Pharmacokinetics of florfenicol after intravenous and intramuscular administration in New Zealand White rabbits

The pharmacokinetic disposition and bioavailability of florfenicol (FF) were determined after single intravenous (i.v.) and intramuscular (i.m.) administrations of 25 mg/kg b.w. to ten healthy New Zealand White rabbits. Plasma FF concentrations were determined by high-performance liquid chromatography (HPLC). The plasma pharmacokinetic values for FF were best described by a one-compartment open model. The elimination half-life (t_1/2β) was different (p < 0.05) however, the area under curve (AUC) was similar (p > 0.05) after i.v. and i.m. administrations. FF was rapidly eliminated (t_1/2β 1.49 ± 0.23 h), slowly absorbed and high (F, 88.75 ± 0.22%) after i.m. injection. In addition, FF was widely distributed to the body tissues (V_ss 0.98 ± 0.05 L/kg) after i.v. injection. In this study the time that plasma concentration exceeded the concentration of 2 μg/mL was approximately 6 h. For bacteria with MIC of 2 μg/mL, frequent administration at this dose would be needed to maintain the concentration above the MIC. However, it is possible that rabbit pathogens may have MIC values less than 2 μg/mL which would allow for less frequent administration. Further studies are necessary to identify the range of MIC values for rabbit pathogens and to identify the most appropriate PK-PD parameter needed to predict an effective dose.     

Plasma endothelin-1 immunoreactivity in normal dogs and dogs with acquired heart disease

We sought to measure plasma endothelin-1 (ET-1) concentrations in normal dogs and to compare them with those measured in dogs with acquired heart disease with or without pulmonary edema. A sandwich enzyme-linked immunosorbent assay kit was validated and used to measure ET-1 immunoreactivity in plasma samples obtained from 32 normal dogs and 46 dogs with either dilated cardiomyopathy (DCM, n = 27) or degenerative valvular disease (CDVD, n = 19) with (n = 30) or without (n = 16) overt congestive heart failure (CHF). Plasma ET-1 concentrations (geometric mean, 95% confidence interval of geometric mean) were 1.17 (1.04-1.32) fmol/mL in the 32 normal control dogs, 1.25 (0.981-1.60) fmol/mL in 16 dogs with DCM (n = 9) or CDVD (n = 7) without CHF, and 2.51 (2.10-3.01) fmol/mL in 30 dogs with DCM (n = 18) and CDVD (n = 12) with CHE Plasma immunoreactivity of ET-1 was significantly higher in dogs with CHF in comparison with normal dogs (P < .001) and dogs with heart disease without CHF (P < .001). No significant difference was found between normal dogs and dogs with heart disease but without CHF (P > .05). Significant correlations were between plasma ET-I concentrations and left atrial:aortic ratio (P < .0001, r2 = .39), left ventricular internal dimension at end-diastole indexed to aortic diameter (P < .0001, r2 = .30) or body surface area (BSA) (P = .0071, r2 = .10), and left ventricular internal dimension at end-systole indexed to aortic diameter (P = .0003, r- = .17) or BSA (P = .0008, r2 = .15).     

安岳柠檬及土壤中元素含量的初步测定与评价

采用原子吸收光谱法初步测定了安岳部分地区柠檬及土壤中Cu、Mn、Zn、Fe、Ca、Mg的含量,土壤中Pb、Cd含量。结果表明,试验样品中营养元素丰富。各元素含量总的变化趋势是:果核果皮果肉,并且具有一定的分布特性,Ca、Mg、Fe含量相对较高;土壤中有害元素Pb、Cd远低于我国无公害水果种植地土壤的最低限量;柠檬与土壤中金属元素存在相关性,试验品中各种金属元素变异系数大,说明环境条件和种植技术影响着元素在柠檬中的积累。试验结果为提高和保持土壤及果品的优良特性,优化种植管理提供了基础信息。     

不同预处理方法对黑大豆中微量元素含量测定的影响

采用湿法消解和微波消解2种前处理方法,用原子吸收光谱法快速测定黑大豆中Ca、Mg、Cu、Zn含量.结果表明:微波消解和湿法消解样品中Ca、Mg、Zn、Cu的含量分别为220 85、1834 03、27 09、8.77 μg·g-1和221.08、1914 58、17.88、11.08 μg·g-1,说明黑大豆中含有丰富的Ca、Mg元素,其次是Zn和Cu,样品的预处理方法不同,Ca、Cu、Zn的结果差别不大,Mg元素测定结果差别较大.微波和湿法消解后Ca、Cu、Zn加标回收率分别为83.76％、92.86％、96.54％和89.65％、87.50％、88.63％,各元素的精密度为0 2％～1.4％.Mg元素由于基体干扰,2种方法回收结果均不理想.综合考虑,微波消解预处理后元素的回收率较高,测定结果更为准确.     

不同施肥管理方式下潮褐土区夏玉米N2O排放量研究

在田间试验条件下,分析了不同施肥管理方式对潮褐土区夏玉米农田N2O排放量的影响。试验结果表明,随施氮量增加,N2O排放量呈递增趋势,二者呈显著正相关;DMPP的施用对减少N2O排放较其它处理有明显效果。实验同时证明田间土壤湿度和温度变化对N2O的排放影响较大。     

“果树栽培学”理论教学改革实践与探索

＂果树栽培学＂是农业院校园艺专业一门重要的专业课程,其理论教学应结合生产实际,优化课程内容,创新教学手段,多元化设计教学方法,改革教学效果评价体系,提升教师教学水平以及加强实践教学基地建设,以培养宽口径、厚基础的专业技术人才。     

原子荧光法测定茶叶中的微量硒

采用氢化物发生—原子荧光光谱法测定了6种茶叶中的微量硒,即先用4体积HNO3+1体积HClO4混合酸消化茶叶样品,而后测定消化液中的硒含量。硒浓度在0～40.00μg/L范围内与荧光强度呈线性关系,线性方程为If=30.9649C+97.714,线性相关系数r=0.9998。样品6次测定结果的相对标准偏差为1.8%,加标回收率为98.4%～102.5%。     

农村废弃物排放及资源化现状分析

农村废弃物是我国农村环境的主要污染源,但同时也蕴藏着丰富的资源。针对新农村建设过程中农村废弃物排放量大且数量不清、利用率不高等现状,对中部地区农村的代表——董家湾村进行实地调研,从农作物秸秆、人畜粪便和生活垃圾3个方面估算该村废弃物产生量,并对其资源化潜力和方式进行了初探。分析表明,目前中部地区农村废弃物利用率较低,但资源化潜力巨大。     

新疆天山北坡经济带社会经济发展现状综合分析

利用功效系数法时新疆天山北坡经济带社会经济发展现状进行了综合评价,结果表明：天山北坡经济带8市3县社会经济发展水平呈明显的空间梯度性分布。结合分析结果,探讨了功效系数法在社会经济发展综合评价中的应用.     

农地征用补偿方法和标准的合理化探讨

探讨了在农地征用过程中,收益还原法和市场比较法在确定补偿金额方面存在的问题。介绍了中国农地的价值构成,并以中国重庆市为例,对现行农地征用补偿标准的不合理之处进行了分析。研究表明：以收益还原法确定补偿金额的方法是正确的,但是现行的补偿标准有待进一步完善。