Lu-jun Li

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Phytochemical investigation of the leaf of Ilex centrochinensis led to the isolation and characterization of four flavans, one flavanone (5), and one flavone (6), including a new compound whose structure was elucidated as (2S)-5,3',4'-trihydroxy-7-methoxyflavan (1) and a new natural product whose structure was elucidated as(More)
Grassland conversion to cropland (GCC) may result in loss of a large amount of soil organic carbon (SOC). However, the assessment of such loss of SOC still involves large uncertainty due to shallow sampling depth, soil bulk density estimation and spatial heterogeneity. Our objectives were to quantify changes in SOC, soil total nitrogen (STN) and C:N ratio(More)
Four new alkenes (1-4), and six known alkenes (5-12) were isolated from Murraya koenigii (L.) Spreng. Their structures were elucidated on the basis of spectroscopic analyses and references. Compounds (1-12) were evaluated for antioxidative activities. Among them, compounds 1, 2, 4, and 7 exhibited significant antioxidative activities using(More)
Species diversity and productivity are the important indices of the structure and functioning of ecosystems. With Keerqin sandy grassland as test object, this paper studied its species composition, species diversity, and productivity under effects of different level nitrogen (N) addition. Nitrogen addition altered the species composition and the dominant(More)
This study was carried out to evaluate the anti-inflammatory and free radical scavenging activities of flavans from flex centrochinensis S. Y. Hu in vitro and their structure-activity relationship. LPS-stimulated RAW 264.7 macrophage was used as inflammatory model. MTT assay for cell availability, Griess reaction for nitric oxide (NO) production, the(More)
Labile fractions of soil organic matter (SOM) respond rapidly to land management practices and can be used as a sensitive indicator of changes in SOM. However, there is little information about the effect of agroforestry practices on labile SOM fractions in semiarid regions of China. In order to test the effects of land use change from monocropping to(More)
A field experiment was conducted to evaluate the influences of long-term applications of organic amendments and chemical fertilizers on nitrous oxide (N2O) emissions from Mollisols in northeast China and to relate soil N2O fluxes to soil moisture and temperature. A closed-chamber method was used to determine soil N2O flux during the maize growing season in(More)
Taking 5-, 10-, 15-, and 20 years old poplar (Populus euramericana cv. "N 3016") shelterbelts in Jianping County, Liaoning Province as test objects, the effects of establishing shelterbelts on the farmland soil microbial biomass carbon and nitrogen, and microbial activity were evaluated. After the establishment of shelterbelts, the concentrations of organic(More)
BACKGROUND Soil organic carbon (SOC) is fundamental for mitigating climate change as well as improving soil fertility. Databases of SOC obtained from soil surveys in 1981 and 2011 were used to assess SOC change (0-20 cm) in croplands of Heilongjiang Province in northeast China. Three counties (Lindian, Hailun and Baoqing) were selected as typical croplands(More)
OBJECTIVE To investigate the chemical constituents in leaves of Ilex centrochinensis and their antitumor bioactivity. METHOD Various chromatography techniques such as column chromatography on silica gel, Sephadex LH-20 and preparative HPLC were used to isolate and purify the compounds and their structures were identified by spectral data and(More)