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   5546篇
  免费   5篇
  国内免费   1篇
电工技术   1篇
化学工业   29篇
金属工艺   5篇
建筑科学   11篇
能源动力   2篇
轻工业   9篇
无线电   20篇
一般工业技术   21篇
冶金工业   5445篇
原子能技术   1篇
自动化技术   8篇
  2017年   2篇
  2016年   2篇
  2014年   12篇
  2013年   2篇
  2012年   3篇
  2011年   6篇
  2010年   1篇
  2009年   5篇
  2008年   4篇
  2007年   1篇
  2006年   6篇
  2005年   5篇
  2004年   8篇
  2003年   8篇
  2002年   1篇
  2000年   1篇
  1999年   162篇
  1998年   1655篇
  1997年   902篇
  1996年   640篇
  1995年   332篇
  1994年   316篇
  1993年   335篇
  1992年   36篇
  1991年   59篇
  1990年   80篇
  1989年   66篇
  1988年   64篇
  1987年   82篇
  1986年   58篇
  1985年   60篇
  1984年   1篇
  1983年   12篇
  1982年   32篇
  1981年   35篇
  1980年   42篇
  1979年   3篇
  1978年   8篇
  1977年   144篇
  1976年   339篇
  1975年   12篇
  1970年   1篇
  1969年   1篇
  1965年   1篇
  1964年   1篇
  1961年   1篇
  1955年   5篇
排序方式: 共有5552条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
996.
997.
Three hr after i.p. administration of a single dose of 30 mg/kg of morphine to male mice, an increase in specific activity of NADPH-cytochrome c reductase by about 10% and the content of cytochrome P-450 by about 14% of their liver microsomes was observed.Administration of 30 mg/kg of morphine, once daily,during 5 days, caused about 16% and 9% increases in specific activity of c reductase and the content of P-450 respectively. Administration of a single dose of morphine to male and female mice caused no sex-dependent differences in the specific activity of c reductase and the content of P-450. Repeated administration of morphine up to 100 mg/kg to male mice increased the specific activity of microsomal c reductase by about 70%. Repeated administration of morphine up to 55 mg/kg also increased the microsomal content of P-450 by about 22%, but with higher doses of morphine, the content of P-450 declined and finally dropped below control levels. The levels of c-reductase activity and P-450 content returned to normal levels about 2 weeks after termination of morphine administration.  相似文献   
998.
999.
Cryonecrosis of the upper lobe of the lung and bronchi was safely inudced in healthy dogs by application of the cryoprobe to serosal surfaces or, through a bronchotomy, to the mucosal surfaces under direct vision. Seven days after cryosurgery, hyperemia of the bronchus was seen. By 14 days the bronchus at the target site was covered with cuboidal epithelium. Reappearance of normal ciliated epithelium occurred by 180 days after cryosurgery. Cartilage remained intact, and there was no evidence of formation of a stricture or other gross alteration of bronchial architecture. In the lung there was coagulation necrosis; and by 14 days after cryosurgery, there was fibrosis in the target area. There were no complications of the pleural space. Cryosurgery of tissues at the margins of the bronchotomy does not impair healing. Cryosurgery may reduce the necessity for extensive surgery in selected patients with bronchopulmonary tumors, including those inaccessible to the rigid bronchoscope. Clinically, eight patients with recurrent bronchogenic tumors have received palliation by transbronchoscopic cryosurgery.  相似文献   
1000.
Maturation of lungs was studied morphologically in fetuses of does made diabetic with alloxan. The lungs of fetuses of does treated with alloxan 24 h after mating appeared to be less mature than control lungs, as shown by significant decrease in areal density of air space (p < 0.01) and by increases in areal density of alveolar epithelium and capillaries (p < 0.02). In alloxan fetuses, ultrastructural techniques revealed that type II cells had 10 times the control value for areal density of glycogen (p < 0.01) and 2.5 times that of rough endoplasmic reticulum (p < 0.05), but the proportion of type II cells and the number of lamellar bodies per type II cell profile were similar in both groups. Ultrastructural examination of capillaries demonstrated that their migration and the fusion of their basement membrane with that of alveolar epithelium did not occur as frequently in alloxan fetuses as in control fetuses. Biochemically, the lungs of alloxan fetuses contained significantly more glycogen and protein (p < 0.01) than control lungs, but the deoxyribonucleic acid was similar. The alloxan fetuses had a disturbance of lung structural maturation that was consistent with our previous findings of delayed functional maturation without accompanying change in disaturated phosphatidylcholine levels and ratio of lecithin to sphingomyelin.  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