层间剪切带粒度分形几何特征及工程地质意义

本文对分形几何方法表征土的粒度组成加以了补充, 并用它来描述和表征层间剪切带的粒度组成, 据此将其划分为五个类型。在此基础上较为深入地阐述了其工程地质意义, 并着重讨论了用它来识别层间剪切带所遭受的构造变形破坏程度、演化阶段问题等。     

我国工程地质学发展战略的思考

本文就我国工程地质学在”十一五”期间的发展战略进行了讨论,包括工程地质学面临的机遇和挑战;围绕的科学问题;在我国地球系统科学发展中的作用以及今后的发展趋势等。     

汶川地震地质灾害后效应分析

汶川地震过去3a了。3a来,大量的国内外学者对地震灾区地震地质灾害的发育分布规律、形成机理及防治对策给予了高度关注,发表了大量的研究成果。人们在关注同震地质灾害的同时,更对地震灾区今后地质灾害的发生规律及演化趋势、持续时间倾注了极大的关心,因为震后连续3a,尤其是2010年,灾区地质灾害的频率和规模均出现较震前显著增大的现象。本文收集整理了震前和震后灾区地质灾害的数据资料,尤其研究了震后3a灾区重大地质灾害的特点和发生规律,在此基础上,分析了震后灾区地质灾害可能的持续时间、演化趋势以及高风险区的范围。分析和研究结果认为,震后汶川地震灾区的地质灾害将持续20~25a; 在这段时间内,地质灾害将以4~5a一个高峰为周期,呈震荡式的衰减下降,并最终恢复到震前的水平。震后地质灾害的高风险区将出现在耿达-映秀、小鱼洞、红白-茶坪、擂鼓-陈家坝和青川东河口-窝前这5个地段上。     

有序介孔材料: 历史、 现状与发展趋势

有序介孔材料是指孔径在2~50 nm之间的多孔材料, 是一类具有均匀孔径、 高有序度纳米孔道和高比表面积的新材料. 在过去30年里, 有序介孔材料的研究取得了长足的进步, 在可控合成、 结构设计和调控及功能化等方面形成了系统的理论. 同时, 其应用领域也不断被拓展, 包括能源存储与转化、 催化、 生物医药和传感等方面. 本文首先回顾了有序介孔材料的发展历史, 简要介绍发展过程中“里程碑式”的研究工作; 然后根据构效关系总结了其在不同领域应用的最新进展; 最后讨论了有序介孔材料领域进一步发展所面临的挑战与机遇, 并对未来前景进行了展望.     

Minimum SNR and acquisition for bias-free estimation of fractional anisotropy in diffusion tensor imaging - a comparison of two analytical techniques and field strengths

Although it is known that low signal-to-noise ratio (SNR) can affect tensor metrics, few studies reporting disease or treatment effects on fractional anisotropy (FA) report SNR; the implicit assumption is that SNR is adequate. However, the level at which low SNR causes bias in FA may vary with tissue FA, field strength and analytical methodology. We determined the SNR thresholds at 1.5 T vs. 3 T in regions of white matter (WM) with different FA and compared FA derived using manual region-of-interest (ROI) analysis to tract-based spatial statistics (TBSS), an operator-independent whole-brain analysis tool. Using ROI analysis, SNR thresholds on our hardware-software magnetic resonance platforms were 25 at 1.5 T and 20 at 3 T in the callosal genu (CG), 40 at 1.5 and 3 T in the anterior corona radiata (ACR), and 50 at 1.5 T and 70 at 3 T in the putamen (PUT). Using TBSS, SNR thresholds were 20 at 1.5 T and 3 T in the CG, and 35 at 1.5 T and 40 at 3 T in the ACR. Below these thresholds, the mean FA increased logarithmically, and the standard deviations widened. Achieving bias-free SNR in the PUT required at least nine acquisitions at 1.5 T and six acquisitions at 3 T. In the CG and ACR, bias-free SNR was achieved with at least three acquisitions at 1.5 T and one acquisition at 3 T. Using diffusion tensor imaging (DTI) to study regions of low FA, e.g., basal ganglia, cerebral cortex, and WM in the abnormal brain, SNR should be documented. SNR thresholds below which FA is biased varied with the analytical technique, inherent tissue FA and field strength. Studies using DTI to study WM injury should document that bias-free SNR has been achieved in the region of the brain being studied as part of quality control.     

新疆旅游资源的可持续开发分析

通过对新疆旅游资源类型、特征的分析、归纳，应用旅游目的地生命周期理论，对不同成因、不同类型的旅游产品（资源）的生命力进行了分析．总结出自然环境、人工建筑、人造景观、特殊活动等不同旅游产品（资源）在旅游目的地生命周期中具有不同的生命力曲线分布．得出：新疆旅游资源的可持续开发，现阶段必须以政府主导开发，资源的规划、开发除因地制宜外，要从旅游资源的成因类型特征上进行合理配置，开发是为了保护，保护重于开发．准确地把握旅游产业发展过程中人与自然的关系，达到人与自然的和谐发展．     

Quality in (analytical) R&D – ideas for the next step after EURACHEM/CITAC Guide 2

 The EURACHEM/CITAC Guide 2 is an important step towards the establishment of a quality assurance system in analytical research and development. But it is only the first step because it focuses on the metrological characteristics. In addition to Guide 2 there should be a supplementary guide providing assistance for effective and quality-orientated management of research groups.     

固相微萃取-高效液相色谱联用技术的进展

固相微萃取（SPME）技术是近年来发展起来的一种无溶剂,集采样、萃取、浓缩、进样于一体的样品预处理新技术,它与同效液相色谱技术的联用已受到人们的瞩目;该文评述了SPME-HPLC联用技术的进展,并展望这一技术的应用前景。