t－PA指形区、上皮生长因子样区缺失突变体cDNA克隆的构建及其在哺乳动物细胞中的表达

研究ｔ－ＰＡＦ区和ＥＧＦ区在ｔ－ＰＡ廓清中的作用。利用本室构建的ｔ－ＰＡｃＤＮＡ克隆，采用片段重组技术缺失突变指形区（Ｆ）、上皮生长因子样区（ＥＧＦ）和部分三角区（Ｋ１）（包括２－１０６氨基酸），组装了由逆转录病毒长末端重复顺序（ＬＴＲ）启动和终止的ｐＭＤＢ△ＦＥ表达质粒。该质粒转染ＣＨＯ－ｄｈｆｒ－细胞，阳性克隆的培液中测得纤溶活性，大量培养阳性克隆细胞，从培液中初步纯化了表达产物。结果：以小白鼠为动物模型，测定突变体的血浆半衰期。与天然ｔ－ＰＡ相比，△ＦＥｔ－ＰＡ的半衰期延长６倍。结果表明ｔ－ＰＡＦ区和ＥＧＦ区在体内ｔ－ＰＡ廓清中有显著作用。

Topographic Correction-Based Retrieval of Leaf Area Index in Mountain Areas

Leaf Area Index(LAI)is a key parameter in vegetation analysis and management,especially for mountain areas.The accurate retrieval of LAI based on remote sensing data is very necessary.In a study at the Dayekou forest center in Heihe watershed of Gansu Province,we determined the LAI based on topographic corrections of a SPOT-5.The large variation in the mountain terrain required preprocessing of the SPOT-5 image,except when orthorectification, radiation calibration and atmospheric correction were used.These required acquisition of surface reflectance and several vegetation indexes and linkage to field measured LAI values.Statistical regression models were used to link LAI and vegetation indexes.The quadratic polynomial model between LAI and SAVI (L=0.35)was determined as the optimal model considering the R and R2 value.A second group of LAI data were reserved to validate the retrieval result.The model was applied to create a distribution map of LAI in the area.Comparison with an uncorrected SPOT-5 image showed that topographic correction is necessary for determination of LAI in mountain areas.

Relationship Between Changes of River-lake Networks and Water Levels in Typical Regions of Taihu Lake Basin,China

The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.

Landscape pattern and fragmentation of natural secondary forests in the eastern mountainous region, northeast China： A case study of Mao＇ershan forests in Heilongjiang Province

Mao'ershan region is a representative natural secondary forested region in the eastern mountainous region, northeast of China.. Under the support of ARC/INFO and GIS technology, the landscape shape and fragment indices of Mao'ershan experimental plantation were studied by combining the forest type map (1:10000), which was drawn from the aerial photographs (1999), field investigation (1999) and soil utilized map (1:10000). The results showed that the shape index and shape fragment index of natural landscape were higher than those of artificial landscapes and landscape patch fragment index depended on the number of patches. The natural forest had complex shape, suffering little jamming, and its shape index was higher than that of artificial forest. The manual controlled landscape (e.g. nursery, cropland and cutting blank) had regular shape, and its shape index was smaller. The fragment index of patches in natural forest was higher than that of artificial forest. The soft broad-leaved had the highest fragment index of patch amount.

Simulation and comparative study of two types of Topographic Index model for a homogeneous mountain catchment

In order to expand the application range of the classic Topographic Index model(TOPMODEL) and develop a more appropriate submodel of hydrological processes for use in the land surface model, two types of TOPMODEL are investigated, one with saturated hydraulic conductivity change with depth obeying exponential law(classical e-TOPMODEL or e-TOPMODEL for short) and the other obeying general power law(general p-TOPMODEL or p-TOPMODEL for short). Using observation date in the Suomo River catchment located in the upper reaches of the Yangtze River, the sensitivity study of the p-TOPMODEL was conducted and the simulated results from the model were examined and evaluated first, and then the results were compared with the results from the e-TOPMODEL to find the similarities and differences between the two types of models. The main conclusions obtained from the above studies are(1) topographic index and its distribution derived from the p-TOPPMODEL for the Suomo Basin are sensitive to changes of parameter n and m;(2) changes of n and m have impacts on the simulation results of various hydrological components(such as daily runoff, monthly averaged runoff, monthly averaged surface runoff and subsurface runoff), but have the weaker impacts on forty-year averaged total runoff; and(3) for the same value of m, the simulated results of e-TOPMODEL display higher surface runoff and lower subsurface runoff than the general p-TOPMODEL does but multi-year averaged total runoffs produced from the two types of TOPMODEL show insignificant difference. The differences between the two types of models indicate that it is necessary to pay close attention to correct selection from different hydrological models for use in land surface model development. The result mentioned above is useful to provide some referential information for the model selection.