十种禾草耐寒性的比较研究

通过对十种禾草半致死温度与越冬率的测定,利用最长距离聚类分析方法对其耐寒性进行了综合分析.结果表明,在北京地区耐寒性较强的禾草是草地雀麦、无芒雀麦、苇状羊茅、沙生冰草、长穗偃麦草和猫尾草,耐寒性中等的是紫羊茅、蓝茎冰草和鸭茅,耐寒性最弱的禾草为草芦.     

猪链球菌2型分离株对野生斑马鱼的致病性

以野生斑马鱼为模式动物,对6株mrp＋epf＋sly＋猪链球菌2型（SS2）分离株进行致病性比较。斑马鱼经腹腔接种不同稀释度的SS2分离株,连续观察5d,Kaplan-Meier生存曲线分析并统计半数致死量（LD50）。结果显示,6个分离株对斑马鱼的LD50在10^5cfu-10^6cfu之间,临床株与非临床株的毒力差异不显著（P〉0.05）。从攻毒后死亡的鱼腹腔和脑可分离到SS2,并伴有腹腔出血及肝、肠、脑部炎性病变。表明SS2可感染斑马鱼,为进一步研究SS2的体内感染机制及毒力因子功能等奠定了基础。     

中国结缕草属(Zoysia spp.)植物抗寒性评价

在广泛收集结缕草属(ZoysiaWild.)种质资源基础上,按照形态类型和地理分布,选取40份种质,采用电导法(EL)对其抗寒性进行初步评价。以半致死温度(LT50)为评价指标,在参试材料中除大穗结缕草和来自台湾岛海边沙地的沟叶结缕草外,其它种质都较天堂-419(对照)抗寒;在结缕草属内,抗寒性具有明显的种间差异,耐寒性依次为日本结缕草>中华结缕草>沟叶结缕草>细叶结缕草>长花中华结缕草>大穗结缕草,其中细叶类型的沟叶结缕草和细叶结缕草抗寒性变异较大;日本结缕草和中华结缕草抗寒性变异与地理分布之间没有显著关系,但分布在海边的种类和种质抗寒性明显较低;结缕草属及其中华结缕草的抗寒性与叶长、叶宽以及叶背面被毛之间均存在显著的负相关关系,但这种关系不体现在日本结缕草上。实验结果还表明,EL方法是评价结缕草属抗寒性较为可靠的方法之一。     

电机护环钢在硝酸盐溶液中应力腐蚀开裂的控制过程研究

本文在文献［１］基础上，运用金相，电化学方法研究了５０Ｍｎ１８Ｃｒ４电机护环钢依照ＱＨＪ－７９试验标准在硝酸盐介质中应力腐蚀开裂（即ＳＣＣ）的性质，结果指出，此体系中ＳＣＣ的控制过程为阳极溶解。     

Chemically and genetically immunocompromised mice are not more susceptible than immunocompetent mice to infection with Cryptosporidium muris

The prevailing paradigm is that immunosuppressed individuals are more susceptible to infection and are at higher risk of infection from Cryptosporidium oocysts if present in drinking water. To test this hypothesis, three immune conditions were examined: genetically immunocompromised T cell deficient CD-1 nude mice, B and T cell deficient Fox Chase CB-17/IcrClB SCID mice, and chemically immunosuppressed C57Bl/6 mice. Chemical immunosuppression was induced with a single subcutaneous injection of methylprednisolone acetate (MPA) at 600 mg/kg. The MPA immunosuppressed C57Bl/6 mice were characterized by a sustained decrease in circulating CD3, CD4 and CD8 T-lymphocytes of greater than 80% and a similar decrease in B-lymphocytes. A sharp rise in circulating mature segmented neutrophils followed MPA injection, dropping sharply after 10-14 days, mirroring the decrease in lymphocytes. The cessation of oocyst production after MPA was not accompanied by a radical rise in circulating CD3 or CD4 T-lymphocytes, but rather a rise in CD8 T-lymphocytes. The ID50 for the MPA immunosuppressed C57Bl/6 mice was 122 oocysts, whereas the ID50 for the C57Bl/6 immunocompetent group was 44. The genetically immunocompromised mice showed similar differences. The ID50 for CD-1 nude mice was 166 oocysts compared to 64 in CD-1 immunocompetent mice. For Fox Chase CB-17/IcrClB SCID and the immunocompetent CB-17 mice, the ID50's were 83 and 60 oocysts, respectively. These results suggest that the lack of an immune response does not increase the ability of C. muris to establish a productive infection and produce oocysts.     

西芹黄萎病防治药剂筛选和毒力测定

本文针对西芹黄萎病病原菌开展室内防治药剂筛选和药剂毒力测定。按照药剂最大推荐剂量从14种供试药剂中初筛出8种有效药剂,以进口多菌灵、菌哥、新世生、瓜果类太宝、太医最佳,对菌丝生长的抑制率达100%。8种药剂对病原菌菌丝生长的EC50依次为进口多菌灵（0.0063 mg/ml）＜太医（0.0073 mg/ml）＜活根菌灭（0.0077 mg/ml）＜枯萎灵（0.0079 mg/ml）＜瓜果类太保（0.0092 mg/ml）＜根腐宁（0.0103 mg/ml）＜新世生(0.0192 mg/ml) ＜菌哥（0.0844mg/ml）,进口多菌灵和活根菌灭对病原菌孢子萌发的EC50分别为1.50×10-4 mg/ml和1.55×10-4 mg/ml。     

Statistical tools for determining appropriate selection of regression models for analysis of environmental fate datasets

BACKGROUND: In the NAFTA regulatory community, a currently consistent methodology used to estimate dissipation times for environmental fate data is not applied. RESULTS: This work demonstrates through a case study that the inappropriate use of pseudo-first-order regression models can result in inaccurate estimates of soil degradation rates, and it proposes some statistical tools that can be used to identify an appropriate statistical model to fit a particular environmental fate dataset. Diagnostic procedures have been proposed to identify the appropriate scale, and statistical testing procedures have been proposed to select the appropriate model within that scale. CONCLUSION: Results from this work demonstrate that, unless the proposed diagnostic and statistical procedures are used, inaccurate estimates of dissipation times may result.     

用微量细胞培养ELISA测定HCLV TCID_(50)

应用猪瘟兔化弱毒制备的猪瘟兔化疫苗常因为剂量不足而引起免疫失败。究其原因主要是因为兔检(RID)合格的猪瘟兔化苗批间差异较大,质量不稳定。为此建立微量细胞培养ELISA用以测定HCLV TCID50,并获得成功,可以替代RID测毒。     

盐酸多西环素缓释注射液的安全毒性试验

报道了盐酸多西环素缓释注射液对昆明系小白鼠的急性毒性、蓄积毒性、耐受性和对靶动物的安全性试验的结果。采用改良krber法测得小白鼠LD50为304.8mg·kg-1,95%的可信限为263.0～353.2mg·kg-1;采用剂量定期递增染毒法测得对小白鼠的蓄积系数大于5.3;小白鼠对该药无耐受性(与空白对照组比较P>0.05);靶动物安全性试验中未出现不良反应。试验表明盐酸多西环素缓释注射液按临床拟用剂量使用安全。     

春丰50苦瓜的选育

以曼谷青皮、碧绿1号和钦州大肉苦瓜为育种材料,采用双父本混合花粉杂交和后代系谱选择育成优良自交系,再经配合力测定选出优良一代杂种春丰50。该品种生长势强,果实粗棒形,纵径26.3cm,横径6.45cm,皮色翠绿油亮,一般单果质量420g左右。平均每667m~2产量3 500kg。