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   3272篇
  免费   496篇
  国内免费   14篇
耳鼻咽喉   45篇
儿科学   93篇
妇产科学   41篇
基础医学   413篇
口腔科学   113篇
临床医学   354篇
内科学   768篇
皮肤病学   69篇
神经病学   213篇
特种医学   244篇
外国民族医学   1篇
外科学   491篇
综合类   311篇
一般理论   2篇
预防医学   262篇
眼科学   45篇
药学   188篇
中国医学   3篇
肿瘤学   126篇
  2021年   53篇
  2020年   27篇
  2019年   42篇
  2018年   54篇
  2017年   46篇
  2016年   44篇
  2015年   55篇
  2014年   59篇
  2013年   102篇
  2012年   145篇
  2011年   141篇
  2010年   90篇
  2009年   102篇
  2008年   124篇
  2007年   130篇
  2006年   113篇
  2005年   118篇
  2004年   140篇
  2003年   102篇
  2002年   123篇
  2001年   118篇
  2000年   122篇
  1999年   118篇
  1998年   85篇
  1997年   88篇
  1996年   93篇
  1995年   61篇
  1994年   65篇
  1993年   55篇
  1992年   74篇
  1991年   78篇
  1990年   71篇
  1989年   66篇
  1988年   84篇
  1987年   85篇
  1986年   87篇
  1985年   68篇
  1984年   47篇
  1983年   50篇
  1982年   42篇
  1981年   28篇
  1980年   41篇
  1979年   35篇
  1978年   27篇
  1976年   21篇
  1973年   23篇
  1972年   22篇
  1969年   21篇
  1968年   20篇
  1967年   21篇
排序方式: 共有3782条查询结果,搜索用时 609 毫秒
1.
2.
3.
4.
L Disney  B Weir  K Petruk 《Neurosurgery》1987,20(5):695-701
Of 736 patients with intracranial aneurysms seen at the University of Alberta from 1968 to 1985, 437 were admitted on the day of or the day after subarachnoid hemorrhage (SAH) from a supratentorial aneurysm. Of these, 205 were managed from 1968 through 1977 and 232 were managed from 1978 through early 1985 after a policy of early aneurysm operation had been implemented. Postoperative and management mortality and morbidity rates were related to the grade of the patient at the time of admission and the time interval before operation. Overall management mortality (and postoperative mortality) rates for patients treated before 1978 were 47% (19%) for all grades, 17% (12%) for Grades 1 and 2, 51% (25%) for Grades 3 and 4, and 100% (100%) for Grade 5. Since 1978, mortality has been reduced to 38% (11%) for all grades, 10% (5%) for Grades 1 and 2, 39% (17%) for Grades 3 and 4, and 96% (60%) for Grade 5. Management mortality for patients operated on Day 0 to 3 was lower than for those operated later after SAH both before and after 1978. Postoperative mortality was lowered in all patients operated from 1978 to 1985 regardless of the interval from SAH to operation, and management mortality was reduced overall, as well as for patients operated on day 0 to 3, in those treated from 1978 to 1985. The authors conclude that a policy of early aneurysm operation has contributed to a reduction of both postoperative and management mortality.  相似文献   
5.
We sought to simultaneously confirm that substantial recovery at day 1 and day 7 after acute ischaemic stroke onset is associated with subsequent neurological deterioration in patients of the Acute Stroke Therapy by Inhibition of Neutrophils randomized clinical trial. Substantial recovery was assessed by improvement in the National Institutes of Health Stroke Score (NIHSS). Neurological deterioration was defined as any stroke event or NIHSS worsening from recovery assessment to day 90. After adjusting for age, t-PA and day 1 NIHSS, there was a non-significant tendency of substantial (pre-specified as 75%) recovery at day 1 to be associated with later deterioration [odds ratio (OR) 2.47; 95% CI, 0.95–6.50]. The corresponding OR for substantial (pre-defined as 65%) recovery at day 7 was 1.84 (0.85–3.96). Other thresholds for recovery were significantly associated with later deterioration: >50%, 80%, 90% and 100% for day 1 and >50%, 60%, 70%, 90% and 100% for day 7. The effect of recovery at day 1 was more important than that of later recovery. This study confirms the association between recovery and subsequent neurological deterioration and is the first to indicate the greater importance of acute recovery at day 1 in comparison with later recovery.  相似文献   
6.
7.
The efficacy of the 21-aminosteroid U74006F was investigated using different dosages in a restricted, randomized, placebo-controlled trial. Forty cynomolgous monkeys were divided into five groups of eight. There were two groups given treatment with placebos, one being saline and the other the vehicle in which U74006F was delivered. There were three U74006F treatment dosage groups: 0.3, 1.0, and 3.0 mg/kg. Each monkey underwent baseline cerebral angiography followed by right-sided craniectomy and subarachnoid placement of a clot around the middle cerebral artery (MCA). Treatment was administered intravenously every 8 hours for 6 days. Seven days after experimental subarachnoid hemorrhage, angiography was repeated, and the animals were killed. In both saline or vehicle placebo treatment groups, significant vasospasm (VSP) occurred on the clot side in the extradural internal carotid artery (C3), the intradural internal carotid artery, the precommunicating segment of the anterior cerebral artery (A1,) and the MCA (P less than 0.01). After U74006F treatment, significantly less VSP developed in the A1 on the clot side (0.3 mg/kg U74006F treatment group) and the MCA (all U74006F treatment groups, P less than 0.05). When the percentages of change from the baseline for the vessel diameters on the clot side were compared, VSP was attenuated in the A1 (P less than 0.05) and MCA (P less than 0.001) of all U74006F treatment groups as compared with the placebo treatment groups. Only 0.3 mg/kg of U74006F significantly prevented VSP in C3 (P less than 0.01). Although the 0.3 mg/kg dosage appeared to have the most favorable effect, no significant differences were observed among the three dosage groups. Electron microscopy of the MCA on the clot side in the animals treated with U74006F still showed luminal convolutions and morphological changes in the endothelial cells. These changes appeared less prominent in those MCAs with milder VSP. If these results in primates are applicable to humans, U74006F would be useful in reducing VSP after aneurysmal subarachnoid hemorrhage.  相似文献   
8.
A postal questionnaire was sent to all members of the Northern Ireland Society of Anaesthetists to determine current practice in anaesthesia for children with acute appendicitis. Respondents were asked to describe their usual practice in such cases. They were also asked about the occurrence of complications due to the use of suxamethonium, and for their views on the use of rocuronium in such cases. Few major differences in anaesthetic technique were demonstrated. 74% of consultants and 84% of trainees always perform a rapid sequence induction for appendicectomy. However 15% of consultants do not feel that this is necessary. Only 6% of consultants and 6% of trainees would normally use rocuronium, with the majority still preferring suxamethonium. Only 28% of consultants and 20% of trainees see rocuronium as a possible alternative to suxamethonium in these cases, although others expressed increasing concern over the use of suxamethonium in children. There was wide variation in the type of intra-operative and post-operative analgesia prescribed, with less than one third of consultants and trainees using combinations of opioids, local anaesthetics and non-steroidal anti-inflammatory drugs.  相似文献   
9.
10.
Mildly elevated maternal plasma homocysteine (Hcy) levels (hyperhomocysteinemia) have recently been observed in some neural tube defect (NTD) pregnancies. Plasma levels of Hcy are governed by both genetic and nutritional factors and the aetiology of NTDs is also known to have both genetic and nutritional components. We therefore examined the frequency of relatively common mutations in the enzyme cystathionine β-synthase (CBS), which is one of the main enzymes that controls Hcy levels, in the NTD population. Neither the severely dysfunctional G307S CBS allele nor the recently reported 68 bp insertion/I278T CBS allele was observed at increased frequency in the cases relative to controls. We therefore conclude that loss of function CBS alleles do not account for a significant proportion of NTDs in Ireland.  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