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   7162篇
  免费   1038篇
  国内免费   194篇
耳鼻咽喉   44篇
儿科学   110篇
妇产科学   68篇
基础医学   379篇
口腔科学   101篇
临床医学   1083篇
内科学   649篇
皮肤病学   74篇
神经病学   794篇
特种医学   216篇
外科学   1378篇
综合类   1142篇
预防医学   495篇
眼科学   98篇
药学   420篇
  2篇
中国医学   1090篇
肿瘤学   251篇
  2025年   15篇
  2024年   300篇
  2023年   318篇
  2022年   590篇
  2021年   685篇
  2020年   666篇
  2019年   491篇
  2018年   399篇
  2017年   352篇
  2016年   396篇
  2015年   298篇
  2014年   675篇
  2013年   527篇
  2012年   418篇
  2011年   397篇
  2010年   313篇
  2009年   274篇
  2008年   269篇
  2007年   201篇
  2006年   168篇
  2005年   123篇
  2004年   119篇
  2003年   93篇
  2002年   45篇
  2001年   44篇
  2000年   36篇
  1999年   38篇
  1998年   26篇
  1997年   19篇
  1996年   19篇
  1995年   12篇
  1994年   8篇
  1993年   7篇
  1992年   6篇
  1991年   2篇
  1990年   4篇
  1989年   3篇
  1987年   4篇
  1986年   5篇
  1985年   6篇
  1984年   4篇
  1982年   2篇
  1981年   1篇
  1980年   3篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
排序方式: 共有8394条查询结果,搜索用时 15 毫秒
1.
Zusammenfassung Im Jahr 1988 wurde erstmals von der m?glichen Wirksamkeit der Valproins?ure in der Migr?neprophylaxe berichtet. Seit 1992 sind insgesamt 359 Patienten in 5 Doppelblindstudien untersucht. In allen Studien ergab sich eine signifikant überlegene Wirksamkeit im Vergleich zu Placebo, eine Studie belegt einen gleichen Effekt wie Propranolol. Es fehlen noch Wirksamkeitsanalysen, die sich am Plasmaspiegel orientieren. Die Nebenwirkungen entsprechen denen aus der Epilepsietherapie, scheinen aber im Vergleich zu Propranolol etwas h?her zu liegen. International und nach den Empfehlungen der Deutschen Migr?ne- und Kopfschmerzgesellschaft gilt Valproins?ure mittlerweile als etabliertes Mittel der zweiten Wahl.   相似文献   
2.
In 1942, Jaffe and Lichtenstein introduced the term aneurysmal bone cyst (ABC). Primary ABC is characterized by the presence of spongy or multi-cameral cystic tissue filled with blood. The process is benign, but it is locally destructive and has a high propensity for recurrence. In this paper, we present the third case of multiple metachronous primary ABCs as a rare variant of ABC. We describe the 10-year history of a 12-year-old boy with metachronous multiple primary ABCs at five different sites (right proximal humerus, right ulna, bilateral distal radius and right lateral clavicle). Furthermore, our patient suffered from vascular malformations, such as aortic isthmus stenosis, hypoplastic thoraco-abdominal aorta and bilateral renal artery stenosis. To date, in contrast to solitary ABC, the multiple lesions have been found more frequently in male individuals. Using interphase cytogenetics, we analyzed three of five of the patients ABCs and one of these was also analyzed by GTG-banding. No chromosomal abnormalities were found. Significantly, we excluded the missense mutation of codon 201 in guanine nucleotide-binding protein 1 gene consistently found in McCune-Albright syndrome (MAS) and in non-MAS cases of polyostotic fibrous dysplasia of bone with or without secondary ABC.  相似文献   
3.
The organization of chains of oligopeptidoglycan in the saccular wall is of critical importance in the study of the mechanism and physiology of prokaryotic wall growth. The electron microphotographs of De Pedro et al, present new findings and can be used to negate or at least raise questions about the previously accepted conclusion that the glycan chains are oriented transversely to the axis of rod-shaped Escherichia coli. This suggests caution in assuming that the glycan chains in the murein structure are parallel to each other and are perpendicular to the axis of the cell.These results should reopen the question of not only the orientation of the peptidoglycan chains, but the possibility of variability in orientation. Three classes of hypotheses about wall growth are reconsidered and problems with them are presented. The new results from De Pedro's laboratory and the experimental glycan chain length distribution argue against proposed systematic models. These include models that postulate belts or hoops stretched around the circumference of the cell and mechanisms that insert new chains of the length of presumptive “docking” strands in the stress-bearing wall. They are consistent, however, with the surface stress theory that proposes that random enzyme action together with physical forces are involved in the elongation of the rod-shaped Gram-negative wall.  相似文献   
4.
Reid E 《Journal of neurology》1999,246(11):995-1003
The hereditary spastic paraplegias are a complex group of neurodegenerative conditions which are characterised by slowly progressive lower limb spasticity. This article describes the main clinical features of pure and complicated hereditary spastic paraplegias and summarises recent advances in our understanding of the molecular genetics of these conditions. Received: 2 June 1999 Accepted: 7 August 1999  相似文献   
5.
Related to treatment of senile dementia, 53 articles conformed the statistical demand were analyzed, finding commonly used methods are acupuncture, moxibustion, acupoint-injection, electro-acupuncture, ocular-acupuncture, scalp-acupuncture, digital-acupuncture and acupuncture plus other therapies, key treatment principle is opening orifice and invigorating brain, frequent selected acupoints are Baihui (GV 20), Zusanli (ST 36), Fengchi (GB 20), Fenglong (ST 40), Neiguan (PC 6), Shuigou (GV 26), etc; and the total effective rate is 89.62%. Author: HUANG Qin-feng (1951-), female, associate professor  相似文献   
6.
The newborn brain is particularly vulnerable to seizures which are associated with poor neurodevelopmental outcome. The clinical manifestations of seizures in infants differ from those seen in older children and adults. The problem of electro-clinical dissociation, where there is no temporal correspondence between electrical paroxysms and repetitive stereotyped motor phenomena, is common in the newborn. There is at present very little information on which clinicians can base a rational decision about treatment which is often ineffective and does not alter neurodevelopmental outcome. This review summarizes current knowledge regarding investigation, treatment and prognosis of neonatal seizures. Received: 19 July 1996 / Accepted: 15 August 1996  相似文献   
7.
We present a systematic review of the literature on the prevalence, nature, severity, course, and causes of cognitive deficits in patients with occlusive disease of the carotid artery prior to surgery (if surgery was under discussion). Searches were carried out on Medline and Psychlit from 1980 to 1999 using neurovascular and psychological index terms, and papers and books were checked for further references. Studies describing neuropsychological assessment of groups of patients with carotid obstruction were included. Eighteen studies were found. We extracted from the papers data on study design, demographic characteristics of patients, clinical diagnosis, carotid obstruction, cerebral imaging, time interval between ischemic episode and neuropsychological assessment, neuropsychological asessment procedures, integration and interpretation of test performances, and conclusions of authors. Fourteen studies concluded that there are cognitive deficits both in patients with symptomatic and in those with asymptomatic carotid obstruction; four studies denied cognitive impairment. There were no differences in patient characteristics, study design, or neuropsychological assessment procedures between the 14 studies that found deficits and the 4 that did not. There are indications for a mild, diffuse, detrimental effect of carotid occlusive disease on cognitive functioning. However, methodological problems prevent a definitive conclusion. Further research is needed to confirm these findings and to ascertain the neurovascular risk factors for and the natural course of cognitive impairment in patients with carotid occlusive disease. Received: 12 July 1999/Received in revised form: 10 November 1999/Accepted: 26 January 2000  相似文献   
8.
目的介绍近年来国内针灸治疗慢性盆腔炎的临床概况,以寻求最佳治疗方案。方法从治疗方法及取穴等角度进行综述。结论针灸治疗慢性盆腔炎具有明显优势,但目前疗效标准、远期疗效、不同刺灸法间的疗效比较及现代医学机理方面仍存在一些亟待解决的问题。  相似文献   
9.
目的:通过维脑路通片压片工段工艺质量回顾分析,保证药品质量的安全生产要求。维脑路通是芦丁经羟乙基化半合成的产物,对抗5-羟色胺、缓激肽引起的血管损伤,增加毛细血管抵抗力,能降低毛细血管的通透性和脆性,并有抑制血小板凝集、防止血栓形成的作用,降低毛细血管通透性,可防止血管通透性升高引起的水肿。对急性缺血性脑损伤有显著的保护作用。适用于脑血栓形成和脑栓塞所致的偏瘫、失语以及心肌梗死前综合征、动脉硬化等。维脑路通是临床上治疗闭塞性脑血管病的常用药物。根据2010年修订的《药品生产质量管理规范》第二百六十六条要求,企业至少应当对关键中间控制点及成品的检验结果进行回顾分析。方法:是通过联系跟踪95批次的产品,进行片重的分析。结果:是平均偏差SD=0.000467,平均数average=0.125679,相对平均偏差RSD=0.003716,RSD(%)=0.3716,RSD<3%,符合方法学要求。结论:是验证工厂使用的压片机的性能符合GMP的要求,达到了阶段性的压片工段的质量管理要求。  相似文献   
10.
IntroductionChildren and adolescents with autism spectrum disorder (ASD) appear to be at greater risk of excess weight gain. The aim of this systematic review and meta-analysis was to examine whether children with ASD have a greater prevalence of obesity and whether the prevalence of ASD is higher in children with obesity.MethodsWe conducted a systematic search on PubMed, Scopus, and PsychINFO until May 21, 2021. We used the meta package in the R in order to calculate the pooled prevalence and relative risk of obesity in children with ASD.ResultsWe found 20 eligible studies investigating the prevalence of obesity in children with ASD, with the prevalence ranging from 7.9 to 31.8% and from 1.4 to 23.6% among controls. All but three studies originated from the USA. The proportion of children with obesity in ASD populations was 17% (95% confidence interval [CI]: 13–22). The relative risk of obesity in children with ASD compared with control children was 1.58 (95% CI: 1.34–1.86). There were no controlled studies reporting on the prevalence of ASD in children with obesity.ConclusionChildren and adolescents with ASD have a higher prevalence of obesity than healthy controls. There is a need for further prevalence studies of obesity in children with ASD, especially outside the USA, since the few European studies carried out have failed to show a significant difference between obesity prevalence in children with and without ASD. There is no knowledge at all regarding the prevalence of ASD among children with obesity.  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