怎样做好高中生物新教材中的实验(二)

（续１９９９年第３４卷第１期第３０页）［实验７］影响酶活性的实验１实验的准备工作实验需要的冰水条件，教师应根据学生人数的多少，提前几天制备相应数量的冰块。２实验成功的关键及注意事项实验成功的关键是操作顺序的正确。本实验是验证温度和ｐＨ对酶活性的影响，...     

Diseases and deaths; a summary of data from the Los Angeles County General Hospital, 1918 to 1948

Classification of the 2,557,035 diagnoses made in 1,168,139 different patients at the Los Angeles County General Hospital in the period 1918-48 has been compiled according to the new International List of Causes of Diseases and Death. Similar tabulation of the 377,776 diagnoses made in the 112,409 patients who died while in the hospital reflects the fatality rates associated with these diagnoses. Striking differences are shown in the incidence and fatality rates in the various conditions and great changes have occurred in both during this time. Defects and sources of error in these data are recognized, but they offer a wealth of valuable material for further study and interpretation.     

树qu免疫细胞体外感染Ⅰ型人免疫缺陷病毒的实验研究

至今可以感染Ⅰ型人免疫缺陷病毒(HIV-1)的动物只有黑猩猩和长臂猿，这严重阻碍了HIV-1的疫苗研究和治疗研究。因此，寻找新的可以感染HIV-1的动物模型成为十分迫切的课题。已知树qu对许多重要的医学病毒易感，为了探讨树qu是否可以感染HIV-1，利用不同辅助受体的5种HIV-1病毒株，体外感染云南野生成年树qu的淋巴细胞和单核/巨噬细胞；同时还用这些病毒感染人外周血淋巴细胞或单核细胞。然后用RT-PCR、PCR和流式细胞术分别进行检测。用RT-PCR方法未检测到感染上清中有病毒粒子的存在，用PCR法未能发现树qu的这些免疫细胞中有前病毒DNA，用流式细胞术也未能在这些感染HIV-1的树qu细胞的表面检测到特异抗原；而感染HIV-1的人免疫细胞均为阳性结果。实验结果表明树qu的这些免疫细胞在体外未能感染上HIV-1，可能的原因是树qu的这些免疫细胞的HIV-1受体(CD4)和辅助受体(CCR5或CXCR4)与人的免疫细胞差别较大。