Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not onl...Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not only increase the number of specimens but also expand the chances for people to get direct observation of scientifically valuable materials.Up to now。展开更多
The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the...The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the resonant frequency and switch the frequency channel, a scheme of mechanically tunable FSS is theoretically analyzed by using the method of Floquet's vector modes expansion and fields matching. A double-layer tunable FSS with dipole element can perform a dynamic range of resonant frequency covering whole X-band.展开更多
Thirty-six typical REE deposits extracted from literatures,mineral resource database or reports,which are served as a basis for classifying deposit type.And then the five principal deposit types were identified:(1)alk...Thirty-six typical REE deposits extracted from literatures,mineral resource database or reports,which are served as a basis for classifying deposit type.And then the five principal deposit types were identified:(1)alkali-related type;(2)Ion-adsorbed type;(3)metamorphosed sedimentary type;(4)placer type;(5)sedimentary phosphate type.Data gathered for each deposit includes the deposit scale,geologic settings,main metallogenic ages,main and accessory minerals,and ore-bearing intrusions.展开更多
文摘Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not only increase the number of specimens but also expand the chances for people to get direct observation of scientifically valuable materials.Up to now。
文摘The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the resonant frequency and switch the frequency channel, a scheme of mechanically tunable FSS is theoretically analyzed by using the method of Floquet's vector modes expansion and fields matching. A double-layer tunable FSS with dipole element can perform a dynamic range of resonant frequency covering whole X-band.
基金supported by the China Geological Survey(Grant Nos.12120111210451212011121040)
文摘Thirty-six typical REE deposits extracted from literatures,mineral resource database or reports,which are served as a basis for classifying deposit type.And then the five principal deposit types were identified:(1)alkali-related type;(2)Ion-adsorbed type;(3)metamorphosed sedimentary type;(4)placer type;(5)sedimentary phosphate type.Data gathered for each deposit includes the deposit scale,geologic settings,main metallogenic ages,main and accessory minerals,and ore-bearing intrusions.
