[Characteristics of stable isotopes in precipitation over Northeast China and its water vapor sources].

Based on the data of the hydrogen and oxygen stable isotopes in precipitation over Northeast China provided by the Global Network of Isotopes in Precipitation (GNIP) and the meteorological statistics, the spatial and temporal variations of stable isotopes in precipitation and their influencing factors were analyzed and the Local Meteoric Water Line (LMWL) was established. The results were as follows: delta18O value was low in winter and high in summer; the spatial distribution showed that the weighted delta18O value decreased from the south to the north; the linear relationship between delta18O in precipitation and temperature was significant, but no linear relationship was found for the precipitation amount; delta18O in precipitation can be evaluated quantitatively based on a multiple linear regression equation with delta18O and related parameters (temperature, precipitation amount, elevation, longitude and latitude). The water vapor source of the sampling sites was tracked by HYSPLIT 4.

[Characteristics of delta18O in precipitation and moisture transports over the arid region in Northwest China].

Based on the observed data of stable isotopes in precipitation and meteorological statistics at Urümqi (1986-2003), Zhangye (1986-2003), and Hotan (1988-1992) from IAEA/WMO, the precipitation equation of arid region in Northwest China was calculated through the regression analysis, and the characteristics of stable isotopic in precipitation, as well as the correlation between stable isotopic and meteorological records, were analyzed. The water vapor source of the three sites was tracked by the HYSPLIT4. 9 model, and water vapour transmission regime of arid region in Northwest China was established, while the record of delta18O in cryosphere was discussed.

Pterisolic acids A-F, new ent-kaurane diterpenoids from the fern Pteris semipinnata.

Six new ent-15-oxokauran-19-oic acid derivatives, named pterisolic acids A-F (1-6), were isolated from the ethanol extract of the fern Pteris semipinnata (Pteridaceae), and the structures of these new ent-kauranoids were elucidated on the basis of extensive spectroscopic studies and single crystal X-ray diffraction analysis.

Scutebarbatines W-Z, new neo-clerodane diterpenoids from Scutellaria barbata and structure revision of a series of 13-spiro neo-clerodanes.

Four new neo-clerodane diterpenoids, scutebarbatines W-Z (1-4), were isolated from the ethanol extract of Scutellaria barbata (Labiatae), and their structures were elucidated on the basis of extensive spectroscopic studies. In addition, the proposed structures of at least seven 13-spiro subtype neo-clerodanes: scutehenanine B (5), scutebarbatine G (6), 6-O-nicotinoylscutebarbatine G (7), barbatin A (8), 6,7-di-O-nicotinoylscutebarbatine G (9), 6-O-nicotinoyl-7-O-acetylscutebarbatine G (10), and scutebarbatine F (11), reported by Dai and co-workers from the same species, were incorrectly assigned and have been revised by reanalysis of the published NMR data.

ent-Pimarane diterpenoids from Siegesbeckia orientalis and structure revision of a related compound.

Six new ent-pimarane diterpenoids, namely, ent-14beta,16-epoxy-8-pimarene-3beta,15alpha-diol (1), 7beta-hydroxydarutigenol (2), 9beta-hydroxydarutigenol (3), 16-O-acetyldarutigenol (4), 15,16-di-O-acetyldarutoside (5), and 16-O-acetyldarutoside (6), were isolated from the ethanol extract of Siegesbeckia orientalis. Their structures were elucidated on the basis of spectroscopic studies, and the absolute configuration of 1 was established by the modified Mosher's method. Furthermore, the structure of ent-12beta,16-epoxy-8-pimarene-2alpha,15beta,19-triol, recently isolated from the same plant, should be revised as ent-14beta,16-epoxy-8-pimarene-2alpha,15alpha,19-triol (10).