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   6054篇
  免费   9篇
  国内免费   1篇
电工技术   6篇
综合类   1篇
化学工业   43篇
金属工艺   6篇
机械仪表   8篇
建筑科学   7篇
矿业工程   2篇
能源动力   3篇
轻工业   20篇
无线电   19篇
一般工业技术   34篇
冶金工业   5891篇
原子能技术   2篇
自动化技术   22篇
  2022年   3篇
  2021年   2篇
  2020年   7篇
  2019年   2篇
  2018年   4篇
  2017年   4篇
  2016年   4篇
  2015年   5篇
  2014年   5篇
  2013年   8篇
  2012年   4篇
  2011年   5篇
  2010年   8篇
  2009年   5篇
  2008年   6篇
  2007年   7篇
  2006年   8篇
  2005年   6篇
  2004年   6篇
  2003年   14篇
  2002年   5篇
  2000年   3篇
  1999年   187篇
  1998年   1948篇
  1997年   1109篇
  1996年   713篇
  1995年   382篇
  1994年   281篇
  1993年   365篇
  1992年   43篇
  1991年   44篇
  1990年   56篇
  1989年   46篇
  1988年   38篇
  1987年   39篇
  1986年   35篇
  1985年   47篇
  1983年   10篇
  1982年   21篇
  1981年   40篇
  1980年   53篇
  1979年   2篇
  1978年   17篇
  1977年   136篇
  1976年   300篇
  1975年   16篇
  1973年   3篇
  1972年   2篇
  1963年   1篇
  1955年   4篇
排序方式: 共有6064条查询结果,搜索用时 0 毫秒
41.
An unusual form of left ventricular aneurysm affecting young Negroes has recently been described at the aortic or mitral valve ring; constitutional factors have been postulated. A 4-year-old Negro boy was observed with a left ventricular submitral aneurysm, probably one of the largest and one of the most calcified to be reported. Tuberculous lymphadenitis involving some of the mediastinal lymph nodes was found on postmortem examination; tuberculosis was believed to be a secondary contributing factor. A review of the literature disclosed only 5 other children with calcified left ventricular aneurysms, of which 2 were of the subvalvular type.  相似文献   
42.
We report here an experience with five patients, aged 58 to 70, suffering gangrene of the left colon after spontaneous inferior mesenteric artery occlusion. All cases were the result of arteriosclerosis; in two, small aortic aneurysms were present and might have been responsible for emboli to the inferior mesenteric artery. The dead bowel was resected in all patients; three patients survived. No primary anastomoses were done and they are not recommended. Because ligation of the patent inferior mesenteric artery has been done so often without ill effects during aortic surgery, the collateral circulation to the left colon can be considered excellent. Gangrene is therefore rare and requires major interference with collateral circulation by emboli or arteriosclerotic occlusion. The clinical symptoms and signs may be confusing.  相似文献   
43.
A commercially available recording of Northwestern University Auditory Test No. 6 (N.U. No. 6) produced by Auditec of St. Louis was evaluated in a series of four studies. Interlist equivalence of this version was initially investigated, and then normative intelligibility functions were developed using listerners with normal hearing. Intelligibility functions for the original version of N.U. No. 6. prepared by Northwestern University, were then derived, concurrently with functions of the Auditec version, using (1) a group of listeners with normal hearing; and (2) a group with sensorineural hearing loss. The results demonstrated good interlist equivalence for the Auditec version of N.U. No. 6. The comparative intelligibility functions for the Auditec and Northwestern versions of N.U. No 6 furthermore indicated a difference between the two recordings, but it was concluded that for clinical purposes the two versions may be considered equivalent.  相似文献   
44.
The distressing nature of laryngeal papillomatosis and lack of clinical progress in its treatment are reviewed. Presently accepted and investigative methods of therapy are reviewed with special attention being given to immune therapy. Support for the concept of a viral etiology is discussed and other etiologic agents considered. Known and possibly significant roles of wart virus antibodies are discussed and the importance of complex interplay between maternal and fetal immune systems explored as a possible explanation for some puzzling aspects of laryngeal papillomatosis. Finally, a proposed experimental design is outlined, the purpose of which is to provide a useful animal model to investigate immune changes in laryngeal papillomatosis, as well as effects of surgical or medical therapy.  相似文献   
45.
46.
In order to evaluate the preventive value of specific immune serum globulin against hepatitis type B, we have used this immune globulin in required doses in 12 patients (10 with AU antigen negative and 2 with AU antigen positive) with chronic renal failure who required maintenance hemodialysis for a period of 15 months, and we were able to prevent hepatitis type B in our dialysis patients.  相似文献   
47.
48.
49.
Serum IgE concentrations of patients with paragonimiasis were determined by a radioimmunosorbent test. The mean concentration was 3,462.3 IU/ml in a group of 13 cases of paragonimiasis miyazakii in which patients showed clinical symptoms and/or positive immunological diagnostic tests, and 1,026.6 IU/ml in a control group of 13 individuals who had eaten uncooked freshwater crabs, Potamon dehaani, but had been found to be free from the infection. Moreover, the IgE level of the pleural exudates obtained from four patients with paragonimiasis miyazakii on the day of bleeding or within several days after was significantly higher than that of their sera, ranging between 4,200 IU/ml and 10,000 IU/ml. This was true also in a case of paragonimiasis westermani. Sera and pleural exudates of patients with both forms of paragonimiasis were applied to immunosorbent columns of Sepharose 4B beads coupled with saline extracts of Paragonimus miyazakii, P. weetermani, or P. ohirai. IgE eluted from the corresponding column was considered to be specific, being around 5% to 10% of the total IgE.  相似文献   
50.
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