A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformatio...A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformations in the wavenumber domain, which not only gives a more flexible algorithm of potential field transformations, but also reveals the law of error of potential field transformations in the wavenumber domain. The DFT0η η（0.5, 0.5） reduction-to-pole （RTP） technique derived from the A-E equation significantly improves the resolution and accuracy of RTP anomalies at low magnetic latitudes, including the magnetic equator. The law （origin, form mechanism, and essential properties） of the edge oscillation revealed by the A-E equation points out theoretically a way of improving the effect of existing padding methods in high-pass transformations in the wavenumber domain.展开更多
Phytochemicalinvestigation onthe whole plants of Ypsilandra yunnanensiswas carried out forthe firsttime andledtothe isolation of five new cholestanol glycosides,ypsiyunnosides A–E(1–5),and one known analogue.Their s...Phytochemicalinvestigation onthe whole plants of Ypsilandra yunnanensiswas carried out forthe firsttime andledtothe isolation of five new cholestanol glycosides,ypsiyunnosides A–E(1–5),and one known analogue.Their structures were determined mainly by detailed spectroscopic analysis,including extensive 1D and 2D NMR,MS and UV,as well as chemical methods.Among them,compound 1 possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon,which was identified as(23R,25R)-3β,16α,26-triol-16,23-cyclocholest-5,17(20)-dien-22-one.Their induced platelet aggregation activities and cytotoxicities were evaluated.Graphical Abstract Five new cholestanol glycosides,ypsiyunnosides A–E(1–5),were isolated from the whole plants of Ypsilandra yunnanensis.Compound 1 possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon.Their structures were elucidated by a combination of 1D and 2D NMR,MS and chemical analysis.展开更多
Four new monoterpenoid indole alkaloids,bousmekines A-D(1-4),and one new pyranopyridine alkaloid,bousmekine E(5),were isolated from the twigs and leaves of Bousigonia angustifolia and Bousigonia mekongensis.Their stru...Four new monoterpenoid indole alkaloids,bousmekines A-D(1-4),and one new pyranopyridine alkaloid,bousmekine E(5),were isolated from the twigs and leaves of Bousigonia angustifolia and Bousigonia mekongensis.Their structures including absolute configurations were elucidated by a combination of MS,NMR,ECD calculation,and single-crystal X-ray diffraction analysis.Compound 2 was an eburnea-type MIAs characterized by a rare chlorine atom while 5 possessed a novel pyranopyridine moiety.Their cytotoxicities against several human cancer cell lines were evaluated and compound 1 exhibited significant cytotoxicity with IC50 values of 0.8-7.4μM.展开更多
Uncarialines A-E(1-5),five undescribed monoterpene indole alkaloids,together with five known analogues were obtained from the stems of Uncaria rhynchophylla.Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with ...Uncarialines A-E(1-5),five undescribed monoterpene indole alkaloids,together with five known analogues were obtained from the stems of Uncaria rhynchophylla.Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with a 6/5/10 ring system,while 4 and 5 possessed a rare rearranged scaffold originated from corynantheine-type alkaloids with C-2/C-7 oxidation.Their structures were characterized by a comprehensive analysis of MS,NMR,and ECD.Their effects on blood clotting times of human plasma were evaluated and alkaloid 5 had a slight prolongation effect on both thrombin time and activated partial thromboplastin time(p<0.001).展开更多
文摘A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformations in the wavenumber domain, which not only gives a more flexible algorithm of potential field transformations, but also reveals the law of error of potential field transformations in the wavenumber domain. The DFT0η η（0.5, 0.5） reduction-to-pole （RTP） technique derived from the A-E equation significantly improves the resolution and accuracy of RTP anomalies at low magnetic latitudes, including the magnetic equator. The law （origin, form mechanism, and essential properties） of the edge oscillation revealed by the A-E equation points out theoretically a way of improving the effect of existing padding methods in high-pass transformations in the wavenumber domain.
基金This work was supported by the National Natural Science Funding of China(Grants 31170333 and 31570363).
文摘Phytochemicalinvestigation onthe whole plants of Ypsilandra yunnanensiswas carried out forthe firsttime andledtothe isolation of five new cholestanol glycosides,ypsiyunnosides A–E(1–5),and one known analogue.Their structures were determined mainly by detailed spectroscopic analysis,including extensive 1D and 2D NMR,MS and UV,as well as chemical methods.Among them,compound 1 possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon,which was identified as(23R,25R)-3β,16α,26-triol-16,23-cyclocholest-5,17(20)-dien-22-one.Their induced platelet aggregation activities and cytotoxicities were evaluated.Graphical Abstract Five new cholestanol glycosides,ypsiyunnosides A–E(1–5),were isolated from the whole plants of Ypsilandra yunnanensis.Compound 1 possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon.Their structures were elucidated by a combination of 1D and 2D NMR,MS and chemical analysis.
基金This work was financially supported by Yunnan Applied Basic Research Projects(2018FA049)Top Young Talent of the Ten Thousand Talents Program of Yunnan(to Y.Zhang).
文摘Four new monoterpenoid indole alkaloids,bousmekines A-D(1-4),and one new pyranopyridine alkaloid,bousmekine E(5),were isolated from the twigs and leaves of Bousigonia angustifolia and Bousigonia mekongensis.Their structures including absolute configurations were elucidated by a combination of MS,NMR,ECD calculation,and single-crystal X-ray diffraction analysis.Compound 2 was an eburnea-type MIAs characterized by a rare chlorine atom while 5 possessed a novel pyranopyridine moiety.Their cytotoxicities against several human cancer cell lines were evaluated and compound 1 exhibited significant cytotoxicity with IC50 values of 0.8-7.4μM.
基金Yunnan Applied Basic Research Projects(No.202301AS070057)National Key R&D Program of China(No.2022YFF1100301)Yunnan Revitalization Talents Support Plan-Young Talent Project(to Y.Zhang).
文摘Uncarialines A-E(1-5),five undescribed monoterpene indole alkaloids,together with five known analogues were obtained from the stems of Uncaria rhynchophylla.Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with a 6/5/10 ring system,while 4 and 5 possessed a rare rearranged scaffold originated from corynantheine-type alkaloids with C-2/C-7 oxidation.Their structures were characterized by a comprehensive analysis of MS,NMR,and ECD.Their effects on blood clotting times of human plasma were evaluated and alkaloid 5 had a slight prolongation effect on both thrombin time and activated partial thromboplastin time(p<0.001).
