牛心朴杀鼠活性初报

通过试管和圆形滤纸预试法初步确定了牛心朴(Cynanchum komarovii)乙醇提取液中含有生物碱、酚类物质、鞣质、皂甙、黄酮、甾体(或萜类)、糖、多糖(或甙类)和强心甙等成分。杀鼠活性的测定结果表明,乙醇提取液在饵料中的含量为15％时,小白鼠的平均食毒量为39．04g／kg,对小白鼠的毒杀率为100％;饵料中牛心朴粉的含量为15％和10％时,小白鼠的平均食毒量分别为26．61g／kg和29．27g／kg,对小白鼠的毒杀率分别为100％和90％;提取液中的化学成分基本包括了牛心朴杀鼠的活性成分,且适口性较原粉为好。     

Somatostatin: occurrence in urinary bladder epithelium and renal tubules of the toad, Bufo marinus

Immunohistochemical techniques were used to detect immunoreactive somatostatin-like material in toad urinary bladder epithelium and in kidney distal tubules and collecting ducts. This material has immunological and chromatographic properties identical to those of synthetic cyclic somatostatin. The occurrence of somatostatin-like material in antidiuretic hormone-sensitive portions of the renal urinary system suggests a local regulatory or paracrine role for somatostatin.     

Thermally Switchable Periodicities and Diffraction from Mesoscopically Ordered Materials

Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(N-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and ultraviolet light weakly, whereas arrays of compact shrunken particles diffract efficiently. A tunable diffracting array was also created by embedding a CCA of polystyrene spheres within a PNIPAM hydrogel that swells and contracts with temperature; thus the array lattice constant varies with temperature, and the diffracted wavelength was thermally tunable across the entire visible spectrum. These materials may find applications in many areas of optics and materials science.     

超级稻育成者获世界粮食奖--杂种优势遗传基础的发现叩开了利用杂交稻的大门

很少有一个人被认为他养活了6 000万人,但袁隆平却从来就不是一个普通的人.     

碱性盐胁迫对燕麦矿质离子吸收与分配的影响

为探讨燕麦耐碱性与矿质离子的关系,通过盆栽试验,将碱性盐Na2CO3、NaHCO3按摩尔比1∶1混合设置不同浓度(0、50和100mmol·L-1)胁迫处理,分析燕麦耐碱性品种vao-9和碱敏感性品种白燕5号根、茎、叶对Na+、K+、Ca2+、Mg2+、Fe2+、Cu2+、Zn2+的吸收及分配规律。结果表明,碱性盐胁迫下2个品种根、茎、叶中Na+含量增加,K+、Cu2+含量下降;Ca2+、Mg2+含量在根中增加,在茎、叶中下降,Fe2+、Zn2+含量在不同胁迫程度下和不同器官中变化不同。与白燕5号相比,vao-9吸收的Na+总量较低,K+、Ca2+、Cu2+总量较高,Mg2+、Fe2+、Zn2+总量变化不大。在胁迫浓度达到100mmol·L-1时,vao-9茎中截留Na+,叶片中较K+、Ca2+、Mg2+、Fe2+、Cu2+和Zn2+分配较多,而白燕5号叶片中积累Na+较多,茎中积累K+较多,根中积累Ca2+、Mg2+、Fe2+、Cu2+、Zn2+较多,从而使碱性盐胁迫下vao-9较白燕5号叶片中保持的Na+/K+、Na+/Ca2+和Na+/Mg2+低。可见,在高浓度碱性盐胁迫下vao-9茎中区域化Na+,选择吸收K+、Ca2+、Cu2+,并在叶片中分配较多的矿质离子来保持燕麦体内离子平衡,以适应盐碱胁迫。     

豆米轮作对春玉米土壤固氮细菌群落结构及多样性的影响

为探明大豆-玉米轮作对土壤固氮细菌的影响，以玉米连作为对照(MMM)，以nif-H基因为指示，采用高通量测序技术，分析大豆-玉米2年轮作周期(MSM)和大豆-玉米-玉米3年轮作周期(SMM)下土壤固氮细菌群落结构及多样性。结果表明：大豆-玉米轮作下0～20、20～40 cm土层土壤有机质、全氮、碱解氮、铵态氮和硝态氮均显著增加。固氮细菌的Chao1指数和ACE指数在0～20、20～40 cm土层均为轮作高于对照，轮作下MSM显著高于SMM;Shannon指数和Simpson指数在0～20 cm土层轮作显著高于MMM;20～40 cm土层MSM显著高于MMM。在门水平上，MSM和SMM的0～20、20～40 cm土层变形菌门的相对丰度均高于MMM。在属水平上，2个轮作类型0～20 cm土层的慢生根瘤菌属、弗兰克氏菌属和纤毛菌属相对丰度显著较高；20～40 cm土层慢生根瘤菌属、伪食酸菌属、地杆菌属和固氮弧菌属相对丰度显著较高；MSM 0～20、20～40 cm土层慢生根瘤菌属、甲基孢囊菌属和固氮弧菌属较SMM均提高。方差分析表明，固氮细菌丰度指数（Chao1和ACE指数）与有机质、碱解氮...