Abstract: A system for purifying helium gas, a method, and an application. The system includes a first gas-liquid separation device, a primary helium extraction tower, a second gas-liquid separation device, a secondary helium extraction tower, and a nitrogen removal tower, which are in sequential communication. The first gas-liquid separation device performs first treatment to convert helium-containing natural gas into a first gas and first liquid phases; the primary helium extraction tower performs first distillation on the first gas and first liquid phases to obtain a second gas and second liquid phases; the second gas-liquid separation device performs second treatment to convert the second gas phase to a third gas and third liquid phase; the secondary helium extraction tower performs second distillation on the third gas and third liquid phases to obtain crude helium and a fourth liquid phase form which nitrogen is removed by the nitrogen removal tower.

Abstract: The present invention discloses a group of polycyclic carbamoylpyridone derivatives, pharmaceutical compositions, and a use thereof. The structure of the polycyclic carbamoylpyridone derivatives of the present invention is represented by formula (VII). The polycyclic carbamoylpyridone derivative of the present invention functions as an inhibitor of influenza 5?cap-like structure (CAP)-dependent endonuclease activity and can be used to treat a cold caused by the influenza virus. The present invention also discloses a pharmaceutical composition to inhibit proliferation of the influenza virus.

Abstract: The disclosure discloses a metal foil, a metal foil with a carrier, a copper-clad laminate and a Printed Circuit Board. Herein, a plurality of protrusions are distributed on one face of the metal foil, and the protrusions have the follow microscopic morphology: the lower half part of the protrusion connected with the one face of the metal foil is provided with a limiting part, and the diameter of a circumscribed circle of the cross section of the limiting part is smaller than the skin depth of the metal foil; and the surface area of the part of the protrusion above the limiting part is larger than the surface area of other parts of the protrusion.

Abstract: The present invention discloses a group of polycyclic carbamoylpyridone derivatives, pharmaceutical compositions, and a use thereof. The structure of the polycyclic carbamoylpyridone derivatives of the present invention is represented by formula (VII). The polycyclic carbamoylpyridone derivative of the present invention functions as an inhibitor of influenza 5?cap-like structure (CAP)-dependent endonuclease activity and can be used to treat a cold caused by the influenza virus. The present invention also discloses a pharmaceutical composition to inhibit proliferation of the influenza virus.

Abstract: The present invention relates to the sector of building materials, and more specifically, to a floor connector and a floor with the floor connector. The floor connector includes a first connecting part and a second connecting part used to connect floors, and a supporting part arranged between the bottom surface of the first connecting part and the upper surface of the second connecting part for the purpose of supporting the first connecting part and the second connecting part. The floor includes a main body, a floor pedestal arranged under the main body, and a floor connector used to connect the main body and the floor pedestal. In this solution, the floor can be arranged without a keel, thereby significantly reducing the labor intensity during floor installation. Consisting of three parts, the floor features lightweight and simplification of installation procedure.

Abstract: The present invention relates to the sector of building materials, and more specifically, to a floor connector and a floor with the floor connector. The floor connector includes a first connecting part and a second connecting part used to connect floors, and a supporting part arranged between the bottom surface of the first connecting part and the upper surface of the second connecting part for the purpose of supporting the first connecting part and the second connecting part. The floor includes a main body, a floor pedestal arranged under the main body, and a floor connector used to connect the main body and the floor pedestal. In this solution, the floor can be arranged without a keel, thereby significantly reducing the labor intensity during floor installation. Consisting of three parts, the floor features lightweight and simplification of installation procedure.

Abstract: Purine derivatives of formula I, substituted at the 9-position, are prepared from a chloro substituted purine starting material, first making an alkyl substitution at the 9-position, then forming the desired esterified side chain, reducing this and hydrogenating the resultant diol prior to addition of alkyl carbonyl groups.

Abstract: Purine derivatives, substituted at the 9-position, are prepared from a chloro substituted purine starting material, first making an alkyl substitution at the 9-position, then forming the desired esterified side chain, reducing this and hydrogenating the resultant diol prior to addition of alkyl carbonyl groups.