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   4798篇
  免费   1篇
电工技术   1篇
化学工业   17篇
能源动力   3篇
轻工业   3篇
无线电   14篇
一般工业技术   4篇
冶金工业   4749篇
自动化技术   8篇
  2020年   2篇
  2018年   1篇
  2013年   1篇
  2012年   2篇
  2011年   1篇
  2010年   3篇
  2009年   2篇
  2008年   4篇
  2006年   1篇
  2005年   2篇
  2004年   5篇
  2003年   11篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   142篇
  1998年   1445篇
  1997年   855篇
  1996年   535篇
  1995年   298篇
  1994年   261篇
  1993年   289篇
  1992年   29篇
  1991年   56篇
  1990年   57篇
  1989年   61篇
  1988年   58篇
  1987年   55篇
  1986年   64篇
  1985年   45篇
  1983年   9篇
  1982年   21篇
  1981年   25篇
  1980年   26篇
  1979年   2篇
  1978年   12篇
  1977年   124篇
  1976年   277篇
  1975年   7篇
  1962年   1篇
  1955年   5篇
排序方式: 共有4799条查询结果,搜索用时 15 毫秒
51.
52.
53.
BACKGROUND: Previous studies have suggested altered responses to repeat skin tests in the sites of IgE-mediated late-phase reactions (LPRs) induced within the previous 48 hours. To explore the possible modulation of LPRs in such rechallenge sites, we compared inflammatory responses in skin chambers induced over previous LPR and control sites. METHODS: Skin blisters were induced and unroofed in 12 human subjects over two sites of previous LPRs induced by intradermal injection of pollen antigens 24 hours or 48 hours earlier and two sites previously injected with buffer diluent (B). Skin chambers containing the same antigens were appended to one intradermal antigen site (called Ag/Ag) and one intradermal B site (B/Ag), and B-containing chambers were placed over antigen (Ag/B) and B (B/B) intradermal sites. Fluids were collected after the first and the second through fifth hours of challenge. RESULTS: In skin chamber challenges 24 hours after the intradermal injection, there was no significant difference after the first hours between the Ag/Ag or B/Ag sites in either histamine or tryptase levels; both were significantly higher than at Ag/B or B/B sites (p < 0.01). The same pattern of events was seen in fluids obtained from the second through fifth hours. The same pattern of findings was seen in examination of levels of the total leukocyte accumulation, total eosinophil accumulation, and frequency of activated (EG2+) eosinophils. Levels of lactoferrin, released from activated neutrophils, and eosinophil cationic protein, released from activated eosinophils, were also similar at Ag/Ag and B/Ag sites; both were significantly higher than at B/B sites, whereas levels at Ag/B sites were intermediate between those found at B/Ag and B/B sites. The pattern of events in skin chamber challenges 48 hours after intradermal injection was similar to that seen at 24 hours, except that levels of inflammatory mediators/cells in Ag/B sites were more intermediate between the B/Ag and B/B sites. CONCLUSION: There is no significant alteration of mediator or inflammatory cell responses after antigen rechallenge of previous LPR sites when compared with those found in antigen challenge of non-LPR sites.  相似文献   
54.
55.
56.
57.
Male and female college students were shown videotapes of supposed male offenders describing the details of thefts they had committed. Videotaped sequences were varied so that offenders were 9 to 10 years old or of college age. Also, actors varied in their mode of emotional self-presentation. Comparisons of punishments suggested by subjects indicated that joyful actors received the highest level of punishment while distressed offenders received the lowest level of suggested punishment. It was also found that the emotions of children exerted a greater persuasive effect on subjects' ratings than did the emotions of adults although the pattern of results was similar across ages. These results were discussed as demonstrating that the age and emotion of an offender can exert considerable influence on the attribution of blame made by a disciplinarian.  相似文献   
58.
A study was made of 56 patients with carcinoma of thecervical stump after subtotal hysterectomy who were seen between 1946 and 1972 at the National Women's Hospital, Auckland, New Zealand. The duration of symptoms before diagnosis, stage distribution and five-year survival rates were examined and compared with those in 1459 patients with carcinoma of the cervix, and no previous subtotal hysterectomy, who presented over the same period.  相似文献   
59.
60.
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