电离层电子浓度总含量梯度对GPS差分定位精度的影响

针对GPS定位测量的信号传播路径误差,分析了电离层电子浓度总含量梯度对差分定位精度的影响,利用L1载波重点讨论了1999年-2000年太阳活动期间低纬度赤道异常地区GPS差分定位精度的问题,同时验证对于长基线采用GPS广域差分技术可以使电离层定位误差得到明显提高。     

On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution──origin and evidences of the strong body earthquake──generating model

Ｏｎｔｈｅｐｈｙｓｉｃａｌｍｏｄｅｌｏｆｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｆｉｅｌｄｓａｎｄｔｈｅｍｅｃｈａｎｉｓｍｏｆｐｒｅｃｕｒｓｏｒｓ＇ｔｉｍｅｓｐａｃｅｄｉｓｔｒｉｂｕｔｉｏｎ──ｏｒｉｇｉｎａｎｄｅｖｉｄｅｎｃｅｓｏｆ　ｔｈｅｓｔｒｏｎ...     

区域经济空间集中化的产业成因分析——兼析海南省经济空间集中化问题

经济空间集中化起因于产业经济活动在一定空间内聚集并形成大规模的专业化生产，它以区域城市为增长中心，与区域产业结构转变有着密切的关系。经济空间集中化过程大致可以划分为三个与区域产业结构转变有关的经济增长阶段：初级阶段——均衡低速增长；中级阶段——集中快速增长；高级阶段——稳定增长。     

Formation of Concentric Rings Around Sources

Zones of increased concentration formed by a solvent flowing from a source are considered. A matehmatical model for forming such zones is proposed. It takes into account that such a zone is composed of a set of independent particles. Hence the distribution of a substance around the source can be explained by movement of an individual particle. In the model this movement is a continuous semi-Markov process with terminal stopping at some random point in space. Parameters of the process depend on the velocity field of the flow. Forward and backward partial differential equations for the distribution density of a random stopping point of the process are derived. The forward equation is investigated for the centrally symmetric case. Solutions of the equation demonstrate either a maximum or a local minimum at the source location. In the latter case a concentric ring around the source is formed. If different substances vary in their absorption rates, they can form separable concentration zones as a family of concentric rings.     

Reactive Nitrogen Compounds at Spitsbergen in the Norwegian Arctic

Simultaneousindependent measurements of NO_y and NO_x(NO_x= NO + NO₂) by high-sensitivitychemiluminescence systems and of PAN (peroxyacetylnitrate) and PPN (peroxypropionyl nitrate) by GC-ECDwere made at Spitsbergen in the Norwegian Arcticduring the first half year of 1994. The average mixingratio of the sum of PAN and PPN (denoted PANs)increased from around 150 pptv in early winter to amaximum of around 500 pptv in late March, whereasepisodic peak values reached 800 pptv. This occurredsimultaneously with a maximum in ozone which increasedto 45–50 ppbv in March–April. The average NO_xmixing ratio was 27 pptv and did not show any cyclethrough the period. The NO_y mixing ratio showeda maximum in late March, while the difference betweenNO_y and PAN decreased during spring. This is anindication of the dominance of PAN in the NO_ybudget in the Arctic, but possible changes in theefficiency of the NO_y converter could alsocontribute to this. Although most PAN in theArctic is believed to be due to long range transport,the observations indicate local loss and formationrates of up to 1–2 pptv h^-1 in April–May.Measurements of carbonyl compounds suggest thatacetaldehyde was the dominant, local precursor ofPAN.Now at 1.     

松辽盆地可地浸砂岩型铀矿成矿地质条件

本文重点讨论了松辽盆地的地质背景、铀源条件、铀矿化异常与岩相古地理以及盆地后期改造的关系，介绍了该盆地后期改造的特征、后期改造的动力条件及铀元素的再分配，探讨了铀矿化异常与复合砂体、氧化还原条件及剥蚀面的关系。在此基础上预测了铀成矿远景地区，选出找矿的重点层位。     

An invariance in the carbazoles of petroleum

A remarkable invariance in the ratio of 1,3-dimethylcarbazole （DMC） to 1,6-DMC was discovered in crude oils from the Pearl River Mouth Basin, South China Sea. The remarkably invariant ratio is kept at a constant of about unity regardless of their concentrations, sources or maturities for the sampies. In combination with the molecular structures of 1,3- and 1,6-DMCs, the invariance might indicate that the nitrogen compounds share a common precursor with a skeleton of 1-methylcarbazole and are formed through methylation at C3 and C6 with an essentially identical rate.     

沙坡头没蒿和柠条叶片δ13C 和 N 含量的季节变化特征

通过对腾格里沙漠东南缘沙坡头人工固沙区油蒿和柠条叶片稳定碳同位素分辨率（△）和N 含量的测定，研究了不同种植方式下油蒿和柠条叶片△ 和 N 含量的季节变化及其关系。结果表明：在不同种植方式下，两种植物的△ 与 N 含量在不同月份之间均存在显著差异。油蒿叶片 △ 极显著高于柠条的：在不同种植方式下，油蒿单种下 △ 显著高于混种，柠条则反之。 油蒿叶片 N 含量极显著低于柠条的：不同种植方式下柠条叶片 N 含量无显著差异，而单种油蒿叶片 N 含量则显著低于混种。在 △ 与 N 含量的关系中，柠条叶片 △ 与 N 在两种生境、单种和混种下均极显著正相关，雨明柠条叶片 N 含量可以作为其 △ 与 N 含量的季节变化及其关系在不同微生境有所差异。     

风沙流中沙粒浓度分布的实验研究

利用粒子图像测速技术（PIV）,在风洞内对与天然沙接近的石英沙风沙流沙颗粒浓度沿高度分布进行了研究。对 3种不同轴线风速研究结果表明,风沙流中沙粒浓度沿水平方向基本不变,而随高度呈指数衰减,而且其衰减速率与风速密切相关。风速越大,衰减速率越慢;风速越小,衰减速率越快。风沙运动一旦发生时,靠近沙床表面的沙粒浓度随风速变化很小,可以认为趋于稳定,达到最大值。