首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2篇
  免费   0篇
冶金工业   2篇
  2004年   1篇
  1997年   1篇
排序方式: 共有2条查询结果,搜索用时 125 毫秒
1
1.
This study evaluated the extent to which first-grade class size predicted child outcomes and observed classroom processes for 651 children (in separate classrooms). Analyses examined observed child-adult ratios and teacher-reported class sizes. Smaller classrooms showed higher quality instructional and emotional support, although children were somewhat less likely to be engaged. Teachers in smaller classes rated typical children in those classes as more socially skilled and as showing less externalizing behavior and reported more closeness toward them. Children in smaller classes performed better on literacy skills. Larger classrooms showed more group activities directed by the teacher, teachers and children interacted more often, and children were more often engaged. Lower class sizes were not of more benefit (or harm) as a function of the child's family income. First-grade class size in the range typical of present-day classrooms in the United States predicts classroom social and instructional processes as well as relative changes in social and literacy outcomes from kindergarten to first grade. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
2.
To clarify the role of urokinase plasminogen activator (uPA) in the mechanisms of regulating sperm motility and the ability of fertilizing, we investigated the quantities and activities of uPA in human seminal plasma and on the membrane of spermatozoa. Semens were harvested from 22 infertile patients with asthenospermia and 20 healthy fertile men according to WHO standards. To quantify the membrane-bound uPA in the samples, polyclonal antibodies against human urokinase were employed by means of a sandwich ELISA. The uPA activities in seminal plasma and on the surface of spermatozoa were determined using A-garose-Fibrine-Plate method and the experiment of immunological identification with polyclonal antibodies against urokinase. In lysates of spermatozoa, significantly lower levels of uPA (23.1 +/- 7.35 mu/10(6) cells) and uPA activity (5.13 +/- 3.85 mu/10(6) cells) were found in patient group as compared to healthy fertile men exhibiting normospermia (29.89 +/- 9.40 mu/10(6) cells and 10.17 +/- 6.18 mu/10(6) cells). In seminal plasma, uPA activity in patient group (2134 +/- 1581.3 IU/L) was also found significantly lower than that of normal group (3365 +/- 1859.5 IU/L). Positive correlations were observed between sperm motility and uPA quantities (r = 0.48, P < 0.005), as well as with uPA activities (r = 0.45, P < 0.005). Thus, it is inferred that membrane associated uPA on human spermatozoa may be related directly to sperm motility and fertility.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号