A new bibenzyl glycoside has been isolated from the stems of Dendrobium moniliforme (L.) Sw. (Orchidaceae). Its structure has been identified on the basis of spectroscopic and chemical methods.
A new method for preparing effective inhibition film on copper has been developed. Phenylthiourea (PT) was first absorbed to copper surface to form a monolayer. 1-Dodecanethiol (DT) was then assembled on the surface...A new method for preparing effective inhibition film on copper has been developed. Phenylthiourea (PT) was first absorbed to copper surface to form a monolayer. 1-Dodecanethiol (DT) was then assembled on the surface for modification. Finally, AC voltage was loaded on copper covered the mixed film to improve it further. After these processes, an effective inhibition film was gained because of its high charge transfer resistance and low corrosion current density shown in electrochemical impedance spectra and polarization. The inhibition efficiency was more than 97%.展开更多
A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprecipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the ...A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprecipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the positive nanoparticle were studied by SEM, XRD, FTIR, chemical analysis, spectroanalysis and measuring of electrophoretic mobilities. Preliminary results show the positive nanoparticle is a promising precursor of polymer/LDHs nanocomposite.展开更多
Non-carbon inorganic fullerene-like (IF) nanoscale materials have recently attracted intense interest due to their nested hollow and nanotube structures. In this letter, IF-WS2 nanoparticles prepared by solid-gas rea...Non-carbon inorganic fullerene-like (IF) nanoscale materials have recently attracted intense interest due to their nested hollow and nanotube structures. In this letter, IF-WS2 nanoparticles prepared by solid-gas reaction were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the IF-WS2 nanoparticles have a nested hollow closed spherical structure with diameter of 100-150 nm.展开更多
A facile glycosylation for the synthesis of spirostanol glycosides was reported. Using cadmium carbonate as a catalyst in CH3CN, a series of saponins was synthesized efficiently in a satisfactory yield.
This paper proposes the concept of transaction-type covert storage channels, which are caused by database storage resources. It also proposes that the mode of auditing those channels be based on the transactions. Next...This paper proposes the concept of transaction-type covert storage channels, which are caused by database storage resources. It also proposes that the mode of auditing those channels be based on the transactions. Next, the paper analyzes and resolves the two problems arising from auditing the use of transaction-type covert storage channels in database systems: namely, the relationship between channel variables, which are altered (or viewed) by the transaction and satisfy integrity constraints in DBMS, and database states; and the circumvention of covert storage channel audit in DBMS.展开更多
文摘A new bibenzyl glycoside has been isolated from the stems of Dendrobium moniliforme (L.) Sw. (Orchidaceae). Its structure has been identified on the basis of spectroscopic and chemical methods.
基金Subsidized with the Special Funds for the Major State Basic Research Projects G19990650 and the Chinese National Science Fund (No. 20173033).
文摘A new method for preparing effective inhibition film on copper has been developed. Phenylthiourea (PT) was first absorbed to copper surface to form a monolayer. 1-Dodecanethiol (DT) was then assembled on the surface for modification. Finally, AC voltage was loaded on copper covered the mixed film to improve it further. After these processes, an effective inhibition film was gained because of its high charge transfer resistance and low corrosion current density shown in electrochemical impedance spectra and polarization. The inhibition efficiency was more than 97%.
文摘A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprecipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the positive nanoparticle were studied by SEM, XRD, FTIR, chemical analysis, spectroanalysis and measuring of electrophoretic mobilities. Preliminary results show the positive nanoparticle is a promising precursor of polymer/LDHs nanocomposite.
基金This work was supported by the National Natural Science Foundation of China (50171063 20171039 20003009) the Zhejiang Provincial Natural Science Foundation of China (501074,200053) the Israeli Ministry of Science (Tashtiot) and the Israel Scie
文摘Non-carbon inorganic fullerene-like (IF) nanoscale materials have recently attracted intense interest due to their nested hollow and nanotube structures. In this letter, IF-WS2 nanoparticles prepared by solid-gas reaction were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the IF-WS2 nanoparticles have a nested hollow closed spherical structure with diameter of 100-150 nm.
文摘A facile glycosylation for the synthesis of spirostanol glycosides was reported. Using cadmium carbonate as a catalyst in CH3CN, a series of saponins was synthesized efficiently in a satisfactory yield.
文摘This paper proposes the concept of transaction-type covert storage channels, which are caused by database storage resources. It also proposes that the mode of auditing those channels be based on the transactions. Next, the paper analyzes and resolves the two problems arising from auditing the use of transaction-type covert storage channels in database systems: namely, the relationship between channel variables, which are altered (or viewed) by the transaction and satisfy integrity constraints in DBMS, and database states; and the circumvention of covert storage channel audit in DBMS.
