原油组分和含水率对热波特性影响的研究

原油组分和含水率是影响原油热波特性的重要因素.本文对此作了初步的理论分析.通过对胜利、大庆、中原原油的燃烧试验研究.测定了原油组分及含水率与热波特性之间的关系.进而得出了热波特性回归方程式.试验结果表明,原油含轻组分越多,热波传播速度越快,稳定高温层温度越低;含水率越高.热波传播速度越慢.稳定高温层温度越高.     

颗粒分布对金属基复合材料激光热冲击破坏的影响

从宏观和微观两方面研究了ＳｉＣ颗粒分布状况对陶瓷颗粒增强金属基复合材料激光热冲击破坏的影响,发现微裂纹形成是由基体内的孔洞和颗粒与基体脱胶所引起,而陶瓷颗粒分布不均匀对裂纹的扩展机理有重要影响,它大大降低了复合材料的宏观力学性能     

论施工单位施工阶段的造价控制

在建筑施工中,为了加强施工单位在施工阶段的造价控制,介绍了对施工阶段造价控制的管理方法。     

汽车滚柱式单向超越离合器套环应力计算的曲梁法

对汽车滚柱式单向超越离合器套环进行力学分析，首次提出套环为受集中力作用的超静定曲梁，以此来求解其最大正应力，即曲粱法。采用电测套环工作应力和采取光弹性应力分析方法验证曲梁法的正确性，并指出，多年来国内外按Ｔｈｏｍａｓ视套环为厚壁圆筒，受内压来计算应力是不可取的。     

一种制备不锈钢内衬复合钢管的新工艺

介绍了一种制备不锈钢内衬复合钢管的新型工艺－－ＳＨＳ－离心技术，讨论了所制备的复合管材的组织和不锈钢层的性能，这种不锈钢复合管的内外层可实现冶金结合。ＳＨＳ不锈负抗腐蚀性能优于相应的常规不锈钢，该工艺具有节能、高效、设备简单等优点。     

我国公司治理结构存在的主要问题及其完善的途径

《中华人民共和国公司法》（下称《公司法》）的颁布和实施,为我国国有企业的公司制改革提供了法律依据的法律保障,但在国有企业的公司制改革过程中或在已完成公司制改革的企业中,存在着与《公司法》所规定的公司制企业不相符的问题。本文仅就公司治理结构方面存在的主要问题及如何完善公司治理结构谈点不成熟的看法。     

Single-nucleotide polymorphisms in the public domain: how useful are they?

There is a concerted effort by a number of public and private groups to identify a large set of human single-nucleotide polymorphisms (SNPs). As of March 2001, 2.84 million SNPs have been deposited in the public database, dbSNP, at the National Center for Biotechnology Information (http://www.ncbi.nlm.nih.gov/SNP/). The 2.84 million SNPs can be grouped into 1.65 million non-redundant SNPs. As part of the International SNP Map Working Group, we recently published a high-density SNP map of the human genome consisting of 1.42 million SNPs (ref. 3). In addition, numerous SNPs are maintained in proprietary databases. Our survey of more than 1,200 SNPs indicates that more than 80% of TSC and Washington University candidate SNPs are polymorphic and that approximately 50% of the candidate SNPs from these two sources are common SNPs (with minor allele frequency of > or =20%) in any given population.     

High-performance thin-film transistors using semiconductor nanowires and nanoribbons

Thin-film transistors (TFTs) are the fundamental building blocks for the rapidly growing field of macroelectronics. The use of plastic substrates is also increasing in importance owing to their light weight, flexibility, shock resistance and low cost. Current polycrystalline-Si TFT technology is difficult to implement on plastics because of the high process temperatures required. Amorphous-Si and organic semiconductor TFTs, which can be processed at lower temperatures, but are limited by poor carrier mobility. As a result, applications that require even modest computation, control or communication functions on plastics cannot be addressed by existing TFT technology. Alternative semiconductor materials that could form TFTs with performance comparable to or better than polycrystalline or single-crystal Si, and which can be processed at low temperatures over large-area plastic substrates, should not only improve the existing technologies, but also enable new applications in flexible, wearable and disposable electronics. Here we report the fabrication of TFTs using oriented Si nanowire thin films or CdS nanoribbons as semiconducting channels. We show that high-performance TFTs can be produced on various substrates, including plastics, using a low-temperature assembly process. Our approach is general to a broad range of materials including high-mobility materials (such as InAs or InP).     

Single-nanowire electrically driven lasers

Electrically driven semiconductor lasers are used in technologies ranging from telecommunications and information storage to medical diagnostics and therapeutics. The success of this class of lasers is due in part to well-developed planar semiconductor growth and processing, which enables reproducible fabrication of integrated, electrically driven devices. Yet this approach to device fabrication is also costly and difficult to integrate directly with other technologies such as silicon microelectronics. To overcome these issues for future applications, there has been considerable interest in using organic molecules, polymers, and inorganic nanostructures for lasers, because these materials can be fashioned into devices by chemical processing. Indeed, amplified stimulated emission and lasing have been reported for optically pumped organic systems and, more recently, inorganic nanocrystals and nanowires. However, electrically driven lasing, which is required in most applications, has met with several difficulties in organic systems, and has not been addressed for assembled nanocrystals or nanowires. Here we investigate the feasibility of achieving electrically driven lasing from individual nanowires. Optical and electrical measurements made on single-crystal cadmium sulphide nanowires show that these structures can function as Fabry-Perot optical cavities with mode spacing inversely related to the nanowire length. Investigations of optical and electrical pumping further indicate a threshold for lasing as characterized by optical modes with instrument-limited linewidths. Electrically driven nanowire lasers, which might be assembled in arrays capable of emitting a wide range of colours, could improve existing applications and suggest new opportunities.     

因文求义论

所谓“因文求义”,就是据上下文即具体语境以求义。从训诂的角度看,语境可分为文旨、文义、文理三端,词语训诂只有合乎这三端,才有可能正确。反之,要使词语训诂合乎这三端即具体语境,莫过于因文求义。因文求义的依据是语境对词语具有制约功能,其作用则不仅在于考求词义,还可用来校勘文字。