东灵山3种落叶阔叶林的碳氮元素含量及比率

研究暖温带东灵山3种落叶阔叶林的碳氮元素含量和C:N比率的化学计量特征.结果表明:1)土壤和乔木层的碳元素含量表现为白桦林＞辽东栎+棘皮桦混交林＞辽东栎林,氮元素含量在辽东栎+棘皮桦混交林中最高,为另外2种林型含量的2倍,而3种林型的土壤微生物碳氮元素含量之间没有显著差异;2)不同林型土壤微生物的C:N比率变动很小,并且不受土壤碳氮含量变化的影响;3)3种林型土壤和土壤微生物的C:N比率变化不大,表现出受限制的化学计量学特征.     

New Benzoxazine Secondary Metabolites from an Arctic Actinomycete

Two new secondary metabolites, arcticoside (1) and C-1027 chromophore-V (2), were isolated along with C-1027 chromophore-III and fijiolides A and B (3–5) from a culture of an Arctic marine actinomycete Streptomyces strain. The chemical structures of 1 and 2 were elucidated through NMR, mass, UV, and IR spectroscopy. The hexose moieties in 1 were determined to be d-glucose from a combination of acid hydrolysis, derivatization, and gas chromatographic analyses. Arcticoside (1) and C-1027 chromophore-V (2), which have a benzoxazine ring, inhibited Candida albicans isocitrate lyase. Chromophore-V (2) exhibited significant cytotoxicity against breast carcinoma MDA-MB231 cells and colorectal carcinoma cells (line HCT-116), with IC₅₀ values of 0.9 and 2.7 μM, respectively.     

2ZT—2型甜菜移栽机栽植系统的参数分析

对2ZT-2型甜菜移栽机栽植器进行了运动分析与仿真研究.应用ADAMS建立了移栽机栽植器的模型,通过运动学分析对2ZT-2型甜菜移栽机的相关设计参数进行了优化,得出了影响因素变化时对纸筒苗栽植状态的影响规律,并得出了该甜菜移栽机栽植器合理的特征参数值和鸭嘴开启运动规律.     

Antimicrobial peptides and bacteriocins: alternatives to traditional antibiotics

Antimicrobial peptides (AMPs) are ubiquitous, gene-encoded natural antibiotics that have gained recent attention in the search for new antimicrobials to combat infectious disease. In multicellular organisms, AMPs, such as defensins and cathelicidins, provide a coordinated protective response against infection and are a principal component of innate immunity in vertebrates. In unicellular organisms, AMPs, such as bacteriocins, function to suppress competitor species. Because many AMPs kill bacteria by disruption of membrane integrity and are thus thought to be less likely to induce resistance, AMPs are being extensively evaluated as novel antimicrobial drugs. This review summarizes and discusses the antibiotic properties of AMPs highlighting their potential as alternatives to conventional antibiotics.     

发挥忧信息在农业决策中的作用

阐述了正确评价忧信息在农业决策中的地位和作用,必须坚持的原则,及从提高信息工作者素质入手,搞好忧信息工作的途径和方法.     

大豆新品种豫豆18号的选育及高产稳产性分析

豫豆１８号丰产、稳产、早熟、优质（蛋白质含量４３．２６％）,适应性强。河南省２年区试比对照豫豆２号增产１９．０％,３年国家区试比对照中豆１９号增产１１．０８％,两年河南省生产试验比对照中豆１９号平均增产１１．２％,综合评比居供试材料首位。     

Authentication of Rice by Three-Sided Image Analysis of Kernels Using Two Mirrors

The authentication of rice by imaging three sides (top, side, and front) of a rice kernel using two mirrors was attempted. Nine image characteristics (area, aspect ratio, minimum diameter, maximum diameter, perimeter, and red, green, and blue values) for each side of a rice kernel were measured. Japonica type rices were used for the study; a total of 89 rice samples were used: 40 samples harvested in Korea, 33 in America, 5 in Australia, and 11 in China. Image data collected from 105 kernels per rice sample were used as a calibration data set to develop a model for quadratic discriminant analysis. In overall pairwise trials, on average, 85.8–94.5% correct identification of the cultivated country was obtained, depending on the number of image characteristics used for the discriminant model. For the effective discrimination of the cultivated country, 13 image characteristics were selected. As a test sample set, 20 kernels per sample were used. A model for discriminant analysis with 13 image characteristics yielded an average of 95.0 and 97.5% accuracy for calibration and test sample set, respectively.     

Effect of catheter size and injection rate of contrast agent on enhancement and image quality for triple‐phase helical computed tomography of the liver in small dogs

Rapid contrast injection is recommended for triple‐phase helical computed tomography (CT) of the liver. However, a large‐gauge catheter is needed for faster contrast injection and this is not practical for small breed dogs or cats. The purpose of this crossover group study was to evaluate applicability of a lower injection rate with a small‐gauge (G) catheter for triple‐phase hepatic CT in small dogs. Triple‐phase CT images were acquired for six beagle dogs using three protocols: an injection rate of 1.5 ml/s with a 24 G catheter, 3.0 ml/s with a 22 G catheter, and 4.5 ml/s with a 20 G catheter. Enhancement of the aorta, portal vein, and hepatic parenchyma was measured in each phase (arterial, portal, and delayed) and image quality was scored subjectively by two observers. Injection duration, time to scan delay, and time to peak enhancement were also recorded. Contrast injection duration decreased with a higher injection rate (n = 6, P ≤ 0.01), but time to peak enhancement and time to scan delay were not significantly affected by injection rates and catheter sizes. Contrast injection rate did not significantly affect aortic, portal, and hepatic enhancement. In addition, separation between each phase and quality of images was subjectively scored as good regardless of injection rate. Findings from the current study supported using an injection rate of 1.5 ml/s with a catheter size of 24 G for triple‐phase hepatic CT in small dogs (weight < 12 kg).     

Flavonol glycosides and novel iridoid glycoside from the leaves of Morinda citrifolia

One new iridoid glycoside and five known flavonol glycosides have been isolated from the leaves of Morinda citrifolia. The new iridoid exists as an epimeric mixture in solution. Complete assignments of the proton and carbon chemical shifts for the individual epimers were accomplished on the basis of high-resolution 1D and 2D NMR data. Their antioxidative activities were measured. All of these compounds showed DPPH free radical scavenging activity at the concentration of 30 microM.     

诱杀球对橘大实蝇诱捕效果的研究

为开发一种新型的橘大实蝇诱捕器,研究了不同颜色、直径的诱杀球和不同颜色的粘虫板对橘大实蝇的诱集效果。结果表明,绿色诱杀球的诱杀数量显著大于黄色和黄绿色诱杀球(P0.05);诱杀球上橘大实蝇的诱集数量,随诱杀球直径的增大而显著增加,但在直径7cm以上时,诱杀球的诱集数量增速变缓,其中以直径7cm的绿色诱杀球生产成本和诱集效果最佳;诱杀球能显著提高黄板对橘大实蝇的诱集效果(P0.05)。