915MHz亚铁磁共振升温效应的实验研究

为了改进肿瘤的微波热疗,我们进行９１５ＭＨｚ微波亚铁磁共振的实验研究。结果表明９１５ＭＨｚ微波象２４５０ＭＨｚ一样,有明显而尖锐的亚铁共振升温。实验测量了不同聚集状态,不同饱和磁化强度亚铁磁共振介质的共振升温并用鸡蛋清受热固化来显示共振升温度分布的影响。     

Proterozoic fluvial styles: response to changes in accommodation space (Rivieradal sandstones, eastern North Greenland)

Fluvial styles recorded by the uppermost part of the Neoproterozoic ‘Rivieradal sandstones' succession of eastern North Greenland reflect variations in rate of generated accommodation space and possibly climatic changes. Three facies associations, arranged in two genetic sequences, are recognised within the succession. The lower sequence initially records little available accommodation space. A high degree of reworking results in sheet-like, high-energy, bed-load-dominated, braided river deposits lacking recurrent facies patterns. As accommodation space increases upwards through the sequence, reduction in reworking is recorded by the development of fining- and thickening-upward muddy fluvial cycles. Evidence of desiccation or prolonged periods of drought are absent within the deposits and climate was probably relatively humid. Channel deposits in the lower sequence reflect mixed-load, braided fluvial systems with stable channel banks and floodplains, and the gradient appears to have been low to moderate. These features are generally considered favourable for the establishment of meandering river systems, but channels, nevertheless, retained an overall braided character and their deposits show no evidence of meandering. Despite indications of a climatic setting without significant periods of drought sediments indicate that large fluctuations in discharge occurred within the mixed-load streams and this is suggested to be the main cause for the absence of meandering. The swift and rather dramatic response of the fluvial systems to changes in precipitation, probably resulted from rapid runoff rates caused by the absence of vegetation. The upper sequence shows an initial return to shallow, sandy braided river deposition recording little available accommodation space. A subsequent increase in the rate of generated accommodation space is indicated by the presence of alternating sheet sandstones and sand-streaked mudstones with abundant desiccation cracks. The sheet sandstones show evidence of high-energy, unconfined ephemeral fluvial flash-flood deposition, while the mudstones are interpreted to represent muddy floodplain deposits. The change in fluvial style, combined with the widespread evidence of desiccation, suggest an evolution towards a more semi-arid climate in the upper sequence. This climatic change could account for the reduced clastic input seen in the overlying marine succession which culminated in carbonate platform deposition. The present study suggests that even under conditions considered favourable for the formation of meandering streams, these will rarely occur in Proterozoic deposits due to the lacking influence of vegetation. Although meandering deposits cannot be ruled out as having formed in pre-vegetational times, the conditions for their formation appear to have been even more restricted than previously realised.     

Controls on spatial and temporal distribution of Precambrian eolianites

Inversely graded stratification, generated by the migration of wind ripples, and adhesion structures permit unequivocal identification of Precambrian eolianites. These criteria, in combination with scale of cross-beds, angle of inclination of foresets, geometry of depositional units, and associated non-eolian facies, are used to discriminate between Precambrian dune/draa, dune-plinth, sand-sheet, and interdune deposits that formed in inland and coastal settings. Based on an analysis of published literature, fundamental conclusions can be drawn on the spatial and temporal distribution of Precambrian eolianites. The oldest reported eolianites are from the ca. 2.1 Ga Deweras Group in Zimbabwe and Hurwitz Group in Canada and numerous examples of eolianites are reported from the 1.8 Ga and younger rock record. Lack of Archean and early Paleoproterozoic eolianites and their widespread development after 1.8 Ga are examined with respect to: absence of vegetation, crustal growth and tectonic setting, relative sea-level fluctuations, unfavorable atmospheric and/or climatic change, and non-recognition. The lack of pre-2.2 Ga eolianites may be related to reworking by braided rivers combing across non-vegetated floodplains, reworking of coastal eolianites during transgression or their non-recognition in the Early Precambrian record. The temporal concentration of eolianites at 1.8 Ga may best be related to the early stages of breakup and the assembly phases of supercontinents.     

Precambrian tidal and glacial clastic deposits: implications for Precambrian Earth–Moon dynamics and palaeoclimate

Over the past decade the study of Precambrian clastic tidal rhythmites — stacked laminae of sandstone, siltstone and mudstone that display periodic variations in thickness reflecting a strong tidal influence on sedimentation — has provided accurate palaeotidal and palaeorotational data. Palaeotidal records obtained from tidal rhythmites may be systematically abbreviated, however, and derived periods and frequencies can be misleading. The validity of such values, including past length of day, can be assessed by testing for internal self-consistency through application of the laws of celestial mechanics. Such a test supports the estimated length of day of h derived from the late Neoproterozoic (620 Ma) Elatina–Reynella rhythmites in South Australia, and the indicated mean rate of lunar retreat of cm/year since 620 Ma. The validity of estimated lengths of day obtained from other Precambrian tidal rhythmites remain unverified because the data sets contain only one primary value directly determined from the rhythmites. The Elatina–Reynella data militate against significant Earth expansion at least since 620 Ma, and suggest that the free nutation or ‘tipping' of the Earth's fluid core has undergone a resonance with the Earth's annual forced nutation since the Neoproterozoic. Glaciogenic deposits are readily distinguishable from ejecta resulting from impacts with Earth-crossing bodies. Palaeomagnetic data, based on the geocentric axial dipole model for the geomagnetic field, indicate that Neoproterozoic and Palaeoproterozoic glaciation and cold climate near sea level occurred in low palaeolatitudes. This enigmatic finding may imply global glaciation or an increased obliquity of the ecliptic, and is relevant to modelling the effect of ice sheet formation on the Earth's obliquity history by obliquity–oblateness feedback mechanisms. Through multidisciplinary studies, clastic sedimentology and geophysics together can make substantial contributions to understanding Precambrian Earth–Moon dynamics and global palaeoenvironments.     

三峡工程岩体破坏分析中面连通率研究

介绍了面连通率在岩体破坏研究中的表述方法。连通率的大小可反映破坏概率的大小。选择可能滑动面进行连通率计算方法有：多个结构面组成的折面;单个结构面的扩展面。两种面连通率均反映了在空间平面上结构面的发育程度,揭露更多隐藏的破坏性信息,有利于定量、定位分析岩体稳定性。     

山西孙家庄中酸性杂岩体及其邻近地区的找矿远景评价

通过“面型”岩石测量和多子样剖面岩石测量,对山西孙家庄中酸性杂岩体作出找矿远景评价,并对其邻近地段进行矿化追踪。确定该岩体的主要指示元素和伴生元素,圈出以Cu为主的斑岩矿化多元素组合异常,在Cu异常浓集中心发现斑岩矿化。孙家庄岩体周围地区,存在斑岩型矿化—接触交代矿化—热液多金属矿化的环带状分布模式。     

水氡仪的标定与故障分析

在多年工作的基础上,介绍了水氡仪器的标定方法,分析了水氡仪器常见故障的原因及判别、排除方法等,指出所介绍的方法可供仪器标定人员工作时参考。     

思普地区地震活动和地质构造的相关性研究

红河断裂是云南主要的区域大断裂,区内现代构造运动强烈,但其南段长期无中强地震发生,而离它仅１００ｋｍ的滇西南思普地区地震活动却异常强烈,本在前人工作的基础上,研究了滇西南地区地壳构造和地震活动特点,用人工地震测探等方面的实际资料进一步证实了思普地区存在地较大规模的北东向断层,并提出北东向断层的思普地区地震活动中起重要控制作用的结论。     

山西静乐井水位高值异常及其与华北地震活动的关系

静乐井是山西省地下水观测网中的一口地震观测井。从１９８３￣１９９６年的１４ａ观测中,水位动态变化出现过３个高值时段,水位的高值虽有降雨渗入的影响,但主要可能是反映区域应力场加强的变化过程,因此３个水位高值时段与华北地区中强地震的活跃时期基本吻合。     

浅表地质现象对工程建设的影响及其勘探技术

查明浅表部地层地质条件,对多层及高层建筑均至关重要。针对目前上海地区,在运用小螺纹钻孔进行浅表部工程勘察中存在的一些问题,就其如何合理使用,作了若干方面的探讨。