Through measuration of soil quantity and bedrock and dynamic measuration of soil water arrange in 0～30cm in the shed leaves pine the wood in Ecosystem Position of Daxinganlin in 7-8,2003,the results are as follow: the average of soil bulk density on preface is 0.338g/cm3、1.352g/cm3 in 10、20cm and 20、30cm,then it would increase with depth arden;
The sintering temperatures of homogenized mullite grogs with 70wt.% and 60wt.% Al_2O_3 are 1700℃ and 1600℃, apparent porosity are <2.5% and their bulk density are 2.75g/cm~3 and 2.64 g/cm~3 respectively.
The total recovery rate of powder in system≥99.9%,the pyrolyse temperature of basic zinc carbonate 450~600 ℃,ZnO content in the product 99%~99.9%,specific surface area 80~120 m~3/g and bulk density 0.22~(0.25 g/cm~3.)
The lightweight aggregate concrete with density degree of 1800 and compressive strength of 40～50 MPa has been developed by means of mixing aggregate and clay ceramisite with bulk density of 690 kg/m3 and cylinder compressive strength of 4.32MPa .
When polymerization temperature was in the range of 30-80℃and ethylene pressure was in 0.12-0.72 MPa,the polymerization activity increased as temperature and pressure while the bulk density of the polymer decreased from 0.27 g/cm~3 to 0.22 g/cm~3.
Under following optimal preparation conditions:sodium silicate concentration 0.2 mol/L,reaction temperature 70 t,solution pH 8-9 and calcination temperature 700℃, physical properties of silica gel support were specific surface area 242.22 m2/g,most probable pore diameter 16.45 nm and bulk density 0.492 1 g/mL,which were similar to that of imported Silica Gel 955.
当硅酸钠溶液的浓度为0．2mol／L、溶液pH为8-9、反应温度为70℃、焙烧温度为700℃时,硅胶载体的BET比表面积为242．22m2／g、最可几孔径为16．45 nm、堆密度为0．492 1g/mL,与进口硅胶(Silica Gel 955)的物理性能相近。
As the iodine amount is reduced, bulk density of the prepolymer decreases from 0.28 g/cm3 to 0.25 g/cm3 while the average particle size of the prepolymer increases gradually from 155.42 μm to 186.50 μm, in addition, the content of fine powder of the prepolymer lowered from 27.1% to 14.8%.
The influence of woodland soil bulk density on the growth and distribution of fine root system of main planting tree species in the Weibei Loess Plateau was investigated by means of pot culture and field survey.
Results indicated that in the woodland of Pinus tabulaeformis, soil bulk density increased with the depth at different sites, while in the woodland of Robinia pseudoacacia, soil bulk density was higher than that in P.
Further analysis implied that there existed negative correlations between soil bulk density and fine root length in the woodland of P.
Bulk density of pot culture media had clear effects on the growth and development of P.
The porosity and percentage of tiny sand (diameter 0.05-0.1 mm) and clay particle (diameter >amp;lt; 0.05 mm) increased, bulk density in surface soil decreased, and saturated water-holding capacity improved.