基于用户兴趣变化的高校图书馆个性化图书推荐研究

在众多个性化推荐技术中,协同过滤算法作为一种适用范围广、推荐质量高的算法,在电子商务领域得到了广泛应用,近年来被不少学者引入到图书馆个性化推荐的研究中。然而高校图书馆系统与商业系统相比,普遍存在用户信息少、项目评分严重缺失的问题,极大地影响了个性化推荐的准确率。针对以上问题,文章从高校读者属性和行为特征出发,建立用户兴趣模型,将读者阅读兴趣划分为长期兴趣和短期兴趣,基于用户兴趣度优化项目评分矩阵,进行协同过滤图书推荐。     

Transesterification of epoxidized soybean oil to prepare epoxy methyl esters

Epoxidized methyl esters were prepared by the transesterification of epoxidized soybean oil (ESBO). The transesterification was complete in 10 min at 50 °C without loss of the epoxide function. Epoxidized methyl esters represent a renewable substrate that is readily converted into surfactants, fuel additives, and other industrial products. The implementation of this reaction will increase the availability of epoxidized methyl esters and promote the development of new biobased products.     

新型饲料添加剂—7—异丙氧基异黄酮的合成

７－异丙氧基异黄酮为一种新型饲料添加剂。用间苯二酚与苯乙酸直接酰化制得２，４二羟基苯基苄基酮，在吗啉、吡啶存在条件下与原甲酸三乙酯反应环合，再与乙－溴丙烷反应生成７－异丙氧基异黄酮，总收率为５６％。     

Effect of fractalkine on the expression and secretion of MMP-2 in human monocytes

AIM: To study the effect of fractalkine (CX3CL1, Fkn) on the expression and secretion of matrix metalloproteinase-2 (MMP-2) in cultured human monocyte line U937 cells. METHODS: The cultured U937 cells were incubated with recombinant human Fkn, the supernatant of human renal mesangial cells (HRMC) and Fkn neutralizing antibodies for 24 h. The mRNA expression of MMP-2 was analyzed by RT-PCR. The production of MMP-2 in the supernatant was analyzed by gelatin zymography. RESULTS: The level of MMP-2 mRNA and protein in the cells incubated with recombinant human Fkn decreased compared to control group. Similarly, the level of MMP-2 mRNA in the cells incubated with the supernatant of HRMC reduced compared to control group. However, the level of MMP-2 mRNA and protein in the cells incubated with the supernatant of HRMC adding Fkn neutralizing antibodies increased compared to that incubated with the supernatant of HRMC. CONCLUSION: Fkn inhibits the expression and secretion of MMP-2 in cultured U937 cells. HRMC might mediate the expression and secretion of MMP-2 in U937 cells through Fkn.     

Bioactive carbazole alkaloids from Murraya koenigii (L.) Spreng

Four new carbazole alkaloids (1–4) and fourteen known carbazole alkaloids (5–18) were isolated from Murraya koenigii. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 4, 6, 16, and 17 (10 μM) had moderate hepatoprotective activities against d-galactosamine-induced HL-7702 cell damage. Compounds 11, 12 and 18 showed significant PTP1B inhibitory activity with IC₅₀ values of 1.773, 1.875 and 2.286 μM, respectively.     

Isolation of xanthone and benzophenone derivatives from Cyclopia genistoides (L.) Vent. (honeybush) and their pro-apoptotic activity on synoviocytes from patients with rheumatoid arthritis

A fast and efficient method for the isolation of the C-glucosidated xanthones mangiferin and isomangiferin from the South-African plant Cyclopia genistoides was developed for the first time. The procedure involved extraction, liquid–liquid partitioning with ethyl acetate and subsequent precipitation of mangiferin and isomangiferin from methanol and acetonitrile–water fractions, respectively. Additionally, two benzophenone derivatives: 3-C-β-glucosides of maclurin and iriflophenone, were isolated from C. genistoides extracts using semi-preparative HPLC. Apart from the above, the isolation procedure also yielded hesperidin and small amounts of luteolin. The structures of the compounds were determined by 1D and 2D NMR experiments and/or LC-DAD-ESI–MS. The selected Cyclopia constituents were screened for pro-apoptotic activity on TNF-α-stimulated synovial cells isolated from rheumatoid arthritis patients. The strongest effect, measured as percent of apoptotic cells, was recorded for isomangiferin (75%), followed by iriflophenone 3-C-β-glucoside (71%), hesperidin (67%) and mangiferin (65%). The results are encouraging for further studies on the use of the above compounds in the treatment of rheumatoid arthritis.     

基于GIS的白洋淀流域生态环境评价

采用GIS技术和生态环境状况评价技术规范,对白洋淀流域生态环境状况进行了评价。结果表明:白洋淀流域生态环境状况指数为53.03,属“一般”级别,表现为植被覆盖度中等,生物多样性一般,较适合人类生存。流域水网密度指数和环境质量指数低,仅分别为11.18和12.68,是造成流域内生态环境状况指数偏低的主要原因,也是人类生存的制约因子。     

N-酰基-高丝氨酸内酯类群体感应信号分子检测方法的建立

N-酰基-高丝氨酸内酯（AHL）类化合物是革兰氏阴性菌群体感应系统中最重要的一类信号分子，并调控许多生理特性的表达。但由于AHLs分子为小分子物质，且AHL产生菌所产生的AHL的浓度极低，因此建立有效检测AHLs方法具有非常重要的意义。本研究利用两种细菌生物感应器Chromobacterium violaceum CVO26和Agrobacterium tumefaciens A136（pCF218/pCF372）建立了琼脂扩散法、薄层层析与细菌生物感应器相结合（TLC-Biosensor）、β-半乳糖苷酶活法等检测AHL的生物学方法,为研究革兰氏阴性菌的群体感应系统提供了有效手段。     

Inflammation and coagulation activation are associated with gallstone formation in golden hamsters

AIM: To elucidate the relationship of inflammation, coagulation and cholesterol gallstone formation. METHODS: Hamsters were divided into four groups: control group (feeding normal diet), lithogenic diet (LD) 2 weeks group, LD 6 weeks group and LD+aspirin 6 weeks group. Gallstone incidence, antithrombin antigen (AT-Ⅲ:Ag), antithrombin activity (AT-Ⅲ:Ac), thrombin (F-Ⅱa:Ac), plasminogen activator inhibitor activity (PAI:Ac), plasmin activity (Plm:Ac), D-dimer:Ag and C-reactive protein (CRP) in gallbladder bile were observed as read-out parameters. RESULTS: The incidence of gallstones in control group, LD 2 weeks group, LD 6 weeks group and LD+aspirin group were 0%, 20%, 73% and 25%, respectively. AT-Ⅲ:Ag, F-Ⅱa:Ac, D-dimer and CRP in LD 2 weeks group and LD 6 weeks group were significantly higher than those in the control group (P<0.01). AT-Ⅲ:Ag, PAI:Ac, Plm:Ac, D-dimer and CRP in LD 6 weeks group were significantly higher than those in LD 2 weeks group (P<0.01). AT-Ⅲ:Ag, F-Ⅱa:Ac, PAI:Ac, D-dimer and CRP were strikingly decreased in LD+aspirin group compared with those in LD 6 weeks group (P<0.01). The level of CRP was closely correlated with the concentration of D-dimer (γ=0.752, P<0.01). CONCLUSIONS: Coagulation cascade is activated and crosslinked fibrin forms in gallbladder bile before gallstone formation. “Lithogenic bile” might play a central role in the inflammation of gallbladder mucosa, which activates extrinsic coagulation pathway and leads cholesterol gallstone formation.     

Antifeedant activity of some diterpenoids

The antifeedant activity of six diterpenes against the fourth instar nymphs and adults of Henosepilachna vigntioctopunctata was evaluated using a dual choice leaf disc bioassay. Caryoptin was the most effective antifeedant among the compounds tested. Andrographolide, wightionolide and 3-epicaryoptin did not deter feeding by adults. The possible relationship of structure to antifeedant activity is discussed.