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   1422篇
  免费   99篇
  国内免费   9篇
耳鼻咽喉   11篇
儿科学   89篇
妇产科学   12篇
基础医学   153篇
口腔科学   31篇
临床医学   125篇
内科学   326篇
皮肤病学   24篇
神经病学   108篇
特种医学   252篇
外科学   151篇
综合类   61篇
预防医学   65篇
眼科学   24篇
药学   47篇
中国医学   9篇
肿瘤学   42篇
  2021年   8篇
  2020年   6篇
  2019年   14篇
  2018年   17篇
  2017年   11篇
  2016年   7篇
  2015年   22篇
  2014年   44篇
  2013年   75篇
  2012年   39篇
  2011年   39篇
  2010年   43篇
  2009年   68篇
  2008年   42篇
  2007年   57篇
  2006年   35篇
  2005年   40篇
  2004年   25篇
  2003年   17篇
  2002年   26篇
  2001年   15篇
  2000年   23篇
  1999年   16篇
  1998年   79篇
  1997年   55篇
  1996年   66篇
  1995年   48篇
  1994年   52篇
  1993年   46篇
  1992年   18篇
  1991年   11篇
  1990年   17篇
  1989年   47篇
  1988年   36篇
  1987年   38篇
  1986年   26篇
  1985年   21篇
  1984年   25篇
  1983年   23篇
  1982年   23篇
  1981年   28篇
  1980年   28篇
  1979年   29篇
  1978年   21篇
  1977年   25篇
  1976年   15篇
  1975年   15篇
  1974年   12篇
  1973年   9篇
  1918年   3篇
排序方式: 共有1530条查询结果,搜索用时 15 毫秒
81.
A nationwide study involving 286 children of human immunodeficiency virus (HIV)-infected mothers living in Switzerland has been performed with the participation of all paediatricians interested in HIV infection in the country. Of these children 201 could be followed up prospectively from birth up to a median age of 22 months. Prevalence of HIV infection in Swiss parturients was estimated at 0.1% and apparently remained stable from 1986 to 1989. Vertical transmission rate was estimated at 14%–20%. Variables of maternal or perinatal history were not associated with transmission rate. Transmission to pairs of siblings of the same mothers was discordant in 33% (6 of 18), with always the elder sibling being infected. Postneonatal mortality in infants of HIV-infected mothers followed up from birth was increased 15-fold over the general population with a very high incidence (2 in 100) of sudden infant death apparently unrelated to HIV infection.A complete list of all the participants in the study is available on request  相似文献   
82.
OBJECTIVE: Death by suicide among patients with epilepsy has found scant psychiatric attention, yet it may occur at the rate reported among patients with manic-depressive illness. We aim to clarify the psychopathology and pathogenesis of suicide in epilepsy and to document an effective method of prevention.METHOD: A total of 10,739 patients with epilepsy were seen at the Epi-Care Center in Memphis from 1987 to 1999. The patients with significant psychiatric complications were evaluated systematically and treated with an increasingly effective psychopharmacologic approach.RESULTS: Five suicides were registered during the 12-year period. All occurred in patients with longstanding complex partial seizures and dysphoric disorder a short time after full control of the seizures was achieved. During the last 8years of the 12-year period, more effective pharmacotherapy of the psychiatric complications of epilepsy was used (augmented antidepressant medication), and the two suicides that still occurred had eluded this treatment. Review of earlier series confirms that suicide tends to occur particularly among patients with chronic epilepsy who have obtained good control of their seizures; suicide may occur during interictal dysphoric episodes with or without psychotic features or in a state of postictal depression.CONCLUSIONS: Suppression of seizures in longstanding epilepsy may be associated with suicidal risk. The psychotoxic effect of predominant inhibitory mechanisms appears to be the crucial pathogenetic factor in all suicides. The number of suicides in our series is a fraction of that expected based on previous reports and indicates that prevention by psychopharmacologic treatment is available.  相似文献   
83.
目的 对比分析下肢骨肉瘤的X线与MRI表现,探讨MRI对骨肉瘤的诊断价值。方法 收集经手术或病理穿刺活检证实的下肢骨肉瘤15例,男11例,女4例,均行MRI平扫及增强扫描(4例行CT扫描),并摄有X线平片,对其MRI征象与X线征象作逐一对比。结果 MRI及X线平片对下肢骨肉瘤的诊断准确率均为100%,MRI在显示病变范围、放射状骨针、Codman三角两层结构以及跳跃病灶等方面明显优于X线平片检查。结论 X线平片是诊断骨肉瘤最简便而实用的方法,但MRI可以更好的显示病变的范围,发现早期病变。  相似文献   
84.
神经节细胞瘤是一种神经内分泌肿瘤,其发生与自主神经系统的交感或副交感神经节有关。罕见发生于膀胱、前列腺和子宫。本文作者报道1例发生于儿童头皮的原发性皮肤神经节细胞瘤。对此肿瘤进行了组织学、免疫组化和超微结构研究。该病例可能代表神经嵴细胞向鳃弓发育过程中的一种异常迁移。此外,研究结果还强调在胚胎发育过程中神经嵴和鳃弓/裂之间有复杂的相互作用。  相似文献   
85.
86.
一例AML中一种新的TCRδ基因重排及其分析方法   总被引:5,自引:0,他引:5  
李扬秋 Wichm.  A 《癌症》1996,15(2):90-93
T细胞抗原受体(TCR)功能的表达有赖于该基因在正常T淋巴细胞发育过程中的重排。近年来,已发现一些肿瘤及白血病中出现该基因的异常重排。我们采用聚合链反应(PCR)、“磁珠”固相纯化方法和PCR产物直接测序等方法,从一例AML中发现了一种在白血病中未报道过的TCRδ基因重排,该重排是一种新报道的Dδ区DδX片段的重排,为DδXDδDδJδ不完全重排。在研究白血病TCR基因重排中,采用本文所报道的方法  相似文献   
87.
Blood pressure measurements and Doppler echocardiography at rest and during exercise were performed in 36 patients at an average 17 years after coarctation resection. Interest focused on the study of Doppler systolic and diastolic gradients and half-times during exercise. Blood pressure gradients and Doppler values were compared with the degree of narrowing at the site of the anastomosis measured by magnetic resonance imaging. A systolic half-time of >110 ms together with a diastolic gradient of ≥17 mmHg on exercise Doppler sonography predicted a residual isthmic narrowing of >30%. We propose the use of this noninvasive method for identifying patients with narrowing of >30% at the site of the anastomosis after coarctation resection. In these cases evaluation by an imaging technique is necessary to confirm the need for surgery.  相似文献   
88.
Essential fatty acids are claimed to have positive effects in atopic diseases. In a double blind, placebo controlled, parallel group study 58 out of 60 children, with atopic dermatitis and the need for regular treatment with topical skin steroids, completed a 16 weeks' treatment period with either Epogam evening primrose oil or placebo capsules. Twenty two of these subjects also had asthma. The parents used diaries to record symptom scores and concomitant medication. Peak expiratory flow was measured and disease activity was monitored by the clinician every four weeks. The plasma concentrations of essential fatty acids increased significantly in the group treated with Epogam capsules. The study demonstrated significant improvements of the eczema symptoms but no significant difference was found between the placebo and the Epogam groups. No therapeutic effect was shown on asthma symptoms or fidget.  相似文献   
89.
A premature infant developed pericardial effusion four days after the insertion of a 25-gauge silastic percutaneous central venous catheter. The effusion contained parenteral nutrition fluid and resolved rapidly after withdrawal of the catheter. Pericardial effusion is a potential complication of percutaneous, as well as surgically placed, central venous catheters.  相似文献   
90.
We present a simple, fast, non-radioactive method for the analysis of the polymorphic short tandem repeat (STR) system in the human phenylalanine hydroxylase gene. Previously, sizing of the STR marker involved radiolabelling of PCR amplified fragments and resolution on denaturing polyacrylamide gels using M13 sequencing ladder as a standard. However, this method consistently gave sizes 2 bp longer than the known sequence. The fluorescent method presented here employs internal lane standards and enables accurate sizing of the fragments. To avoid confusion, we suggest that the true fragment lengths are used as reference values in the future. The analysis of STR alleles is valuable for population genetic studies and for targeted mutation screening in phenylketonuria (PKU). It can replace RFLP-based haplotype analysis for carrier detection, and we report its use for prenatal diagnosis in a Northern Irish family with PKU. The analysis of 250 Northern Irish chromosomes, including 128 PKU alleles, showed no significant difference between normal and PKU alleles, with fragment lengths of 238 and 242 bp most common in both groups.  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