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   1987篇
  免费   121篇
  国内免费   56篇
耳鼻咽喉   52篇
儿科学   52篇
妇产科学   21篇
基础医学   181篇
口腔科学   114篇
临床医学   168篇
内科学   339篇
皮肤病学   31篇
神经病学   167篇
特种医学   81篇
外科学   530篇
综合类   56篇
预防医学   123篇
眼科学   23篇
药学   137篇
中国医学   9篇
肿瘤学   80篇
  2023年   19篇
  2022年   36篇
  2021年   62篇
  2020年   47篇
  2019年   49篇
  2018年   60篇
  2017年   46篇
  2016年   48篇
  2015年   59篇
  2014年   77篇
  2013年   97篇
  2012年   107篇
  2011年   120篇
  2010年   63篇
  2009年   63篇
  2008年   81篇
  2007年   97篇
  2006年   81篇
  2005年   78篇
  2004年   67篇
  2003年   61篇
  2002年   56篇
  2001年   53篇
  2000年   59篇
  1999年   46篇
  1998年   31篇
  1997年   41篇
  1996年   30篇
  1995年   10篇
  1994年   17篇
  1993年   15篇
  1992年   28篇
  1991年   36篇
  1990年   26篇
  1989年   31篇
  1988年   18篇
  1987年   19篇
  1986年   32篇
  1985年   22篇
  1984年   23篇
  1983年   12篇
  1982年   14篇
  1981年   10篇
  1980年   10篇
  1979年   10篇
  1976年   13篇
  1974年   16篇
  1973年   10篇
  1970年   8篇
  1969年   8篇
排序方式: 共有2164条查询结果,搜索用时 31 毫秒
991.
Sleep and Breathing - This case-control study assessed the prevalence of psychiatric disorders in Arab (Saudi) patients with narcolepsy using a structured clinical interview. The study...  相似文献   
992.
Background  Loose anagen hair (LAH) syndrome is a phenomenon in early childhood characterized by the presence of easily pluckable hair, where hair tufts can be pulled out easily and painlessly.
Aims  All reports in the English literature described mainly white patients with blond hair. We present the first report of LAH syndrome in dark-skinned children of Upper Egypt.
Patients and methods  Twenty-eight children with LAH were diagnosed and examined from 1996 to 2007. The main complaints were patchy or diffuse alopecia and/or slow growth of hair. Clinical examination, hair pull test, trichogram, and scanning electron microscopy (SEM) were performed.
Results  Children with LAH included 21 girls (75%) and seven boys (25%). Light microscopy of hair pull tests and trichograms disclosed a striking predominance of anagen hairs (90–100%) with misshapen hair bulbs and absent inner and outer root sheaths. SEM confirmed the misshapen anagen bulbs with ruffled appearance of cuticle and the longitudinal groove parallel to the long axis of the hair shaft. Most children improved spontaneously within few years, however, hair shed continued.
Conclusion  LAH syndrome occurs in dark-skinned children and could be under-diagnosed. The condition is of cosmetic concern and does not affect the general health.  相似文献   
993.
OBJECTIVES: 'Choose and Book' is a UK government initiative devised to allow a greater freedom of choice for National Health Service patients. The system is designed to give patients a choice of hospitals and appointment times, as well as giving their general practitioner (GP) more responsibility for appropriate prioritization. We set out to determine the attitudes of UK GPs to the new Choose and Book project and to assess the impact that these changes are likely to have on ENT practice. DESIGN: Postal questionnaire survey. METHODS: Five hundred GPs were sent a questionnaire about the planned Choose and Book referral project. RESULTS: Three hundred and eighty GPs (76 per cent) replied to the questionnaire after reminders were sent. Most were aware of the project and had been sent information about it. Of those who had heard of it, 61.5 per cent did not think it was a good thing. Most stated that both they and their patients were satisfied with current prioritization practices. Many GPs would be willing to delegate responsibility for prioritization to non-clinical staff. Important time and responsibility issues were identified. CONCLUSIONS: The majority of GPs were not in favour of Choose and Book. Many cited difficulties with time constraints and an inflexible system as factors that made Choose and Book unacceptable.  相似文献   
994.
BACKGROUND: Untreated visceral leishmaniasis (VL) is an inevitably fatal childhood disease. First-generation candidate vaccines for VL [autoclaved Leishmania major (ALM) + BCG] have been found to be safe and immunogenic but not superior to BCG alone. Modulation of ALM by adsorption to Alum significantly increases the immunogenicity. The Alum-adsorbed ALM vaccine was found to be safe and strongly immunogenic in healthy adult volunteers in a non-VL-endemic area. This study aimed at establishing the safety and immunogenicity of Alum-precipitated autoclaved L. major + BCG vaccine in children under field conditions. METHODS: A total of 544 healthy, leishmanin non-reactive children (<15 y) were randomly allocated to receive either a single intradermal injection of Alum/ALM + BCG or vaccine diluent (placebo). Volunteers were closely followed for 2 years at 6-month intervals for vaccine safety and immunogenicity.RESULTS: The vaccine was well tolerated with minimal side-effects. Leishmanin skin test conversion (>or=5 mm) was seen in 56%, 50%, 25% and 31% at 6, 12, 18 and 24 months post-vaccination, respectively; conversion in the placebo group was 4%, 12%, 3% and 13% at the same follow-up visits. There was no significant increase in anti-leishmanial antibodies in either study arm at any of the follow-up visits. During the study, four patients in the placebo arm developed parasitologically confirmed VL. CONCLUSION: Alum/ALM + BCG vaccine is safe and immunogenic in children under field conditions. Multiple injections might be needed to obtain results similar to those obtained in healthy volunteers.  相似文献   
995.
996.
997.
Bioreactors are powerful tools with the potential to model tissue development and disease in vitro. For nearly four decades, bioreactors have been used to create tendon and ligament tissue-engineered constructs in order to define basic mechanisms of cell function, extracellular matrix deposition, tissue organization, injury, and tissue remodeling. This review provides a historical perspective of tendon and ligament bioreactors and their contributions to this advancing field. First, we demonstrate the need for bioreactors to improve understanding of tendon and ligament function and dysfunction. Next, we detail the history and evolution of bioreactor development and design from simple stretching of explants to fabrication and stimulation of two- and three-dimensional constructs. Then, we demonstrate how research using tendon and ligament bioreactors has led to pivotal basic science and tissue-engineering discoveries. Finally, we provide guidance for new basic, applied, and clinical research utilizing these valuable systems, recognizing that fundamental knowledge of cell-cell and cell-matrix interactions combined with appropriate mechanical and chemical stimulation of constructs could ultimately lead to functional tendon and ligament repairs in the coming decades.  相似文献   
998.
999.
Several pharmacokinetic studies have suggested that dabigatran possesses a number of ideal properties for expedited removal via extracorporeal methods. However, this practice has not been prospectively evaluated in patients with life-threatening bleeding or requiring emergency surgery secondary to dabigatran-associated coagulopathy. The purpose of this literature review is to evaluate the published evidence surrounding extracorporeal removal of dabigatran in the setting of emergency surgery or life-threatening bleeding. A query of MEDLINE, Web of Science, International Pharmaceutical Abstracts, and Google Scholar using the terms dabigatran, dabigatran etexilate, hemodialysis, renal replacement therapy, hemorrhage, and atrial fibrillation was used to retrieve relevant literature. Furthermore, a manual search of the references of the identified literature was performed to capture additional data. Current evidence suggests that extracorporeal removal of dabigatran may play a role in the setting of life-threatening bleeding and emergent surgery. Conflicting evidence exists with regard to the potential for redistribution based on serum dabigatran concentrations. In addition, a number of practicalities must be considered before incorporating this technique in the clinical setting. Extracorporeal removal of dabigatran may be a treatment modality in selected patients who require emergency reversal.  相似文献   
1000.
The origin and biological role of dynamic motions of folded enzymes is not yet fully understood. In this study, we examine the molecular determinants for the dynamic motions within the β-barrel of superoxide dismutase 1 (SOD1), which previously were implicated in allosteric regulation of protein maturation and also pathological misfolding in the neurodegenerative disease amyotrophic lateral sclerosis. Relaxation-dispersion NMR, hydrogen/deuterium exchange, and crystallographic data show that the dynamic motions are induced by the buried H43 side chain, which connects the backbones of the Cu ligand H120 and T39 by a hydrogen-bond linkage through the hydrophobic core. The functional role of this highly conserved H120–H43–T39 linkage is to strain H120 into the correct geometry for Cu binding. Upon elimination of the strain by mutation H43F, the apo protein relaxes through hydrogen-bond swapping into a more stable structure and the dynamic motions freeze out completely. At the same time, the holo protein becomes energetically penalized because the twisting back of H120 into Cu-bound geometry leads to burial of an unmatched backbone carbonyl group. The question then is whether this coupling between metal binding and global structural motions in the SOD1 molecule is an adverse side effect of evolving viable Cu coordination or plays a key role in allosteric regulation of biological function, or both?  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