上海青龙镇遗址出土瓷器和砖瓦样品热释光特性研究

利用热释光测定年代技术对青龙镇出土样品的烧造年代进行检测分析,以求帮助了解不同历史时期青龙镇瓷器贸易的发展状况。为此,本工作以青龙镇遗址出土瓷器中的67件瓷片及4件砖瓦样品为研究对象,用热释光前剂量饱和指数法测定瓷片样品古剂量;用热释光高温细颗粒技术测定砖瓦样品古剂量;用厚源α粒子计数法和X射线荧光光谱技术测量样品年剂量。瓷片样品热释光年代结果从唐代至南宋不等,砖瓦样品年代结果为北宋时期烧造,与文献记载中隆平寺塔的始建时间相符。     

Identification of ancient starch grains from the tribe Triticeae in the North China Plain

Both macrofossil and microfossil plant remains from the grass family (Poaceae) have been recovered from Neolithic and historic sites in China. Basing our work on the plant taxa that were previously recovered, we analyzed the economically significant genera for modern starch grain analysis with a focus on the important tribe Triticeae. Modern starch grains from the tribe Triticeae were compared with those from other grasses, and criteria for identification were determined. In total, 38 species within 28 genera, 13 tribes and 4 subfamilies were selected for analysis. Results demonstrate that starch grains from members of the tribe Triticeae are discernible from those of other tribes by their distinctive lenticular morphologies and surficial pressure craters. A dichotomous key covering 10 species within 7 genera of the Triticeae was created, thus allowing identification of members of the tribe to the level of genus. Application of the dichotomous key to the ancient starch assemblage recovered from lithic tools excavated from the early Neolithic site of Donghulin demonstrates that plants from the genera Hordeum and Agropyron were exploited alongside millets at this site.     

Structure of grain boundaries in wet,synthetic polycrystalline,statically recrystallizing halite – evidence from cryo‐SEM observations

It is well known from nature and experiments that the presence of brine strongly affects the microstructural evolution and the mechanical and transport properties of halite. Existing interpretations of the grain boundary structure in deformed, wet, salt samples annealed statically at room temperature are based on indirect evidence from reflected light microscopy and conventional scanning electron microscopy. This paper presents direct observations of fluid‐filled grain boundaries using the cryogenic‐scanning electron microscope (cryo‐SEM) in which the grain boundary fluids were frozen before breaking the samples. The rapid cooling transforms the brine into two phases, i.e. ice and hydrohalite, which are easily recognized from characteristic segregation patterns. We studied samples of wet, synthetic, polycrystalline halite annealed under static conditions at room temperature. In coarse‐grained samples, fine‐scale segregation patterns were observed at the boundaries of the primary recrystallizing grains. These points indicate the existence of fluid films with a thickness in the range of 30 nm, but the finer scale structure of the fluid remains unknown. In fine‐grained samples, the distribution and reorganization of fluids with annealing time is recorded by the combination of contact healing and successive accumulation of fluids in triple junction tubes. The contact healing is attributed to the small initial grain size, such that the fluid film necks down by accumulating the fluids into previously existing triple junctions via neck growth. Electron backscatter diffraction measurements of both primary and secondary recrystallized grains indicate that they are euhedral, i.e. the grain growth morphology is controlled by the anisotropy of the grain boundary energy of the growing grain, which results in planar growth faces.     

统购统销初期的粮食票证制度探析--以1953～1957年的河南为个案

1953～1957年的河南在统购统销初期实施粮食票证制度,经历了初创时期、基本成型时期、确立时期三个不同的发展阶段。粮食票证制度的形成,对于保证粮食统购统销政策的贯彻实施提供了有力的保障,并成为粮食统购统销制度的一个重要组成部分。     

The mechanism of fluid infiltration in peridotites at Almklovdalen, western Norway

A major Alpine‐type peridotite located at Almklovdalen in the Western Gneiss Region of Norway was infiltrated by aqueous fluids at several stages during late Caledonian uplift and retrogressive metamorphism. Following peak metamorphic conditions in the garnet–peridotite stability field, the peridotite experienced pervasive fluid infiltration and retrogression in the chlorite–peridotite stability field. Subsequently, the peridotite was infiltrated locally by nonreactive fluids along fracture networks forming pipe‐like structures, typically on the order of 10 m wide. Fluid migration away from the fractures into the initially impermeable peridotite matrix was facilitated by pervasive dilation of grain boundaries and the formation of intragranular hydrofractures. Microstructural observations of serpentine occupying the originally fluid‐filled inclusion space indicate that the pervasively infiltrating fluid was characterized by a high dihedral angle (θ > 60°) and ‘curled up’ into discontinuous channels and fluid inclusion arrays following the infiltration event. Re‐equilibration of the fluid phase topology took place by growth and dissolution processes driven by the excess surface energy represented by the ‘forcefully’ introduced external fluid. Pervasive fluid introduction into the peridotite reduced local effective stresses, increased the effective grain boundary diffusion rates and caused extensive recrystallization and some grain coarsening of the infiltrated volumes. Grain boundary migration associated with this recrystallization swept off abundant intragranular fluid inclusions in the original chlorite peridotite, leading to a significant colour change of the rock. This colour change defines a relatively sharp front typically located 1–20 cm away from the fractures where the nonreactive fluids originally entered the peridotite. Our observations demonstrate how crustal rocks may be pervasively infiltrated by fluids with high dihedral angles (θ > 60°) and emphasize the coupling between hydrofracturing and textural equilibration of the grain boundary networks and the fluid phase topology.     

周恩来与“文化大革命”时期的粮食问题

"文化大革命"使国民经济遭受了严重损失。周恩来殚精竭虑,采取种种措施,稳定粮食局势。他劝说红卫兵和造反派不能冲击农业生产,坚持抓南粮北调局面的改变,用"以出养进"的办法开展粮食外贸,努力解决"三个突破"中的粮食"窟窿"问题,认真贯彻藏粮于民的思想,常抓节约粮食。周恩来高度重视粮食问题的思想和为民谋利的风范至今仍有现实意义。     

Famine responses in the world food crisis 1972–5 and the World Food Conference of 1974

In the early 1970s, there was scarcity in the world grain market, soaring prices and famines in several countries of Asia and Africa. The commercial grain trade was expanded at the expense of food aid. After a brief look at policies addressing the situation in terms of modernised methods of agricultural production for small producers, the article sketches how such policies also affected relief efforts, from the low availability for food aid, the provision of food that was not useful and late deliveries through efforts to tie food aid to local changes in agricultural production and settlement patterns. In part, food aid thus reinforced processes of social differentiation that had contributed to causing the famines in the first place.     

西部大开发与自然环境保护及生态建设

当前已经开始的西部大开发 ,是事关我国现代化建设和中华民族长远生存与发展的重大战略问题。本文在详细分析了西部现有生态环境的基础上 ,对在大开发中如何保护自然环境及进行生态建设作了论证。     

山东省人均粮食变化的时空差异研究

人均粮食占有量是反映粮食供给水平的重要指标。本文分析了山东省人均粮食占有量变化的时空差异研究,并探讨了其与粮食增产的关系,对因地制宜调控人粮关系有一定的参考价值。     

Petrography of ancient Indian lime plaster

Samples of ancient Indian lime plaster have not previously been analysed. Excavation of a seventh century AD baked brick structure provided the necessary samples for a detailed laboratory examination of plaster. The plaster samples were studied by chemical and petrographic methods. The probable sources of lime and sand were indicated by the mineralogy.