Gas hydrates are crystalline clathrate compounds comprised of hydrogen-bonded water cavities, consisting of guest molecules trapped in a lattice of polyhedral water cages under elevated pressures and low temperatures ...Gas hydrates are crystalline clathrate compounds comprised of hydrogen-bonded water cavities, consisting of guest molecules trapped in a lattice of polyhedral water cages under elevated pressures and low temperatures [1]. The structures of the gas hydrates are closely related to the types and sizes of the guest species, and three distinct structures, including cubic structure-I （sI）, hexagonal structure-H （sH）, are cubic structure-II （sII）, and known to form [2].展开更多
In the field of geology,it is necessary to get the information about the rock geological time,which includes absolute geologic age and relative geologic age .Tracing the evolutionary history of the earth is one of the...In the field of geology,it is necessary to get the information about the rock geological time,which includes absolute geologic age and relative geologic age .Tracing the evolutionary history of the earth is one of the research tasks of earth science.Time,space,material and motivation are the basic elements for studying geological processes and enviromnental evolution,and time is the basis for studying geological problems.A clear understanding of the interaction between the above elements will be able to clearly make sure the evolution of the earth and the conditions of rock formation.Nowadays,it is urgent to get the geochronological data of rocks for wide range comparison,so as to study the evolution trend and development rule of the earth's crust .展开更多
To the Editor:The coronavirus disease2019(COVID-19)outbreak developedinto a pandemic.Patientsundergoing hemodialysis(HD)are more susceptible to COVID-19,and isolating patients undergoing HD after exposure are extremel...To the Editor:The coronavirus disease2019(COVID-19)outbreak developedinto a pandemic.Patientsundergoing hemodialysis(HD)are more susceptible to COVID-19,and isolating patients undergoing HD after exposure are extremely challenging since they frequently travel between their homes and dialysis centers,during which they share a hall for dialysis sessions that may last for hours.We successfully quarantined one infected HD patient and other potentially exposed patients.This experience might serve as an important reference for dialysis centers or for people in similar situations across the country to reduce the spread of COVID-19.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61405259,and 11574401)National Basic Research Program of China(GrantNo.2014CB744302)+1 种基金the Specially Founded Program on National Key Scientific Instruments and Equipment Development,China(Grant No.2012YQ140005)the China Petroleum and Chemical Industry Association Science and Technology Guidance Program(Grant No.2016-01-07)
文摘Gas hydrates are crystalline clathrate compounds comprised of hydrogen-bonded water cavities, consisting of guest molecules trapped in a lattice of polyhedral water cages under elevated pressures and low temperatures [1]. The structures of the gas hydrates are closely related to the types and sizes of the guest species, and three distinct structures, including cubic structure-I （sI）, hexagonal structure-H （sH）, are cubic structure-II （sII）, and known to form [2].
基金supported by the National Nature Science Foundation of China(Grant No.61405259)
文摘In the field of geology,it is necessary to get the information about the rock geological time,which includes absolute geologic age and relative geologic age .Tracing the evolutionary history of the earth is one of the research tasks of earth science.Time,space,material and motivation are the basic elements for studying geological processes and enviromnental evolution,and time is the basis for studying geological problems.A clear understanding of the interaction between the above elements will be able to clearly make sure the evolution of the earth and the conditions of rock formation.Nowadays,it is urgent to get the geochronological data of rocks for wide range comparison,so as to study the evolution trend and development rule of the earth's crust .
基金Peking University Special Fund for COVID-19 Prevention and Control(No.PKU2020PKYZX001)。
文摘To the Editor:The coronavirus disease2019(COVID-19)outbreak developedinto a pandemic.Patientsundergoing hemodialysis(HD)are more susceptible to COVID-19,and isolating patients undergoing HD after exposure are extremely challenging since they frequently travel between their homes and dialysis centers,during which they share a hall for dialysis sessions that may last for hours.We successfully quarantined one infected HD patient and other potentially exposed patients.This experience might serve as an important reference for dialysis centers or for people in similar situations across the country to reduce the spread of COVID-19.
