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   4123篇
  免费   21篇
  国内免费   1篇
电工技术   23篇
综合类   1篇
化学工业   122篇
金属工艺   46篇
机械仪表   7篇
建筑科学   60篇
矿业工程   5篇
能源动力   33篇
轻工业   107篇
水利工程   8篇
石油天然气   4篇
无线电   115篇
一般工业技术   223篇
冶金工业   3214篇
原子能技术   11篇
自动化技术   166篇
  2022年   8篇
  2021年   13篇
  2020年   10篇
  2019年   10篇
  2018年   13篇
  2017年   18篇
  2016年   20篇
  2015年   18篇
  2014年   17篇
  2013年   61篇
  2012年   25篇
  2011年   39篇
  2010年   29篇
  2009年   27篇
  2008年   42篇
  2007年   47篇
  2006年   40篇
  2005年   36篇
  2004年   50篇
  2003年   34篇
  2002年   36篇
  2001年   44篇
  2000年   31篇
  1999年   113篇
  1998年   1035篇
  1997年   550篇
  1996年   383篇
  1995年   222篇
  1994年   164篇
  1993年   173篇
  1992年   41篇
  1991年   60篇
  1990年   49篇
  1989年   58篇
  1988年   57篇
  1987年   59篇
  1986年   57篇
  1985年   44篇
  1984年   20篇
  1983年   15篇
  1982年   18篇
  1981年   27篇
  1980年   27篇
  1979年   10篇
  1978年   9篇
  1977年   72篇
  1976年   158篇
  1975年   14篇
  1973年   8篇
  1972年   5篇
排序方式: 共有4145条查询结果,搜索用时 15 毫秒
81.
82.
83.
The evidence for and against the prophylactic use of anticonvulsants and antibiotics in head injury is reviewed. There is a lack of blinded placebo-controlled trials in this area. On balance there is no compelling evidence to support the use of either anticonvulsant or antibiotic prophylaxis in head injury, with the possible exception of antibiotic prophylaxis in compound depressed skull fractures and penetrating brain injuries.  相似文献   
84.
85.
The organic acid composition of aseptically-grown timothy grass (Phleum pratense) was examined. Changes in organic acids of the grass during incubation in small test tubes with and without the addition of lactic acid bacteria were studied. Malic acid, a major acid of the grass, was broken down during incubation mainly by the activity of bacterial enzymes. The amount of succinic acid was increased by the action of both plant and bacterial enzymes. Citric acid was not detected in the aseptically-grown timothy grass but two unidentified acids formed a major part of the total organic acid fraction.  相似文献   
86.
87.
Confidence in and responses to an unreliable test alarm were studied in the presence of nearby unspecified alarms. The test alarm's reliability rate was represented as averaging "true" only 50% or 60% of the time. Confidence or response rates ranged proportionately from 23% to 97% with the number of active alarms within 5, 6, 7, or 9 annunciator arrays. Adjacent alarms resulted in confidence estimates that were higher (by about 10%) than those with the same number of active alarms spaced up to 3 positions away. Simultaneously activated alarms resulted in a more than 20% increase in "true" responses compared with the same number of alarms offset in time by up to 32 s, regardless of which came first. Active alarms "known" to be functionally related to, or independent of, the test alarm substantially raised or lowered responding but did not completely overcome prior effects. These findings indicate that presumptions that operators' responses are not influenced by nearby alarms, regardless of their function, may be unwarranted. Applications of this research include suggestions to improve responding and training recommendations.  相似文献   
88.
89.
90.
Surgical management of locally recurrent rectal cancer   总被引:3,自引:0,他引:3  
The surgical management of locally recurrent rectal cancer may involve major procedures and is not for the faint-hearted. Nevertheless, such treatment is preferable to chemotherapy and radiotherapy; the latter will fail over a period of months during which the patient is likely to experience intractable pain. Radical surgery offers good palliation and a better quality of life. Survival is prolonged by such operations which may be curative in up to one-third of patients. Nevertheless, surgeons must be realistic in their assessment of and discussions with patients.  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