic, future camera views created from previous observations of the scene. The proposed trajectories are quantified and chosen based on the expected localization performance. In this study, we validate the proposed method in field experiments at the Jet Propulsion Laboratory (JPL) Mars Yard. Furthermore, multiple performance metrics are identified and evaluated for reducing the overall runtime of the algorithm. We show how actively steering the perception system increases the localization accuracy compared with traditional fixed‐sensor configurations.  相似文献   
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The image‐based inertial impact (IBII) test has shown promise for measuring properties of composites at strain rates where existing test methods become unreliable due to inertial effects (> 102 s?1 ). Typically, the IBII tests are performed with a single camera, and therefore, to use surface measurements for material property identification, it is necessary to assume that the test is two‐dimensional. In this work, synchronised ultra‐high‐speed cameras are used to quantify the relevance of this assumption when nonuniform, through‐the‐thickness loading is applied to interlaminar samples. Initial experiments revealed that an angular misalignment of approximately 1° between the impact faces of the waveguide and projectile created a bending wave that propagated along the sample behind the axial pulse. Even under these conditions, consistent measurements of stiffness were made by assuming a linear distribution of the behaviour through‐the‐thickness. When the misalignment was reduced to 0.2°, the effects on single‐sided measurements were significantly reduced. The two alignment cases were compared to show that three‐dimensional loading had a small effect on stiffness identification (approximately 5% bias) relative to failure stress (approximately 30% bias). This study highlights the importance of impact alignment for reliable characterisation of the interlaminar failure stress and was used to establish guidelines for diagnosing loading issues from single‐sided measurements.  相似文献   
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