杨柳科植物的分类与分布

杨柳科包含２个亚科、５个属、约５００种；杨亚科由杨属和胡杨属组成，柳亚科由原柳属、钻天柳属和柳属组成；该科广泛自然分布天大约从北纬８２度至南纬５２度的非洲、欧洲、亚洲、南美洲和北美洲。杨属约５０种，分布于欧洲、亚洲、北美洲和非洲北缘；胡杨属约３种，间断分布于热带非洲、古地中海地区和墨西哥；原柳属约５０种，广泛分布于非洲、欧洲、亚洲、南美洲和北美洲；钻天柳属约４种，局限分布于鄂霍次克海和日本海四周地     

A review on starch changes in tobacco leaves during flue-curing

This article discusses a range of studies on starch changes in tobacco leaves during flue-curing. Important effects resulting from using different flue-curing equipment and techniques on starch content are presented. It concludes that future researches should be focused on the structure and physico-chemical properties of tobacco starch during the curing process.     

北京低山地区油松人工林立地指数表的编制及应用

使用252块北京市低山地区油松人工林标准地资料,统计分析各标准地优势木平均树高与年龄的关系,以双曲线式拟合树高生长导向曲线,编制出适用于该地区的油松人工林立地指数表;经X2检验、落点检验和树高生长量检验后证明所编表合格;使用该表对252块标准地进行立地质量评价,结果表明,63%的标准地立地质量处在中等水平;油松最适宜生长的立地条件为阴坡厚土.     

石汉3A韭菜雄性不育系的选育与利用

韭菜为异花授粉作物，但花器小，人工去雄授粉用工量大，一代杂种制种困难，为解决这个问题，笔者从１９８６年开始进行了韭菜雄性不育系的选育工作。１石汉３Ａ雄性不育系选育经过１．１不育株的发现１９８６年秋在菜农石富家汉中冬韭采种田内发现了花药无花粉、雌蕊正常...     

肠球菌在家蚕消化道中的分布

用ＡＰＩ２０ ＳＴＲＥＰ（Ｖ５０） 系统对从健康家蚕消化道来源的８９ 株肠球菌菌株进行数值分类学研究的结果表明：在分离菌株中分布着Ｅｎｔ．ｃａｓｓｅｌｉｆｌａｖｕｓ、Ｅｎｔ．ｆａｅｃａｌｉｓ、Ｅｎｔ．ａｖｉｕｍ 、Ｅｎｔ．ｄｕｒａｎｓ 和Ｅｎｔ．ｇａｌｌｉ ｎａｒｕｍ 等菌种，其分布频率分别为３２６ ％ 、２５９％ 、１５７ ％ 、３４ ％ 和２２ ％ 。其余１８ 个菌株未能被该系统所分类。Ｅｎｔ．ｃａｓｓｅｌｉｆｌａｖｕｓ 和Ｅｎｔ．ｆａｅｃａｌｉｓ 是家蚕消化道内的主要肠球菌菌丛。Ｅｎｔ．ｃａｓｓｅｌｉｆｌａｖｕｓ 在５ 龄初和末的分布频率较高，Ｅｎｔ．ｆａｅｃａｌｉｓ 在５ 龄第４ 和第５ 天的分布频率较高。     

它山之石——且看一个饲料巨头的成功转型

历经近40个月的不懈努力,荷兰泰高由一家多元化的食品、动物营养公司转变成为动物营养和鱼用饲料公司。这期间,公司主动退出了多个行业,剥离出售资产达12亿欧元,裁员30%。转型后公司主营业务更加突出,新兴市场得到进一步开拓,公司现金流充裕,股东利益得到最大体现。泰高2007年所取得的骄人业绩表明,始于2004年秋的战略调整取得了巨大成功。回顾泰高这次战略决策和成功转型的历程,我们或许能够得到一些有益的启示。     

Single Intravascular and Oral Dose Pharmacokinetics of Mebendazole in Blunt Snout Bream,Megalobrama amblycephala

Mebendazole (MBZ) is a broad‐spectrum benzimidazole methylcarbamate anthelmintic used widely in animal husbandry and aquaculture. However, there is no information available on the pharmacokinetic behavior of MBZ in blunt snout bream, Megalobrama amblycephala. In this study, pharmacokinetic parameters of MBZ were estimated in blunt snout bream after intravascular (3 mg/kg body weight [BW]) and oral (20 mg/kg BW) administration. The analyses of plasma samples were performed using ultra performance liquid chromatography with ultraviolet detector. After intravascular administration, plasma concentration–time curves were best described by a two‐compartment open model. The distribution half‐life (t_1/2α), elimination half‐life (t_1/2β), and area under the concentration–time curve (AUC) of blunt snout bream were 0.1 h, 27.9 h, and 56666.0 h.µg/L, respectively. After oral administration, a one‐compartment open model with first‐order absorption best fit the plasma data. The absorption half‐life (t_1/2Ka), elimination half‐life (t_1/2Ke), peak concentration (C_max), time‐to‐peak concentration (T_max), and AUC of blunt snout bream were estimated to be 1.9 h, 34.6 h, 918.1 µg/L, 8.4 h, and 54201.4 h.µg/L, respectively. The oral bioavailability (F) was 14.3 %. The pharmacokinetics of MBZ in blunt snout bream displayed low bioavailability, relatively rapid absorption, and relatively rapid elimination.     

Expression and Biochemical Characterization of a Novel Marine Chitosanase from Streptomyces niveus Suitable for Preparation of Chitobiose

It is known that bioactivities of chitooligosaccharide (COS) are closely related to the degree of polymerization (DP); therefore, it is essential to prepare COS with controllable DP, such as chitobiose showing high antioxidant and antihyperlipidemia activities. In this study, BLAST, sequence alignment and phylogenetic analysis of characterized glycoside hydrolase (GH) 46 endo-chitosanases revealed that a chitosanase Sn1-CSN from Streptomyces niveus was different from others. Sn1-CSN was overexpressed in E. coli, purified and characterized in detail. It showed the highest activity at pH 6.0 and exhibited superior stability between pH 4.0 and pH 11.0. Sn1-CSN displayed the highest activity at 50 °C and was fairly stable at ≤45 °C. Its apparent kinetic parameters against chitosan (DDA: degree of deacetylation, >94%) were determined, with K_m and k_cat values of 1.8 mg/mL and 88.3 s⁻¹, respectively. Cu²⁺ enhanced the activity of Sn1-CSN by 54.2%, whereas Fe³⁺ inhibited activity by 15.1%. Hydrolysis products of chitosan (DDA > 94%) by Sn1-CSN were mainly composed of chitobiose (87.3%), whereas partially acetylated chitosan with DDA 69% was mainly converted into partially acetylated COS with DP 2-13. This endo-chitosanase has great potential to be used for the preparation of chitobiose and partially acetylated COS with different DPs.     

爱尔兰、挪威奶业考察报告

应国际牲畜信息系统成员国会议组委会邀请,中国奶业协会理事长刘成果率团于2006年5月22日至31日赴爱尔兰科克市参加国际牲畜信息系统成员国会议;同     

柑桔高接换种及早果的全息胚关系

通过柑桔高接换种树的生物学机制研究，经统计分析认为：高接换种后，树冠形态建成（恢复）及提早结实是由于成熟枝这一全息胚经嫁接成活后其生长发育过程压缩了发育时间轴的结果，即存在着严密的全息—分形生物学原理。