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   714410篇
  免费   49698篇
  国内免费   1318篇
耳鼻咽喉   9217篇
儿科学   23485篇
妇产科学   17772篇
基础医学   111541篇
口腔科学   20184篇
临床医学   64768篇
内科学   135736篇
皮肤病学   16334篇
神经病学   50408篇
特种医学   26055篇
外国民族医学   76篇
外科学   105722篇
综合类   15036篇
现状与发展   2篇
一般理论   166篇
预防医学   52335篇
眼科学   16539篇
药学   54656篇
  3篇
中国医学   2372篇
肿瘤学   43019篇
  2019年   5587篇
  2018年   8026篇
  2017年   6246篇
  2016年   6935篇
  2015年   7705篇
  2014年   10457篇
  2013年   15690篇
  2012年   21005篇
  2011年   21986篇
  2010年   12951篇
  2009年   12179篇
  2008年   20436篇
  2007年   21973篇
  2006年   22408篇
  2005年   20900篇
  2004年   20422篇
  2003年   19328篇
  2002年   18810篇
  2001年   36538篇
  2000年   37077篇
  1999年   30576篇
  1998年   7991篇
  1997年   6756篇
  1996年   7046篇
  1995年   6689篇
  1994年   6168篇
  1993年   5662篇
  1992年   23107篇
  1991年   23068篇
  1990年   22414篇
  1989年   22202篇
  1988年   20155篇
  1987年   19550篇
  1986年   18591篇
  1985年   17429篇
  1984年   12793篇
  1983年   10835篇
  1982年   5978篇
  1979年   11599篇
  1978年   8188篇
  1977年   6894篇
  1976年   6633篇
  1975年   7320篇
  1974年   8565篇
  1973年   8190篇
  1972年   7695篇
  1971年   7169篇
  1970年   6916篇
  1969年   6346篇
  1968年   5816篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
71.
72.
In order to study the involvement of NMDA-receptor activation in brain development, rat pups were chronically treated with the non-competitive NMDA antagonist MK-801 during the neonatal period. We recorded the cortical EEG at various vigilance states throughout the treatment period. Spectral analysis of the EEG showed reduced power in the delta (delta) frequency range (1.5-4 Hz) during quiet sleep and less power in the theta (theta) range (4-7 Hz) during REM-sleep in MK-801 animals than in controls. No significant differences were found for the total time spent in each of the different vigilance states. We conclude that chronic MK-801 treatment probably causes a developmental retardation in state-related brain activities.  相似文献   
73.
74.
75.
The administration of prophylactic antibiotics in surgery is appropriate for many patients. Data have shown extending the duration of prophylaxis beyond 48 hours does not lower the rate of postoperative-infection. The purpose of this project was to concurrently assess the duration of prophylactic antibiotic use. A total of 95 patients were monitored over 3 weeks. Eighty patients (84.2%) received antimicrobial therapy. In 23 of these patients (28.75%) the duration of antibiotic administration was longer than 2 days without clinical or microbiological evidence of infection. In 5 other patients only postoperative antibiotics were prescribed. The cost difference between the actual duration of antibiotic administration and 2 days of the same regimen was +1,364.58. Extrapolating for one year, it can be estimated that antibiotic costs could be reduced about +23,600. Pharmacists can focus on the duration of antibiotic prophylaxis as a cost containment measure.  相似文献   
76.
Endogenous opioids are present in neurons of the vagus and the intrinsic nervous system and they are colocalized with gastrin in antral G-cells. This raises the possibility that endogenous opioids modulate gastrin release. Stimulation of both cervical vagi (10V, 5Hz, 5ms) elicited an increase of arterial plasma gastrin levels at intragastric pH7 or pH2. The response at pH2 was 30% of that at luminal pH7. Atropine reduced vagally stimulated gastrin levels substantially. At luminal pH2 the small residual noncholinergic response was mediated neither by adrenergic mechanisms nor by endogenous opioids. At luminal pH 7 adrenergic blockade with phentolamine and propranolol reduced vagally stimulated gastrin by 60%. In the presence of atropine adrenergic blockade elicited only a small inhibitory effect suggesting that vagal activation of adrenergic mechanisms depends on atropine-sensitive cholinergic pathways. Blockade of opiate receptors by naloxone had no effect on vagal gastrin release, however, the noncholinergic gastrin response was reduced significantly by naloxone, suggesting that cholinergic mechanisms normally restrain activation of endogenous opioids during vagal stimulation. Naloxone had no effect on the noncholinergic, nonadrenergic stimulation of gastrin levels. These data suggest that endogenous opioids can contribute to vagal gastrin release provided the cholinergic restraint is blocked and adrenergic mechanisms stimulate endogenous opioids. In conclusion a major role of endogenous opioids in the regulation of vagal gastrin release can not be detected.  相似文献   
77.
The article presents part of the results of a Federal German investigation of psychiatric confinement in cases of delinquency in accordance with German law. Among the 674 inmates whose case history could be included in the investigation, there was a predominance of alcohol dependence in two-thirds of them. Confinement occurred mostly only after addiction and delinquencies had been going on for a long time. In more than one-half of the patients no attempt had previously been made to treat and manage their alcohol addiction. Every fourth patient is confined without first consulting a psychiatric expert. Basing on sociobiographic characteristics it is possible to form two contrasting groups of patients: a smaller group where addiction has set in early and delinquency at a late stage, and a larger one with early onset of delinquency developing parallel to the abuse of alcohol. This leads to conclusions with regard to the development of specific treatment guidelines.  相似文献   
78.
79.
80.
10 patients with CLL and 2 with CML were treated with gradually increasing doses of 1 alpha(OH)D3, up to 4 micrograms daily during 6 wk. 3 patients with preleukemia and 1 with myelofibrosis were treated with 2 micrograms daily of 1 alpha(OH)D3 for a prolonged period up to 17 wk. The treatment with 1 alpha (OH)D3 did not result in changes of disease parameters in any of the patients under study. Receptor studies for 1,25(OH)2D3 were performed in 8 CLL patients and revealed only 1 patient with increased specific receptor binding capacity. The maximum tolerable dose of 1 alpha(OH)D3 varied individually, but was in the range of 2-4 micrograms daily.  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