Recent ice ages on Mars

A key pacemaker of ice ages on the Earth is climatic forcing due to variations in planetary orbital parameters. Recent Mars exploration has revealed dusty, water-ice-rich mantling deposits that are layered, metres thick and latitude dependent, occurring in both hemispheres from mid-latitudes to the poles. Here we show evidence that these deposits formed during a geologically recent ice age that occurred from about 2.1 to 0.4 Myr ago. The deposits were emplaced symmetrically down to latitudes of approximately 30 degrees--equivalent to Saudi Arabia and the southern United States on the Earth--in response to the changing stability of water ice and dust during variations in obliquity (the angle between Mars' pole of rotation and the ecliptic plane) reaching 30-35 degrees. Mars is at present in an 'interglacial' period, and the ice-rich deposits are undergoing reworking, degradation and retreat in response to the current instability of near-surface ice. Unlike the Earth, martian ice ages are characterized by warmer polar climates and enhanced equatorward transport of atmospheric water and dust to produce widespread smooth deposits down to mid-latitudes.     

苯酚-硫酸法测定藏木香中多糖含量

采用传统的水煮醇沉法从藏木香中提取可溶性多糖,通过Sevag法脱蛋白后,以葡萄糖为对照品,使用苯酚-硫酸法测定多糖含量.结果表明,在波长486nm处测定吸光度,10-100μg/mL范围内吸光度与被测含量之间具有良好的线性关系,藏木香中多糖的含量为64.37%.     

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.     

甘青青兰挥发性成分GC/MS分析

目的：分离鉴定出甘青青兰（Dracocephalum tanguticum Maxim.）挥发油的化学成分.方法：用气相色谱-质谱（GC/MS）联用技术及峰面积归一化法测定各组分的相对含量.结果：共鉴定出23种化合物,占总色谱峰总面积的87.46%.结论：甘青青兰挥发油中的化学成分主要为[-]-反-松香芹乙酯和桉油精,两者分别占总挥发油中化学成分的60.30%和9.31%.     

钢管相贯口变参数变结构建库与数据提取方法研究

零件的批处理和零件库的建立是计算机辅助设计的重要内容之一，以钢管相贯口为例应用UG的几种建库方法，通过分析电子表格、零件族、GRIP编程在变参变结构的复杂零件建库时存在的问题，提出了一种将零件族和GRIP编程相结合的建库方法来建立变参变结构的复杂零件的零件库。     

带有时变时滞的中立型随机系统的鲁棒镇定和H_∞控制

研究了带有时变时滞的中立型随机系统的鲁棒镇定和H∞控制问题.利用Lyapunov泛函方法和It o^公式,基于状态反馈控制器,以线性矩阵不等式(LMI)形式给出了闭环系统鲁棒镇定及H∞控制的新方法.最后,数值算例说明了该方法的有效性.     

论竞技健美操技术创新的概念与分类

该研究以竞技健美操技术创新为研究对象,采用文献资料法、案例分析法,对查阅的文献和案例进行综合的归纳分析,在研究竞技健美操技术创新发展现状基础上,结合其他项目技术创新的特点,对竞技健美操技术创新的概念进行了阐述;对竞技健美操技术创新进行了系统的分类.