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1.
3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from 1H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2p-bromo-6p-(3q,4q-dimethoxybenzyl)- 3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(2),2,3-dibromo-1-(2p-bromo-6p-(2q-bromo-4q,5q-dimethoxy-benzyl)-3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(3),3,4-dibromo-5-(2p-bromo-6p-(2q-bromo-4q,5q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol(4)and 3,4-dibromo-5-(2p-bromo-6p-(3q,4q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol (5).PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay,and compounds 3 and 4 demonstrated interesting activity against PTP1B.  相似文献   

2.
The quantitative correlation between rheological properties and structural characteristic values of chilled abalone meat was studied. Structural changes were observed, and these values were enumerated using image processing and analysis technique. Structural changes in the myofibrils and collagen fibrils were the greatest in chilling for 24 h. After chilling for 48h, similar structures of vertical and cross sections were observed. For chilling from 0h to 72h, the instantaneous modulus E0 of the both section meat decreases gradually with time, but no significant differences were observed after chilling for 48h. The relaxation time and viscosity of both sections attained the same values for the same chilling time, but increased gradually with increasing chilling time. Meanwhile, a negative correlation between the structural characteristic values (Dm, Am, Rvm), and rheological properties (E1, τ1 , η1) clearly exists. Some logarithmic expressions have been obtained for these negative correlations. These r  相似文献   

3.
Changes in tissue structure, rheological property and water content of dry abalone meat in the process of water restora- tion were studied. The weight and volume of dry abalone meat increased with water restoration. When observed under a light micro- scope, structural change in myofibrils was obvious and a distinct network was found. When water restoration time increased from 24 h to 72 h, the instantaneous modulus E0 and viscosity η1 increased, whereas the rupture strength and relaxation time (τ1) were re- duced. There were no significant changes of rheological parameters (E0, η1, τ1, rupture strength) from 72 h to 96 h of water restoration. Therefore, the dry abalone meat was swollen enough at the time of 72 h. The rheological parameters were obviously influenced by the structural changes.  相似文献   

4.
Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.  相似文献   

5.
The relations between δ18O and temperature on the different time scales were analysed, according to the data from Tuotuohe (34°13′N, 96°25′E; 4533 m a. s. l.), Delingha (37°22′N, 97°22′E; 2981 m a. s. l.) and Xining (36°37′N, 101°46′E; 2261 m a. s. l.) in the Qinghai-Xizang Plateau. The results show that the significance of d δ18O/dT on different time scales are different. The d δ18O/dT on the synoptic scale reflects the interdependent relation between δ18O and temperature in the short-term synoptic scale process; the d δ18O/d T on the seasonal scale reflects the relation between them whithin a year; and the d δ18O/d T on the climatic scale reflects the relation between them in the long-term climatic change. The calculated d δ18O/dT on climatic scale is very close to the theoretical values on the condition of advection transport for Tuotuohe Station. However, there are great differences between the calculated and the theoretical values for Delingha and Xining stations.  相似文献   

6.
The total organic carbon (TOC) content series from the lake sediment of Minqin Basin (100°57′–104°57′E, 37°48′–39°17′N) in northwestern China, which has a 10 000-year-long paleo-climatic proxy record, was used to analyze the Holocene climate changes in the local region. The proxy record was established in the Sanjiaocheng (SJC), Triangle Town in Chinese, Section (103°20′25″E, 39°00′38″N), which is located at the northwestern boundary of the present Asian summer monsoon in China, and is sensitive to global environmental and climate changes. Applying singular spectrum analysis (SSA) to the TOC series, principal climatic oscillations and periodical changes were studied. The results reveal 3 major patterns of climate change regulated by reconstructed components (RCs). The first pattern is natural long-term trend of climatic change in the local area (Minqin Basin), indicating a relatively wetter stage in early Holocene (starting at 9.5 kaBP), and a relatively dryer stage with a strong lake desiccation and a declined vegetation cover in mid-Holocene (during 7–6 kaBP). From 4.0 kaBP to the present, there has been a gradually decreasing trend in the third reconstructed component (RC3) showing that the local climate changed again into a dryer stage. The second pattern shows millennial-centennial scale oscillations containing cycles of 1 600 and 800 years that have been present throughout almost the entire Holocene period of the last 10 000 years. The third pattern is a millennial-centennial scale variation with a relatively smaller amplitude and unclear cycles showing a nonlinear interaction within the earth’s climate systems.  相似文献   

7.
Experimental study on the viscoelastic behaviors of debris flow slurry   总被引：1，自引：0，他引：1  
The rheological properties of most liquid in nature are between liquids and solids,including both elastic changes and viscosity changes,that is socalled "viscoelastic".Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study.The debris flow slurry samples were from Jiangjiagou Ravine,Yunnan Province,China.The experimental results were found that at the low and middle stages of shearing,when the angular velocity ω<72.46 s-1,the loss modulus(G") was greater than the storage modulus(G’),i.e.G">G’.At the late stage of shearing,when the angular velocity ω≧72.46 s-1,the storage modulus was greater than or equal to the loss modulus,i.e.G’≧G",tanδ≦1(where phase-shift angleδ=G"/G’),and the debris flow slurry was in a gel state.Therefore,the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.  相似文献   

8.
SOME NEW SPECIES OF NANNOPLANKTON IN JIAOZHOU BAY, SHANDONG, CHINA   总被引：1，自引：0，他引：1  
Three new spades and a new variety of nannoplankton, Chrysochromulina papillata, Gaysochromulina chiton var. minuta, Paraphysomonas simplexocorbita and Paraphysomonas bisorbulina are reported in this paper. All were isolated from the preliminary culture samples of seawater collected from Jiaozhou Bay, Shandong, China. The three species occurred at Station 1(120° 14.56′ E, 36°4′N) in November 1984, the new variety at Station 2 (120° 16.35° E,36°4.5′N) in January, 1985. The morphological features, especially the structures of the scales of these new nannoplankton,. are described. The differences between the new species and the related ones are discussed; their movement and nutrition, and the temperature and salinity of their biotopes are also mentioned.  相似文献   

9.
The distributions of SiO_3-Si, PO_4-P, NO_3-N and NO_2-N concentrations in the seawater, iceand snow from 82°45′21″W, 88°01′20″N to the North Pole are reported and the exchange of thenutrients among the seawater, ice and snow are discussed. The average concentrations of the nutrients inthe seawater near the North Pole were 4.9±2.4μmol/L for SiO_3-Si; 0.60±0.10μmol/L for PO_4-P,3.4±1.7μmol/L for NO_3-N and 0.13±0.04μmol/L for NO_2-N. The nutrient concentrations inthe ice and snow in the North Pole were 0.20 and 0.65μmol/L for SiO_3-Si; 0.22 and 0.25μmol/L forPO_4-P; 1.6 and 5.8μmol/L for NO_3-N, 0.19 and 0.15μmol/L for NO_2-N.  相似文献   

10.
Little has been done in measurement and research of the flux of CH4 emission from paddy fields in Changchun area, Jilin Province, China before 1994. So the purpose of the study is to offer available regional data of CH4 emission flux and to discuss the factors which affect CH4 emission from paddy fields. Experimental paddy fields are chosen using TM pictures respectively in Xinlicheng (43°49′N, 125°20′E) of the Yitong River’s and in Wanchang (43°44′10″N, 125°53′11″E) of the Yinma River’s alluvial plain. The fluxes of CH4 emission from paddy fields are measured by the method of static chamber in Changchun area in 3 consecutive years. The research results show that the peak of CH4 emission from paddy fields occurs during the booting stage. The mean fluxes of CH4 emission are 7.056 mg/m(2 · h) and 0.489 mg/(m2 · h) in the paddy fields of flood and discontinuous irrigation respectively. The contrastive study holds that climate condition, the way of water management and fertilizer variation have significant influence on fluxes of CH4 emission from paddy fields. The difference of climatic conditions causes the interannual change of the flux of CH4 emission from paddy fields. In general, the flux of CH4 emission from paddy fields of flood irrigation is greater than that from paddy fields of discontinuous irrigation. To change the way of water management perhaps in an available way to reduce CH4 emission flux from paddy fields. Foundation item: Under the auspices of Jilin Commttee of Science and Technology (grant 963416 - 1), and Changchun Jingyuetan Remote Sensing Test Site of the Chinese Academy of Sciences (grant 9504). Biography: YAN Min-hua (1964 -), female, a native of Liaoning Province, master, associate professor. Her research interests include climate change, greenhouse gases and wetland climate.  相似文献   

11.
During the 13th (1996–1997) and the 19th (2002–2003) Chinese National Antarctica Research Expeditions, we collected 60 discrete surface seawater samples along the cruise from the Chanjiang River (Yangtze) estuary (30°59′S, 122°26′E) through Taiwan Strait, the South China Sea, and the Eastern Indian Ocean to Prydz Bay, Antarctica (69°10′S, 74°30′E), and analyzed them for the 226Ra specific activity. The 226Ra specific activity of the Chanjiang River estuary surface water (3.15 Bq/m3) was found to be the highest among all the surface samples because of the desorption of 226Ra from riverine particles. Between Chanjiang River estuary and 40°S, 226Ra specific activity was found to be relatively uniform with a mean value of 1.07 Bq/m3 (n = 19, SD = 0.14), similar to that of the open ocean. From 40°S to 65°S, 226Ra specific activity increased intensively, then decreased moderately further southwards. Near the Antarctic shore, it increased again, to 2.31 Bq/m3. This distribution was controlled by a combination of deep water upwelling, Southern Ocean fronts, water mixing and the continental 226Ra import. In Prydz Bay and the adjacent sea area, the mean 226Ra activity value was 2.26 Bq/m3 (n = 31, SD = 0.28), with a relatively higher value outside of the bay and low 226Ra activity value in the center of the bay. This was consistent with the topography and hydrological setting of the bay. In addition, we extended the study area northward to the Arctic, by combining the published 226Ra dataset for surface water from the Bering Sea to the Japan Sea. We also discuss the 226Ra distribution of high latitude oceanic surface water and its mechanisms.  相似文献   

12.
AncientLoulanTOWnwasafamoustownontheSilkROadinthehistory,butsuddenlydisappearedfromthehistoricalrecords1400yearsago.Untilthespringof1900,Aierdeke,theUygurguideoftheexploringpartyledbyMr.SVehHedin,aSWedishexplorer,discoveredthismystery,whichmadeasensationintheworld.Afterwards,alotofexplorersathomeandabroad,E.NuntingtrnfromAmerica(1905),SirAureSteinfromEngland(1906,Igl4),azureOtanietal.fromJapan(1908--1911)wentthereoneafteranotherandthelastinvestigationofwidescopewasdonebyanarchaeologi…  相似文献   

13.
Requirement for dietary n−3 HUFA (n−3 highly unsaturated fatty acid) for growth and survival of black sea bream (Sparus macrocephalus) larvae was studied using rotifers andArtemia at various levels of n−3 HUFA. Five treatments with rotifers andArtemia differing in n−3 HUFA were prepared by enriching them with various oil emulsions. Results indicated that dietary n−3 HUFA significantly influence fish n−3 HUFA levels and are essential for growth and survival of black sea bream larvae. The results also indicated that the incorporation of n−3HUFA TG (triacylglycerols) into tissues of larval black sea bream was more effective from natural fish oil in comparison with n−3 HUFA fatty acid ethyl esters from ethyl-esterified oil. Project No. 39770588 supported by the NSFC.  相似文献   

14.
Preconsolidation stress ( σ P') is the maximum effective stress that a soil has suffered throughout its life. From a geotechnical point of view, pre-consolidation stress has great importance because it separates elastic and reversible deformations from inelastic and only partially irreversible deformations and marks the starting point of high compressibility. In this study we calculated the preconsolidation stress for 72 undisturbed soil samples from the Yellow River Delta, using the oedometer tes...  相似文献   

15.
1　Introduction　Actinisanimportantcontractileproteinineukary oticcells .Itisoneofthetwomajorcomponentsin volvedinthecontractionofmusclecells .Innon mus clecells ,itisthemajorpartofcytoskeletoninvolvedinmanyprocessessuchascellmotility ,endocytosis ,exocyt…  相似文献   

16.
Bromophenols are a set of natural products widely distributed in seaweed, most of which exhibit interesting and useful biological activities. To develop a reliable and efficient synthetic route to these natural bromophenols, three of them, 3,4-dibromo-5-(2′-bromo-3′,4′-dihydroxy-6′-methoxymethyl-benzyl)-benzene-1,2-diol (compound 9), 3,4-dibromo-5-(2′-bromo-6′-ethoxy methyl-3′,4′-dihydroxybenzyl)-benzene-1,2-diol (compound 10), and 3-bromo-4-(3′-bromo-4′,5′-dihydroxy benzyl)-5-(ethoxymethyl)-benzene-1,2-diol (compound 14), isolated from red marine algae, have been synthesized in eight steps with an overall yield of 14.4%, 14.4%, and 18.2% respectively, via a practical approach employing bromination, Wolff-Kishner-Huang reduction and a Friedel-Crafts reaction as key steps. The protein tyrosine phosphatase 1B (PTP1B) inhibitory activities of the synthetic compounds were evaluated by the colorimetric assay. The results show that these compounds are moderate PTP1B inhibitors. The synthesis of these bromophenol derivatives makes in vivo studies of their structure-activity relationships and inhibition activity against PTP1B possible.  相似文献   

17.
The requirement for dietary n−3 HUFA (highly unsaturated fatty acid) for growth and survival of black seabream (Sparus macrocephalus) larvae was tested usingArtemia with various levels of n−3 HUFA. Four treatments withArtemia differing in their n−3 HUFA were prepared by feeding them various oil emulsions. The results indicated that dietary n−3 HUFA significantly influences fish n−3 HUFA levels and are necessary for good growth and survival of black seabream larvae. The proper value of n−3 HUFA level and DHA, EPA level inArtemia should be 4.273% and 0.873% (wet weight) for good growth and survival in black seabream larvae respectively. Contribution No. 3044 from the Institute of Oceanology, Chinese Academy of Sciences. Project 39470562 supported by NSFC.  相似文献   

18.
To investigate the antitumor effect of bromophenol derivatives in vitro and Leathesia nana extract in vivo, six bromophenol derivatives 6-(2,3-dibromo-4,5-dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (1), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (2), 3-bromo-4-(2,3-dibromo-4,5-dihydroxybenzyl)-5-methoxymethyl-pyrocatechol (3), 2,2′,3,3′-tetrabromo-4,4′,5,5′-tetrahydroxy-diphenylmethane (4), bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (5), 2,2′,3-tribromo-3′,4,4′,5-tetrahydroxy-6′-ethyloxymethyldiphenylmethane (6) were isolated from brown alga Leathesia nana, and their cytotoxicity were tested by MTT assays in human cancer cell lines A549, BGC-823, MCF-7, B16-BL6, HT-1080, A2780, Bel7402 and HCT-8. Their inhibitory activity against protein tyrosine kinase (PTK) with over-expression of c-kit was analyzed also by ELISA. The antitumor activity of ethanolic extraction of Leathesia nana (EELN) was evaluated on S180-bearing mice. All compounds showed very potent cytotoxicity against all of the eight cancer cell lines with IC50 below 10 μg/mL. In PTK inhibition study, all bromophenol derivatives showed moderate inhibitory activity and compounds 2, 5 and 6 showed significant bioactivity with the inhibition ratio of 77.5%, 80.1% and 71.4%, respectively. Pharmacological studies reveal that EELN could inhibit the growth of Sarcoma 180 tumor and increase the indices of thymus and spleen to improve the immune system remarkably in vivo. Results indicated that the bromophenol derivatives and EELN can be used as potent antitumor agents for PTK over-expression of c-kit and considered in a new therapeutic strategy for treatment of cancer. Supported by the National High Technology Research and Development Program of China (863 Program, No. 2007AA09Z410) and Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-209)  相似文献   

19.
Twenty-four compounds including eight steroids (1–8), nine triterpenoids (9–16, 24), three flavonoids (20–22), and four benzenecarboxylic derivatives (17–19, 23) were isolated and identified from stems and twigs of medicinal mangrove plant Sonneratia caseolaris. The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compounds 1, 4–20 and 22–24 were isolated and identified for the first time from S. caseolaris. In the in vitro cytotoxic assay against SMMC-7721 human hepatoma cells, compound 21 (3′,4′,5,7-tetrahydroxyflavone) exhibited significant activity with IC50 2.8 μg/mL, while oleanolic acid (14), 3,3′-di-O-methyl ether ellagic acid (18), and 3,3′,4-O-tri-O-methyl ether ellagic acid (19) showed weak activity. None of these compounds displayed significant antibacterial activites. Supported by the National Natural Science Foundation of China (No. 30770234); Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-211-04); Department of Science and Technology of Shandong Province (No.2006GG2205023)  相似文献   

20.
From 1997 to 2000, four field surveys were conducted in the East China Sea (ECS) (23°30′–33°00′N, 118°30′–128°00′E). A field data yield density model was used to determine the optimal salinities for 19 dominant copepod species to establish the relationship between surface salinities and abundance of those species. In addition, ecological groups of the copepods were classified based on optimal salinity and geographical distribution. The results indicate that the yield density model is suitable for determining the relationship between salinity and abundance. Cosmocalanus darwini, Euchaeta rimana, Pleuromamma gracilis, Rhincalanus cornutus, Scolecithrix danae and Pareucalanus attenuatus were determined as oceanic species, with optimal salinities of >34.0. They were stenohaline and mainly distributed in waters influenced by the Kuroshio or Taiwan warm current. Temora discaudata, T. stylifera and Canthocalanus pauper were nearshore species with optimal salinities of <33.0 and most abundant in coastal waters. The remaining 10 species, including Undinula vulgaris and Subeucalanus subcrassus, were offshore species, with optimal salinity ranging from 33.0–34.0. They were widely distributed in nearshore, offshore and oceanic waters but mainly in the mixed water of the ECS.  相似文献   

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