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   718314篇
  免费   49760篇
  国内免费   1372篇
耳鼻咽喉   9240篇
儿科学   23517篇
妇产科学   17780篇
基础医学   112226篇
口腔科学   20063篇
临床医学   65484篇
内科学   137410篇
皮肤病学   16405篇
神经病学   50531篇
特种医学   26260篇
外国民族医学   79篇
外科学   106361篇
综合类   14854篇
现状与发展   2篇
一般理论   164篇
预防医学   51948篇
眼科学   16511篇
药学   54783篇
  3篇
中国医学   2381篇
肿瘤学   43444篇
  2021年   5820篇
  2019年   5743篇
  2018年   8234篇
  2017年   6363篇
  2016年   7088篇
  2015年   7890篇
  2014年   10743篇
  2013年   15984篇
  2012年   21485篇
  2011年   22556篇
  2010年   13258篇
  2009年   12453篇
  2008年   20782篇
  2007年   22317篇
  2006年   22676篇
  2005年   21186篇
  2004年   20665篇
  2003年   19593篇
  2002年   19068篇
  2001年   36480篇
  2000年   37048篇
  1999年   30518篇
  1998年   8004篇
  1997年   6769篇
  1996年   7053篇
  1995年   6680篇
  1994年   6147篇
  1992年   23058篇
  1991年   23005篇
  1990年   22370篇
  1989年   22148篇
  1988年   20105篇
  1987年   19477篇
  1986年   18530篇
  1985年   17356篇
  1984年   12730篇
  1983年   10776篇
  1982年   5943篇
  1979年   11535篇
  1978年   8146篇
  1977年   6842篇
  1976年   6611篇
  1975年   7295篇
  1974年   8511篇
  1973年   8159篇
  1972年   7672篇
  1971年   7138篇
  1970年   6882篇
  1969年   6313篇
  1968年   5785篇
排序方式: 共有10000条查询结果,搜索用时 15 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