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   1556篇
  免费   1篇
电工技术   1篇
化学工业   3篇
金属工艺   5篇
机械仪表   1篇
轻工业   5篇
石油天然气   3篇
一般工业技术   8篇
冶金工业   1527篇
自动化技术   4篇
  2020年   1篇
  2018年   1篇
  2015年   1篇
  2013年   2篇
  2012年   2篇
  2009年   1篇
  2008年   1篇
  2005年   1篇
  2004年   4篇
  2003年   2篇
  1999年   25篇
  1998年   404篇
  1997年   252篇
  1996年   166篇
  1995年   94篇
  1994年   74篇
  1993年   100篇
  1992年   9篇
  1991年   13篇
  1990年   7篇
  1989年   7篇
  1988年   7篇
  1987年   9篇
  1986年   7篇
  1985年   7篇
  1983年   2篇
  1982年   14篇
  1981年   22篇
  1980年   28篇
  1979年   3篇
  1978年   4篇
  1977年   91篇
  1976年   183篇
  1975年   7篇
  1973年   1篇
  1965年   2篇
  1959年   2篇
  1955年   1篇
排序方式: 共有1557条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
A complicated, almost critical situation has arisen in Ukraine in the early nineties in respect of drug maintenance of the population and health- and preventive-care institutions. Satisfaction of the public's needs for medicinal preparations was no more than 11 to 12% with home-made produce and up to 25% with foreign deliveries taken into account. Over the recent years (1995-1997), there has been a positive growing tendency in the total volume of home drug production (9 to 10% annually).  相似文献   
65.
To investigate the repair of oxidative damage in DNA, we have established an in vitro assay utilizing human lymphoblastoid whole cell extracts and plasmid DNA damaged by exposure to methylene blue and visible light. This treatment has been shown to produce predominantly 7-hydro-8-oxodeoxyguanosine (8-oxodG) in double-stranded DNA at low levels of modification. DNA containing 1. 6 lesions per plasmid is substrate for efficient repair synthesis by cell extracts. The incorporation of dGMP is 2.7 +/- 0.5 times greater than the incorporation of dCMP, indicating an average repair patch of 3-4 nucleotides. Damage-specific nicking occurs within 15 min, while resynthesis is slower. The incorporation of dGMP increases linearly, while the incorporation of dCMP exhibits a distinct lag. Extracts from xeroderma pigmentosum (XP) complementation groups A and B exhibit 25 and 40%, respectively, of the incorporation of dCMP compared with normal extracts, but extracts from an XP-D cell line exhibit twice the activity. These data suggest that the efficient repair of 8-oxodG lesions observed in human cell extracts involves more than one pathway of base excision repair.  相似文献   
66.
The effects of an alternative chelation program in thalassemic patients with severe iron overload are investigated. The schedule of treatment, feasible at home, consists in the administration of deferoxamine intravenously (100 mg/kg/die 8 hours 10 days a month), followed by 50 mg/kg/die subcutaneously in the remaining 20 days of the month. The results in 34 patients who underwent this program over 8 months are reported. After intensive chelation therapy serum ferritin and transaminase levels were significantly lower, and daily urinary iron excretion values were significantly higher when compared to the levels observed before the treatment. After the period of study, echocardiography revealed an ejection fraction (EF) significantly higher in 15 out of 34 cardiopathic patients. In conclusion, the alternative chelation program is effective in reducing iron overload of thalassemic patients, protecting them also against cardiac disease.  相似文献   
67.
68.
Whether a high-resolving light scattering spectrometer may be used in medical practice is discussed in the paper. The results of the experiments on blood components and microorganisms are discussed.  相似文献   
69.
Male rats with a genetic predisposition to cataleptic reactions revealed a reduced motor activity and a diminished activation of mineralocorticoid and testosterone synthesis in response to a mild stress as compared with the Wistar rats. The reactions, however, were exactly opposite in the Wistar rats with signs of cataleptic features. The data obtained suggest that, when creating genetic animal models of human diseases, the initial stages of breeding should correspond to early stages of the disease whereas advanced stages of breeding are similar to later, chronic phases of the disease.  相似文献   
70.
The removal of tooth structure during preparation results in varying degrees of pulpal hyperemia. The ability of the pulpal tissue to respond either by recovery or degeneration depends in part upon the adequacy and fit of the provisional restoration. The response of the gingival tissue also depends on a large degree on the success of the temporary coverage. Provisional restorations are commonly given less attention and importance thereby biologic, mechanical, and esthetic considerations are not adequately met. Since a provisional restoration must be made or improvised during the same appointment in which the abutment teeth are prepared, costly chairside time most often leads to an unacceptable restoration. Failures such as color instability, color incompatibility, inappropriate anatomic contours, fractures, occlusal disharmony, changes in tooth position, gingival inflammation, and unhealthy periodontal conditions are usually encountered. A technique of fabricating an exacting provisional restoration with compliance to optimum quality is presented.  相似文献   
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