论情报学的数学计量化研究

认为情报学研究中呈现出强烈的数学计量化或者说定量化趋势,在此基础上,较为系统地阐述情报学的数学计量化 研究,重点论述情报学数学计量化研究中从文献计量学到信息计量学(情报计量学),再到网络信息计量学的演进路向。

FTIR Spectroscopic Study of Broad Bean Diseased Leaves

[Objective] The aim was to indentify diseased leaves of broad bean by vibra- tional spectroscopy. [Method] In this paper, broad bean rust, fusarium rhizome rot, broad bean zonate spot, yellow leaf curl virus and normal leaves were studied using Fourier transform infrared spectroscopy combined with chemometrics. [Result] The spectra of the samples were similar, only with minor differences in absorption inten- sity of several peaks. Second derivative analyses show that the significant difference of all samples was in the range of 1 200-700 cm2. The data in the range of 1 200- 700 cm＇ were selected to evaluate correlation coefficients, hierarchical cluster analy- sis （HCA） and principal component analysis （PCA）. Results showed that the correla- tion coefficients are larger than 0.928 not only between the healthy leaves, but also between the same diseased leaves. The values between healthy and diseased leaves, and among diseased leaves, are all declined. HCA and PCA yielded about 73.3% and 82.2% accuracy, respectively. [Conclusion] This study demonstrated that FTIR techniques might be used to detect crop diseases.

Experimental and Theoretical Study of Deprotonation of DNA Adenine Cation Radical

Among all the DNA components, extremely redox-active guanine （G） and adenine （A） bases are subject to facile loss of an electron and form cation radicals （G＋＂ and A＋＇） when exposed to irradiation or radical oxidants. The subsequent deprotonation of G＋＇ and A＋＇ can invoke DNA damage or interrupt hole transfer in DNA. However, compared with intensive reports for G＋, studies on the deprotonation of A＋ are still limited at present. Herein, we investigate the deprotonation behavior of A＋. by time-resolved laser flash photolysis. The deprotonation product of A（N6-H）＇ is observed and the deprotonation rate constant, （2.0±0.1）×10 7 s-1, is obtained at room temperature. Further, the deprotonation rate con- stants of A＋. are measured at temperatures varying from 280 K to 300 K, from which the activation energy for the N6-H deprotonation is determined to be （17.1±1.0） kJ/mol by Arrhenius equation. In addition, by incorporating the aqueous solvent effect, we perform density functional theory calculations for A＋ deprotonation in free base and in duplex DNA. Together with experimental results, the deprotonation mechanisms of A＋ in free base and in duplex DNA are revealed, which are of fundamental importance for understanding the oxidative DNA damage and designing DNA-based electrochemical devices.

Model-based optical metrology and visualization of 3-D complex objects

This letter addresses several key issues in the process of model-based optical metrology, including three dimensional (3D) sensing, calibration, registration and fusion of range images, geometric representation, and visualization of reconstructed 3D model by taking into account the shape measurement of 3D complex structures,and some experimental results are presented.

Metabonomic study of rats exposed to cigarette sidestream smoke

A metabonomic approach was undertaken in order to detect urinary endogenous and exogenous metabolites and to evaluate the effects of passive exposure to cigarette sidestream smoke on rats. Urinary samples from three groups of rats were determined including control rats, rats treated with blended cigarettes(nonmenthol cigarettes) and rats treated with menthol cigarettes. The total urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol(NNAL), total 1-hydroxypyrene(1-HOP) and 3-hydroxybenzo[a] pyrene(3-HOBaP) were determined for assessing exposure to cigarette sidestream smoke toxins. Urinary endogenous metabolites in the three groups of rats were also analyzed and the data were processed by chemometrics. Eleven endogenous metabolites were found and identified. Their relative levels were compared among the three groups. The results show that cigarette sidestream smoke has complex effect on rats. Blended cigarette group makes difference to menthol cigarette group in the rats' urinary metabolic changes. Menthol adding to cigarettes has positive and negative effects on rats, respectively. The urinary metabolic profiling of menthol cigarette group is closer to that of control group.

我国MARC研究文献的发展趋势与预测

利用《中文科技期刊全文数据库》(图书情报专辑)作为数据分析源,采用一元线性回归分析法研究我国MARC文献资源的发展规律和研究热点,指出我国MARC研究文献从1990-1994年为萌芽阶段,1995-1999年逐渐形成研究领域,2000-2004年进入研究高峰,未来5年仍将呈现持续增长趋势。

21世纪的情报学研究趋势(一)

将21世纪的情报学研究归纳为12大趋势(数学计量化、心理学化、社会学化、传播学化、经济学化、史学及未来学化、技术科学化、生态环境化、人文伦理化、政策法规化、知识化、学体化),并全面、系统地对其——进行阐述。

Shifts in chemical and microbiological properties belowground of invader Ageratina adenophora along an altitudinal gradient

Tropical mountain ecosystems are usually colonized by numerous invasive plant species and represent an ideal‘natural laboratory’to study the effects of altitude on plant invasion.The aim of this study was to investigate the soil chemical and microbiological properties along an altitudinal gradient on a mountain colonized by the invader Ageratina adenophora.Rhizosphere soil of A.adenophora was collected over an altitudinal gradient(1400–2400 m)in Ailao Shan,China.We determined soil organic carbon(C),nutrient contents,enzyme activities,bacterial community composition as well as C and nitrogen(N)contents of the plant roots.Ecoenzymatic stoichiometric indices were calculated to estimate the relative C,N or P limitations of the microbial community.There was a significant effect of altitude on soil organic C in the rhizosphere,and a turning point in these measured variables was detected at an altitude of 2000 m.At low elevations,the rapid growth of invasive plants depleted the deficient phosphorus(P)in tropical soils,leading to microbial P limitation;at high elevations,microbes invested more energy to obtain C from resistant litter,leading to microbial C limitation.Bacterial beta diversity and soil pH contributed most to the altitudinal differences in ecoenzymatic stoichiometry,and Proteobacteria and Acidobacteria were the dominant bacterial phyla that determined the nutrient uptake status of microorganisms.These results demonstrate how microbial nutrient acquisition belowground of A.adenophora along an altitudinal gradient,which could contribute to further knowledge about the effects of altitude on biological invasion.