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   3757篇
  免费   2篇
化学工业   10篇
轻工业   2篇
石油天然气   2篇
无线电   4篇
一般工业技术   2篇
冶金工业   3735篇
自动化技术   4篇
  2024年   1篇
  2021年   1篇
  2016年   2篇
  2015年   1篇
  2005年   1篇
  2004年   3篇
  2003年   7篇
  2001年   1篇
  2000年   1篇
  1999年   100篇
  1998年   1055篇
  1997年   584篇
  1996年   440篇
  1995年   232篇
  1994年   187篇
  1993年   239篇
  1992年   33篇
  1991年   57篇
  1990年   67篇
  1989年   92篇
  1988年   46篇
  1987年   73篇
  1986年   48篇
  1985年   63篇
  1984年   2篇
  1983年   5篇
  1982年   21篇
  1981年   16篇
  1980年   35篇
  1979年   2篇
  1978年   7篇
  1977年   88篇
  1976年   237篇
  1975年   7篇
  1969年   1篇
  1965年   1篇
  1955年   3篇
排序方式: 共有3759条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
1. Experiments have been performed in sheep to determine the contribution of lymph formed within a lymph node to the total protein output in lymph leaving the node. 2. The lymphatic duct leaving the popliteal lymph node was cannulated and the protein and lymphocyte output in efferent lymph determined. The afferent lymph flow to the popliteal node was then diverted and lymph formed only within the lymph node collected from the efferent cannula. It appeared from the results that the popliteal lymph node forms lymph at the rate of approximately 1 ml. per hour and may contribute 30-50% of the protein output observed in efferent lymph. 3. The importance of lymph formation within the lymph node varied between nodes found in different regions of the body. This was due in part to the different protein concentrations in the afferent lymph to the different nodes. 4. A positive correlation was found between the protein and lymphocyte concentrations in efferent lymph from the popliteal lymph node in seven out of eleven sheep and in lymph formed within the popliteal lymph node in two out of three sheep. It is suggested that this relationship may be due to an increased transfer of plasma proteins through the post-capillary venules in the lymph node accompanying the continual traffic of lymphocytes across the wall of these vessels. The results indicated that the protein transfer across the post-capillary venules was not an indiscriminate transfer of plasma per se but a selective transport from the blood plasma compartment based on molecular size.  相似文献   
56.
The degeneration of the substantia nigra that characterises Parkinson's disease may cause an alteration in sensitivity of striatal dopamine receptors. The development of denervation supersensitivity has been held to be responsible for some of the effects of chronic levodopa therapy. The rotating rodent is an animal model commonly used to study the phenomenon of striatal dopamine receptor supersensitivity, and to investigate drugs which may prove to be beneficial in the treatment of Parkinson's disease. We have investigated as to whether long-term oral administration of levodopa to mice with unilateral destruction of striatal dopaminergic nerve terminals influences dopaminergic receptor denervation supersensitivity as judged by the circling response following systemically administered levodopa. It does not do so and the relevance of these findings to the treatment of Parkinson's disease is discussed.  相似文献   
57.
Aspergillus terreus infection limited to the L1-2 disk space and first and second lumbar vertebrae developed in a patient not predisposed to invasive aspergillosis. The observation of morphologically distinct secondary spores (aleuriospores) on microscopic examination of open biopsy specimens permitted a preliminary identification of A terreus, which was confirmed by culture. The infection was eradicated with amphotericin B in a total dose of 3 gm. Aspergillus terreus is usually a saprophyte. The present case and four others collected from the literature establish this species as an invasive pathogen.  相似文献   
58.
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