全文获取类型
收费全文 | 4798篇 |
免费 | 1篇 |
专业分类
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 |
出版年
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.
SE Kenny JM Vanderwinden RJ Rintala MG Connell DA Lloyd JJ Vanderhaegen MH De Laet 《Canadian Metallurgical Quarterly》1998,33(1):94-98
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.
Transformation-induced alterations in adhesion. Binding of pre-formed cell aggregates to cell layers 总被引:1,自引:0,他引:1
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.
JJ Oats 《Canadian Metallurgical Quarterly》1976,83(11):896-899
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.