Thư viện tài liệu, ebook tổng hợp lớn nhất Việt Nam

Glass ceramics doped with rare earth ions of P2O5, CaO, Na2O, MgO and RE2O3 (PCNM: RE with RE: Dy, Eu, Tb) were fabricated by the solid state reaction method. The diagram of X-ray diffraction patterns confirmed the obtained materials were type of glass ceramics. Surveying luminescence spectra (PL) of the obtained materials when using the appropr...

8 trang | Chia sẻ: yendt2356 | Ngày: 27/11/2020 | Lượt xem: 1015 | Lượt tải: 1

Qua việc phân tích nguyên nhân và mức ñộ thiệt hại do thiên tai gây ra ở huyện Hướng Hóa, tỉnh Quảng Trị ñã phần nào làm nổi bật lên ñược mức ñộ nghiêm trọng cũng như tính khắc nghiệt của các tai biến như lũ quét, trượt lở ñất. Mỗi lần xảy ra thiên tai là một lần tính mạng con người, cơ sở vật chất và các hoạt ñộng sản xuất bị ñe dọa và ảnh hưở...

12 trang | Chia sẻ: huongnt365 | Ngày: 27/11/2020 | Lượt xem: 1382 | Lượt tải: 1

The Central Coast with a long coastline and many sand dunes has favorable conditions for accumulation of many groups of placers, in which the most specific mineral is titanium group. Being easy to exploit by opencast methods and high economic value, tittanium brings significant income for the local people. Currently, Binh Dinh is one of provinc...

12 trang | Chia sẻ: huongnt365 | Ngày: 27/11/2020 | Lượt xem: 1020 | Lượt tải: 1

Định nghĩa Cho A, B ∈ Mn(R). A được gọi là đồng dạng với B nếu tồn tại ma trận khả nghịch P sao cho A =P^-1. BP. Định nghĩa Cho A ∈ Mn(R). Ma trận A được gọi là chéo hóa được nếu nó đồng dạng với ma trận đường chéo.

15 trang | Chia sẻ: hoant3298 | Ngày: 27/11/2020 | Lượt xem: 1212 | Lượt tải: 1

Ruby powder (-Al2O3: Cr3+) was synthesized by urea-nitrate solution combustion method with optimal conditions. The studies of X-ray diffraction, photoluminescence were presented. The results showed that the crystalline structure of ruby powder has single hexagonal phase structure (-Al2O3), emission of ruby has narrow lines with maximum at 694...

6 trang | Chia sẻ: yendt2356 | Ngày: 27/11/2020 | Lượt xem: 1074 | Lượt tải: 1

CONCLUSION Effects of T were investigated in conditions of isothermal, adiabatic US (same PUS), and sole thermal hydrolysis. Subsequently, its effects were looked into associated with PUS (varying PUS and probe size) for the same ES and then the same treatment duration. Cavitation and thermal hydrolysis seem to show almost additional effect...

9 trang | Chia sẻ: thucuc2301 | Ngày: 27/11/2020 | Lượt xem: 957 | Lượt tải: 1

Land which is the precious natural resources has been increasingly exploited for human demands. The rational use of land is very important because it not only decides directly to the socio-economic development but also ensures the regeneration of natural resources. The analysis of current status and changes of the use of land in the period from...

12 trang | Chia sẻ: dntpro1256 | Ngày: 27/11/2020 | Lượt xem: 1159 | Lượt tải: 1

Soil erosion by water now is an alarming problem in developing countries due to its harmful impacts. Soil erosion makes nutrient, yield depletion, during which impact on food security, poverty and water pollution in watersheds. With the development of RS and GIS, researchers have released many soil erosion models to estimate soil loss, establish...

12 trang | Chia sẻ: dntpro1256 | Ngày: 27/11/2020 | Lượt xem: 1279 | Lượt tải: 1

Phosphate luminescent materials PCZ with components of P2O5, CaO, and ZnO doped rare earth ions (PCZ:RE and RE: Eu, Dy) have been prepared by melt method, based on mixture NH4H2PO4, CaCO3, ZnO, Eu2O3 and Dy2O. Amorphous state of received materials was confirmed by the X-ray diffraction diagram. The optical transitions of the Eu3+ and Dy3+ ion i...

8 trang | Chia sẻ: yendt2356 | Ngày: 27/11/2020 | Lượt xem: 990 | Lượt tải: 1

Ha Tinh is one of the provinces most affected by natural hazards, especially flash floods. Sloping hilly terrain conditions, reduced covering density of forest and unfavorable weather conditions are potential hazards to flash floods. Flash floods potential area mapping at Huong Khe district, Ha Tinh province was carried out using Remote Sens...

6 trang | Chia sẻ: huongnt365 | Ngày: 27/11/2020 | Lượt xem: 1289 | Lượt tải: 1