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   2394831篇
  免费   173547篇
  国内免费   3519篇
耳鼻咽喉   33071篇
儿科学   78092篇
妇产科学   63938篇
基础医学   352548篇
口腔科学   66902篇
临床医学   214419篇
内科学   466446篇
皮肤病学   53083篇
神经病学   188933篇
特种医学   89349篇
外国民族医学   490篇
外科学   360980篇
综合类   48010篇
现状与发展   12篇
一般理论   862篇
预防医学   185716篇
眼科学   55637篇
药学   177989篇
  11篇
中国医学   4885篇
肿瘤学   130524篇
  2021年   20495篇
  2019年   20772篇
  2018年   28712篇
  2017年   21501篇
  2016年   24017篇
  2015年   26944篇
  2014年   37962篇
  2013年   56361篇
  2012年   77994篇
  2011年   82997篇
  2010年   48944篇
  2009年   46011篇
  2008年   77272篇
  2007年   82223篇
  2006年   82938篇
  2005年   80374篇
  2004年   76830篇
  2003年   73860篇
  2002年   71374篇
  2001年   109621篇
  2000年   112244篇
  1999年   94140篇
  1998年   27273篇
  1997年   23863篇
  1996年   24241篇
  1995年   22841篇
  1994年   20992篇
  1993年   19786篇
  1992年   72175篇
  1991年   70232篇
  1990年   68542篇
  1989年   65792篇
  1988年   60409篇
  1987年   59229篇
  1986年   55309篇
  1985年   53079篇
  1984年   39373篇
  1983年   33460篇
  1982年   19882篇
  1979年   35923篇
  1978年   25692篇
  1977年   21250篇
  1976年   20353篇
  1975年   21845篇
  1974年   26184篇
  1973年   24832篇
  1972年   23229篇
  1971年   22076篇
  1970年   20271篇
  1969年   19335篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A study of intravenous (i.v.) cannula usage for medical emergencies admitted to hospitals in the Newham Health District was undertaken during two defined periods (24 and 35 days). Almost half the cannulas inserted (47%) were not flushed following an initial bolus injection of heparinized saline. The duration that cannulas remained in a vein ranged from 24 hours to 8 days (median 2 days) and inflammation around the cannula site was related to the length of time since insertion but unrelated to whether the cannula was flushed regularly or to the type of fluid used. Our findings indicate a substantial wastage of i.v. cannulas due to difficulties with insertion and suggest that isotonic saline, without heparin, is effective in maintaining cannula patency for 48 hours. It is concluded that these findings are not unique to the Newham Health District and worthwhile financial savings should be achieved throughout the NHS if clinicians reconsider the indications and use of i.v. cannulas for their patients.  相似文献   
992.
M.A. Sabbahi  E.M. Sedgwick   《Brain research》1987,423(1-2):125-134
The H-reflex of 120 soleus motoneurons was recorded using fibre EMG. The recovery profile of these motoneurons was studied during monitoring surface H-reflex records in 28 adult subjects. The spectrum of motoneurons tested was homogeneous with two extremes of neurons having different characteristics. A motoneuron population (forming about 69% of our sample) had a high threshold level for electrical stimuli, short recovery time, and short recovery fringe time (called type A). A second population of motoneurons (forming about 20-30% of our sample) had a low threshold level for electrical stimuli, long recovery fringe time (called type B). During an isometric muscle contraction every motoneuron showed an early shift in recovery time (i.e. each had a shorter recovery time) with shortened recovery fringe time. These changes were larger for motoneurons type B than motoneurons type A. With paired identical electrical stimuli of varying interstimulus intervals a motoneuron may fire in response to the conditioning and test stimuli giving an H2, but not in response to both stimuli. This occurred for interstimulus intervals of 4-11 ms. A strong inhibition period was recorded with interstimulus intervals of 12-80 ms in which all motoneurons did not show any recovery. Most motoneurons recovered in orderly fashion between 80 and 300 ms of interstimulus interval, and this recovery coincided with the fast recovery recorded in surface H-reflex. All motoneurons were recovered by 3000 ms of interstimulus intervals. These findings emphasize the importance of eliciting the H-reflex every 3-5 s in H-reflex methodology in order to be assured that all excited motoneurons have been recovered.  相似文献   
993.
994.
Two hundred and thirty pregnancies were studied in 196 diabetic women. Seven women with babies found to have major malformations had a higher median first trimester haemoglobin A1 (12.9%) than the median HbA1 (10.8%) in those with normal babies (p = 0.06). No relationship was found between the occurrence of minor malformations and first trimester maternal haemoglobin A1. Two of the seven congenital malformations were diagnosed antenatally at a time when therapeutic abortion could be offered. Expert antenatal ultrasound scanning should be offered to all pregnant diabetic women as poor glycaemic control at the time of conception and organogenesis, as evidenced by raised first trimester HbA1, predisposes to congenital malformation.  相似文献   
995.
This paper gives the historical sketch necessary for an understanding of the current state of American psychiatry. It reviews some of the reasons why the rendering of good hospital care must be reconsidered, and describes some of the main features of the future public institution.  相似文献   
996.
During almost 12 years of development and clinical trials, diclofenac sodium has been shown to be both effective and safe as a new nonsteroidal antiinflammatory drug (NSAID) for the treatment of rheumatic diseases including ankylosing spondylitis (AS). We compared the safety and efficacy of 75, 100, or 125 mg/day of diclofenac with the same doses of indomethacin in a multicenter, randomized, parallel group trial in patients with AS. A single blind placebo washout period of 2 days to 2 weeks preceded the 13-week double blind treatment period. Both diclofenac and indomethacin produced significant (p less than 0.001) improvement from baseline for all 14 efficacy variables analyzed. There were no significant between treatment differences. Differences favored diclofenac in the frequency and the severity of adverse experiences reported and in the frequency of complaints affecting the central nervous system.  相似文献   
997.
Various cases are presented demonstrating the role of computed tomography (CT) in the assessment of serosal and bowel wall pathology. Reference is made to the morphology of the lesions. Illustrative examples of tumors, secondary malignant dissemination, irradiation injury to the gut, and intramural gas associated with ulcerative colitis, are all illustrated.  相似文献   
998.
999.
1000.
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