肉制品中亚硝酸盐含量的检测     

庞向红  梁淑珍  魏云汉 《河北北方学院学报(自然科学版)》1996,(2)

对市售肉制品中的6个品种、60份样品亚硝酸盐含量进行了测定,结果表明抽查的国营肉联厂生产的肉制品中亚硝酸盐含量符合国家食品卫生标准,而个体户的产品有超标现象。  相似文献   

兰州百合微繁的研究     

徐凌飞  庞勇  周连霞  王贵章  王婧  叶红霞 《勤云标准版测试》2005,(5)

以兰州百合的鳞茎增殖为基础,进行了离体微繁研究。鳞茎增殖的适宜激素组合为0.9mg/LBA 0.1~0.2mg/LNAA。培养基中总离子浓度和氮浓度过高或过低都会影响兰州百合增殖,3种基本培养基N6、MS、和1/2MS以N6增殖效果最好。适当提高糖浓度对鳞茎增殖有促进作用,在各处理中以蔗糖浓度为40g/L增殖倍数高。兰州百合的适宜生根培养基为1/2MS IBA0.1mg/L,生根率达100%,生根苗移栽成活率达90%。  相似文献   

山羊骨髓间充质干细胞生物学性能鉴定及诱导分化为心肌细胞的研究     

庞全海张慧茹  华进联马勇江 窦忠英 《勤云标准版测试》2005,(5)

 研究了关中奶山羊骨髓间充质干细胞的分离、培养和生物学特性，并在体外诱导分化为心肌细胞表型。结果表明，山羊MSCs具有很好增殖能力；能够耐受反复冷冻和解冻；表达细胞表面标志CD44、CD105、CD166，弱表达CD34、CD106，而不表达CD14、CD45。该类细胞用5-氮胞苷诱导分化后，能够表达心肌α-actin，并呈PAS染色阳性。  相似文献   

不同温度条件下小菜蛾实验种群的研究   总被引：12，自引：0，他引：12  

但建国  梁广文 《华南农业大学学报》1995,16(3):11-16

该文研究了１１种恒温（８－３５℃）对小菜蛾实验种群的存活，繁殖与种群增长的影响。结果表明，小菜蛾世代存活率与温度之间呈抛物线相关，以２５℃时的存活率最高。在３５℃以上的高温下，卵不能孵化，肾对８℃及以下的低温特别敏感，雌虫产卵期随温度的升高而缩短。８－３０℃下雌虫的繁殖动态下可用类似于统计学的Ｇａｍｍａ分布函数来拟合。雌虫繁殖力和种趋势指数与温度之间均呈抛物线相关，也均在２３℃时达到最大值，内禀增  相似文献   

Impaired immunoproteasome assembly and immune responses in PA28-/- mice     

Preckel T  Fung-Leung WP  Cai Z  Vitiello A  Salter-Cid L  Winqvist O  Wolfe TG  Von Herrath M  Angulo A  Ghazal P  Lee JD  Fourie AM  Wu Y  Pang J  Ngo K  Peterson PA  Früh K  Yang Y 《Science (New York, N.Y.)》1999,286(5447):2162-2165

In vitro PA28 binds and activates proteasomes. It is shown here that mice with a disrupted PA28b gene lack PA28a and PA28b polypeptides, demonstrating that PA28 functions as a hetero-oligomer in vivo. Processing of antigenic epitopes derived from exogenous or endogenous antigens is altered in PA28-/- mice. Cytotoxic T lymphocyte responses are impaired, and assembly of immunoproteasomes is greatly inhibited in mice lacking PA28. These results show that PA28 is necessary for immunoproteasome assembly and is required for efficient antigen processing, thus demonstrating the importance of PA28-mediated proteasome function in immune responses.  相似文献   

广西普通野生稻资源遗传多样性初探--Ⅱ普通野生稻遗传多样性保护技术探讨   总被引：5，自引：0，他引：5  

陈成斌  庞汉华 《广西农学报》2002,(6):20-25

本文论述普通野生稻遗传多样性的鉴定评价与保护技术,提出保护体系及对策原则,为确保普通野生稻资源的长期安全保存提供有效措施.  相似文献   

Giant Friedel Oscillations on the Beryllium(0001) Surface     

PT Sprunger  L Petersen  EW Plummer  E Laegsgaard  F Besenbacher 《Science (New York, N.Y.)》1997,275(5307):1764-1767

Large-amplitude electron density oscillations were observed on a Be(0001) surface by means of variable-temperature scanning tunneling microscopy. Fourier transforms of the images showed a ring of radius 2kF, where kF is the Fermi wave vector of the Be(0001) surface state. This wavelength was expected from Friedel oscillations caused by electronic screening of surface defects, but the amplitude of the waves for energies near the Fermi energy was anomalously large and inconsistent with the Friedel concept of screening. The enhanced amplitude of the waves must be a many-body effect, either in the electron gas (possibly an incipient charge density wave) or in the response of the lattice (electron-phonon coupling).  相似文献   

陕西关中地区蓖麻新品种高产栽培技术     

庞宁  姚学慧  杨世琦  孙兆敏 《陕西农业科学》2005,(4):135-136

1关中地区蓖麻生产概况 蓖麻(Castor-oil plant)属大戟科经济作物，掌状裂叶，盾状着生，圆锥花序顶生，雌花位于上部，雄花位于下部，雄蕊很多，蒴果具有软刺，种子有种阜，胚乳丰富。蓖麻原产于非洲东部，其栽培历史悠久，为世界十大油料作物之一。世界蓖麻年种植面积在330万hm^2，蓖麻籽年产量120万t左右，主要生产国有印度、中国和巴西。我国常年种植面积约27万hm^2，  相似文献   

The composition of phobos: evidence for carbonaceous chondrite surface from spectral analysis     

Pang KD  Pollack JB  Veverka J  Lane AL  Ajello JM 《Science (New York, N.Y.)》1978,199(4324):64-66

A reflectance spectrum of Phobos (from 200 to 1100 nanometers) has been compiled from the Mariner 9 ultraviolet spectrometer, Viking lander imaging, and ground-based photometric data. The reflectance of the martian satellite is approximately constant at 5 percent from 1100 to 400 nanometers but drops sharply below 400 nanometers, reaching a value of 1 percent at 200 nanometers. The spectral albedo of Phobos bears a striking resemblance to that of asteroids (1) Ceres and (2) Pallas. Comparison of the reflectance spectra of asteroids with those of meteorites has shown that the spectral signature of Ceres is indicative of a carbonaceous chondritic composition. A physical explanation of how the compositional information is imposed on the reflectance spectrum is given. On the basis of a good match between the reflectance spectra of Phobos and Ceres and the extensive research that has been done to infer the composition of Ceres, it seems reasonable to believe that the surface composition of Phobos is similar to that of carbonaceous chondrites. This suggestion is consistent with the recently determined low density of Mars's inner satellite. Our result and recent Viking noble gas measurements suggest different modes of origin for Mars and Phobos.  相似文献   

水稻黄矮病毒结构蛋白的分离及其小鼠腹水抗体的制备     

秦文胜  高东明  陈声祥  方荣祥  庞震 《浙江大学学报(农业与生命科学版)》1993,(4)

从人工接种感染黄矮病毒(Rice Yellow Stunt Virus,RYSV)的水稻茎杆中提取得到了部分纯化的RYSV制品,病毒制品经Tricine-SDS-PAGE得到分子量分别为84 kD,60 kD,31 kD和29.5 kD的4条主要蛋白带和分子量为170kD和43kD的两条次要蛋白带。根据弹状病毒结构蛋白命名法,按分子量大小依次命名为L,G,N,NS,M_1和M_2蛋白。从电泳凝胶上切下G和N蛋白带,制成抗原免疫BALB/C小鼠;制得G和N蛋白小鼠腹水抗体。经Dot-blot试验测得N蛋白抗体效价为1:1000,G蛋白抗体效价为1:400。  相似文献